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MPEC 2017-L47 : S/2017 J 1

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M.P.E.C. 2017-L47 Issued 2017 June 5, 15:17 UT The Minor Planet Electronic Circulars contain information on unusual minor planets and routine data on comets. They are published on behalf of Division F of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. Prepared using the Tamkin Foundation Computer Network MPC@CFA.HARVARD.EDU URL https://www.minorplanetcenter.net/ ISSN 1523-6714 S/2017 J 1 Additional Observations: SK17J010 C2016 02 05.64655 11 23 30.14 +04 02 03.2 23.7 rcEL047568 SK17J010 C2016 02 05.65734 11 23 29.95 +04 02 04.5 23.7 rcEL047568 SK17J010 C2016 04 10.25724 10 58 12.55 +07 04 03.1 23.8 rcEL047568 SK17J010 C2016 04 10.49682 10 58 08.58 +07 04 31.6 23.8 rcEL047568 SK17J010 C2017 02 24.56974 13 18 34.49 -06 53 43.2 23.8 rcEL047568 SK17J010 C2017 02 24.64168 13 18 33.24 -06 53 37.5 23.8 rcEL047568 SK17J010 C2017 03 23.24858 13 08 05.54 -06 00 40.0 24.0 rcEL047807 SK17J010 C2017 03 23.27130 13 08 04.87 -06 00 36.9 23.9 rcEL047807 SK17J010 C2017 03 26.28417 13 06 36.13 -05 52 56.5 23.9 rcEL047807 SK17J010 C2017 03 26.32711 13 06 34.81 -05 52 49.6 23.8 rcEL047807 SK17J010 C2017 04 22.11022 12 53 07.38 -04 43 04.4 23.8 rcEL047304 SK17J010 C2017 04 22.14163 12 53 06.48 -04 42 59.8 23.8 rcEL047304 SK17J010 C2017 04 23.15981 12 52 37.95 -04 40 34.5 23.8 rcEL047304 SK17J010 C2017 04 23.18409 12 52 37.27 -04 40 30.9 23.9 rcEL047304 Observer details: 304 Las Campanas Observatory. Observer S. S. Sheppard. 6.5-m Magellan-Baade telescope + CCD. 568 Mauna Kea. Observers S. S. Sheppard, D. J. Tholen, C. Trujillo. 8.2-m Subaru Telescope + CCD. 807 Cerro Tololo. Observers S. S. Sheppard, C. Trujillo. 4.0-m CTIO reflector + CCD. Orbital elements: S/2017 J 1 Epoch 2017 Sept. 4.0 TT = JDT 2458000.5 MPC M 161.32649 (2000.0) P Q n 0.48965383 Peri. 79.73238 -0.31399774 -0.90701199 a 0.1569807 Node 326.77425 -0.93870913 +0.34086171 e 0.3968680 Incl. 149.19651 +0.14223425 +0.24727019 P 2.01 H 16.5 P/d 735.21 From 14 observations 2016 Feb. 5-2017 Apr. 23, mean residual 0".28. Residuals in seconds of arc 160205 568 0.1+ 0.0 170224 568 0.1+ 0.5+ 170422 304 0.0 0.3- 160205 568 0.3+ 0.1- 170323 807 0.2+ 0.1+ 170422 304 0.1+ 0.2- 160410 568 0.1+ 0.2+ 170323 807 0.2+ 0.2- 170423 304 0.1- 0.4- 160410 568 0.4- 0.2+ 170326 807 0.4- 0.2+ 170423 304 0.1+ 0.2- 170224 568 0.3+ 0.5+ 170326 807 0.6- 0.4+ Gareth V. Williams (C) Copyright 2017 MPC M.P.E.C. 2017-L47

MPEC number: Enter an MPEC number in one of the following forms:</s>The advent of monster telescopes equipped with super-sensitive, wide-field detectors has been a boon for astronomical discoveries, among them a bevy of tiny moonlets around the outer planets. For example, observations made from 2000 to 2003 yielded 46 moons around Jupiter — more than two-thirds of the planet's total!Now astronomer Scott Sheppard (Carnegie Institution for Science)As Sheppard explains, "We were continuing our survey looking for very distant objects in the outer solar system, which includes looking for Planet X , and Jupiter just happened to be in the area we were looking in 2016 and 2017." So they took a minor detour to image some fields that were very close to Jupiter.With magnitudes hovering near 24, these barely-there moonlets must be only 1 or 2 km across. So for now all that's really known is the character of their orbits:Sheppard discovered this moonlet during an observing run on March 8, 2016, with the 6.5-m Magellan-Baade reflector at Las Campanas Observatory in Chile. Averaging 20,600,000 from Jupiter, it's in an elongated orbit inclined 140° with an eccentricity of 0.14. It takes 1.65 years to orbit the planet. ( See Animation Although Sheppard first sighted this moon last year, its orbit remained uncertain until he teamed up with David Tholen (University of Hawai'i) and Chadwick Trujillo (Gemini Observatory), who swept it up six weeks ago with the 8.2-m Subaru reflector on Mauna Kea.Sheppard and Trujillo recorded the second new find on March 23, 2017, using the venerable 4-m Victor Blanco reflector at Cerro Tololo Inter-american Observatory in Chile. It also turned up in images recorded with Subaru in 2016 and earlier this year, which allowed the team to confirm its existence. This moon likewise is far from Jupiter, at an average distance of 23,500,000 km. In this very elongated orbit, inclined 149° with an eccentricity of 0.40, the moonlet takes 2.01 years to go around Jupiter.( See Animation Both of these discoveries, as with the vast majority of Jupiter's moons, occupy retrograde orbits, with inclinations greater than 90°, meaning that they move in directions opposite that of the planet's spin. These distant, irregular orbits imply that these bodies formed elsewhere in the outer solar system and were captured while passing by early in the planet's history.According to an orbital assessment published in April by Marina Brozović and Robert A. Jacobson (Jet Propulsion Laboratory), 11 of Jupiter's irregular satellites have orbits known so poorly that they're considered "lost." Sheppard and his collaborators found all but one of those in 2003, and they haven't been observed since.However, that's changing. The time Sheppard and Trujillo spent scrutinizing the region around Jupiter has already led to the recovery of S/2003 J 5 S/2003 J 15 , and S/2003 J 18 , as well as a better orbit for S/2011 J 2 "We have for sure recovered five of the lost moons," Sheppard says, noting that the 2016 and 2017 observations could be easily linked to some of 2003's uncertain finds. "We have several more Jupiter moons in our new 2017 observations and likely have all of the lost moons in our new observations," he continues, but to ensure the identifications he'll need to return to those big telescopes for more observations in early 2018.If you're interested in all these crazy outer-planet moons, be sure to check out Sheppard's compilations for Jupiter and the other outer planets.
Another satellite of Jupiter is announced, S/2017 J 1, just 3 days after the announcement of S/2016 J 1.