Swift/XRT position of SRGA J181414.6-225604
ATel #14528; Craig Heinke (Alberta), Tom Maccarone (Texas Tech), G. R. Sivakoff (Alberta), A. Bahramian(Curtin), J. Kennea (Penn State), J. Strader (Michigan State)
on 8 Apr 2021; 01:27 UT
Credential Certification: Tom Maccarone (thomas.maccarone@ttu.edu)
Subjects: Optical, X-ray, Binary, Transient
SRG's ART-XC and eROSITA telescopes recently detected a hard X-ray transient, SRGA J181414.6-225604, in the Galactic Bulge (ATel #14510), which was also detected by NICER (ATel #14527). The Palomar Gattini-IR survey detected rapid infrared variability from a bright (2MASS K_s=6.2) red (J=8.3) star in the error circle (ATel #14527), which was also coincident with IRAS 1811-2257. The WISE colors of this object (W1=5.47+-0.06,W2=4.87+-0.03, W3=3.99+-0.01 and W4=3.24+-0.02) also mark the object as unusually red, probably due to local dust (likely marking the object as a D-type symbiotic X-ray binary).
We report a Neil Gehrels Swift Observatory X-ray Telescope observation on April 7, 2021, of 895 seconds in photon-counting mode. One source is detected in the field, with a countrate of 0.06 counts/s (about 55 counts). The J2000 position of this source, using the Leicester tools for enhanced X-ray positions (Evans et al. 2009, MNRAS, 2009, 397, 1177) is:
RA: 18 14 14.77
Dec: -22 56 20.2,
with an error radius of 3.0â (at 90% confidence). Simultaneous Swift UVOT observations place an upper limit of 19.7 (Vega) mag in the UW1 band.
The X-ray position is 0.8â away from the position of the suggested variable infrared counterpart from ATel #14257, which was identified with IRAS 1811-2257 / 2MASS J18141475-2256195. This strongly supports the identification of the SRG X-ray transient with the variable infrared source.
An absorbed power-law model reasonably fits the Swift/XRT spectra, with N_H=(3+3/-2)*1e22, photon index of 1.0+1.1-0.9, and an unabsorbed 0.3-10 keV flux of (1.1+1.0/-0.3)*1e-11 erg/cm^2/s (90% confidence intervals). This is roughly consistent with the SRG and NICER flux estimates, and with a luminosity of about 8e34 (d/ 8 kpc)^2 erg/s.
We thank the Swift team for the rapid scheduling of this observation.
