LEDA 735555: eROSITA detection of a flare in 2020-2022

ATel #17777; Arne Rau, Pietro Baldini, Andrea Merloni (all MPE)
on 7 May 2026; 06:57 UT
Credential Certification: Arne Rau (arau@mpe.mpg.de)

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We report on the eROSITA (Predehl et al. 2021) observations of LEDA 735555, for which a recent significant brightening has been reported by Einstein Probe (Hu et al., ATel#17775).

The source was observed during the five eROSITA all-sky surveys between 2020 and 2022 with typical net exposure times of ~250s per survey spread over approximately 1 day each. The source was detected in all observations, showing an initially steady flux increase by a factor of 9 over the first 1.5 years, but then faded again:

#MJD, UT, Flux
58895, 2020-02-06, (0.9+/-0.4) E-13 cgs
59075, 2020-08-14, (2.5+/-0.5) E-13 cgs
59246, 2021-02-01, (5.7+/-0.9) E-13 cgs
59435, 2021-08-09,(9.5+/-1.0) E-13 cgs
59617, 2022-02-07, (6.0+/-1.0) E-13 cgs

The fluxes are reported in the 0.5-10 keV band, and are derived by fitting the corresponding X-ray spectra with a powerlaw, taking into account Galactic absorption, and modeling the background.

When compared to optical lightcurves (e.g., ATLAS) the eROSITA lightcurve appears to show a flare coincident with AT 2021jbt (https://www.wis-tns.org/object/2021jbt/discovery-cert), but on broader timescales.