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Magellan Near-IR Ks Imaging of the AXP 1E1547.0-5408 Field on 2009 Jan. 18

ATel #1904; Z. Wang (McGill), W. J. Fischer (Toledo), J. J. Tobin (Michigan), J. Hernandez
on 22 Jan 2009; 21:10 UT
Credential Certification: Z. Wang (wangzx@physics.mcgill.ca)

Subjects: Infra-Red, Transient, Pulsar

Referred to by ATel #: 1907, 1909

We observed the field of the anomalous X-ray pulsar (AXP) 1E1547.0-5408 on 2009 January 18, using the PANIC camera on the 6.5-meter Magellan/Baade telescope at Las Campanas Observatory in Chile. The on-source time was 17 min in Ks-band, resulting in a 3-sigma limiting magnitude of 20.1. Comparing our image with that reported by Gelfand & Gaensler (ApJ, 667, 1111), we detected three additional sources around the object that was found to be located within the Chandra error circle by them. In our image, the object had Ks = 16.0+/-0.05, consistent with their magnitude value. The nearby three sources had Ks = 18 - 20 mag, roughly consistent with what was reported by Mignani et al. (ATEL #1758). Given the very high extinction to the AXP (Halpern et al. 2008, ApJ, 676, 1178), it is likely that none of the three sources is the counterpart. Assuming that the X-ray flux has decreased by a factor of 7 since 2008 October 4 (Dib et al., ATEL #1770; R. Dib, private communication), we expect that the AXP would have Ks > 20.2 mag. Therefore, our observation was likely not deep enough. However, given the renewed activity in the AXP (GCN #8833, #8835), found four days after our observation, new near-IR observations of the field are encouraged, in case that the source has recently brightened.