March 21, 2018

Event: Nova in Carina - ASASSN-18fv

Discovered by: All Sky Automated Survey for SuperNovae (ASAS-SN)

Discovery magnitude: brighter than magnitude 10 V (image was saturated)

Discovery date: 2018 March 20.32 UT

Coordinates (2000.0): R.A. 10 36 13.71 Decl. -59 35 55.1 (from VSX)

Spectra: Spectroscopy indicating that ASASSN-18fv is a classical nova brightening and in the optically thick (Fe curtain) phase was obtained by P. Luckas (ATel #11460) on 2018 March 21.49 UT with an Alpy600 spectrograph having a resolution of about 540 in the range 3800-7300A and using a Atik414 CCD.

Earlier spectroscopy by J. Strader et al. (ATel #11456) had not ruled out a galactic nova, but it was thought the transient might be a large outburst of a young stellar object.

Observing recommendations: Observations of all types (visual, CCD, DSLR, PEP, spectroscopy) and multiple bands as instrumentation permits are strongly encouraged as the nova evolves.

Observations reported to the AAVSO:

2018 March 15.34 UT, <17.0 V (ASAS-SN; ATel #11454);

20.32, >10 V (brighter than 10 V (saturated); ASAS-SN, discovery; ATel #11454);

21.44380, 6.5 (R. Stubbings, Tetoora Road, VIC, Australia);

21.47, 7.19 B (M. Brown et al., Hutton-Westfold Observatory, Monash University; ATel #11457);

21.47, 6.62 V (M. Brown et al.; ATel #11457);

21.47847, 7.4 (A. Pearce, Nedlands, W. Australia);

21.48819, 7.2 (Pearce);

21.54653, 7.1 (Pearce);

21.634, 5.9: (N. Brown, Two Rocks, W. Australia);

Charts: Charts with a comparison star sequence for ASASSN-18fv may be created using the AAVSO Variable Star Plotter (VSP). It is recommended that observers use the binocular chart option if creating an 'a' or 'b' scale chart because there are so many comp stars in the region. Also, we suggest that observers choose the option not to display other variables.

Sebastian Otero notes that a good binocular chart can be obtained using a 300 arc minutes field of view and limiting magnitude 9.0. He provides a link to such a chart:

https://www.aavso.org/apps/vsp/chart/?fov=297.0&star=ASASSN-18fv&orientation=visual&maglimit=9.0&resolution=150&binoc=on&north=down&east=right&type=chart&special=binoc

Submit observations: Please submit observations to the AAVSO International Database using the name ASASSN-18FV. Once a GCVS name is announced in an IAU Circular or CBET, please use that name.

AAVSO Forums: ASASSN-18fv is the topic of the AAVSO Time Sensitive Alerts forum thread https://www.aavso.org/bright-nova-carina and the AAVSO Novae forum thread https://www.aavso.org/asassn-18fv-probable-nova-10-mag-or-brighter-carina

Notes:

a. Unless otherwise noted and except for observations reported to the AAVSO, the information in this Alert Notice is taken from ATels #11454 (K. Z. Stanek et al.), #11456 (J. Strader et al.), #11457 (M. Brown et al.), and #11460 (P. Luckas).

b. Stanek et al. (ATel #11454) note that no outbursts or variability were seen at this location on earlier ASAS-SN images since coverage of the location began in February 2016.

c. Strader et al. (ATel#11456) report that the nova matches to within 0.1" a star in the Gaia DR1 catalog, which has J2000 position end figures 15.4138s 53.648". This star is also present in VPHAS+ DR2 catalog (Drew et al 2014, MNRAS, 440, 2036), with g~20.1 and r ~ 19.5. Magnitude calculations yield g=7.80, r=7.27, i=7.19, B=8.07, V=7.45 for the nova, and imply that the object has brightened by at least -12.3 mag in g.

Congratulations to the ASAS-SN team on this discovery!

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.

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Researchers publish observations of a possible nova (ASASSN-18fv) in the constellation Carina.