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Three overlooked novae from the OGLE-IV sky survey

ATel #6406; P. Mroz, A. Udalski (Warsaw University Observatory, Poland), on behalf of the OGLE team
on 20 Aug 2014; 14:26 UT
Credential Certification: Przemek Mroz (pmroz@astrouw.edu.pl)

Subjects: Optical, Nova, Transient

We report the discovery of three overlooked novae located toward the Galactic bulge, very close to the galactic plane. Novae were found in data from the Optical Gravitational Lensing Experiment (OGLE) in the course of a search for cataclysmic variables. Eruptions occurred in 2010 and 2011.

A location of OGLE-2010-NOVA-01 is (RA,DEC) = (17:54:34.76, -23:32:21.5) J2000.0 or (l,b) = (5.66285, 1.04546), 3 arcsec from a bright star (I~13.4 mag). In the image taken on 2010 June 26.34391 UT, the nova was already overexposed. In the previous frame, taken on 2010 June 17.32489 UT, no progenitor could be detected (so it must have been fainter than I>21.2 mag). The star declined quickly on a timescale t_3~10 d. ~80 days after the peak, it faded below the detection limit. Following the classification scheme of Strope et al. (2010, AJ 140, 34), the nova is of S(10) type.

The next star, OGLE-2010-NOVA-02, is located at (RA,DEC) = (17:36:59.70, -29:08:14.9) J2000.0 or (l,b) = (358.83201, 1.49351). The eruption started between 2010 September 26.03510 UT and 2010 October 03.00293 UT, given the non-detection on the former frame. In the pre-explosion images, the nearest star is faint (I~19 mag) and located 1.0 arcsec SE from the nova position. The progenitor must have been fainter than I>21.2 mag. The decline is very slow with t_3~180 d; the nova faded below the detection limit in 2014, ~3 years after the eruption. The light curve is smooth with some oscillations (amplitude 0.5 mag) ~150 d after the peak.

OGLE-2011-NOVA-02 has coordinates (RA,DEC) = (17:36:59.57, -29:51:56.2) J2000.0 or (l,b) = (358.21729, 1.10300). In the first image in 2011 season, taken on February 10.35534 UT, the nova had an I-band magnitude of ~13.1 mag. In the previous frame, taken in 2010 October, no progenitor could be detected - the eruption occurred during a seasonal gap. The decline timescale is t_3<~60 d. The light curve is smooth with some oscillations (amplitude 0.5 mag) in 2011 February.

We used the VVV extinction map (Gonzalez et al., 2012, A&A 543, 13) to find color excess E(J-Ks) in 2 arcmin regions around novae:

Name E(J-Ks)
OGLE-2010-NOVA-01 1.04
OGLE-2010-NOVA-02 0.92
OGLE-2011-NOVA-02 1.13

Neither infrared nor X-ray counterparts to our objects were found in HEASARC and IRSA archives.

Finding charts and light curves are available here.