Light Curves of Dwarf Plutonian Planets and other Large Kuiper Belt
  Objects: Their Rotations, Phase Functions and Absolute Magnitudes
arXiv:0704.1636v2  [astro-ph]  13 Apr 2007
Light Curves of Dwarf Plutonian Planets and other Large Kuiper
Belt Objects: Their Rotations, Phase Functions and Absolute
Magnitudes
Scott S. Sheppard
Department of Terrestrial Magnetism, Carnegie Institution of Washington,
5241 Broad Branch Rd. NW, Washington, DC 20015
sheppard@dtm.ciw.edu
ABSTRACT
I report new time-resolved light curves and determine the rotations and phase
functions of several large Kuiper Belt objects, which includes the dwarf planet
Eris (2003 UB313). Three of the new sample of ten Trans-Neptunian objects
display obvious short-term periodic light curves. (120348) 2004 TY364 shows a
light curve which if double-peaked has a period of 11.70±0.01 hours and a peak-
to-peak amplitude of 0.22±0.02 magnitudes. (84922) 2003 VS2 has a well defined
double-peaked light curve of 7.41±0.02 hours with a 0.21±0.02 magnitude range.
(126154) 2001 YH140 shows variability of 0.21± 0.04 magnitudes with a possible
13.25±0.2 hour single-peaked period. The seven new KBOs in the sample which
show no discernible variations within the uncertainties on short rotational time
scales are 2001 UQ18, (55565) 2002 AW197, (119979) 2002 WC19, (120132) 2003
FY128, (136108) Eris 2003 UB313, (90482) Orcus 2004 DW, and (90568) 2004
GV9. Four of the ten newly sampled Kuiper Belt objects were observed over a
significant range of phase angles to determine their phase functions and absolute
magnitudes. The three medium to large sized Kuiper Belt objects 2004 TY364,
Orcus and 2004 GV9 show fairly steep linear phase curves (∼ 0.18 to 0.26 mags
per degree) between phase angles of 0.1 and 1.5 degrees. This is consistent with
previous measurements obtained for moderately sized Kuiper Belt objects. The
extremely large dwarf planet Eris (2003 UB313) shows a shallower phase curve
(0.09 ± 0.03 mags per degree) which is more similar to the other known dwarf
planet Pluto. It appears the surface properties of the largest dwarf planets in the
Kuiper Belt maybe different than the smaller Kuiper Belt objects. This may have
to do with the larger objects ability to hold more volatile ices as well as sustain
atmospheres. Finally, it is found that the absolute magnitudes obtained using
the phase slopes found for individual objects are several tenths of magnitudes
different than that given by the Minor Planet Center.
http://arxiv.org/abs/0704.1636v2
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Subject headings: Kuiper Belt — Oort Cloud — minor planets, asteroids — solar
system: general — planets and satellites: individual (2001 UQ18, (126154) 2001
YH140, (55565) 2002 AW197, (119979) 2002 WC19, (120132) 2003 FY128, (136199)
Eris 2003 UB313, (84922) 2003 VS2, (90482) Orcus 2004 DW, (90568) 2004 GV9,
and (120348) 2004 TY364)
1. Introduction
To date only about 1% of the Trans-Neptunian objects (TNOs) are known of the nearly
one hundred thousand expected larger than about 50 km in radius just beyond Neptune’s
orbit (Trujillo et al. 2001). The majority of the largest Kuiper Belt objects (KBOs) now
being called dwarf Plutonian planets (radii > 400 km) have only recently been discovered
in the last few years (Brown et al. 2005). The large self gravity of the dwarf planets will
allow them to be near Hydrostatic equilibrium, have possible tenuous atmospheres, retain
extremely volatile ices such as Methane and are likely to be differentiated. Thus the surfaces
as well as the interior physical characteristics of the largest TNOs may be significantly
different than the smaller TNOs.
The largest TNOs have not been observed to have any remarkable differences from the
smaller TNOs in optical and near infrared broad band color measurements (Doressoundiram
et al. 2005; Barucci et al. 2005). But near infrared spectra has shown that only the three
largest TNOs (Pluto, Eris (2003 UB313) and (136472) 2005 FY9) have obvious Methane on
their surfaces while slightly smaller objects are either spectrally featureless or have strong
water ice signatures (Brown et al. 2005; Licandro et al. 2006). In addition to the Near
infrared spectra differences, the albedos of the larger objects appear to be predominately
higher than those for the smaller objects (Cruikshank et al. 2005; Bertoldi et al. 2006; Brown
et al. 2006). A final indication that the larger objects are indeed different is that the shapes
of the largest KBOs seem to signify they are more likely to be in hydrostatic equilibrium
than that for the smaller KBOs (Sheppard and Jewitt 2002; Trilling and Bernstein 2006;
Lacerda and Luu 2006).
The Kuiper Belt has been dynamically and collisionally altered throughout the age of
the solar system. The largest KBOs should have rotations that have been little influenced
since the sculpting of the primordial Kuiper Belt. This is not the case for the smaller KBOs
where recent collisions and fragmentation processes will have highly modified their spins
throughout the age of the solar system (Davis and Farinella 1997). The large volatile rich
KBOs show significantly different median period and possible amplitude rotational differ-
ences when compared to the rocky large main belt asteroids which is expected because of
– 3 –
their differing compositions and collisional histories (Sheppard and Jewitt 2002; Lacerda and
Luu 2006).
I have furthered the photometric monitoring of large KBOs (absolute magnitudes H <
5.5 or radii greater than about 100 km assuming moderate albedos) in order to determine
their short term rotational and long term phase related light curves to better understand
their rotations, shapes and possible surface characteristics. This is a continuation of previous
works (Jewitt and Sheppard 2002; Sheppard and Jewitt 2002; Sheppard and Jewitt 2003;
Sheppard and Jewitt 2004).
2. Observations
The data for this work were obtained at the Dupont 2.5 meter telescope at Las Campanas
in Chile and the University of Hawaii 2.2 meter telescope atop Mauna Kea in Hawaii.
Observations at the Dupont 2.5 meter telescope were performed on the nights of Febru-
ary 14, 15 and 16, March 9 and 10, October 25, 26, and 27, November 28, 29, and 30 and
December 1, 2005 UT. The instrument used was the Tek5 with a 2048 × 2048 pixel CCD
with 24 µm pixels giving a scale of 0.′′259 pixel−1 at the f/7.5 Cassegrain focus for a field
of view of about 8′.85 × 8′.85. Images were acquired through a Harris R-band filter while
the telescope was autoguided on nearby bright stars at sidereal rates (Table 1). Seeing was
generally good and ranged from 0.′′6 to 1.′′5 FWHM.
Observations at the University of Hawaii 2.2 meter telescope were obtained on the nights
of December 19, 21, 23 and 24, 2003 UT and used the Tektronix 2048 × 2048 pixel CCD.
The pixels were 24 µm in size giving 0.′′219 pixel−1 scale at the f/10 Cassegrain focus for
a field of view of about 7′.5 × 7′.5. Images were obtained in the R-band filter based on the
Johnson-Kron-Cousins system with the telescope auto-guiding at sidereal rates using nearby
bright stars. Seeing was very good over the several nights ranging from 0.′′6 to 1.′′2 FWHM.
For all observations the images were first bias subtracted and then flat-fielded using the
median of a set of dithered images of the twilight sky. The photometry for the KBOs was
done in two ways in order to optimize the signal-to-noise ratio. First, aperture correction
photometry was performed by using a small aperture on the KBOs (0.′′65 to 1.′′04 in radius)
and both the same small aperture and a large aperture (2.′′63 to 3.′′63 in radius) on several
nearby unsaturated bright field stars. The magnitude within the small aperture used for the
KBOs was corrected by determining the correction from the small to the large aperture using
the PSF of the field stars. Second, I performed photometry on the KBOs using the same field
stars but only using the large aperture on the KBOs. The smaller apertures allow better
– 4 –
photometry for the fainter objects since it uses only the high signal-to-noise central pixels.
The range of radii varies because the actual radii used depends on the seeing. The worse
the seeing the larger the radius of the aperture needed in order to optimize the photometry.
Both techniques found similar results, though as expected, the smaller aperture gives less
scatter for the fainter objects while the larger aperture is superior for the brighter objects.
Photometric standard stars from Landolt (1992) were used for calibration. Each in-
dividual object was observed at all times in the same filter and with the same telescope
setup. Relative photometric calibration from night to night was very stable since the same
fields stars were observed. The few observations that were taken in mildly non-photometric
conditions (i.e. thin cirrus) were easily calibrated to observations of the same field stars on
the photometric nights. Thus, the data points on these mildly non-photometric nights are
almost as good as the other data with perhaps a slightly larger error bar. The dominate
source of error in the photometry comes from simple root N noise.
3. Light Curve Causes
The apparent magnitude or brightness of an atmospherless inert body in our solar system
is mainly from reflected sunlight and can be calculated as
mR = m⊙ − 2.5log
2φ(α)/(2.25× 1016R2∆2)
in which r [km] is the radius of the KBO, R [AU] is the heliocentric distance, ∆ [AU] is
the geocentric distance, m⊙ is the apparent red magnitude of the sun (−27.1), mR is the
apparent red magnitude, pR is the red geometric albedo, and φ(α) is the phase function in
which the phase angle α = 0 deg at opposition and φ(0) = 1.
The apparent magnitude of the TNO may vary for the main following reasons:
1) The geometry in which R,∆ and/or α changes for the TNO. Geometrical consider-
ations at the distances of the TNOs are usually only noticeable over a few weeks or longer
and thus are considered long-term variations. These are further discussed in section 5.
2) The TNOs albedo, pR, may not be uniform on its surface causing the apparent
magnitude to vary as the different albedo markings on the TNOs surface rotate in and out
of our line of sight. Albedo or surface variations on an object usually cause less than a 30%
difference from maximum to minimum brightness of an object. (134340) Pluto, because of
its atmosphere (Spencer et al. 1997), has one of the highest known amplitudes from albedo
variations (∼ 0.3 magnitudes; Buie et al. 1997).
3) Shape variations or elongation of an object will cause the effective radius of an object
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to our line of sight to change as the TNO rotates. A double peaked periodic light curve
is expected to be seen in this case since the projected cross section would go between two
minima (short axis) and two maxima (long axis) during one complete rotation of the TNO.
Elongation from material strength is likely for small TNOs (r < 100 km) but for the larger
TNOs observed in this paper no significant elongation is expected from material strength
because their large self gravity.
A large TNO (r > 100 km) may be significantly elongated if it has a large amount of
rotational angular momentum. An object will be near breakup if it has a rotation period
near the critical rotation period (Pcrit) at which centripetal acceleration equals gravitational
acceleration towards the center of a rotating spherical object,
Pcrit =
where G is the gravitational constant and ρ is the density of the object. With ρ = 103 kg m−3
the critical period is about 3.3 hours. At periods just below the critical period the object
will likely break apart. For objects with rotations significantly above the critical period the
shapes will be bimodal Maclaurin spheroids which do not shown any significant rotational
light curves produced by shape (Jewitt and Sheppard 2002). For periods just above the
critical period the equilibrium figures are triaxial ellipsoids which are elongated from the
large centripetal force and usually show prominent rotational light curves (Weidenschilling
1981; Holsapple 2001; Jewitt and Sheppard 2002).
For an object that is triaxially elongated the peak-to-peak amplitude of the rotational
light curve allows for the determination of the projection of the body shape into the plane
of the sky by (Binzel et al. 1989)
∆m = 2.5log
− 1.25log
a2cos2θ + c2sin2θ
b2cos2θ + c2sin2θ
where a ≥ b ≥ c are the semiaxes with the object in rotation about the c axis, ∆m is
expressed in magnitudes, and θ is the angle at which the rotation (c) axis is inclined to the
line of sight (an object with θ = 90 deg. is viewed equatorially). The amplitudes of the light
curves produced from rotational elongation can range up to about 0.9 magnitudes (Leone et
al. 1984).
Assuming θ = 90 degrees gives a/b = 100.4∆m. Thus the easily measured quantities of
the rotation period and amplitude can be used to determine a minimum density for an object
if it is assumed to be rotational elongated and strengthless (i.e. the bodies structure behaves
like a fluid, Chandrasekhar 1969). The two best cases of this high angular momentum
– 6 –
elongation in the Kuiper Belt are (20000) Varuna (Jewitt and Sheppard 2002) and (136108)
2003 EL61 (Rabinowitz et al. 2006).
4) Periodic light curves may be produced if a TNO is an eclipsing or contact binary. A
double-peaked light curve would be expected with a possible characteristic notch shape near
the minimum of the light curve. Because the two objects may be tidally elongated the light
curves can range up to about 1.2 magnitudes (Leone et al. 1984). The best example of such
an object in the Kuiper Belt is 2001 QG298 (Sheppard and Jewitt 2004).
5) A non-periodic short-term light curve may occur from a complex rotational state, a
recent collision, a binary with each component having a large light curve amplitude and a
different rotation period or outgassing/cometary activity. These types of short term vari-
ability are expected to be extremely rare and none have yet been reliably detected in the
Kuiper Belt (Sheppard and Jewitt 2003; Belskaya et al. 2006)
4. Light Curve Results and Analysis
The photometric measurements for the 10 newly observed KBOs are listed in Table 1,
where the columns include the start time of each integration, the corresponding Julian date,
and the magnitude. No correction for light travel time has been made. Results of the light
curve analysis for all the KBOs newly observed are summarized in Table 2.
The phase dispersion minimization (PDM) method (Stellingwerf 1978) was used to
search for periodicity in the individual light curves. In PDM, the metric is the so-called
Theta parameter, which is essentially the variance of the unphased data divided by the
variance of the data when phased by a given period. The best fit period should have a very
small dispersion compared to the unphased data and thus Theta << 1 indicates that a good
fit has been found. In practice, a Theta less than 0.4 indicates a possible periodic signature.
4.1. (120348) 2004 TY364
Through the PDM analysis I found a strong Theta minima for 2004 TY364 near a period
of P = 5.85 hours with weaker alias periods flanking this (Figure 1). Phasing the data to all
possible periods in the PDM plot with Theta < 0.4 found that only the single-peaked period
near 5.85 hours and the double-peaked period near 11.70 hours fits all the data obtained
from October, November and December 2005. Both periods have an equally low Theta
parameter of about 0.15 and either could be the true rotation period (Figures 2 and 3). The
peak-to-peak amplitude is 0.22± 0.02 magnitudes.
– 7 –
If 2004 TY364 has a double-peaked period it may be elongated from its high angular
momentum. If the TNO is assumed to be observed equator on then from Equation 3 the
a : b axis ratio is about 1.2. Following Jewitt and Sheppard (2002) I assume the TNO is
a rotationally elongated strengthless rubble pile. Using the spin period of 11.7 hours, the
1.2 a : b axis ratio found above and the Jacobi ellipsoid tables produced by Chandrasekhar
(1969) I find the minimum density of 2004 TY364 is about 290 kg m
−3 with an a : c axis
ratio of about 1.9. This density is quite low which leads one to believe either the TNO is
not being viewed equator on or the relatively long double-peaked period is not created from
high angular momentum of the object.
4.2. (84922) 2003 VS2
The KBO 2003 VS2 has a very low Theta of less than 0.1 near 7.41 hours in the PDM
plot (Figure 4). Phasing the December 2003 data to this period shows a well defined double-
peaked period (Figure 5). The single peaked period for this result would be near 3.71 hours
which was a possible period determined for this object by Ortiz et al. (2006). The 3.71 hour
single-peaked period does not look as convincing (Figure 6) which confirms the PDM result
that the single-peaked period has about three times more dispersion than the double-peaked
period. This is likely because one of the peaks is taller in amplitude (∼ 0.05 mags) and a
little wider. The other single-peaked period of 4.39 hours (Figure 7) and the double-peaked
period of 8.77 hours (Figure 8) mentioned by Oritz et al. (2006) do not show a low Theta
in the PDM and also do not look convincing when examining the phased data. The peak-
to-peak amplitude is 0.21 ± 0.02 magnitudes, which is similar to that detected by Ortiz et
al. (2006).
The fast rotation of 7.41 hours and double-peaked nature suggests that 2003 VS2 may
be elongated from its high angular momentum. Using Equation 3 and assuming the TNO
is observed equator on the a : b axis ratio is about 1.2. Using the spin period of 7.41 hours,
the 1.2 a : b axis ratio and the Jacobi ellipsoid tables produced by Chandrasekhar (1969) I
find the minimum density of 2003 VS2 is about 720 kg m
−3 with an a : c axis ratio of about
1.9. This result is similar to other TNO densities found through the Jacobian Ellipsoid
assumption (Jewitt and Sheppard 2002; Sheppard and Jewitt 2002; Rabinowitz et al. 2006)
as well as recent thermal results from the Spitzer space telescope (Stansberry et al. 2006).
– 8 –
4.3. (126154) 2001 YH140
(126154) 2001 YH140 shows variability of 0.21 ± 0.04 magnitudes. The PDM for this
TNO shows possible periods near 8.5, 9.15, 10.25 and 13.25 hours though only the 13.25
hour period has a Theta less than 0.4 (Figure 9). Visibly examining the phased data finds
only the 13.25 hour period is viable (Figure 10). This is consistent with the observation that
one minimum and one maximum were shown on December 23, 2003 in about six and a half
hours, which would give a single-peaked light curve of twice this time or about 13.25 hours.
Ortiz et al. (2006) found this object to have a similar variability but with very limited data
could not obtain a reliable period. Ortiz et al. did have one period of 12.99 hours which
may be consistent with our result.
4.4. Flat Rotation Curves
Seven of the ten newly observed KBOs; 2001 UQ18, (55565) 2002 AW197, (119979) 2002
WC19, (120132) 2003 FY128, (136199) Eris 2003 UB313, (90482) Orcus 2004 DW, and (90568)
2004 GV9 showed no variability within the photometric uncertainties of the observations
(Table 2; Figures 11 to 21). These KBOs thus either have extremely long rotational periods,
are viewed nearly pole-on or most likely have small peak-to-peak rotational amplitudes.
The upper limits for the objects short-term rotational variability as shown in Table 2 were
determined through a monte carlo simulation. The monte carlo simulation determined the
lowest possible amplitude that would be seen in the data from the time sampling and variance
of the photometry as well as the errors on the individual points.
Ortiz et al. (2006) reported a possible 0.04± 0.02 photometric range for (90482) Orcus
2004 DW and a period near 10 hours. I do not confirm this result here. Ortiz et al. (2006)
also reported a marginal 0.08± 0.03 photometric range for (55565) 2002 AW197 with no one
clear best period. I can not confirm this result and find that for 2002 AW197 the rotational
variability appears significantly less than 0.08 magnitudes.
Some of the KBOs in this sample appear to have variability which is just below the
threshold of the data detection and thus no significant period could be obtained with the
current data. In particular 2001 UQ18 appears to have a light curve with a significant
amplitude above 0.1 magnitudes but the data is sparser for this object than most the others
and thus no significant period is found. Followup observations will be required in order
to determine if most of these flat light curve objects do have any significant short-term
variability.
– 9 –
4.5. Comparisons with Size, Amplitude, Period, and MBAs
In Figures 22 and 23 are plotted the diameters of the largest TNOs and Main Belt
Asteroids (MBAs) versus rotational amplitude and period, respectively. Most outliers on
Figure 22 can easily be explained from the discussion in section 3. Varuna, 2003 EL61 and
the other unmarked TNOs with photometric ranges above about 0.4 magnitudes are all
spinning faster than about 8 hours. They are thus likely hydrostatic equilibrium triaxial
Jacobian ellipsoids which are elongated from their rotational angular momentum (Jewitt
and Sheppard 2002; Sheppard and Jewitt 2002; Rabinowitz et al. 2006). 2001 QG298’s
large photometric range is probably because this object is a contact binary indicative of its
longer period and notched shaped light curve (Sheppard and Jewitt 2004). Pluto’s relatively
large amplitude light curve is best explained through its active atmosphere (Spencer et
al. 1997). Like the MBAs, the photometric amplitudes of the TNOs start to increase
significantly at sizes less than about 300 km in diameter. The likely reason is this size range
is where the objects are still large enough to be dominated by self-gravity and are not easily
disrupted through collisions but can still have their angular momentum highly altered from
the collisional process (Farinella et al. 1982; Davis and Farinella 1997). Thus this is the
region most likely to be populated by high angular momentum triaxial Jacobian ellipsoids
(Farinella et al. 1992).
From this work Eris (2003 UB313) has one of the highest signal-to-noise time-resolved
photometry measurements of any TNO searched for a rotational period. There is no obvi-
ous rotational light curve larger than about 0.01 magnitudes in our extensive data which
indicates a very uniform surface, a rotation period of over a few days or a pole-on view-
ing geometry. Carraro et al. (2006) suggest a possible 0.05 magnitude variability for Eris
between nights but this is not obvious in this data set. The similar inferred composition
and size of Eris to Pluto suggests these objects should behave very similar (Brown et al.
2005,2006). Since Pluto has a relatively substantial atmosphere at its current position of
about 30 AU (Elliot et al. 2003; Sicardy et al. 2003) it is very likely that Eris has an active
atmosphere when near its perihelion of 38 AU. At Eris’ current distance of 97 AU its surface
thermal temperature should be over 20 degrees colder than when at perihelion. Like Pluto,
Eris’ putative atmosphere near perihelion would likely be composed of N2, CH4 or CO which
would mostly condense when near aphelion (Spencer et al. 1997; Hubbard 2003), effectively
resurfacing the TNO every few hundred years. This is the most likely explanation as to why
the surface of Eris appears so uniform. This may also be true for 2005 FY9 which appears
compositionally similar to Pluto (Licandro et al. 2006) and at 52 AU is about 15 degrees
colder than Pluto.
Figure 23 shows that the median rotation period distribution for TNOs is about 9.5 ±
– 10 –
1 hours which is marginally larger than for similarly sized main belt asteroids (7.0 ± 1
hours)(Sheppard and Jewitt 2002; and Lacerda and Luu 2006). If confirmed, the likely
reason for this difference are the collisional histories of each reservoir as well as the objects
compositions.
5. Phase Curve Results
The phase function of an objects surface mostly depends on the albedo, texture and
particle structure of the regolith. Four of the newly imaged TNOs (Eris 2003 UB313, (120348)
2004 TY364, Orcus 2004 DW, and (90568) 2004 GV9) were viewed on two separate telescope
observing runs occurring at significantly different phase angles (Figures 24 to 27). This
allowed their linear phase functions,
φ(α) = 10−0.4βα (4)
to be estimated where α is the phase angle in degrees and β is the linear phase coefficient in
magnitudes per degree (Table 3). The phase angles for TNOs are always less than about 2
degrees as seen from the Earth. Most atmosphereless bodies show opposition effects at such
small phase angles (Muinonen et al. 2002). The TNOs appear to have mostly linear phase
curves between phase angles of about 2 and 0.1 degrees (Sheppard and Jewitt 2002,2003;
Rabinowitz et al. 2007). For phase angles smaller than about 0.1 degrees TNOs may display
an opposition spike (Hicks et al. 2005; Belskaya et al. 2006).
The moderate to large KBOs Orcus, 2004 TY364, and 2004 GV9 show steep linear R-band
phase slopes (0.18 to 0.26 mags per degree) similar to previous measurements of similarly
sized moderate to large TNOs (Sheppard and Jewitt 2002,2003; Rabinowitz et al. 2007). In
contrast the extremely large dwarf planet Eris (2003 UB313) has a shallower phase slope (0.09
mags per degree) more similar to Charon (∼ 0.09 mags/deg; Buie et al. (1997)) and possibly
Pluto (∼ 0.03 mags/deg; Buratti et al. (2003)). Empirically lower phase coefficients between
0.5 and 2 degrees may correspond to bright icy objects whose surfaces have probably been
recently resurfaced such as Triton, Pluto and Europa (Buie et al. 1997; Buratti et al. 2003;
Rabinowitz et al. 2007). Thus Eris’ low β is consistent with it having an icy surface that
has recently been resurfaced.
In Figures 28 to 32 are plotted the linear phase coefficients found for several TNOs versus
several different parameters (reduced magnitude, albedo, rotational photometric amplitude
and B − I broad band color). Table 4 shows the significance of any correlations. Based on
only a few large objects it appears that the larger TNOs may have lower β values. This
is true for the R-band and V-band data at the 97% confidence level but interestingly using
– 11 –
data from Rabinowitz et al. (2007) no correlation is seen in the I-band (Table 4). Thus
further measurements are needed to determine if there is a significantly strong correlation
between the size and phase function of TNOs. Further, it may be that the albedos are anti-
correlated with β, but since we have such a small number of albedos known the statistics don’t
give a good confidence in this correlation. If confirmed with additional observations, these
correlations may be an indication that larger TNOs surfaces are less susceptible to phase
angle opposition effects at optical wavelengths. This could be because the larger TNOs
have different surface properties from smaller TNOs due to active atmospheres, stronger
self-gravity or different surface layers from possible differentiation.
5.1. Absolute Magnitudes
From the linear phase coefficient the reduced magnitude, mR(1, 1, 0) = mR−5log(R∆) or
absolute magnitude H (Bowell et al. 1989), which is the magnitude of an object if it could be
observed at heliocentric and geocentric distances of 1 AU and a phase angle of 0 degrees, can
be estimated (see Sheppard and Jewitt 2002 for further details). The results for mR(1, 1, 0)
and H are found to be consistent to within a couple hundreths of a magnitude (Table 3 and
Figures 24 to 27). It is found that the R-band empirically determined absolute magnitudes
of individual TNOs appears to be several tenths of a magnitude different than what is given
by the Minor Planet Center (Table 3). This is likely because the MPC assumes a generic
phase function and color for all TNOs while these two physical properties appear to be
significantly different for individual KBOs (Jewitt and Luu 1998). The work by Romanishin
and Tegler (2005) attempts to determine various absolute magnitudes of TNOs by using
main belt asteroid type phase curves which are not appropriate for TNOs (Sheppard and
Jewitt 2002).
6. Summary
Ten large trans-Neptunian objects were observed in the R-band to determine photomet-
ric variability on times scales of hours, days and months.
1) Three of the TNOs show obvious short-term photometric variability which is taken
to correspond to their rotational states.
• (120348) 2004 TY364 shows a double-peaked period of 11.7 hours and if single-peaked
is 5.85 hours. The peak-to-peak amplitude of the light curve is 0.22± 0.02 mags.
– 12 –
• (84922) 2003 VS2 has a well defined double-peaked period of 7.41 hours with a peak-
to-peak amplitude of 0.21± 0.02 mags. If the light curve is from elongation than 2003
VS2’s a/b axis ratio is at least 1.2 and the a/c axis ratio is about 1.9. Assuming 2003
VS2 is elongated from its high angular momentum and is a strengthless rubble pile it
would have a minimum density of about 720 kg m−3.
• (126154) 2001 YH140 has a single-peaked period of about 13.25 hours with a photo-
metric range of 0.21± 0.04 mags.
2) Seven of the TNOs show no short-term photometric variability within the measure-
ment uncertainties.
• Photometric measurements of the large TNOs (90482) Orcus and (55565) 2002 AW197
showed no variability within or uncertainties. Thus these measurements do not confirm
possible small photometric variability found for these TNOs by Ortiz et al. (2006).
• No short-term photometric variability was found for (136199) Eris 2003 UB313 to about
the 0.01 magnitude level. This high signal to noise photometry suggests Eris is nearly
spherical with a very uniform surface. Such a nearly uniform surface may be explained
by an atmosphere which is frozen onto the surface of Eris when near aphelion. The
atmosphere, like Pluto’s, may become active when near perihelion effectively resurfac-
ing Eris every few hundred years. The Methane rich TNO 2005 FY9 may also be in a
similar situation.
3) Four of the TNOs were observed over significantly different phase angles allowing
their long term photometric variability to be measured between phase angles of 0.1 and 1.5
degrees.
• TNOs Orcus, 2004 TY364 and 2004 GV9 show steep linear R-band phase slopes between
0.18 and 0.26 mags/degree.
• Eris 2003 UB313 shows a shallower R-band phase slope of 0.09 mags/degree. This is
consistent with Eris having a high albedo, icy surface which may have recently been
resurfaced.
• At the 97% confidence level the largest TNOs have shallower R-band linear phase
slopes compared to smaller TNOs. The largest TNOs surfaces may differ from the
smaller TNOs because of their more volatile ice inventory, increased self-gravity, active
atmospheres, differentiation process or collisional history.
– 13 –
3) The absolute magnitudes determined for several TNOs through measuring their phase
curves show a difference of several tenths of a magnitude from the Minor Planet Center values.
• The values found for the reduced magnitude, mR(1, 1, 0), and absolute magnitude, H ,
are similar to within a few hundreths of a magnitude for most TNOs.
Acknowledgments
Support for this work was provided by NASA through Hubble Fellowship grant # HF-
01178.01-A awarded by the Space Telescope Science Institute, which is operated by the
Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS
5-26555.
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This preprint was prepared with the AAS LATEX macros v5.2.
– 16 –
Table 1. Observations of Kuiper Belt Objects
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
2001 UQ18 uq1223n3025 1.17 320 2003 12 23.22561 22.20 0.04
uq1223n3026 1.15 320 2003 12 23.23060 22.30 0.04
uq1223n3038 1.02 320 2003 12 23.28384 22.38 0.04
uq1223n3039 1.01 320 2003 12 23.28882 22.56 0.04
uq1223n3051 1.01 350 2003 12 23.34333 22.40 0.04
uq1223n3052 1.01 350 2003 12 23.35123 22.48 0.04
uq1223n3070 1.15 350 2003 12 23.41007 22.37 0.04
uq1223n3071 1.17 350 2003 12 23.41540 22.28 0.04
uq1224n4024 1.21 350 2003 12 24.21433 22.30 0.03
uq1224n4025 1.19 350 2003 12 24.21969 22.15 0.03
uq1224n4033 1.03 350 2003 12 24.27591 22.07 0.03
uq1224n4034 1.02 350 2003 12 24.28125 22.04 0.03
uq1224n4041 1.00 350 2003 12 24.31300 22.11 0.03
uq1224n4042 1.00 350 2003 12 24.31834 22.14 0.03
uq1224n4051 1.04 350 2003 12 24.36433 22.22 0.03
uq1224n4052 1.05 350 2003 12 24.36967 22.18 0.03
uq1224n4061 1.17 350 2003 12 24.41216 22.27 0.03
uq1224n4062 1.20 350 2003 12 24.41750 22.22 0.03
uq1224n4072 1.50 350 2003 12 24.46253 22.14 0.03
uq1224n4073 1.56 350 2003 12 24.46781 22.09 0.03
(126154) 2001 YH140 yh1219n1073 1.10 300 2003 12 19.42900 20.85 0.02
yh1219n1074 1.08 300 2003 12 19.43381 20.82 0.02
yh1219n1084 1.01 300 2003 12 19.47450 20.81 0.02
yh1219n1085 1.01 300 2003 12 19.47935 20.79 0.02
yh1219n1092 1.00 300 2003 12 19.51172 20.77 0.02
yh1219n1093 1.00 300 2003 12 19.51657 20.80 0.02
yh1219n1112 1.06 300 2003 12 19.56332 20.86 0.02
yh1219n1113 1.08 300 2003 12 19.56815 20.80 0.02
yh1219n1116 1.15 350 2003 12 19.59215 20.81 0.02
yh1219n1117 1.18 350 2003 12 19.59764 20.79 0.02
– 17 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
yh1219n1122 1.36 350 2003 12 19.63042 20.87 0.02
yh1219n1123 1.41 350 2003 12 19.63587 20.85 0.02
yh1219n1125 1.50 350 2003 12 19.64669 20.95 0.03
yh1221n2067 1.46 300 2003 12 21.35652 20.98 0.02
yh1221n2068 1.42 300 2003 12 21.36124 20.92 0.02
yh1223n3059 1.24 300 2003 12 23.38285 20.86 0.02
yh1223n3060 1.21 300 2003 12 23.38762 20.89 0.02
yh1223n3078 1.03 300 2003 12 23.44626 20.88 0.02
yh1223n3079 1.02 300 2003 12 23.45102 20.87 0.02
yh1223n3086 1.00 300 2003 12 23.48192 20.92 0.02
yh1223n3087 1.00 300 2003 12 23.48668 20.91 0.02
yh1223n3091 1.00 300 2003 12 23.51268 20.94 0.02
yh1223n3092 1.01 300 2003 12 23.51744 20.95 0.02
yh1223n3101 1.08 300 2003 12 23.55695 20.92 0.02
yh1223n3102 1.09 300 2003 12 23.56169 20.96 0.03
yh1223n3106 1.18 300 2003 12 23.58754 20.98 0.03
yh1223n3107 1.20 300 2003 12 23.59231 21.01 0.03
yh1223n3114 1.31 300 2003 12 23.61182 21.03 0.03
yh1223n3115 1.34 300 2003 12 23.61659 20.99 0.03
yh1223n3119 1.56 300 2003 12 23.64084 20.99 0.03
yh1224n4047 1.49 300 2003 12 24.34589 20.90 0.02
yh1224n4048 1.44 300 2003 12 24.35066 20.91 0.02
yh1224n4057 1.18 300 2003 12 24.39217 20.85 0.02
yh1224n4058 1.16 300 2003 12 24.39693 20.85 0.02
yh1224n4068 1.03 300 2003 12 24.44421 20.87 0.02
yh1224n4069 1.02 300 2003 12 24.44898 20.87 0.02
yh1224n4080 1.00 300 2003 12 24.49899 20.84 0.02
yh1224n4081 1.00 300 2003 12 24.50375 20.86 0.02
yh1224n4088 1.02 300 2003 12 24.52567 20.82 0.02
yh1224n4089 1.03 300 2003 12 24.53043 20.83 0.02
– 18 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
yh1224n4093 1.08 300 2003 12 24.55588 20.81 0.02
yh1224n4094 1.09 300 2003 12 24.56065 20.82 0.02
yh1224n4102 1.23 300 2003 12 24.59447 20.87 0.02
yh1224n4103 1.25 300 2003 12 24.59926 20.82 0.02
yh1224n4107 1.44 300 2003 12 24.62661 20.87 0.02
(55565) 2002 AW197 aw1223n3088 1.09 220 2003 12 23.49223 19.89 0.01
aw1223n3089 1.08 220 2003 12 23.49606 19.89 0.01
aw1223n3093 1.03 220 2003 12 23.52320 19.87 0.01
aw1223n3094 1.03 220 2003 12 23.52704 19.88 0.01
aw1223n3103 1.02 220 2003 12 23.56663 19.89 0.01
aw1223n3104 1.02 220 2003 12 23.57046 19.89 0.01
aw1223n3108 1.05 220 2003 12 23.59807 19.89 0.01
aw1223n3109 1.06 220 2003 12 23.60190 19.89 0.01
aw1223n3116 1.11 220 2003 12 23.62171 19.87 0.01
aw1223n3117 1.12 220 2003 12 23.62556 19.89 0.01
aw1223n3122 1.26 220 2003 12 23.65822 19.87 0.01
aw1223n3123 1.28 220 2003 12 23.66201 19.89 0.01
aw1224n4066 1.34 220 2003 12 24.43521 19.87 0.01
aw1224n4067 1.32 220 2003 12 24.43903 19.86 0.01
aw1224n4078 1.09 220 2003 12 24.48975 19.89 0.01
aw1224n4079 1.08 220 2003 12 24.49358 19.89 0.01
aw1224n4086 1.04 220 2003 12 24.51683 19.86 0.01
aw1224n4087 1.03 220 2003 12 24.52066 19.89 0.01
aw1224n4091 1.01 220 2003 12 24.54768 19.90 0.01
aw1224n4092 1.01 220 2003 12 24.55158 19.90 0.01
aw1224n4100 1.04 220 2003 12 24.58659 19.86 0.01
aw1224n4101 1.04 220 2003 12 24.59042 19.86 0.01
aw1224n4105 1.10 220 2003 12 24.61789 19.86 0.01
aw1224n4106 1.12 220 2003 12 24.62172 19.87 0.01
aw1224n4111 1.25 220 2003 12 24.65382 19.86 0.01
– 19 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
aw1224n4112 1.27 220 2003 12 24.65766 19.87 0.01
aw1224n4113 1.30 220 2003 12 24.66150 19.88 0.01
aw1224n4114 1.32 220 2003 12 24.66534 19.88 0.01
(119979) 2002 WC19 wc1219n1033 1.19 350 2003 12 19.27766 20.56 0.02
wc1219n1045 1.05 300 2003 12 19.32341 20.61 0.02
wc1219n1046 1.04 300 2003 12 19.32826 20.59 0.02
wc1219n1057 1.00 300 2003 12 19.36042 20.60 0.02
wc1219n1058 1.00 300 2003 12 19.36529 20.57 0.02
wc1219n1066 1.01 300 2003 12 19.40263 20.56 0.02
wc1219n1067 1.02 300 2003 12 19.40748 20.57 0.02
wc1219n1077 1.11 300 2003 12 19.44804 20.61 0.02
wc1219n1078 1.12 300 2003 12 19.45289 20.58 0.02
wc1219n1088 1.33 300 2003 12 19.49419 20.59 0.02
wc1219n1089 1.37 300 2003 12 19.49909 20.55 0.02
wc1219n1094 1.58 300 2003 12 19.52222 20.57 0.02
wc1219n1095 1.64 300 2003 12 19.52704 20.58 0.02
wc1221n2026 1.64 300 2003 12 21.21505 20.56 0.02
wc1221n2027 1.59 300 2003 12 21.21980 20.57 0.02
wc1221n2042 1.26 300 2003 12 21.25881 20.55 0.02
wc1221n2043 1.24 300 2003 12 21.26356 20.53 0.02
wc1221n2065 1.01 300 2003 12 21.33897 20.58 0.02
wc1221n2066 1.01 300 2003 12 21.34373 20.63 0.02
wc1223n3027 1.38 300 2003 12 23.23616 20.57 0.02
wc1223n3028 1.34 300 2003 12 23.24092 20.60 0.02
wc1223n3044 1.05 300 2003 12 23.30891 20.57 0.02
wc1223n3045 1.04 300 2003 12 23.31367 20.57 0.02
wc1223n3057 1.00 300 2003 12 23.37221 20.58 0.02
wc1223n3058 1.00 300 2003 12 23.37696 20.56 0.02
wc1223n3076 1.10 320 2003 12 23.43506 20.57 0.02
wc1223n3077 1.12 320 2003 12 23.44005 20.60 0.02
– 20 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
wc1223n3084 1.25 320 2003 12 23.47067 20.61 0.02
wc1223n3085 1.28 320 2003 12 23.47566 20.60 0.02
wc1224n4026 1.44 300 2003 12 24.22597 20.55 0.02
wc1224n4027 1.40 300 2003 12 24.23073 20.56 0.02
wc1224n4035 1.10 300 2003 12 24.28804 20.58 0.02
wc1224n4036 1.09 300 2003 12 24.29281 20.61 0.02
wc1224n4043 1.02 300 2003 12 24.32492 20.58 0.02
wc1224n4044 1.02 300 2003 12 24.32969 20.58 0.02
wc1224n4053 1.00 300 2003 12 24.37574 20.54 0.02
wc1224n4054 1.01 300 2003 12 24.38049 20.56 0.02
wc1224n4063 1.07 350 2003 12 24.42313 20.57 0.02
wc1224n4076 1.32 300 2003 12 24.47888 20.58 0.02
wc1224n4077 1.35 300 2003 12 24.48365 20.61 0.02
(120132) 2003 FY128 fy0309n037 1.16 350 2005 03 09.30416 20.29 0.02
fy0309n038 1.17 350 2005 03 09.30906 20.31 0.02
fy0309n045 1.32 350 2005 03 09.34449 20.29 0.02
fy0309n046 1.35 350 2005 03 09.34942 20.28 0.02
fy0309n051 1.55 350 2005 03 09.37484 20.28 0.02
fy0309n052 1.60 350 2005 03 09.37975 20.30 0.02
fy0310n113 1.37 300 2005 03 10.13114 20.33 0.02
fy0310n114 1.34 300 2005 03 10.13543 20.31 0.02
fy0310n121 1.15 300 2005 03 10.18141 20.27 0.02
fy0310n122 1.14 300 2005 03 10.18572 20.29 0.02
fy0310n131 1.08 250 2005 03 10.23854 20.28 0.02
fy0310n132 1.08 250 2005 03 10.24229 20.27 0.02
fy0310n142 1.17 300 2005 03 10.30636 20.29 0.02
fy0310n146 1.27 300 2005 03 10.33107 20.27 0.02
fy0310n147 1.29 300 2005 03 10.33564 20.27 0.02
fy0310n152 1.51 300 2005 03 10.36726 20.25 0.02
fy0310n153 1.55 300 2005 03 10.37157 20.22 0.02
– 21 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
(136199) Eris 2003 UB313 ub1026c142 1.71 350 2005 10 25.02653 18.372 0.006
ub1026c143 1.65 350 2005 10 25.03144 18.374 0.005
ub1026c150 1.37 300 2005 10 25.06369 18.370 0.005
ub1026c156 1.35 300 2005 10 25.06800 18.361 0.005
ub1026c162 1.11 250 2005 10 25.19559 18.361 0.005
ub1026c170 1.11 250 2005 10 25.19931 18.364 0.005
ub1026c171 1.16 250 2005 10 25.22449 18.360 0.005
ub1026c174 1.16 250 2005 10 25.22825 18.370 0.005
ub1026c175 1.25 300 2005 10 25.25305 18.327 0.005
ub1026c178 1.27 300 2005 10 25.25694 18.365 0.005
ub1026c179 1.38 300 2005 10 25.27710 18.350 0.005
ub1026c183 1.41 300 2005 10 25.28146 18.369 0.005
ub1026c184 1.54 300 2005 10 25.29766 18.365 0.005
ub1026c187 1.58 300 2005 10 25.30202 18.351 0.005
ub1026c188 1.78 350 2005 10 25.31871 18.364 0.006
ub1026c189 1.85 350 2005 10 25.32363 18.364 0.006
ub1027c043 1.83 250 2005 10 26.01513 18.356 0.006
ub1027c044 1.78 250 2005 10 26.01890 18.362 0.006
ub1027c049 1.34 200 2005 10 26.06597 18.360 0.005
ub1027c050 1.18 300 2005 10 26.10460 18.352 0.005
ub1027c069 1.10 300 2005 10 26.14440 18.348 0.005
ub1027c070 1.11 250 2005 10 26.19650 18.352 0.005
ub1027c074 1.11 250 2005 10 26.20049 18.365 0.005
ub1027c075 1.15 300 2005 10 26.21742 18.348 0.005
ub1027c084 1.16 300 2005 10 26.22174 18.359 0.005
ub1027c085 1.20 300 2005 10 26.23858 18.351 0.005
ub1027c088 1.22 300 2005 10 26.24295 18.331 0.005
ub1027c089 1.36 300 2005 10 26.27118 18.352 0.005
ub1027c092 1.39 300 2005 10 26.27555 18.345 0.005
ub1027c093 1.51 350 2005 10 26.29210 18.344 0.005
– 22 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
ub1027c096 1.56 350 2005 10 26.29702 18.345 0.005
ub1027c097 1.61 350 2005 10 26.30193 18.357 0.005
ub1028c240 1.65 300 2005 10 27.02670 18.350 0.005
ub1028c246 1.33 300 2005 10 27.06572 18.362 0.005
ub1028c258 1.10 250 2005 10 27.14482 18.357 0.005
ub1028c266 1.12 250 2005 10 27.19952 18.359 0.005
ub1028c267 1.12 250 2005 10 27.20321 18.367 0.005
ub1028c271 1.18 300 2005 10 27.22789 18.370 0.005
ub1028c272 1.19 300 2005 10 27.23216 18.366 0.005
ub1028c276 1.29 300 2005 10 27.25643 18.272 0.005
ub1028c277 1.31 300 2005 10 27.26070 18.376 0.005
ub1028c280 1.42 300 2005 10 27.27739 18.375 0.005
ub1028c281 1.45 300 2005 10 27.28171 18.369 0.005
ub1028c282 1.48 300 2005 10 27.28598 18.371 0.005
ub1028c283 1.52 300 2005 10 27.29033 18.372 0.005
ub1028c284 1.56 300 2005 10 27.29462 18.371 0.005
ub1028c285 1.61 300 2005 10 27.29900 18.381 0.005
ub1028c286 1.65 300 2005 10 27.30333 18.392 0.005
ub1028c287 1.70 300 2005 10 27.30761 18.393 0.006
ub1028c288 1.76 300 2005 10 27.31197 18.383 0.006
ub1028c289 1.82 300 2005 10 27.31625 18.369 0.006
ub1028c290 1.89 300 2005 10 27.32052 18.388 0.006
ub1028c291 1.96 300 2005 10 27.32484 18.367 0.006
ub1028c292 2.04 300 2005 10 27.32916 18.405 0.007
ub1028c293 2.13 300 2005 10 27.33347 18.378 0.007
ub1128n027 1.11 250 2005 11 28.10847 18.389 0.005
ub1128n028 1.12 250 2005 11 28.11219 18.382 0.005
ub1128n029 1.12 250 2005 11 28.11593 18.401 0.005
ub1128n032 1.16 250 2005 11 28.13378 18.391 0.005
ub1128n033 1.17 250 2005 11 28.13749 18.383 0.005
– 23 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
ub1128n034 1.18 250 2005 11 28.14118 18.391 0.005
ub1128n035 1.19 250 2005 11 28.14496 18.389 0.005
ub1128n036 1.21 250 2005 11 28.14866 18.386 0.005
ub1128n037 1.22 250 2005 11 28.15236 18.380 0.005
ub1128n038 1.23 250 2005 11 28.15614 18.376 0.005
ub1128n039 1.25 250 2005 11 28.15983 18.397 0.005
ub1128n040 1.27 250 2005 11 28.16353 18.393 0.005
ub1128n041 1.28 250 2005 11 28.16732 18.379 0.005
ub1128n042 1.30 250 2005 11 28.17102 18.378 0.005
ub1128n043 1.32 250 2005 11 28.17472 18.402 0.005
ub1128n044 1.34 250 2005 11 28.17850 18.379 0.005
ub1128n045 1.37 250 2005 11 28.18220 18.385 0.005
ub1128n046 1.39 250 2005 11 28.18589 18.380 0.005
ub1128n047 1.42 250 2005 11 28.18969 18.375 0.005
ub1128n048 1.44 250 2005 11 28.19339 18.387 0.005
ub1128n049 1.47 250 2005 11 28.19708 18.396 0.005
ub1128n050 1.51 250 2005 11 28.20084 18.393 0.005
ub1128n051 1.54 250 2005 11 28.20453 18.390 0.005
ub1128n052 1.58 250 2005 11 28.20822 18.391 0.005
ub1128n053 1.61 250 2005 11 28.21195 18.391 0.005
ub1128n054 1.66 250 2005 11 28.21565 18.376 0.005
ub1128n055 1.70 250 2005 11 28.21935 18.386 0.005
ub1128n056 1.75 250 2005 11 28.22311 18.377 0.006
ub1128n057 1.80 250 2005 11 28.22680 18.379 0.006
ub1128n058 1.85 250 2005 11 28.23050 18.382 0.006
ub1128n059 1.91 250 2005 11 28.23437 18.393 0.006
ub1128n060 1.98 250 2005 11 28.23800 18.386 0.006
ub1128n061 2.05 250 2005 11 28.24173 18.376 0.007
ub1128n062 2.13 250 2005 11 28.24546 18.383 0.007
ub1129n112 1.15 250 2005 11 29.02268 18.424 0.005
– 24 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
ub1129n119 1.09 250 2005 11 29.08304 18.432 0.005
ub1129n120 1.09 250 2005 11 29.08673 18.429 0.005
ub1129n121 1.10 250 2005 11 29.09043 18.421 0.005
ub1129n122 1.10 250 2005 11 29.09412 18.430 0.005
ub1129n123 1.10 250 2005 11 29.09782 18.426 0.005
ub1129n124 1.11 250 2005 11 29.10161 18.426 0.005
ub1129n125 1.11 250 2005 11 29.10530 18.431 0.005
ub1129n126 1.12 250 2005 11 29.10900 18.435 0.005
ub1129n127 1.12 250 2005 11 29.11269 18.418 0.005
ub1129n128 1.13 250 2005 11 29.11639 18.422 0.005
ub1129n129 1.14 250 2005 11 29.12018 18.435 0.005
ub1129n130 1.14 250 2005 11 29.12387 18.425 0.005
ub1129n131 1.15 250 2005 11 29.12757 18.418 0.005
ub1129n132 1.16 250 2005 11 29.13136 18.421 0.005
ub1129n133 1.17 250 2005 11 29.13506 18.421 0.005
ub1129n134 1.18 250 2005 11 29.13876 18.420 0.005
ub1129n135 1.20 250 2005 11 29.14254 18.415 0.005
ub1129n136 1.21 250 2005 11 29.14624 18.419 0.005
ub1129n137 1.22 250 2005 11 29.14993 18.424 0.005
ub1129n138 1.24 250 2005 11 29.15373 18.426 0.005
ub1129n139 1.25 250 2005 11 29.15742 18.422 0.005
ub1129n142 1.35 250 2005 11 29.17679 18.418 0.005
ub1129n143 1.37 250 2005 11 29.18049 18.421 0.005
ub1129n144 1.40 250 2005 11 29.18418 18.408 0.005
ub1129n145 1.43 250 2005 11 29.18788 18.422 0.005
ub1129n146 1.45 250 2005 11 29.19158 18.397 0.005
ub1129n147 1.48 250 2005 11 29.19531 18.412 0.005
ub1129n148 1.52 250 2005 11 29.19901 18.403 0.005
ub1129n149 1.55 250 2005 11 29.20270 18.394 0.005
ub1129n150 1.59 250 2005 11 29.20640 18.401 0.005
– 25 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
ub1129n151 1.63 250 2005 11 29.21010 18.400 0.005
ub1129n152 1.67 250 2005 11 29.21388 18.405 0.005
ub1129n153 1.71 250 2005 11 29.21758 18.401 0.005
ub1129n154 1.76 250 2005 11 29.22127 18.391 0.005
ub1129n155 1.81 250 2005 11 29.22496 18.397 0.006
ub1129n156 1.87 250 2005 11 29.22866 18.396 0.006
ub1129n157 1.93 250 2005 11 29.23238 18.415 0.006
ub1129n158 2.00 250 2005 11 29.23607 18.399 0.006
ub1130n226 1.13 250 2005 11 30.11178 18.386 0.005
ub1130n227 1.13 250 2005 11 30.11548 18.386 0.005
ub1130n228 1.14 250 2005 11 30.11918 18.394 0.005
ub1130n229 1.15 250 2005 11 30.12288 18.394 0.005
ub1130n230 1.16 250 2005 11 30.12657 18.390 0.005
ub1130n231 1.17 250 2005 11 30.13027 18.383 0.005
ub1130n232 1.18 250 2005 11 30.13397 18.398 0.005
ub1130n233 1.19 250 2005 11 30.13766 18.394 0.005
ub1130n234 1.20 250 2005 11 30.14136 18.392 0.005
ub1130n235 1.21 250 2005 11 30.14515 18.384 0.005
ub1130n236 1.23 250 2005 11 30.14884 18.391 0.005
ub1130n237 1.24 250 2005 11 30.15254 18.387 0.005
ub1130n238 1.26 250 2005 11 30.15624 18.391 0.005
ub1130n239 1.28 250 2005 11 30.15993 18.397 0.005
ub1130n240 1.29 250 2005 11 30.16370 18.388 0.005
ub1130n241 1.31 250 2005 11 30.16740 18.405 0.005
ub1130n242 1.33 250 2005 11 30.17110 18.379 0.005
ub1130n243 1.36 250 2005 11 30.17480 18.388 0.005
ub1130n244 1.38 250 2005 11 30.17849 18.383 0.005
ub1130n247 1.50 250 2005 11 30.19434 18.386 0.005
ub1130n248 1.53 250 2005 11 30.19804 18.394 0.005
ub1130n249 1.57 250 2005 11 30.20173 18.393 0.005
– 26 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
ub1130n250 1.60 250 2005 11 30.20543 18.400 0.005
ub1130n251 1.64 250 2005 11 30.20912 18.397 0.005
ub1130n252 1.69 250 2005 11 30.21281 18.390 0.005
ub1130n253 1.73 250 2005 11 30.21651 18.387 0.005
ub1130n254 1.78 250 2005 11 30.22020 18.403 0.006
ub1130n255 1.84 250 2005 11 30.22389 18.399 0.006
ub1130n256 1.90 250 2005 11 30.22768 18.379 0.006
ub1130n257 1.96 250 2005 11 30.23138 18.394 0.006
ub1130n258 2.03 250 2005 11 30.23514 18.393 0.007
ub1201n327 1.10 300 2005 12 01.04542 18.378 0.005
ub1201n333 1.10 250 2005 12 01.08574 18.376 0.005
ub1201n334 1.10 250 2005 12 01.08943 18.397 0.005
ub1201n335 1.10 250 2005 12 01.09313 18.386 0.005
ub1201n338 1.12 250 2005 12 01.10868 18.391 0.005
ub1201n339 1.13 250 2005 12 01.11237 18.381 0.005
ub1201n340 1.14 250 2005 12 01.11606 18.398 0.005
ub1201n341 1.15 250 2005 12 01.11976 18.382 0.005
ub1201n342 1.16 250 2005 12 01.12347 18.385 0.005
ub1201n343 1.17 250 2005 12 01.12725 18.389 0.005
ub1201n344 1.18 250 2005 12 01.13095 18.388 0.005
ub1201n345 1.19 250 2005 12 01.13465 18.386 0.005
ub1201n346 1.20 250 2005 12 01.13843 18.384 0.005
ub1201n347 1.21 250 2005 12 01.14212 18.381 0.005
ub1201n348 1.23 250 2005 12 01.14581 18.381 0.005
ub1201n351 1.30 250 2005 12 01.16207 18.379 0.005
ub1201n352 1.32 250 2005 12 01.16577 18.394 0.005
ub1201n353 1.34 250 2005 12 01.16946 18.394 0.005
ub1201n354 1.36 250 2005 12 01.17316 18.385 0.005
ub1201n355 1.39 250 2005 12 01.17685 18.383 0.005
ub1201n356 1.41 250 2005 12 01.18055 18.391 0.005
– 27 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
ub1201n357 1.44 250 2005 12 01.18424 18.379 0.005
ub1201n358 1.47 250 2005 12 01.18793 18.377 0.005
ub1201n359 1.50 250 2005 12 01.19163 18.381 0.005
ub1201n360 1.53 250 2005 12 01.19548 18.394 0.005
ub1201n361 1.57 250 2005 12 01.19918 18.389 0.005
ub1201n362 1.61 250 2005 12 01.20287 18.388 0.005
ub1201n363 1.65 250 2005 12 01.20688 18.388 0.005
ub1201n364 1.69 250 2005 12 01.21058 18.377 0.005
ub1201n365 1.74 250 2005 12 01.21427 18.390 0.006
ub1201n366 1.79 250 2005 12 01.21797 18.396 0.006
ub1201n367 1.85 250 2005 12 01.22166 18.396 0.006
ub1201n368 1.96 250 2005 12 01.22846 18.390 0.007
ub1201n369 2.03 250 2005 12 01.23228 18.382 0.007
(84922) 2003 VS2 vs1219n1031 1.07 250 2003 12 19.26838 19.39 0.01
vs1219n1032 1.06 250 2003 12 19.27266 19.36 0.01
vs1219n1043 1.02 250 2003 12 19.31376 19.37 0.01
vs1219n1044 1.02 250 2003 12 19.31810 19.41 0.01
vs1219n1055 1.03 220 2003 12 19.35203 19.53 0.01
vs1219n1056 1.04 220 2003 12 19.35594 19.52 0.01
vs1219n1064 1.11 220 2003 12 19.39432 19.53 0.01
vs1219n1065 1.12 220 2003 12 19.39821 19.52 0.01
vs1219n1075 1.29 220 2003 12 19.43959 19.39 0.01
vs1219n1076 1.31 220 2003 12 19.44346 19.38 0.01
vs1219n1086 1.67 230 2003 12 19.48544 19.34 0.01
vs1219n1087 1.72 230 2003 12 19.48944 19.38 0.01
vs1221n2024 1.26 220 2003 12 21.20617 19.52 0.01
vs1221n2025 1.24 220 2003 12 21.21014 19.52 0.01
vs1221n2040 1.10 220 2003 12 21.24958 19.53 0.01
vs1221n2041 1.09 220 2003 12 21.25340 19.52 0.01
vs1221n2046 1.05 220 2003 12 21.27486 19.46 0.01
– 28 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
vs1221n2047 1.05 220 2003 12 21.27870 19.45 0.01
vs1223n3022 1.21 200 2003 12 23.21214 19.41 0.01
vs1223n3023 1.19 200 2003 12 23.21579 19.44 0.01
vs1223n3024 1.17 250 2003 12 23.22026 19.46 0.01
vs1223n3042 1.02 220 2003 12 23.30008 19.34 0.01
vs1223n3043 1.02 220 2003 12 23.30391 19.33 0.01
vs1223n3055 1.07 220 2003 12 23.36359 19.46 0.01
vs1223n3056 1.07 220 2003 12 23.36743 19.50 0.01
vs1223n3074 1.28 220 2003 12 23.42704 19.47 0.01
vs1223n3075 1.31 220 2003 12 23.43087 19.46 0.01
vs1223n3082 1.55 200 2003 12 23.46289 19.36 0.01
vs1223n3083 1.59 200 2003 12 23.46644 19.35 0.01
vs1224n4022 1.23 250 2003 12 24.20522 19.35 0.01
vs1224n4023 1.21 250 2003 12 24.20940 19.38 0.01
vs1224n4030 1.05 220 2003 12 24.26469 19.37 0.01
vs1224n4031 1.05 220 2003 12 24.26848 19.38 0.01
vs1224n4039 1.02 220 2003 12 24.30385 19.51 0.01
vs1224n4040 1.02 220 2003 12 24.30871 19.52 0.01
vs1224n4049 1.06 220 2003 12 24.35630 19.45 0.01
vs1224n4050 1.06 220 2003 12 24.36014 19.44 0.01
vs1224n4059 1.19 220 2003 12 24.40395 19.34 0.01
vs1224n4060 1.20 220 2003 12 24.40778 19.32 0.01
vs1224n4070 1.50 220 2003 12 24.45457 19.43 0.01
vs1224n4071 1.53 220 2003 12 24.45839 19.48 0.01
(90482) Orcus 2004 DW dw0214n028 1.22 200 2005 02 14.11873 18.63 0.01
dw0214n029 1.21 200 2005 02 14.12189 18.65 0.01
dw0215n106 1.84 250 2005 02 15.03735 18.64 0.01
dw0215n107 1.78 250 2005 02 15.04156 18.66 0.01
dw0215n108 1.73 250 2005 02 15.04534 18.65 0.01
dw0215n109 1.69 250 2005 02 15.04911 18.64 0.01
– 29 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
dw0215n113 1.42 250 2005 02 15.07806 18.65 0.01
dw0215n114 1.39 250 2005 02 15.08183 18.65 0.01
dw0215n118 1.26 220 2005 02 15.10658 18.65 0.01
dw0215n119 1.25 220 2005 02 15.10998 18.64 0.01
dw0215n128 1.11 220 2005 02 15.17545 18.65 0.01
dw0215n129 1.11 220 2005 02 15.17885 18.65 0.01
dw0215n140 1.18 220 2005 02 15.24664 18.65 0.01
dw0215n141 1.19 220 2005 02 15.25007 18.65 0.01
dw0215n147 1.33 220 2005 02 15.28450 18.63 0.01
dw0215n148 1.35 220 2005 02 15.28789 18.66 0.01
dw0215n155 1.68 230 2005 02 15.32663 18.65 0.01
dw0215n156 1.73 230 2005 02 15.33014 18.64 0.01
dw0216n199 1.76 250 2005 02 16.04005 18.65 0.01
dw0216n200 1.72 250 2005 02 16.04379 18.67 0.01
dw0216n205 1.51 250 2005 02 16.06390 18.66 0.01
dw0216n206 1.47 250 2005 02 16.06767 18.67 0.01
dw0216n209 1.37 250 2005 02 16.08251 18.65 0.01
dw0216n210 1.35 250 2005 02 16.08625 18.66 0.01
dw0216n217 1.17 250 2005 02 16.13055 18.66 0.01
dw0216n218 1.16 250 2005 02 16.13437 18.66 0.01
dw0216n235 1.21 250 2005 02 16.25223 18.64 0.01
dw0216n247 1.81 300 2005 02 16.33285 18.66 0.01
dw0309n014 1.21 250 2005 03 09.05919 18.71 0.01
dw0309n015 1.20 250 2005 03 09.06295 18.70 0.01
dw0309n022 1.11 300 2005 03 09.11334 18.72 0.01
dw0309n023 1.11 300 2005 03 09.11762 18.71 0.01
dw0309n027 1.11 300 2005 03 09.13928 18.69 0.01
dw0309n028 1.11 300 2005 03 09.14363 18.70 0.01
dw0310n091 1.43 250 2005 03 10.01315 18.71 0.01
dw0310n092 1.40 250 2005 03 10.01688 18.71 0.01
– 30 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
dw0310n097 1.27 250 2005 03 10.04113 18.72 0.01
dw0310n098 1.25 250 2005 03 10.04487 18.72 0.01
dw0310n107 1.12 250 2005 03 10.09569 18.71 0.01
dw0310n108 1.12 250 2005 03 10.09945 18.72 0.01
dw0310n125 1.26 250 2005 03 10.20552 18.70 0.01
dw0310n126 1.28 250 2005 03 10.20927 18.71 0.01
dw0310n135 1.67 300 2005 03 10.26076 18.72 0.01
(90568) 2004 GV9 gv0215n130 1.75 250 2005 02 15.18402 19.75 0.03
gv0215n131 1.70 250 2005 02 15.18792 19.81 0.03
gv0215n142 1.19 250 2005 02 15.25502 19.77 0.03
gv0215n143 1.17 250 2005 02 15.25891 19.73 0.03
gv0215n153 1.03 250 2005 02 15.31558 19.74 0.03
gv0215n154 1.03 250 2005 02 15.31931 19.79 0.03
gv0215n159 1.00 250 2005 02 15.34893 19.77 0.03
gv0215n160 1.00 250 2005 02 15.35268 19.80 0.03
gv0215n165 1.01 250 2005 02 15.38618 19.79 0.03
gv0215n166 1.02 250 2005 02 15.38992 19.83 0.03
gv0216n229 1.41 250 2005 02 16.21394 19.74 0.03
gv0216n230 1.38 250 2005 02 16.21768 19.76 0.03
gv0216n242 1.05 300 2005 02 16.29937 19.76 0.03
gv0216n254 1.01 300 2005 02 16.37745 19.75 0.03
gv0309n029 1.46 300 2005 03 09.14960 19.64 0.02
gv0309n030 1.42 300 2005 03 09.15392 19.66 0.02
gv0309n033 1.01 300 2005 03 09.27972 19.75 0.02
gv0309n034 1.00 300 2005 03 09.28405 19.73 0.02
gv0309n039 1.01 300 2005 03 09.31533 19.70 0.02
gv0309n040 1.01 300 2005 03 09.31965 19.67 0.02
gv0309n047 1.06 300 2005 03 09.35654 19.70 0.02
gv0309n048 1.07 300 2005 03 09.36090 19.68 0.02
gv0309n054 1.18 300 2005 03 09.39525 19.68 0.02
– 31 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
gv0309n055 1.20 300 2005 03 09.39959 19.69 0.02
gv0310n115 1.51 300 2005 03 10.14103 19.64 0.02
gv0310n116 1.44 300 2005 03 10.14905 19.66 0.02
gv0310n127 1.11 300 2005 03 10.21489 19.64 0.02
gv0310n128 1.09 300 2005 03 10.21918 19.68 0.02
gv0310n143 1.01 300 2005 03 10.31197 19.75 0.02
gv0310n148 1.04 300 2005 03 10.34106 19.72 0.02
gv0310n149 1.05 300 2005 03 10.34539 19.77 0.02
gv0310n155 1.14 300 2005 03 10.38172 19.76 0.02
gv0310n158 1.20 300 2005 03 10.39711 19.72 0.02
gv0310n159 1.22 300 2005 03 10.40147 19.73 0.02
(120348) 2004 TY364 ty1025n041 1.89 400 2005 10 25.01425 19.89 0.01
ty1025n042 1.81 400 2005 10 25.01944 19.86 0.01
ty1025n047 1.45 400 2005 10 25.05162 19.87 0.01
ty1025n048 1.41 400 2005 10 25.05711 19.92 0.01
ty1025n067 1.04 350 2005 10 25.18450 19.98 0.01
ty1025n068 1.04 350 2005 10 25.18939 19.99 0.01
ty1025n072 1.06 350 2005 10 25.21357 19.95 0.01
ty1025n073 1.07 350 2005 10 25.21847 19.92 0.01
ty1025n082 1.12 350 2005 10 25.24193 19.89 0.01
ty1025n083 1.13 350 2005 10 25.24683 19.90 0.01
ty1025n086 1.19 350 2005 10 25.26632 19.90 0.01
ty1025n087 1.21 350 2005 10 25.27123 19.90 0.01
ty1025n090 1.29 350 2005 10 25.28657 19.89 0.01
ty1025n091 1.32 350 2005 10 25.29147 19.95 0.01
ty1025n094 1.42 350 2005 10 25.30718 19.95 0.01
ty1025n095 1.46 350 2005 10 25.31207 20.00 0.01
ty1025n098 1.63 350 2005 10 25.32928 19.98 0.01
ty1025n099 1.69 350 2005 10 25.33418 19.97 0.01
ty1025n100 1.76 350 2005 10 25.33909 20.02 0.01
– 32 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
ty1025n101 1.83 350 2005 10 25.34410 20.03 0.01
ty1026n144 1.71 400 2005 10 26.02367 19.85 0.01
ty1026n145 1.64 400 2005 10 26.02917 19.86 0.01
ty1026n151 1.30 350 2005 10 26.07121 20.02 0.01
ty1026n157 1.13 400 2005 10 26.11043 20.07 0.01
ty1026n163 1.06 400 2005 10 26.14943 20.03 0.01
ty1026n172 1.06 400 2005 10 26.20516 19.92 0.01
ty1026n176 1.09 400 2005 10 26.22689 19.88 0.01
ty1026n177 1.10 400 2005 10 26.23234 19.90 0.01
ty1026n181 1.16 450 2005 10 26.25425 19.94 0.01
ty1026n182 1.19 450 2005 10 26.26393 19.92 0.01
ty1026n185 1.27 400 2005 10 26.28048 19.95 0.01
ty1026n186 1.30 400 2005 10 26.28599 19.98 0.01
ty1026n190 1.45 450 2005 10 26.30748 20.03 0.01
ty1026n191 1.50 450 2005 10 26.31356 20.09 0.01
ty1026n192 1.56 450 2005 10 26.31963 20.09 0.01
ty1026n193 1.62 450 2005 10 26.32568 20.07 0.01
ty1026n194 1.70 450 2005 10 26.33173 20.09 0.01
ty1026n195 1.78 450 2005 10 26.33774 20.10 0.01
ty1026n196 1.87 450 2005 10 26.34378 20.08 0.01
ty1027n241 1.58 400 2005 10 27.03210 20.01 0.01
ty1027n247 1.28 400 2005 10 27.07100 20.04 0.01
ty1027n264 1.05 400 2005 10 27.18749 19.89 0.01
ty1027n265 1.05 400 2005 10 27.19292 19.87 0.01
ty1027n269 1.07 400 2005 10 27.21551 19.91 0.01
ty1027n270 1.08 400 2005 10 27.22094 19.90 0.01
ty1027n274 1.14 400 2005 10 27.24440 19.90 0.01
ty1027n275 1.15 400 2005 10 27.24988 19.89 0.01
ty1027n278 1.22 350 2005 10 27.26622 19.98 0.01
ty1027n279 1.24 350 2005 10 27.27115 19.99 0.01
– 33 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
ty1027n294 1.83 400 2005 10 27.33881 20.09 0.01
ty1027n295 1.92 400 2005 10 27.34429 20.09 0.01
ty1027n296 2.02 400 2005 10 27.34976 20.10 0.01
ty1128n030 1.07 350 2005 11 28.12175 19.99 0.01
ty1128n031 1.07 350 2005 11 28.12665 19.99 0.01
ty1128n063 1.87 400 2005 11 28.25204 20.17 0.01
ty1128n064 1.96 400 2005 11 28.25747 20.15 0.01
ty1129n117 1.05 350 2005 11 29.07101 20.00 0.01
ty1129n118 1.04 350 2005 11 29.07586 20.00 0.01
ty1129n140 1.17 350 2005 11 29.16375 20.11 0.01
ty1129n141 1.19 350 2005 11 29.16860 20.12 0.01
ty1129n159 1.76 350 2005 11 29.24196 20.17 0.01
ty1129n160 1.83 350 2005 11 29.24682 20.13 0.01
ty1129n161 1.91 350 2005 11 29.25167 20.15 0.01
ty1129n162 1.99 350 2005 11 29.25657 20.08 0.01
ty1130n224 1.05 350 2005 11 30.10029 19.98 0.01
ty1130n225 1.05 350 2005 11 30.10514 20.00 0.01
ty1130n245 1.27 350 2005 11 30.18325 20.18 0.01
ty1130n246 1.30 350 2005 11 30.18810 20.15 0.01
ty1130n259 1.77 350 2005 11 30.23992 20.12 0.01
ty1130n260 1.84 350 2005 11 30.24478 20.10 0.01
ty1130n261 1.92 350 2005 11 30.24963 20.13 0.01
ty1130n262 2.01 350 2005 11 30.25454 20.11 0.01
ty1201n328 1.06 400 2005 12 01.05104 19.99 0.01
ty1201n336 1.05 350 2005 12 01.09816 20.08 0.01
ty1201n337 1.05 350 2005 12 01.10301 20.07 0.01
ty1201n349 1.14 350 2005 12 01.15006 20.18 0.01
ty1201n350 1.16 350 2005 12 01.15492 20.13 0.01
ty1201n370 1.77 350 2005 12 01.23777 20.05 0.01
ty1201n371 1.85 350 2005 12 01.24262 20.07 0.01
– 34 –
Table 1—Continued
Name Imagea Airmass Expb UT Datec Mag.d Err
(sec) yyyy mm dd.ddddd (mR) (mR)
ty1201n372 1.93 350 2005 12 01.24748 20.08 0.01
ty1201n373 2.02 350 2005 12 01.25239 20.04 0.01
aImage number.
bExposure time for the image.
cDecimal Universal Date at the start of the integration.
dApparent red magnitude.
eUncertainties on the individual photometric measurements.
– 35 –
Table 2. Properties of Observed KBOs
Name Ha mR
b Nightsc ∆mR
d Singlee Doublef
(mag) (mag) (#) (mag) (hrs) (hrs)
2001 UQ18 5.4 22.3 2 < 0.3 - -
(126154) 2001 YH140 5.4 20.85 4 0.21± 0.04 13.25± 0.2 -
(55565) 2002 AW197 3.3 19.88 2 < 0.03 - -
(119979) 2002 WC19 5.1 20.58 4 < 0.05 - -
(120132) 2003 FY128 5.0 20.28 2 < 0.08 - -
(136199) Eris 2003 UB313 -1.2 18.36 7 < 0.01 - -
(84922) 2003 VS2 4.2 19.45 4 0.21± 0.02 - 7.41± 0.02
(90482) Orcus 2004 DW 2.3 18.65 5 < 0.03 - -
(90568) 2004 GV9 4.0 19.68 4 < 0.08 - -
(120348) 2004 TY364 4.5 19.98 7 0.22± 0.02 5.85± 0.01 11.70± 0.01
aThe visible absolute magnitude of the object from the Minor Planet Center. The values from
the MPC differ than the R-band absolute magnitudes found for the few objects in which we have
actual phase curves as shown in Table 3.
bMean red magnitude of the object. For the four objects observed at significantly different phase
angles the data near the lowest phase angle is used: Eris in Oct. 2005, Orcus in Feb. 2005, 90568
in Mar. 2005, and 120348 in Oct. 2005.
cNumber of nights data were taken to determine the lightcurve.
dThe peak to peak range of the lightcurve.
eThe lightcurve period if there is one maximum per period.
fThe lightcurve period if there are two maximum per period.
– 36 –
Table 3. Phase Function Data for KBOs
Name mR(1, 1, 0)
a Hb MPCc β(α < 2◦)d
(mag) (mag) (mag) (mag/deg)
(136199) Eris 2003 UB313 −1.50± 0.02 −1.50± 0.02 −1.65 0.09± 0.03
(90482) Orcus 2004 DW 1.81± 0.05 1.81± 0.05 1.93 0.26± 0.05
(90568) 2004 GV9 3.64± 0.06 3.62± 0.06 3.5 0.18± 0.06
(120348) 2004 TY364 3.91± 0.03 3.90± 0.03 4.0 0.19± 0.03
aThe R-band reduced magnitude determined from the linear phase coefficient found
in this work.
bThe R-band absolute magnitude determined as described in Bowell et al. (1989).
cThe R-band absolute magnitude from the Minor Planet Center converted from the
V-band as is shown in Table 2 to the R-band using the known colors of the objects:
V-R= 0.45 for Eris (Brown et al. 2005), V-R= 0.37 for Orcus (de Bergh et al. 2005),
and a nominal value of V-R= 0.5 for 90568 and 120348 since these objects don’t have
known V-R colors.
dβ(α < 2◦) is the phase coefficient in magnitudes per degree at phase angles < 2◦.
– 37 –
Table 4. Phase Function Correlations
β vs.a rcorr
b Nc Sigd
mR(1, 1, 0) 0.50 19 97%
mV (1, 1, 0) 0.54 16 97%
mI(1, 1, 0) 0.12 14 < 60%
pR -0.51 5 65%
pV -0.38 9 70%
pI -0.27 10 < 60%
∆m -0.21 19 < 60%
B − I -0.20 11 < 60%
aβ is the linear phase coefficient in magnitudes per degree at phase
angles < 2◦. In the column are what β is compared to in order to see
if there is any correlation; mR(1, 1, 0), mV (1, 1, 0) and mI(1, 1, 0) are
the reduced mangitudes in the R, V and I-band respectively and are
compared to the value of β determined at the same wavelength; pR, pV
and pI are the geometric albedos compared to β in the R, V and I-band
respectively; ∆m is the peak-to-peak amplitude of the rotational light
curve; and B − I is the color. The phase curves in the R-band are
from this work and Sheppard and Jewitt (2002;2003) while the V and
I-band data are from Buie et al. (1997) and Rabinowitz et al. (2007).
The albedo information is from Cruikshank et al. (2006) and the colors
from Barucci et al. (2005).
brcorr is the Pearson correlation coefficient.
cN is the number of TNOs used for the correlation.
dSig is the confidence of significance of the correlation.
– 38 –
Fig. 1.— The Phase Dispersion Minimization (PDM) plot for (120348) 2004 TY364. The
best fit single-peaked period is near 5.85 hours.
– 39 –
Fig. 2.— The phased best fit single-peaked period for (120348) 2004 TY364 of 5.85 hours. The
peak-to-peak amplitude is about 0.22 magnitudes. The data from November and December
has been vertically shifted to correspond to the same phase angle as the data from October
using the phase function found for this object in this work. Individual error bars for the
measurements are not shown for clarity but are generally ±0.01 mags as seen in Table 1.
– 40 –
Fig. 3.— The phased double-peaked period for (120348) 2004 TY364 of 11.70 hours. The
data from November and December has been vertically shifted to correspond to the same
phase angle as the data from October using the phase function found for this object in this
work. Individual error bars for the measurements are not shown for clarity but are generally
±0.01 mags as seen in Table 1.
– 41 –
Fig. 4.— The Phase Dispersion Minimization (PDM) plot for (84922) 2003 VS2. The best
fit is the double-peaked period near 7.41 hours.
– 42 –
Fig. 5.— The phased best fit double-peaked period for (84922) 2003 VS2 of 7.41 hours. The
peak-to-peak amplitude is about 0.21 magnitudes. The two peaks have differences since one
is slightly wider while the other is slightly shorter in amplitude. This is the best fit period
for (84922) 2003 VS2. Individual error bars for the measurements are not shown for clarity
but are generally ±0.01 mags as seen in Table 1.
– 43 –
Fig. 6.— The phased single-peaked period for (84922) 2003 VS2 of 3.70 hours. The single
peaked period for 2003 VS2 does not look well matched and has a larger scatter about the
solution compared to the double-peaked period shown in Figure 5. Individual error bars for
the measurements are not shown for clarity but are generally ±0.01 mags as seen in Table
– 44 –
Fig. 7.— The phased single-peaked period for (84922) 2003 VS2 of 4.39 hours. Again, the
single peaked period for 2003 VS2 does not look well matched and has a larger scatter about
the solution compared to the double-peaked period shown in Figure 5. Individual error bars
for the measurements are not shown for clarity but are generally ±0.01 mags as seen in Table
– 45 –
Fig. 8.— The phased double-peaked period for (84922) 2003 VS2 of 8.77 hours. This double-
peaked period for 2003 VS2 does not look well matched and has a larger scatter about the
solution compared to the 7.41 hour double-peaked period shown in Figure 5. Individual
error bars for the measurements are not shown for clarity but are generally ±0.01 mags as
seen in Table 1.
– 46 –
Fig. 9.— The Phase Dispersion Minimization (PDM) plot for 2001 YH140. The best fit is
the single-peaked period near 13.25 hours. The other possible fits near 8.5, 9.15 and 10.25
hours don’t look good when phasing the data and viewing the result by eye.
– 47 –
Fig. 10.— The phased best fit single-peaked period for 2001 YH140 of 13.25 hours. The peak-
to-peak amplitude is about 0.21 magnitudes. Individual error bars for the measurements are
not shown for clarity but are generally ±0.02 mags as seen in Table 1.
– 48 –
Fig. 11.— The flat light curve of 2001 UQ18. The KBO may have a significant amplitude
light curve but further observations are needed to confirm.
– 49 –
Fig. 12.— The flat light curve of (55565) 2002 AW197. The KBO has no significant short-term
variations larger than 0.03 magnitudes over two days.
– 50 –
Fig. 13.— The flat light curve of (119979) 2002 WC19. The KBO has no significant short-
term variations larger than 0.03 magnitudes over four days.
– 51 –
Fig. 14.— The flat light curve of (119979) 2002 WC19. The KBO has no significant short-
term variations larger than 0.03 magnitudes over four days.
– 52 –
Fig. 15.— The flat light curve of (120132) 2003 FY128. The KBO has no significant short-
term variations larger than 0.08 magnitudes over two days.
– 53 –
Fig. 16.— The flat light curve of Eris (2003 UB313) in October 2005. The KBO has no
significant short-term variations larger than 0.01 magnitudes over several days.
– 54 –
Fig. 17.— The flat light curve of Eris (2003 UB313) in November and December 2005. The
KBO has no significant short-term variations larger than 0.01 magnitudes over several days.
– 55 –
Fig. 18.— The flat light curve of (90482) Orcus 2004 DW in February 2005. The KBO has
no significant short-term variations larger than 0.03 magnitudes over several days.
– 56 –
Fig. 19.— The flat light curve of (90482) Orcus 2004 DW in March 2005. The KBO has no
significant short-term variations larger than 0.03 magnitudes over several days.
– 57 –
Fig. 20.— The flat light curve of (90568) 2004 GV9 in February 2005. The KBO has no
significant short-term variations larger than 0.1 magnitudes over several days.
– 58 –
Fig. 21.— The flat light curve of (90568) 2004 GV9 in March 2005. The KBO has no
significant short-term variations larger than 0.1 magnitudes over several days.
– 59 –
Fig. 22.— This plot shows the diameter of asteroids and TNOs versus their light curve
amplitudes. The TNOs sizes if unknown assume they have moderate albedos of about 10
percent. For objects with flat light curves they are plotted at the variation limit found by
observations.
– 60 –
Fig. 23.— Same as the previous figure except the diameter versus the light curve period
is plotted. The dashed line is the median of known TNOs rotation periods (9.5 ± 1 hours)
which is significantly above the median large MBAs rotation periods (7.0± 1 hours). Pluto
falls off the graph in the upper right corner because of its slow rotation created by the tidal
locking to its satellite Charon.
– 61 –
Fig. 24.— The phase curve for Eris (2003 UB313). The dashed line is the linear fit to the
data while the solid line uses the Bowell et al. (1989) H-G scattering formalism. In order to
create only a few points with small error bars, the data has been averaged for each observing
night.
– 62 –
Fig. 25.— The phase curve for (90482) Orcus 2004 DW. The dashed line is the linear fit
to the data while the solid line uses the Bowell et al. (1989) H-G scattering formalism. In
order to create only a few points with small error bars, the data has been averaged for each
observing night.
– 63 –
Fig. 26.— The phase curve for (120348) 2004 TY364. The dashed line is the linear fit to the
data while the solid line uses the Bowell et al. (1989) H-G scattering formalism. In order to
create only a few points with small error bars, the data has been averaged for each observing
night.
– 64 –
Fig. 27.— The phase curve for (90568) 2004 GV9. The dashed line is the linear fit to the
data while the solid line uses the Bowell et al. (1989) H-G scattering formalism. In order to
create only a few points with small error bars, the data has been averaged for each observing
night.
– 65 –
Fig. 28.— The R-band reduced magnitude versus the R-band linear phase coefficient β(α < 2
degrees) for TNOs. R-band data is from this work and Sheppard and Jewitt (2002),(2003)
as well as Sedna from Rabinowitz et al. (2007) and Pluto from Buratti et al. (2003). A
linear fit is shown by the dahsed line. Larger objects (smaller reduced magnitudes) may
have smaller β at the 97% confidence level using the Pearson correlation coefficient.
– 66 –
Fig. 29.— Same as Figure 28 except for the V-band (squares) and I-band (diamonds). Pluto
and Charon data are from Buie et al. (1997) and the other data are from Rabinowitz et al.
(2007). Error bars are usually less than 0.04 mags/deg. The V-band data shows a similar
correlation (97% confidence, dashed line) as found for the R-band data in Figure 28, that
is larger objects may have smaller β. There is no correlation found using the I-band data
(dotted line).
– 67 –
Fig. 30.— Same as Figures 28 and 29 except is the albedo versus linear phase coefficient for
TNOs. Filled circles are R-band data, squares are V-band and diamonds are I-band data.
Albedos are from Cruikshank et al. (2006).
– 68 –
Fig. 31.— Same as Figure 28 except is the light curve amplitude versus the linear phase
coefficient for TNOs. TNOs with no measured rotational variability are plotted with their
possible amplitude upper limits. No significant correlation is found.
– 69 –
Fig. 32.— Same as Figure 28 except is the B-I broad band colors versus the linear phase
coefficient for TNOs. Colors are from Barucci et al. (2005). No significant correlation is
found.
