GROND multi-color imaging of the GRB 161219B / SN 2016jca field.

This folder contains optical/near-infrared imaging of the field of GRB 161219B (Swift trigger 727541; D'Ai, GCN #20296) collected simultaneously with the Gamma-Ray Burst Optical/Near Infrared imager (GROND; Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPG telescope on ESO's LaSilla observatory. These data include a time-series of SN 2016jca following GRB 161219B with nearly daily monitoring around peak, and are published in Cano et al. 2017 (arXiv:1704.05401).<br><br>The data were obtained in the grizJHK photometric bands. They were collected over a period of several nights starting from 2016-12-20, and consisted of several dithered images that are stacked to yield one fits image per epoch per band. <br><br>Data were automatically processed with the GROND pipeline, which uses standard procedures in python/pyraf/IRAF (see e.g., Kruehler et al. 2008, ApJ, 685, 376). The data are sky-subtracted and astrometrically calibrated against the Pan-STARRS or GAIA catalogs.<br><br>Critical information can be found in the fits header, the following keywords are particularly useful:<br><br>- EXPTIME = Exposure time of a single image<br>- NIMGS = Total number of images combined<br>- COMBINE = How the images were combined<br>- IMGEXP = Summed exposure of the image<br>- MJD-MID = Midtime of the image<br>- FILTER = Filter band of the observation<br>- AIRMASS = Average airmass of the observation<br>- FWHM = FWHM of the stellar PSF<br>- ASTRRMS1 = Uncertainty of the astrometric solution in RA<br>- ASTRRMS2 = Uncertainty of the astrometric solution in DEC<br>- MAGLIM = Limiting magnitude of the image<br>- INTERPSM = Individual images are resampled during shifting and adding, this number describes an empirical estimate by what factor the noise is smoothed (i.e., too low as estimated by the rms in the image). In particular in the NIR bands, standard procedure will underestimate the photometric error by this factor.<br>