Confirmation of the NIR counterpart to IGR J17511-3057
ATel #2233; M. A.P. Torres (CfA), P. G. Jonker (SRON/CfA), D. Steeghs (Warwick/CfA), I. Damjanov (Toronto Univ.), E. Caris, K. Glazebrook (Swinburne U. of Technology)
on 9 Oct 2009; 12:10 UT
Credential Certification: Manuel Torres (mtorres@cfa.harvard.edu)
Subjects: Infra-Red, Binary, Neutron Star, Transient, Pulsar
We report follow-up observations confirming the near-infrared (NIR)
counterpart to the newly discovered accreting millisecond pulsar
IGR J17511-3057 (Baldoven et al. 2009, ATel #2196; Markwardt et
al. 2009, ATel #2197). A Ks~18 mag candidate counterpart was
suggested in Torres et al. (ATel #2216) on the basis of its coincidence
with the Chandra localization of the X-ray source (Nowak et al. 2009,
ATel #2215). The candidate counterpart is not present in UKIDSS pre-outburst
imaging of the field containing IGR J17511-3057.
Our observations consist of a series of Ks-band images obtained
with the 6.5m Magellan Baade telescope between 2009 Oct 7 00:08-00:21
UT using the PANIC camera and totaling 450s on source. The seeing was
0.5 arcsec during the observations. Photometric and astrometric
scales were defined with the same 2MASS references used in ATel
#2216.
The images show that the proposed counterpart candidate has faded
significantly during the observations to Ks > 18.8 (3-sigma upper limit
magnitude). This large photometric variability confirms
the candidate reported in ATEL #2216 as the NIR counterpart to IGR
J17511-3057.
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