Optical colors of MAXIJ1348-630
ATel #12448; Roberto Nesci (INAF/IAPS-Roma), Mariateresa Fiocchi (INAF/IAPS-Roma)
on 29 Jan 2019; 19:35 UT
Credential Certification: Roberto Nesci (Roberto.Nesci@iaps.inaf.it)
Subjects: Optical, X-ray, Binary, Black Hole, Neutron Star
Following the MAXI alert in ATel #12425 of a new X-ray source detection, and its optical identification in ATel #12430 and ATel #12439, we observed the source with the REM telescope on La Silla, starting on MJD 58512.339, in the g,r,i Sloan filters and exposures of 270s. Aperture photometry was made using 12 nearby comparison stars taken from the APASS 9 catalog. We obtained g=16.25(+-0.06) mag, r=15.30 (+-0.05) mag, i=14.84 (+-0.04) mag. Adopting an absorption in the V band of 2.4 mag, as suggested in ATel #12439, and the extinction curve by Cardelli, Clayton, and Mathis (1989, ApJ 345,245), the intrinsic values should be g=13.42, r=13.21 and i=13.28: such color indices near zero are expected for an X-ray binary in outburst. A mechanical failure prevented the acquisition of nearly simultaneous J,H,K images. We will try to continue the monitoring of the source while it will be observed by INTEGRAL (ATel #12441) to allow multiwavelength coverage.
