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eROSITA’s first all-sky image

Recently the first all-sky image of the X-ray sky was released by the eROSITA instrument on-board the Spectrum-Roentgen-Gamma” (SRG) mission. It is fascinating that they refer to a million X-ray, which is almost 10 times more than what has been discovered from all X-ray surveys so far, so a bright X-ray future lies ahead! The […]

ATel #12237: A B1-2e optical classification for the optical counterpart of XTE J0052-723 (SXP 4.78; Swift J005139.2-721704)

Building upon our previous ATel #12224 we managed to obtain an optical spectrum of the counterpart. The full text follows: ATel #12237; G. Maravelias (NOA), V. Antoniou (TTU/SAO), K. Boutsia (LCO), A. Zezas (UoC/SAO), A. Z. Bonanos (NOA), F. Haberl (MPE), D. Hatzidimitriou (UoA/NOA) on 21 Nov 2018; 23:36 UT / In ATel #12224 we […]

ATel #12224: XTE J0052-723 (SXP 4.78; Swift J005139.2-721704), a newly identified Be/X-ray binary pulsar

The ATel #12224 was released on 17 Nov 2018 (19:01 UT) regarding the identification of the proposed optical counterpart to the source XTE J0052-723 (SXP 4.78; Swift J005139.2-721704) as an Hα emitting OB star. The full text follows. ATel #12224; G. Maravelias (NOA), V. Antoniou (TTU/SAO), A. Zezas (UoC/SAO), A. Strantzalis (UoA), D. Hatzidimitriou (UoA), […]

New Paper on BeXRBs – 5 new BeXRBs in the SMC and the link of the supergiant B[e] star LHA 115-S 18 with an X-ray source

Optical spectra of 5 new Be/X-ray Binaries in the Small Magellanic Cloud and the link of the supergiant B[e] star LHA 115-S 18 with an X-ray source Grigoris Maravelias, Andreas Zezas, Vallia Antoniou, Despoina Hatzidimitriou The Small Magellanic Cloud (SMC) is well known to harbor a large number of High-Mass X-ray Binaries (HMXBs). The identification […]

Transformation factors for X-ray fluxes

In the following tables are given the transformation factors of the fluxes from a specific X-ray energy band to the 0.5-7 band, assuming Gamma 1.7 with Nh 6e20 and 0. Table 1 >>> Gamma Nh   MinE MaxE ModeledFx  Fx_in_0.5-7_band 1.7   6.0E20 2.0  25.0 7.4353E-9  1.524470492137473 1.7   6.0E20 0.1  2.0  2.177E-9   0.44635349756468984 1.7   6.0E20 3.0  10.0 3.234E-9   […]