2MASS J18455462-0039341 / Swift J1845.7-0037 is a double star
ATel #13218; Iain A Steele (Liverpool JMU)
on 23 Oct 2019; 14:00 UT
Credential Certification: Iain Steele (iainsteele@mac.com)
Subjects: Infra-Red, X-ray, Binary, Neutron Star, Transient, Variables
I performed infrared (H band) imaging of the field of the suggested optical counterpart (2MASS J18455462-0039341) to the X-ray transient Swift J1845.7-0037 / MAXI J1847-004 (ATel #4130, #13191, #13189, #13195, #13208) which is suggested as the Be star counterpart of the system by SED fitting (ATel #13211).
Observations were obtained using the IO:I camera of the 2.0m Liverpool Telescope on the night of 2019 Oct 22.
In my images the 2MASS source is clearly resolved into a double star with separation ~ 1.5 arcsec. The 2MASS position is midway between the two objects, indicating that the 2MASS magnitudes (and likely the IR magnitudes from other surveys) are a combination of the fluxes from the two objects and that caution should be used when carrying out SED fitting in this case.
The two objects (which I designate here A and B) have J2000 coordinates:
Object A: RA = 18:45:54.67 DEC -00:39:34.3
Object B. RA = 18:45:54.58 DEC -00:39:34.0
With respect three other 2MASS sources in our images, I measure magnitudes of H=15.0 and H=15.3 for the objects A and B respectively (compared with the 2MASS value of H=14.59).
Liverpool Telescope
