The onset of a new outburst from the millisecond X-ray pulsar IGR J17511-3057 as detected by INTEGRAL

ATel #17029; V. Sguera (INAF-OAS Bologna, Italy)
on 11 Feb 2025; 15:05 UT
Credential Certification: Vito Sguera (vito.sguera@inaf.it)

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IGR J17511-3057 is a millisecond X-ray pulsar whose last outburst was detected in March 2015 (ATel #7275).

During observations performed in the direction of the Galactic center from 10 Feb 2025 at 06:49 UTC to 11 Feb 2025 at 03:17 UTC, INTEGRAL detected a new hard X-ray outburst from IGR J17511-3057. The source was detected at 15 sigma level and 7 sigma level in the energy bands 28-60 keV and 60-100 keV, respectively. The effective exposure time is 19 ks. The measured X-ray fluxes are 16.8+/-1.2 mCrab or 1.4 x 10^-10 erg cm^-2 s^-1 (28-60 keV) and 21.2+/-3.1 mCrab or 1.7 x 10^-10 erg cm^-2 s^-1 (60-100 keV).

Previously, IGR J17511-3057 was in the field of view of INTEGRAL during observations performed from 7 Feb 2025 at 15:04 UTC to 8 Feb 2025 at 11:21 UTC for an effective exposure time of 13 ks. The source was not detected, and the corresponding 3 sigma upper limit is 5 mCrab or 4 x 10^-11 erg cm^-2 s^-1 (28-60 keV).

Further INTEGRAL observations in the direction of the source are planned for the following days, and simultaneous observations at other wavelengths are encouraged