grout and ungrout

grout is a routine specifically designed for tiles coming from VISTA. The program is used to remove the effects of the time variation of the point spread function and any variation in the magnitude zero-point in the 96 images that typically make up a VISTA tile. The user specifies an input catalogue (incatalogue) which should originate from running imcore on a VISTA tile. The provenance information in the header of the catalogue will give a list of the files that were used to create the tile. Even if this catalogue came from a tile that was made with nebulised pawprints, grout only requires access to the pawprint confidence maps and catalogues. If these are not in the current working directory, then you can specify where they are with the command line switch --srcpath. The input catalogue is copied to an output FITS file specified as outcatalogue and the fluxes for the first seven apertures as well as the peak fluxes will be modified by the analysis. All the rest of the information will remain the same. grout will attempt to work out an MJD for each object based on the average MJD for each stack and a weighted mean MJD for each point in the output tile. A keyword called MJD_DAY will be added to the catalogue table extension. This will be the integer part of the MJD from the first contributing stack. The first unused column in the catalogue (usually called 'Blank##') will be renamed MJDoff. It will contain the number of minutes to be added to MJD_DAY in order to get the MJD of a given object. Hence for the ith object: MJD_i = MJD_DAY + MJDoff_i / 1440.0. A map of the distribution of mean MJD offset (in minutes) can be generated if an output filename is specified with the optional switch --mjdmap.

SYNOPSIS

grout incatalogue outcatalogue

ARGUMENTS

incatalogue

Input FITS file with the source catalogue generated from a VISTA tile.

outcatalogue

Output FITS file with the modified source catalogue.

OPTIONS

The following options are supported. Default values are specified after the equal sign.

--srcpath=.

The path to the source FITS files. If the FITS files that made up the tile aren't in the current working directory, then this is where to give the path to those files

--mjdmap=""

If a file name is specified here, then a map of the distribution of MJD offsets is created. The units will be in minutes to be added to the value of the header keyword MJD_DAY.

--(no)verbose (no)

If set then some verbose output will be generated

--(no)apcor_fix (yes)

If set then the aperture corrections are applied.

--(no)magzpt_fix (no)

If set then the magnitude zero point correction is applied.

UNGROUT

ungrout is the companion program. It takes the same two catalogue arguments and the options --srcpath and --(no)verbose (no), and has two switches that select which corrections are applied: --(no)apcor_fix (yes) for the aperture corrections and --(no)magzpt_fix (yes) for the magnitude zero point. grout accepts the same two switches, with --(no)magzpt_fix off by default.

ungrout incatalogue outcatalogue