Continued monitoring of black hole transient 4U 1543-47 with SSM onboard AstroSat

ATel #14795; Ravishankar, B. T., Ramadevi, M. C., Vaishali, S., Abhilash, R. Sarwade (URSC), Dipankar Bhattacharya (IUCAA), Seetha, S. (RRI)
on 18 Jul 2021; 05:30 UT
Distributed as an Instant Email Notice Transients
Credential Certification: M. C. Ramadevi (mc.ramadevi@gmail.com)

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We report on the continued monitoring of the black hole X-ray binary 4U 1543-47 with SSM onboard AstroSat. SSM has been monitoring the source since MJD 59381. The first detection of the source was reported by MAXI (Negoro et al. ATel #14701) and has been reported to reach its Eddington luminosity on June 14, 2021 (Negoro et al. ATel #14708). Follow-up observations of the source in X-rays by NICER (Connors et al. ATel #14725) and LAXPC onboard AstroSat (Garg et al. ATel #14749) have also been reported.

The source has been found in the decay of the outburst and the flux has gradually fallen from ~4 Crab on MJD 59395 to ~2 Crab on MJD 59405 over two weeks. The intensity of the source in the energy band of 2.5 to 10 keV as on 2021-07-16 at 09:16:31.008 UT (MJD 59411.386470) is 4.7 +/- 0.8 photons/sqcm/s which is equivalent to ~1.9 Crab. The SSM lightcurve of the source from this preliminary analysis can be found at "http://astrosat-ssc.iucaa.in/4U1543-47"

The source will be continued to be observed with SSM. Follow-up observations with other missions are encouraged.

For comparison of the fluxes, this work has made use of MAXI On-demand 2.5 to 10 keV band data, provided by RIKEN, JAXA and the MAXI team. We are also thankful to the AstroSat team at ISTRAC/ISRO for enabling the observations of the source with SSM.

SSM lightcurve of Black Hole Transient 4U1543-47