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New nova candidate in M31 found with Swift/UVOT

ATel #9187; M. Henze (CSIC-IEEC), M. J. Middleton (Cambridge)
on 24 Jun 2016; 13:19 UT
Credential Certification: Martin Henze (henze@ice.cat)

Subjects: Ultra-Violet, Nova, Transient

Referred to by ATel #: 9408

We report the detection of a new nova candidate close to the M31 core detected in recent monitoring observations with the Swift satellite. The new object is clearly detected in a 1.5 ks UVOT observation on 2016-06-21.01 UT at a position of RA = 00h42m44.65s, Dec = +41o15'50.4" (J2000, 1σ statistical uncertainty of 0.2"). Its uvw1 (181-321 nm) filter magitude can be estimated as 18.1±0.3 mag. Nothing is visible at these coordinates in the preceding monitoring pointings of the field, with the latest non-detection on 2016-06-15.57 UT (0.7 ks) with a 3σ upper limit of uvw1 > 17.9 mag. Furthermore, no object can be found at this position in the U-band images of the Local Group Galaxies Survey (Massey et al. 2006).

We also detected UV emission from the nearby object M31N 2016-05b (ATel #9098), a recent Fe II class nova (ATel #9143). This nova was seen in the last three Swift observations on 2016-06-07.21 UT (uvw1 = 17.5±0.3 mag; 0.2 ks pointing), 2016-06-15.57 UT (uvw1 = 17.5±0.2 mag; 0.7 ks), and 2016-06-21.01 UT (uvw1 = 17.8±0.2; 1.5 ks). Nothing was detected in a 2.8 ks Swift/UVOT image taken on 2016-05-24.12 UT with a 3σ upper limit of uvw1 > 19.1 mag.

All magnitudes are in the UVOT photometric system (Poole et al. 2008) and have not been corrected for extinction. We wish to thank the Swift Team for making these observations possible, in particular N. Gehrels, the duty scientists as well as the science planners.