VVV near-infrared observations of the Swift J174540.2-290037 field
ATel #9152; N. Masetti (INAF/IASF, Bologna), R. K. Saito (Univ. Federal de Sergipe), A. F. Rojas, D. Minniti (UNAB, Santiago) & R. Contreras (PUC, Santiago)
on 14 Jun 2016; 16:47 UT
Credential Certification: Nicola Masetti (masetti@iasfbo.inaf.it)
Subjects: Infra-Red, X-ray, Transient
We explored the archival images of the near-infrared (NIR) VVV survey (vvvsurvey.org; Minniti et al. 2010, New Astron., 15, 433) of the Galactic Bulge and inner disk, obtained with the 4.1m VISTA telescope at Cerro Paranal (Chile), containing the soft X-ray error box the transient Swift
J174540.2-290037 (ATel #9109) that was recently detected with Swift (see also GCN Circs. #19499, #19505, #19514, #19515, #19516, #19518 and #19521).
Our aim was to search for the presence of (possibly variable) NIR objects within the 3.7 arcsec-sized Swift/XRT error circle of the source.
JHKs images were acquired on 15 August 2010 between 03:23 and 03:32 UT under an average seeing of 0.9 arcsec. Further Z- and Y-band frames were secured on 24 August 2011 between 02:46 and 02:51 UT with a seeing of 1.0 arcsec. Exposure times were 24 s in the J band, 8 s in both H and Ks, and
20 s in both Z and Y bands; the image scale is 0.34 arcsec/pixel for all frames.
Two NIR sources with incomplete photometry were found within the XRT error circle. Ordered by distance from the soft X-ray centroid, their coordinates and magnitudes are the following:
Source #1 (d=1.75 arcsec)
RA = 17 45 40.33
Dec = -29 00 39.4
J = 17.27+-0.05
H = 12.42+-0.01
Source #2 (d=2.39 arcsec)
RA = 17 45 40.44
Dec = -29 00 37.4
Z = 20.1+-0.2
Y = 19.4+-0.2
H = 13.31+-0.01
Coordinate errors are +-0.1 arcsec at 1 sigma confidence level.
We remark that this region is extremely crowded even in the NIR, and no claim on the variability and on the association of any of these two sources with the X-ray transient can be made at this stage.
