GCN Circular 31594
Subject
ZTF22aaajecp/AT2022cmc: Liverpool Telescope photometry
Event
Date
2022-02-15T23:25:52Z (5 years ago)
From
Daniel Perley at Liverpool JMU <d.a.perley@ljmu.ac.uk>
D. A. Perley (LJMU) reports:
We acquired multicolor imaging of the fast optical transient ZTF22aaajecp (AT2022cmc; Andreoni et al. 2020, GCN 31590) using the IO:O camera of the 2m robotic Liverpool Telescope. The afterglow was observed across four separate epochs in g, r, i, and z filters during the night ending 2022-02-15 UT, with the first epoch beginning at 00:50 and the last at 05:54. The images show a clear detection of the transient in all bands. Photometry with reference to SDSS secondary standard stars in the field gives the following magnitudes during the final epoch:
MJD dt(d) filter mag unc
59625.2461 3.8003 g 20.72 0.16
59625.2501 3.8042 r 20.17 0.09
59625.2540 3.8082 i 20.16 0.07
59625.2580 3.8121 z 19.91 0.11
The dt column above is the time in days after the first detection as reported by Andreoni et al. (2022-02-11 10:42 UT).
The SED is consistent with a power-law with an index of beta=-1 (f_nu ~ nu^beta), similar to GRB afterglows. This provides additional evidence in support of the interpretation of this event as a relativistic cosmological explosion (see also Perley et al., GCN 31592). Spectroscopic confirmation is still required.
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