AstroNote 2021-20

The Zwicky Transient Facility (ZTF; ATel #11266) reports the discovery last night of ZTF21aaeyldq (AT2021any), a rapidly fading optical transient located at:

and detected in the high-cadence partnership survey by a filter designed to find fast transients (Ho et al. 2020, ApJ, 905, 2). 

The source was discovered on UT 2021-01-16T06:59:45.6 at r=17.9 mag, only 22 minutes after the last non-detection (limiting mag r~20.28). Two additional r-band observations over the next 3.3 hours revealed rapid fading by 2 magnitudes. No counterpart is visible in deep Legacy Survey pre-imaging (>24 mag; Dey et al. 2019, ApJ, 157, 5). 

The color of the transient is moderately red (g-r~0.3 mag).  While the source is close to the Galactic plane (+16 deg), extinction along the line of sight is low (E(g-r)~0.07 mag; Schlafly et al. 2011, ApJ, 737, 2).

We urge additional multi-band photometry to establish the rate of fading and color of this transient.

ZTF is a project led by PI S. R. Kulkarni at Caltech (see ATEL #11266), and includes IPAC; WIS, Israel; OKC, Sweden; JSI/UMd, USA; UW,USA; DESY, Germany; NRC, Taiwan; UW Milwaukee, USA and LANL USA. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. Alert distribution service provided by DIRAC@UW. Alert filtering is done with Kowalski (Duev et al. 2019), the GROWTH marshal system (supported by NSF PIRE grant 1545949), and by Fritz (van der Walt et al. 2019, Duev et al. 2019, Kasliwal et al. 2019).