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GCN Circular 29305

ZTF Discovery of ZTF21aaeyldq (AT2021any): a Hostless, Young, and Rapidly Fading Transient
2021-01-16T21:45:39Z (4 years ago)
Daniel Perley at Liverpool JMU <>
A. Y. Q. Ho (UC Berkeley), D. A. Perley (LJMU), Y. Yao (Caltech), and I. 
Andreoni (Caltech) report on behalf of the Zwicky Transient Facility 

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

08:15:15.34 -05:52:01.2 (J2000)
123.813909 -5.867007 (J2000)

and detected as part of 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).

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