Candidate near-infrared counterpart to SAX J1753.5-2349
ATel #2526; M. A.P. Torres (CfA), P. G. Jonker (SRON/CfA), D. Steeghs (Warick/CfA), J. Chaname (Carnegie/DTM)
on 31 Mar 2010; 00:17 UT
Credential Certification: Manuel Torres (mtorres@cfa.harvard.edu)
Subjects: Infra-Red, Binary, Neutron Star, Transient
Referred to by ATel #: 2540
We report on near-infrared follow-up observations of the field
containing the currently active X-ray transient SAX J1753.5-2349
(Chenevez et al. ATel #2505).
Our observations consist of a series of 15s Ks-band images totalling
450s on source and acquired on 2010 Mar 27 09:19 - 09:31 UT with the
PANIC camera mounted on the 6.5m Baade telescope at Las Campanas
Observatory. The observations were performed during good sky
conditions and with 0.35" seeing. Additional 3s exposures were acquired to
derive an astrometric and absolute flux calibration of the data using
2MASS objects in the field of view. This delivered a positional RMS
< 0.1" and a photometric zero point accuracy of ~ 0.1 mag.
We searched for counterpart candidates within the 2.3" Swift X-ray
position for SAX J1753.5-2349 (Starling & Evans 2008, ATel #1814). To do this
we compared our data to pre-outburst imaging obtained in 2007 May
and available from the UKIDSS survey (http://www.ukidss.org). Our
mosaic image shows a Ks = 15.63 +/- 0.01 mag point-like source at R.A
(J2000)=17:53:31.89, Dec (J2000)=-23:49:14.8. The UKIDSS images show
no evidence for this object, indicating it was much fainter at the
time. We estimate Ks > 17.8.
We consider this variable source the likely near-infrared
counterpart to SAX J1753.5-2349.
Finding chart
