INTEGRAL hard X-ray non-detection of the new transient MAXI J1735-272
ATel #14985; V. Sguera (INAF-OAS Bologna, Italy), L. Sidoli (INAF-IASF Milano, Italy)
on 19 Oct 2021; 17:42 UT
Credential Certification: Vito Sguera (sguera@iasfbo.inaf.it)
Subjects: X-ray, Transient
The sky region of the X-ray transient MAXI J1735-272, recently discovered by MAXI/GSC on
17 October 2021 (ATel #14979), was covered by INTEGRAL public ToO observations of 4U 1820-30
carried out from 17 October 2021 at 11:23 to 18 October 2021 03:02 (UTC).
MAXI J1735-272 was not detected by IBIS/ISGRI in the energy band 25-60 key (2.3 ks on-source exposure), the derived 3 sigma upper limit is about 13 mCrab or 1.1 x 10 -10 erg cm-2 s-1. This could indicate a very short decay time for the new transient, as suggested by Swift follow-up as well (ATel #14983). In addition, we note that the closest source to MAXI J1735-272 detected by IBIS/ISGRI above 20 keV is SLX 1735-269, located about 16 arcminutes outside the MAXI uncertainty ellipse.
Previously to its discovery, MAXI J1735-272 was in the field of view of INTEGRAL during public ToO observations of
V4641 Sgr performed from 15 October 2021 at 21:39 to 16 October 2021 at 22:52 UTC (5 ks on-source exposure).
Also on this occasion, MAXI J1735-272 was not detected by IBIS/ISGRI in the energy band 25-60 keV and the corresponding 3 sigma upper limit is about 8 mCrab or 7.3 x 10
-11 erg cm
-2 s
-1.