AstroNote 2024-272

AT2024wpp was initially detected by the Zwicky Transient Facility (ZTF) in alert forced photometry on MJD 60578.43651 (2024-09-25 10:28:34) at g=20.78 +/- 0.27 mag (a 4-sigma detection; internal name ZTF24abjjpbo). One night later, it had brightened by 3 magnitudes and exhibited blue colors (g-r=-0.4 mag). It was flagged as a transient of interest due to the rapid rise and proximity of 3” to a diffuse galaxy in the Legacy Survey 9th data release with a photo-z of 0.11 +/- 0.05 (68% confidence; Zhou et al. 2023). 

We obtained ugriz imaging with the IO:O instrument on the 2m Liverpool Telescope (LT; at MJD 60580.05216), as well as spectroscopy with SPRAT (on LT; MJD 60580.18196) and with the Goodman High Throughput Spectrograph on the 4m SOAR telescope (MJD 60580.16631). The spectra show a featureless blue continuum. 

We obtained a Swift ToO observation totaling 3.5ks beginning at MJD 60580.40419. We tentatively identify a source consistent with the optical transient position. However, due to a cosmic ray there is a hot line in the image that passes through the source position, so additional observations will be needed for verification.

We encourage additional multiwavelength 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 Oskar Klein Center at Stockholm University, the University of Maryland, University of California, Berkeley , the University of Wisconsin at Milwaukee, University of Warwick, Ruhr University Bochum, Cornell University, Northwestern University and Drexel University. Operations are conducted by COO, IPAC, and UW.