Ultraviolet detections of three probable novae in M31

ATel #14716; David Modiano, Sill Verberne, Rudy Wijnands (Anton Pannekoek Institute for Astronomy)
on 15 Jun 2021; 09:39 UT
Credential Certification: David Modiano (d.modiano@uva.nl)

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Recently we initiated the Transient UV Objects (TUVO) project, in which we search for serendipitous UV transients in near-real time in Swift/UVOT data using a purposely-built pipeline. We report on UV observations (all performed using the uvw1 filter of the UVOT) of three probable novae which have been recently discovered in M31 and which we have also detected as part of our TUVO project. We detected the probable nova AT2021jwr (located at RA=00:42:46.560, Dec=+41:14:26.30; J2000; see TNS ID 82054) on 26 May at a magnitude of 18.9 +/- 0.1, on 9 June at a magnitude of 18.8 +/- 0.2, and on 13 June at a magnitude of 19.7 +/- 0.2. The last UVOT non-detection was on 3 March with a magnitude limit of < 20.8. The source was first detected from the ground on 15 April (TNS ID 82054) at a magnitude of 18 (clear filter). The brightness during the various detections suggests that this nova is decaying slowly. The second probable nova (AT2021pap; located at RA=00:43:05.89, Dec=+41:15:48.2; J2000; see TNS ID 85592 and ATEL #14682) was detected on 9 June at a magnitude of 19.3 +/- 0.2 and on 13 June at a magnitude of 19.1 +/- 0.1. The last UVOT non-detection was on 26 May with a magnitude limit of < 21. The source was detected from the ground (ATEL #14682) on 5 and 7 June in the R band at a magnitude of 18.3 +/- 0.2 and 17.0 +/- 0.1, respectively. We detected the third probable nova PNV J00425897+4118085 (located at RA=00:42:58.97, Dec=+41:18:08.5; J2000; see ATEL #14702) on 13 June at a magnitude of 17.82 +/- 0.08. The last UVOT non-detection was on 9 June with a magnitude limit of < 19.6. The source was detected from the ground (ATEL #14702) on 12 June in the R band at a magnitude of 17.5+-0.1. All UVOT magnitudes given are in the AB system. Further Swift observations in U and UV bands have been approved to monitor these sources in the coming weeks.