TITLE:   GCN CIRCULAR
NUMBER:  17549
SUBJECT: Chandra X-ray observations of SWIFT J0045.2+4151 (aka Sw J0045 aka GRB 150301C aka p[PFH2005] 622)
DATE:    15/03/07 22:09:02 GMT
FROM:    David Burrows at PSU/Swift  <dnburrows@gmail.com>

Kari A. Frank (PSU), David N. Burrows (PSU), Alessandro Maselli (INAF-IASFPA), Phil Evans (U. Leicester), Chryssa Kouveliotou (GWU), Ersin Gogus (Sabanci Univ.), Daniele Malesani (DARK/NBI):


On Friday, March 6, 2014, beginning at 2015-03-06T16:29:31 (T0+468.4 ks relative to the Swift BAT trigger) we obtained a Chandra DDT observation at the position of the XMM-Newton source [PFH2005] 622 (Pietsch et al. 2005, ApJ 434, 483, ATel #7181), coincident with the BAT source SWIFT J0045.2+4151 (GCN #17512, GCN #17516, ATel #7166, ATel #7176).  Net exposure time was 9.94 ks. The source was detected at the > 10 sigma level, with a count rate of 0.0023 (-0.0011,+0.0012) counts/s in the 0.5-8 keV band (errors are 90% confidence).    

The Chandra source position is:

RA(J2000) = 00h 45m 14.78s
Dec(J2000) = +41d 50m 34.53s

with a 90% uncertainty of 0.8 arcsec.  A total of 23 source counts were detected. This position is consistent with the XMM position of [PFH2005] 622 and the XRT position (ATel #7166).

Assuming a powerlaw spectrum with photon index of 2, we find a flux 2.05e-14 (-0.97,+1.07) erg/cm^2/s (errors are 90% confidence).  This is about 10 times fainter than the flux measured in the first XRT observation (ATel #7166), and similar to the archival XMM fluxes for [PFH2005] 622 reported in ATel #7181, though it is brighter than the 6.9e-15 erg/cm2/s reported by Pietsch et al. (2005).

At the distance of M31, the observed flux corresponds to a luminosity of 9.5e35 erg/s.