Swift J174510.8-262411: GROND discovery of a candidate near-IR counterpart
ATel #4380; Arne Rau, Fabian Knust, D. Alexander Kann, Jochen Greiner (all MPE Garching)
on 17 Sep 2012; 15:21 UT
Credential Certification: Arne Rau (arau@mpe.mpg.de)
Subjects: Optical, Transient, Variables
We observed the new transient Swift J174510.8-262411 / Swift trigger #533836 (Cummings et al. 2012, GCN 13744; Cummings et al. 2012, GCN #13745) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) at the 2.2m MPG/ESO telescope at La Silla Observatory (Chile). Observations were obtained on September 17th 01:40 UT and 03:49 UT for ~20min each and were compared to publicly available deep near-IR images obtained on June 24th 2011 as part of the VISTA Variables in the Via Lactea Survey (Minniti et al. 2010, New Astronomy, 15, 433; Saito et al. 2010, The Messenger, 141, 24).
Within the 5.8" Swift/XRT error circle (Cummings et al. 2012, GCN 13744) we identify a variable source in the GROND images that has brightened by approx. 3 magnitudes with respect to the deeper VISTA J-band image. We suggest this object to be the near-IR counterpart of Swift J174510.8-262411. Its position is
RA(J2000) = 17:45:10.82
Dec(J2000) = -26:24:12.7
with an uncertainty of 0"4 in both coordinates and it has an observed AB magnitude of
J~16.5 +/- 0.5
calibrated against 2MASS field stars. The high stellar density and moderate seeing (~1"9) lead to a rather large uncertainty in the photometry and an further analysis (e.g., multi-band magnitudes and spectral energy distribution) requires future observations under more favorable conditions.
An image of the field can be found here:
http://www.mpe.mpg.de/~arau/transients/swiftJ1745-2624.html
