VVV near-IR observations of V6585 Sgr progenitor

ATel #14625; T. S. Ferreira, R. K. Saito (Universidade Federal de Santa Catarina), D. Minniti (Universidad Andres Bello, Vatican Observatory)
on 14 May 2021; 13:38 UT
Credential Certification: Roberto Saito (saito@astro.ufsc.br)

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Following the spectroscopic follow-up observations of V6585 Sgr (a.k.a. PNV J17581670-2914490) by Taguchi et al. (2021, ATels #14513/#14514) and Bayless et al. (2021, ATel #14553) and later Swift observations by Sokolovsky et al. (2021, ATel #14535), we explored archival near-IR (NIR) images from the VVV Survey (vvvsurvey.org; Minniti et al. 2010, New Astron., 15, 433) of the Galactic bulge within the area containing the reported object.

A single source with flag "-1", indicating a stellar source in all five ZYJHKs NIR bands, was detected within 2 arcsecond radius from the target position as reported by Taguchi et al. (2021, ATel #14513), at coordinates:

 
RA  (J2000): +269.5702134 
Dec (J2000): -29.2469424 

and presenting the following NIR magnitudes (yyyy-mm-dd):

 
Z:  16.44+/-0.07 (2010-08-30) 
Y:  15.97+/-0.08 (2010-08-30) 
J:  15.24+/-0.06 (2011-05-09) 
H:  14.40+/-0.05 (2011-05-09) 
Ks: 14.11+/-0.05 (2012-03-26) 

Moreover, we searched for variability in the NIR data of V6595 Sgr progenitor making use of the Lomb-Scargle (LS; Lomb 1976, Ap&SS 39; Scargle 1982, ApJ 1:263) and the Phase Dispersion Minimisation methods (PDM, Stellingwerf 1978, Astrophysical. J. v224) across 101 VVV-DR4 Ks-band epochs over three years of observations, from September 2010 to September 2013. The object shows a low significance, likely periodic signal of period P_LS = 0.2841 days and P_PDM = 0.2920 days, with an amplitude of Delta_Ks ~ 0.2 mag in both methods.