Optical Observations of EXO 0748-676 in Quiescence
ATel #1816; Robert Hynes, Erica Jones (Louisiana State University)
on 28 Oct 2008; 19:02 UT
Credential Certification: Robert Hynes (rih@phys.lsu.edu)
Subjects: Infra-Red, Optical, Binary, Neutron Star, Transient
EXO 0748-676 has been reported to be in X-ray quiescence by Wolff et
al. (ATEL #1812). We performed optical (R band) and near-IR (J band)
observations of the optical counterpart, UY Vol, on 2008 October 28.33
using Andicam on the SMARTS 1.3m telescope. We obtained a total of
1350 sec exposure in R and 1000 sec in J. The observations
corresponds to binary orbital phases 0.38-0.49.
The counterpart is detected in R but clearly considerably fainter
than previously observed. From our preliminary photometry, we
estimate R=21.9+/-0.1. No counterpart is visible in the J band
images.
The quiescent position measured relative to nearby stars agrees with
that previously measured in the bright state using the same instrument
to better than 0.2 pixels (0.1 arcsec) so we believe this is indeed
the X-ray binary rather than a previously undetected interloper.
We will continue to monitor the source.
