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ATEL # 2900; P. D'Avanzo (INAF-OAB), P. Goldoni (APC/Univ. Paris 7 and SAp/CEA), A. Patruno (Univ. of Amsterdam), P. Casella (Univ. of Southampton), S. Campana (INAF-OAB), D. M. Russell (Univ. of Amsterdam), T. M. Belloni (INAF-OAB)
on 2 Oct 2010; 10:19 UT
Password Certification: Paolo D'Avanzo (email@example.com)
Subjects: Infra-Red, Optical, Ultra-Violet, Binaries, Transients
We observed the optical and NIR counterpart of the recently discovered X-ray transient MAXI J1659-152 (Negoro et al. 2010, ATel #2873; Mangano et al. 2010, GCN #11296) with the REM telescope located in La Silla (Chile) in imaging mode using the V, R, I, J, H and K filters. Observations were carried out on 2009 Sept. 30, starting from 23:43 UT (MJD 55469.985) for a total duration of six minutes. The source is well detected in all bands with a magnitude of R = 16.3 (calibrated against Landolt standard stars) and H = 14.7 (calibrated against the 2MASS catalogue).
We compared our REM data with the Swift-UVOT observations obtained on MJD ~ 55470.240 UT with the UVM2 filter (about six hours later) and corrected the entire dataset for interstellar reddening assuming an E(B-V) ~ 0.34 estimated from the X-ray N_H reported by Kennea et al. (ATel #2877). The whole spectral energy distribution (computed in wavelength units) can be fitted with a single power-law with spectral index of -2.3 +/- 0.1. The expected variability of ~0.1 mag (see Russell et al., ATel #2884) should not affect significantly the SED. We do not see any evidence of flux excess in the NIR bands from, e.g., synchrotron emission from the jet which is commonly seen in the NIR in black-hole X-ray binaries.
Combined UVOT-REM SED of MAXI J1659-152