SCUBA2MEM - Calculate bolometer positions as tangent plane offsets

Description:

This routine reads in SCUBA demodulated data and writes it out along with the positions of the bolometers on the sky for each sample. The positions of the chop beams can be requested as well as the positions of the tracking centre. Returns tangent plane offsets from the map centre in arcseconds. Additionally, the LST of each sample is stored as axis information.

Usage:

scuba2mem in out

Parameters:

IN = CHAR (Read)

The name ofthe input files to be processed. This is a demodulated data file. RESTORE should not have been run on it. Multiple file names can be specified (see the documentation on GRP). All the input files are referenced to the same output coordinate frame.

LAT = CHAR (Read)

The latitude of the output map centre. The supplied default value is that of the map centre of the observation in the output coordinates.

LONG = CHAR (Read)

The longitude of the output map centre. The supplied default value is that of the map centre of the observation in the output coordinates.

MSG_FILTER = CHAR (Read)

Message filter level. Default is NORM.

NBEAMS = INTEGER (Read)

Number of output beams to be written to file. NBEAMS=1 just writes the Middle beam, NBEAMS=2 writes the Left (negative) and Right beams, NBEAMS=3 writes Middle, Left and Right beams.

OUT = NDF (Write)

This parameter specifies the name of the output file to be used to store the positional information. The file format is described below.

OUT_COORDS = CHAR (Read)

The coordinate system of the output map. Available coordinate systems are:

• AZ: Azimuth/elevation offsets

• NA: Nasmyth offsets

• PL: RA/Dec Offsets from moving centre (eg Planets)

• RB: RA/Dec (B1950)

• RJ: RA/Dec (J2000)

• RD: RA/Dec (epoch of observation)

• GA: Galactic coordinates (J2000)

SHIFT = REAL( 2 ) (Read)

The pointing shift [X,Y] to be applied that would bring the map into the correct position. This is a shift in the output coordinate frame. CHANGE_POINTING should be used to add Az/El pointing offsets.

Examples:

scuba2mem out_coords=GA o34_lon_ext o34_mem nbeams=1 $\backslash$$\backslash$

Calculate the coordinates of all bolometer positions in tangent plane offsets from the GA map centre.

scuba2mem o34_lon_ext nbeams=3 $\backslash$$\backslash$

Calculate all chop positions for o34_lon_ext. Use RJ coordinates.

Notes:

• Can be used on JIGGLE and SCAN data.

• The coordinates of the selected output frame are written to the output FITS extension in keywords OUT_CRDS, OUTLONG and OUTLAT. The full FITS header of the observation itself is still available.

Format of output file

SCUBA DBMEM requires the data, positions of every beam and the LST for every point. This information (along with a standard FITS header) is stored as a standard NDF. The data array is constructed as follows:

3 dimensional: N_BOL $*$ N_POS $*$ ((N_BEAM $*$ 2) $+$ 1)

where N_BOL is the number of bolometers, N_POS is the number of samples for each bolometer (time axis), N_BEAM is the number of beams.

The 3rd dimension contains the actual data value plus positions of every beam associated with the data point. Each beam has two positions (X offset and Y offset) Axis components store bolometer number, LST and beam weight.

Related Applications

SURF: extract_data, rebin
DBMEM, PIXON

Copyright

Copyright (C) 1995,1996,1997,1998,1999 Particle Physics and Astronomy Research Council. All Rights Reserved.