AstroSat observation of SRGA J144459.2-604207 during a possible re-flare
ATel #16551; Aman Kaushik (Tata Institute of Fundamental Research), Yash Bhargava (Tata Institute of Fundamental Research), Sudip Bhattacharyya (Tata Institute of Fundamental Research)
on 22 Mar 2024; 06:43 UT
Credential Certification: Yash Bhargava (yash.bhargava_003@tifr.res.in)
Subjects: X-ray, Neutron Star, Transient, Pulsar
The new X-ray transient SRGA J144459.2-604207 was discovered with SRG/Mikhail Pavlinsky ART-XC telescope and reported on February 21, 2024 (ATel #16464). The source was also bright on February 17, 2024, at 10:27 and 22:50 UT which was found later in the MAXI/GSC Nova-Alert system (ATel #16469). The source has been followed up by various instruments (ATel #16469, #16470, #16471, #16474, #16475, #16476, #16477, #16483, #16485, #16487, #16495, #16510, #16511, #16548). SRGA J144459.2-604207 indicated millisecond pulsations (ATel #16474) and demonstrated type 1 X-ray bursts (ATel #16475, #16485) confirming the compact object as a Neutron Star.
Following an indication of re-flare in the MAXI lightcurve, we observed the source with AstroSat using the Soft X-ray Telescope (SXT) instrument in Photon Counting mode for a net exposure of 22 ks. This is the first AstroSat observation of this source. The spectrum was extracted in the energy range 0.3-10 keV and was above the background in 1-4 keV. The spectrum can be described by an absorbed blackbody with nH = 0.67*1022 cm-2 and a blackbody temperature = 0.47+/-0.02 keV. The absorbed flux in 0.3-10 keV is estimated to be 7.34*10-12 ergs/cm2/s while the unabsorbed flux in the same energy range is estimated to be 1.4*10-11 erg/cm2/s. We encourage further multi-wavelength observations if the re-flaring episode continues.
We would like to thank the AstroSat team and ISRO for their immediate efforts towards scheduling and observations of the source. Furthermore, we extend our gratitude to the SXT Payload Operation Centre for promptly processing the data.
