C. Sanchez-Fernandez (ESAC/ESA, Spain), E. Kuulkers (ESTEC/ESA, The Netherlands), C. Ferrigno (ISDC, Switzerland), J. Chenevez (DTU, Denmark), M. Del Santo (INAF/IASF, Italy), on behalf of a larger collaboration
ATel #16507; C. Sanchez-Fernandez (ESAC/ESA, Spain), E. Kuulkers (ESTEC/ESA, The Netherlands), C. Ferrigno (ISDC, Switzerland), J. Chenevez (DTU, Denmark), M. Del Santo (INAF/IASF, Italy), on behalf of a larger collaboration
on 6 Mar 2024; 15:56 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Celia Sanchez-Fernandez (celia.sanchez@sciops.esa.int)
Subjects: X-ray, Request for Observations, Neutron Star, Transient, Pulsar
Referred to by ATel #: 16510
Following the INTEGRAL detection of quasi-periodic thermonuclear burst activity from the accreting millisecond X-ray pulsar SRGA J144459.2-60420 on (UT) 2024-02-24 09:31:21 - 2024-02-25 02:51:28 (ATel #16485; see also #16464, #16469, #16474, #16480, #16493, #16495) follow-up INTEGRAL observations of the target were conducted in the periods: (UT) 2024-02-26 14:22:37 - 2024-02-27 21:16:05 and (UT) 2024-02-29 09:10:30 - 2024-03-01 11:25:14.
Quasi-periodic thermonuclear burst trains were also detected these new observations. The burst recurrence times are stable during a single observation (with a typical duration 90 ks). However, in the combined data-set an overall decrease in the burst frequency is observed together with a decrease in the persistent emission. This is indicative of an evolution of the burst recurrence time in response to a decreasing mass accretion rate onto the neutron star.
The average persistent fluxes and burst recurrence times derived from these observations are as follows.
2024-02-24 09:31:21 - 2024-02-25 02:51:28(UT), 3-25 keV: 98 +/- 67 mCrab; 28-40 keV: 95 +/- 50 mCrab; Burst rec: 1.7h
2024-02-26 14:22:37 - 2024-02-27 21:16:05(UT), 3-25 keV: 80 +/- 59 mCrab; 28-40 keV: 93 +/- 50 mCrab; Burst rec: ~2.0h
2024-02-29 09:10:30 - 2024-03-01 11:25:14(UT), 3-25 keV: 77 +/- 52 mCrab; 28-40 keV: 67 +/- 46 mCrab; Burst rec: 2.9h
We caution that the fluxes quoted here are based on near real time data, and could be refined.
Further observations of the source are encouraged. We thank the INTEGRAL Mission Operations and Science Operations teams for the prompt implementation of these observations.
