AstroNote 2022-270

We report the discovery of the fast, blue optical transient ZTF22acaruqr/AT2022adzb with the Zwicky Transient Facility (ZTF, Bellm et al. 2019, Graham et al. 2019) at coordinates:

RA = 08:18:03.60 (124.5150135d)

Dec = +55:19:20.43 (55.3223413d)

ZTF22acaruqr was first detected on 2022-12-22 06:42 UT at r = 20.6 ± 0.2 mag. The last ZTF upper limit before the first detection was measured on 2022-12-21 10:28 UT in r-band. ZTF22acaruqr was also detected in i-band a few hours later at 2022-12-22 09:51 UT at i = 20.6 ± 0.2 mag. Since detection, ZTF22acaruqr has faded ~1 magnitude, with an r-band detection at 2022-12-23 09:17 with r = 21.7 ± 0.1 mag. The color at the observed peak therefore appears to be red, with the near-simultaneous g-band limit of g > 20.5 at 2022-12-22 07:55 UTC, from forced PSF photometry.

There is no cataloged source at the transient location in deep Legacy Survey DR9 and Pan-STARRS (Chambers et al., 2016) archival images. The Galactic extinction on the line of sight is E(B-V)=0.05 mag (Planck Collaboration et al., 2014). The source is located at Galactic coordinates of l, b = 162.666742 deg, 34.18 deg.

We caution that the observed light curve behavior and moderate Galactic latitude could indicate that ZTF22acaruqr is a Galactic cataclysmic variable. However, we find an extragalactic origin for the transient more likely based on the information currently available.

We note that Fermi trigger 693355175 occurred in close time-proximity to ZTF22acaruqr (detection at 2022-12-21 22:39 UT), although the associated skymap is not consistent at the 95% level, so it is likely unrelated.

Follow-up observations with the Neil Gehrels Swift Observatory were requested by our team. Additional follow-up observations are encouraged.

ZTF22aayluxo was discovered by the ''ZTF Realtime Search and Triggering'' project (ZTFReST; Andreoni & Coughlin et al., 2021) within the ZTF Collaboration.

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.