GROWTH-India Telescope pre-discovery detection and follow-up of the M31 Nova AT2022acwk
ATel #15864; Judhajeet Basu (IIA), Vishwajeet Swain (IITB), Harsh Kumar (IITB), Sudhanshu Barway (IIA), G. C. Anupama (IIA), Varun Bhalerao (IITB) (on behalf of the GIT team)
on 19 Jan 2023; 06:50 UT
Distributed as an Instant Email Notice Novae
Credential Certification: Sudhanshu Barway (sudhanshu.barway@iiap.res.in)
We report the pre-discovery detection and follow-up magnitudes of the M31 nova AT2022acwk (ATel #15863 ) based on our M31 survey with the 0.7 m GROWTH-India Telescope (GIT). Nova AT2022acwk was discovered at mag 16.377 by ATLAS bot (https://www.wis-tns.org/object/2022acwk) on 13th Dec 2022 07:58 UTC. Our M31 data from 12th Dec 2022 revealed the source to have a magnitude of 17.50 (r' filter) and 17.46 (g' filter) on 12th Dec 18:00-19:00 UTC which brightened to 16.48 (r' filter) and 16.34 (g' filter) on 13th Dec 17:45-18:30 UTC, suggesting that the optical peak could be somewhere between 08:00-18:30 UTC on 13th Dec 2022. The nova rapidly rose at a rate of ~1 mag/day towards maximum, and then faded quickly by ~2 mags in 3 days before flaring again, with an increase in the magnitude by ~0.5 mag on 20th Dec and 31st Dec in its r' filter lightcurve. We have observations from 12th Dec 2022 till 5th Jan 2023. Further observations of AT2022acwk are underway to determine the lightcurve class.
The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.
The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/ .
