Chandra Location of SGR 0501+4516
ATel #1824; Peter Woods (Dynetics), Ersin Gogus (Sabanci Univ), and Chryssa Kouveliotou (MSFC) report on behalf of a larger collaboration
on 30 Oct 2008; 22:36 UT
Credential Certification: Peter Woods (Peter.Woods@dynetics.com)
Subjects: Infra-Red, X-ray, Neutron Star, Soft Gamma-ray Repeater, Pulsar
Referred to by ATel #: 1837
The recently discovered Soft Gamma Repeater SGR 0501+4516 (Barthelmy et al. GCN 8113) was observed with the Chandra HRC-I on 2008 September 25 for an exposure of 10ks. The resulting image revealed two X-ray point sources - SGR 0501+4516 and a previously uncatalogued X-ray source (CXOU J050111.3+451525) displaced by 1.4 arcmin from the SGR location. The locations of these two sources are the following:
SGR 0501+4516
RA = 05h 01m 06.756s
DEC = +45d 16m 33.92s
CXOU J050111.3+451525
RA = 05h 01m 11.327s
DEC = +45d 15m 25.28s
A search through the 2MASS catalogue revealed only one object (2MASS 05011132+4515252) within 10 arcsec of CXOU J050111.3+451525.
2MASS 05011132+4515252
RA = 05h 01m 11.328s
DEC = +45d 15m 25.25s
The location for this 2MASS star has a quoted uncertainty of 0.06 arcsec. The statistical uncertainty of the X-ray location of CXOU J050111.3+451525 is 0.09 arcsec (22 source counts). The X-ray and IR locations are well within the uncertainties, thus CXOU J050111.3+451525 is very likely the X-ray counterpart to 2MASS 05011132+4515252. Given the excellent alignment between these two localizations of presumably the same object, we estimate the absolute positional uncertainty of SGR 0501+4516 to be 0.11 arcsec (1 sigma). This position is consistent with the variable IR source discovered by Tanvir et al. (GCN 8126), thus confirming this object as the IR counterpart to SGR 0501+4516.
We thank Allyn Tennant for useful discussions and Harvey Tananbaum and the Chandra team for carrying out this ToO observation.
