Archival Chandra and HST observations of Swift J0045.2+4151
ATel #7187; A. K.H. Kong (National Tsing Hua University, Taiwan)
on 8 Mar 2015; 16:27 UT
Credential Certification: Albert Kong (akong@phys.nthu.edu.tw)
Subjects: Optical, X-ray, Gamma-Ray Burst, Soft Gamma-ray Repeater, Transient
We report on archival Chandra HRC-I observations of Swift J0045.2+4151 (also known as GRB 150301C; GCN #17512,#17516, ATel #7166,#7176,#7181). Chandra HRC-I observed the region of Swift J0045.2+4151 15 times for a total exposure of ~19 ks between 1999 and 2001 as part of an X-ray survey of M31 (see Williams et al. 2004, ApJ, 609, 735). The source with a position provided by a recent Chandra ACIS observation (ATel #7185) was not detected in the combined 19-ks HRC-I image with a 3 sigma 0.5-8 keV unabsorbed flux limit of 2.2e-14 erg/s/cm^2, by assuming an absorbed powerlaw model (N_H=7e20 cm^-2, Photon index=2). This flux limit is consistent with previous XMM-Newton measurements (ATel #7181) and a recent DDT Chandra detection (ATel #7185).
We also checked the Hubble Source Catalog (http://archive.stsci.edu/hst/hsc/) for the potential optical counterpart (GCN #17541,#17547). Within the 0.8 arcsec error circle derived by a recent Chandra observation (ATel #7181), there is one bright source detected with WFC3/UVIS with F275W=20.77+/-0.03 and F336W=20.67+/-0.05. This is apparently the proposed UVOT source associated with Swift J0045.2+4151. We visually inspected the HST images and note that there are at least 3 much fainter sources within the Chandra error circle. The true optical counterpart of Swift J0045.2+4151 may be a different source.
