AstroNote 2024-242

During the night of 2024 August 31 (UT), the Zwicky Transient Facility (ZTF) detected a new optical transient ZTF24abefmrx at the following position (J2000):

RA, Dec = 21:44:29.64, +44:03:10.97 (326.123518, 44.053046)

The transient was found in the public survey, and reported to the Transient Name Server by Pérez-Fournon et al. (Report No. 223940) where it was assigned the name AT 2024uaq. The source was found at a low galactic latitude (b = -6.97), and was first detected on MJD 60553.27, at a magnitude r = 19.73 +/- 0.12 mag. Forced photometry at the position of the detection yielded a previous detection one day earlier on MJD 60552.26, at a magnitude r  = 21.2 +/- 0.3 mag. Therefore, the transient had brightened by 1.5 mag in one day. Subsequently, forced photometry run over the next few days showed that  ZTF detected the source on MJD 60554.38 at a magnitude r = 20.37 +/- 0.14, and on MJD 60556.30 at a magnitude r = 20.86 +/- 0.25 mag, showing the source was rapidly fading. 

Follow-up, host-subtracted photometry obtained with the Lowell Discovery Telescope (LDT) on MJD 60557.13 confirmed the rapidly fading nature of the source, with a magnitude r  = 21.07 +/- 0.05, showing a decay rate of around 0.25 mag/day. A g band observation was also obtained with LDT at a magnitude g = 21.61 +/- 0.06. 

The Galactic extinction along the line of sight of the source is E(B-V) = 0.37, and the extinction-corrected g-r color of the source at peak was g-r=-0.1 mag. The latest LDT observation showed the source had reddened, with a color g-r=0.4 mag. A faint galaxy can be seen at the position of the source in Pan-STARRS1 imaging, at a magnitude r~21.6 mag, and an offset of 1.05 arcseconds. We encourage further photometric and spectroscopic follow-up observations.

Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Grant No. AST-2034437 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, Deutsches Elektronen-Synchrotron and Humboldt University, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, and IN2P3, France. Operations are conducted by COO, IPAC, and UW.