Near-IR source content of the error region for SWIFT J174540.7-290015

ATel #8689; Deno Stelter (University of Florida), Stephen Eikenberry (UF), Alan Garner (UF), Yigit Dallilar (UF), Amy Gottlieb (UF)
on 12 Feb 2016; 22:30 UT
Credential Certification: Stephen Eikenberry (eiken@astro.ufl.edu)

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We present broadband NIR photometry of three sources in response to the Swift trigger for the Galactic Center transient SWIFT J174540.7-290015 ( ATEL #8649 ), as a baseline reference for possible NIR variable counterpart searches.

We cross-referenced the source position to the ISPI catalog of NIR point sources made with observations from the CTIO 4m Blanco Telescope on 10 August 2005 with the ISPI instrument (DeWitt et al, 2010). This is a highly-crowded and high-extinction area of the Galactic Center, and there are many possible sources below the confusion limit in the 2.2-arcsec 90% confidence circle from Swift. However, we also find 3 resolved NIR point sources detected above the confusion limit within the SWIFT 90% confidence circle.

We find one source with matching detections in all 3 bands of the catalog (JHKs):

J: 17.161 (0.074) mag

H: 12.804 (0.016) mag

Ks: 10.54 (0.018) mag

We find one source with matching detections in only H and Ks bands:

H: 14.119 (0.020) mag

Ks: 11.65 (0.015) mag

We find one source with a detection in Ks-band only:

Ks: 11.809 (0.050) mag

We note that both sources with color information appear to be slightly redder than average for the Galactic Center region, which would seem to indicate either higher local extinction in this area, or else locations of the sources at the farther side of the Galactic Center region.

For the unresolved background, our 50% completeness limits were calculated using artificial star tests and are typically:

J: 18.4 mag

H: 16.4 mag

Ks: 14.5 mag

References:

DeWitt, C., Bandyopadhyay, R.M., Eikenberry, S.S., Blum, R., Olsen, K., Sellgren, K., Sarajedini, A., ApJ, 2010, 721, 1663 (doi: http://dx.doi.org/10.1088/0004-637X/721/2/1663 )