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ATEL # 1551; K. J. Perry, J. M. Miller, E. Cackett, (University of Michigan), D. Altamirano (University of Amsterdam)
on 30 May 2008; 13:45 UT
Password Certification: Jon Miller (firstname.lastname@example.org)
Subjects: X-ray, Binaries, Neutron Stars, Transients
We report on six observations of the ultra-compact X-ray binary 4U 1850-087 (P_orb = 21 min) in a rare high flux state, taken by Swift. Observations were made on 12, 14, 15, 16, 18, and 20 May 2008. Fits to the XRT spectra were made over the 0.5-10 keV band, assuming a column density of 2.4 E+21. The distance was assumed to be 6.8 kpc (Sidoli et al. 2004). The photon index ranged from 2.09 to 2.30, the unabsorbed flux ranged from 2.55 E-10 to 6.0 E-10 cgs, and the luminosity ranged from 1.1 E+36 to 3.4 E+36 erg/s. A blackbody component was not required by the spectra, with an upper limit flux of 1.5 E-10 cgs.