MAXI J1828-249: GROND observations of the optical/NIR counterpart
ATel #5482; Arne Rau, Mohit Tanga, Jochen Greiner (all MPE Garching)
on 18 Oct 2013; 13:02 UT
Credential Certification: Arne Rau (arau@mpe.mpg.de)
Subjects: Infra-Red, Optical, Binary, Black Hole, Transient
Referred to by ATel #: 5559
We report on optical-near-Infrared follow-up observations of the transient MAXI J1828-249 (ATels #5474, #5476, #5478, #5479) with GROND (Greiner et al. 2008, PASP 120, 405) at the 2.2m MPG telescope at La Silla Observatory (Chile). Simultaneous imaging in g'r'i'z'JHK was obtained on 2013-10-18 starting 00:37:27 UT. We detect a bright optical/NIR counterpart at the position of the UVOT uvm2 source reported by Kennea et al. (ATel #5479) and measure the following magnitudes (all in the AB system):
g' = 17.2 +/- 0.1
r' = 16.9 +/- 0.1
i' = 16.9 +/- 0.1
z' = 16.8 +/- 0.1
J = 16.8 +/- 0.1
H = 16.9 +/- 0.1
K = 17.2 +/- 0.2
calibrated against GROND zeropoints in g'r'i'z' and 2MASS field stars in JHK. No correction for the expected Galactic foreground reddening of E(B-V)~0.34mag (Schlafly et al. 2011) has been applied. No statement about variability can be made at this point in time.
The foreground reddening corrected optical/NIR spectral energy distribution is best fit by a simple power law reminiscent of an accretion disk spectrum. This supports the suggestion that the optical/NIR source is the counterpart to MAXI J1828-249.
