OGLE-IV Pre-discovery Observations of Two Recent Galactic Novae

ATel #9683; P. Mroz, A. Udalski, P. Pietrukowicz (Warsaw University Observatory), on behalf of the OGLE team
on 28 Oct 2016; 10:51 UT
Credential Certification: Przemek Mroz (pmroz@astrouw.edu.pl)

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Two classical novae located toward the Galactic bulge were recently discovered. Both objects are located in the area that is regularly monitored by the OGLE-IV Survey.

TCP J18102829-2729590 (CBET 4332; ATel #9658) was discovered on 2016 Oct. 20.383 UT. The object is located in the OGLE-IV field BLG519. The star was saturated in the image acquired on 2016 October 20.98993 UT, meaning it was brighter than I=11 mag. The last pre-eruption image was taken on October 14.01912 UT. We measured the equatorial coordinates of the nova of R.A. = 18:10:28.29, Decl. = -27:29:59.3 (J2000.0). The progenitor is undetected in the OGLE deep template image, meaning I > 22 mag. Finding charts can be found here.

ASASSN-16ma (ATels #9669, #9678, #9680) is located in the OGLE-IV field BLG531. We measured the nova centroid on two 10-s exposures acquired on October 27: R.A. = 18:20:52.25, Decl. = -28:22:12.1 (J2000.0). The accuracy of astrometric transformations is about 0.1 arcsec. The progenitor is undetected in the OGLE deep template image, meaning I > 22 mag. Saito et al. (ATel #9680) proposed that star VVV J182052.14-282212.8 is the pre-nova. That star is located 1.6 arcsec from the nova and it cannot be the progenitor. Finding charts can be found here.

Precise I-band photometry of the star will be available via the OGLE CVOM system once the stars fade below the saturation limit.