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ATEL # 1758; R. P. Mignani (UCL-MSSL), N. Rea (U. Amsterdam), G.L. Israel, V. Testa (INAF-OAR), P. Esposito (INAF-IASF) on behalf of a larger collaboration
on 3 Oct 2008; 22:37 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Nanda Rea (N.Rea@sron.nl)
Subjects: Infra-Red, Request for Observations, Pulsars, Transients
On 2008 October 3rd, Swift-BAT triggered on several short bursts from the direction of the Anomalous X-ray Pulsar (AXP) 1E1547.0-5408 (Krimm et al. GCN 8311, 8312; Rea et al. Atel #1756). This is the second known transient radio AXP discovered to date (Gelfand & Gaensler 2007; Camilo et al. 2007), and it showed the previous X-ray outburst around June 2007 (Halpern et al. 2008).
During the decay of the 2007 X-ray outburst we observed 1E 1547.0-5408 in the Ks band (on 2007 July 8th, 12th, and August 17th) with the NAOS -CONICA (NACO) instrument mounted at the ESO- VLT (Mignani, Rea, Testa, et al., 2008 submitted). We have detected four objects close to the source error circle (labeled 1-4 in the finding chart available at http://staff.science.uva.nl/~nrea/ESO_VLT_1E1547.png ). The brightest one (object #3) has K= 16.22 +/-0.06, while objects #2 and #4 have K=18.51+/-0.06 and K=18.54+/-0.06, respectively. None of them was found to vary in the three nights. The faintest object, #1 (Ks = 20.3 +/- 0.07), was detected on the night of July 12th, 2007 only, although we could not claim any significant variability because the July 8th and August 17th observations were highly affected by bad atmospheric conditions. The source brightness is consistent with that of typical NIR counterparts of AXPs.
Given the X-ray re-activation of the AXP 1E1547.0-5408, NIR follow-ups would be crucial to assess with higher significance the possible variability of source #1, a candidate NIR counterpart to this transient AXP.
ESO-VLT NIR finding chart for the AXP 1E1547.0-5408