The likely progenitor of Nova ASASSN-18ds
ATel #11365; R. Kammers, T. S. Ferreira, R. K. Saito (Universidade Federal de Santa Catarina), D. Minniti (Universidad Andres Bello, Millennium Institute of Astrophysics, Vatican Observatory)
on 27 Feb 2018; 16:28 UT
Credential Certification: Roberto Saito (saito@astro.ufsc.br)
Subjects: Infra-Red, Nova
Stanek et al. (ATel #11348) recently reported on the detection of a likely Galactic Nova in the Milky Way disk, confirmed by spectroscopic observations at ESO NTT and SALT telescopes (Schmidtobreick et al. 2018, ATel #11360; Aydi et al. 2018, ATel #11364, respectively). ASASSN-18ds is located at coordinates RA, DEC (J2000) = 17:03:47.509, -38:16:57.14, corresponding to l, b = 347.384, 1.925, within the area covered by the VVV Survey in the Galactic disk (vvvsurvey.org; Minniti et al. 2010, New Astronomy, 15, 433).
Multiband near-IR VVV observations taken in 2010 show the presence of a source 1.3 arcsec away from the reported target position. During the 2010-2013 seasons VVV Ks-band observations of the likely progenitor of Nova ASASSN-18ds show no significant variation in brightness with mean_Ks=14.54+/-0.03, which is within the VVV photometric errors at these magnitudes. Other nearby sources found in the VVV data down to the limiting magnitude of Ks=18.1 mag in the field are more distant (about 4 arcs apart) from the reported target position.
According to Schlafly et al. (2011, ApJ 737, 103S) the mean extinction for the region around the source position is A_V=7.38 mag, corresponding to A_K=0.87 mag, assuming the Cardelli et al. (1989, ApJ, 345, 245) extinction law.
VVV coordinates and magnitudes for the likely progenitor of Nova ASASSN-18ds are listed below. We note that the photometric flags indicate a possible contamination by an undetected blended source.
VVV ID: VVV J170347.58-381658.3
RA, DEC (J2000) = 17:03:47.559, -38:16:58.31
L, B = 347.3874, 1.9309
VVV multi-band data
Band Ks-mag Ks-err flag
Z = 17.381+/-0.017 +1
Y = 16.606+/-0.016 +1
J = 15.732+/-0.015 +1
H = 14.965+/-0.015 +1
Ks = 14.558+/-0.016 +1
VVV Ks-band variability data
MJD Ks-mag Ks-err flag
55374.21630277 14.558+/-0.016 +1
55428.14744049 14.544+/-0.023 +1
55434.14087105 14.550+/-0.022 +1
55766.21068887 14.520+/-0.029 +1
55769.20922439 14.568+/-0.027 +1
55780.11150854 14.536+/-0.022 -2
55803.01784942 14.534+/-0.023 +1
56090.22195304 14.555+/-0.021 +1
56096.16484719 14.465+/-0.020 +1
56105.07454494 14.515+/-0.026 +1
56112.07906054 14.475+/-0.018 +1
56114.01557428 14.568+/-0.022 +1
56115.04735228 14.516+/-0.020 +1
56126.22693012 14.556+/-0.024 +1
56470.24303955 14.585+/-0.025 +1
56473.14880138 14.558+/-0.020 +1
56474.08923339 14.540+/-0.021 +1
56486.13952338 14.539+/-0.021 +1
56497.09318649 14.584+/-0.024 +1
56511.03620023 14.549+/-0.024 +1
56512.05967214 14.540+/-0.024 +1
56512.17139243 14.553+/-0.024 +1
56513.05582285 14.522+/-0.024 +1
56513.13269333 14.596+/-0.025 +1
56514.08213266 14.603+/-0.029 +1
56515.06366720 14.484+/-0.023 +1
56522.02125391 14.525+/-0.023 +1
56524.11743066 14.505+/-0.022 +1
56525.05432194 14.528+/-0.023 +1
56525.12538349 14.547+/-0.023 +1
56526.06090606 14.592+/-0.025 +1
56527.07177302 14.532+/-0.022 +1
56536.99696866 14.612+/-0.036 +1
56537.04268127 14.539+/-0.026 +1
56537.11685762 14.523+/-0.025 +1
56538.00929730 14.542+/-0.024 +1
The VVV data are in the natural VISTA Vegamag system. Photometric flags are described in Saito et al. 2012 (A&A, 537, A107): -1 corresponds to a stellar object, whereas +1 to a non-stellar source.
We gratefully acknowledge use of data from the ESO Public Survey programme ID 179.B-2002 taken with the VISTA telescope, and data products from the Cambridge Astronomical Survey Unit. R.K., T.S.F. and R.K.S. acknowledge support from CNPq/Brazil.
