AstroNote 2024-209

The transient AT2024qfm was first detected by ZTF on 2024 July 24 UT (MJD 60515.41087) with an initial magnitude of r = 19.57 +/- 0.22 mag.  Additional ZTF observations between July 27-29 showed evidence of fading from the initial detection, and on July 29 the source was saved as a fast transient candidate by human scanners monitoring the ZTF fast-transient filter (Ho et al. 2022) and the ZTFRest filter.  The source was also independently identified and reported as a fast transient candidate using Fastfinder (Fulton et al., AstroNote 2024-206).

We triggered Liverpool Telescope imaging observations using IO:O in the griz filters, which were taken on the nights of July 29 and 30 (local time).  Conditions were good throughout both sequences, although most images were affected by stability problems with the secondary mirror and show extended, very asymmetric PSFs.

We have carried out preliminary image subtraction and photometry of the images, using Pan-STARRS as a reference.  The data are consistent with a continued decline of the light curve and have maintained a blue post-peak colour, consistent with previous luminous FBOTs such as AT2018cow and AT2020xnd (e.g. Perley et al. 2019, MNRAS, 484, 1031; Perley et al. 2021, MNRAS, 508, 5138).

Photometry from our first LT epoch gives the following magnitudes:

The photometry is consistent with the Lulin 1m observations by Lai et al. (AstroNote 2024-208).

Further imaging observations and spectroscopy are planned.