TITLE:   GCN CIRCULAR
NUMBER:  27779
SUBJECT: GRB 200522A: Coincident catalogued galaxy at z~0.4
DATE:    20/05/22 14:05:54 GMT
FROM:    Wen-fai Fong at Northwestern U  <wfong@northwestern.edu>

W. Fong, K. Paterson (Northwestern) and E. Berger (Harvard) report:

"We searched the location of the short GRB 200522A (GCN 27778; Evans et al.) in the SDSS DR12 and PS1-3Pi surveys at the XRT afterglow candidate position. The current XRT position fully encompasses a catalogued galaxy in both SDSS and PS1-3Pi, with a position of RA = 0:22:43.717, Dec = -0:16:57.52 (Alam et al. 2015, Chambers et al. 2016). This galaxy has SDSS magnitudes* of u = 22.55, g = 22.11, r = 21.17, i = 20.87, z = 20.69 mag. The SDSS photometric redshift estimate is z_phot = 0.4 +/- 0.1.

Adopting r=21.17 mag and the XRT positional uncertainty, we estimate a probability of chance coincidence of ~0.01. If the association to this galaxy is correct, pending the precise position of the GRB afterglow, this would place GRB 200522A in lower 35% of the Swift short GRB redshift distribution (c.f., Fong et al. 2017, Gompertz et al. 2020).

Follow-up, where possible, is highly encouraged."


* Information pulled from SDSS: http://skyserver.sdss.org/DR12//en/tools/explore/summary.aspx?id=1237663783662977850