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Optical re-brightening of the black hole transient XTE J1752-223

ATel #2804; J. M. Corral-Santana (IAC, ULL), J. Casares (IAC, ULL), P. Rodríguez-Gil (ING, IAC, ULL)
on 19 Aug 2010; 12:16 UT
Credential Certification: P. Rodriguez-Gil (prguez@ll.iac.es)

Subjects: Optical, Binary, Black Hole, Transient

We observed the black hole candidate XTE J1752-223 (ATel #2258) with the William Herschel Telescope (WHT) and the ACAM imager/spectrograph at the Observatorio del Roque de los Muchachos, La Palma, Spain. Two R-band exposures of 60 and 200 s and one I-band exposure of 200 s were taken under photometric conditions and 1.0-1.2-arcsec seeing on Aug 8.925, Aug 8.927 and Aug 8.930, respectively. Due to the seeing conditions we were not able to fully resolve the nearby star 0.8 arcsec north of the target. R-band images were combined and small aperture photometry of XTE J1752-223 yields R=18.8 ± 0.1 and I=17.7 ± 0.1. These magnitudes might be slightly overestimated due to the contribution of the nearby star, especially in the R-band where the seeing was worse (1.2 arcsec). However, visual comparison of our I-band image with that of Russell et al. (ATel #2775) shows XTE J1752-223 clearly brighter in our data (see link below), indicating that it is currently brighter than the reported quiescence level (ATel #2775). Therefore, XTE J1752-223 seems to be undergoing an optical re-brightening. We encourage further optical/IR monitoring to follow the evolution of this black hole transient. These observations were performed during the IAC Director's Discretionary Time. The William Herschel Telescope is operated on the island of La Palma by the Isaac Newton Group (ING) in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias (IAC).