This routine calculates
the sky contribution by attempting to remove the source from the input data stream. The source
signal can either be calculated by this routine or by reading in a model of the source from a
file.
When calculating the source structure internally a similar method to that used by DESPIKE is
employed. The input data are placed into bins of size one quarter beamwidth. The median of each bin
is calculated and this is treated as the source model (cf. REBIN_METHOD=MEDIAN in
rebin).
Once the source model is available, it is removed from all of the input data. The source-removed data
are then analysed with the sky emission derived from the mean of the signal across the array for all
the sample times.
Since the sky signal is expected to vary on timescales of the order of one second, an option is included
for smoothing the sky signal. This is especially useful for scan map data where samples are taken at
7.8∼Hz.
BOXSZ = INTEGER (Given)
Size of smoothing box in seconds. This
is used to smooth the time series. Default is 2.0 seconds.
IN = CHAR (Read)
The name of the input
file to be processed. This parameter is requested repeatedly until a NULL value (!) is supplied. LOOP
must be TRUE. IN can include a SCUBA section. Like the REF parameter this parameter accepts a text
file.
LOOP = LOGICAL (Read)
Task will ask for multiple input files if true. Only REF is
read if noloop.
MODEL = NDF (Read)
NDF containing the model of the source. The
astrometry is read from this file. The model must have been generated by SURF since it relies on
the presence of certain FITS keywords.
MSG_FILTER = CHAR (Read)
Message filter
level. Allowed values are QUIET, NORM and VERB. Default is NORM.
NOSRC = NDF
(Write)
File to store source removed data. This can be used to check the source removal.
Note that this output file can not be used directly by SURF for further processing since the
header is incomplete. No file is written by default.
OUT_COORDS = CHAR (Read)
The
coordinate system to be used for the model determination. Available coordinate systems are:
-
AZ: Azimuth/elevation offsets
-
NA: Nasmyth offsets
-
PL: RA/Dec Offsets from moving centre (e.g. Planets)
-
RB: RA/Dec (B1950)
-
RJ: RA/Dec (J2000)
-
RD: RA/Dec (epoch of observation)
-
GA: Galactic coordinates (J2000)
For RD current epoch is taken from the first input file.
REF = CHAR (Given)
The name
of the first NDF to be processed. The name may also be the name of an ASCII text file
containing NDF and parameter values. REF can include a SCUBA section. See
rebin for
more information on the format of the ASCII input file.
SHIFT_DX = REAL (Read)
The
pointing shift (in X) to be applied that would bring the maps in line. This is a shift in the
output coordinate frame.
SHIFT_DY = REAL (Read)
The pointing shift (in Y) to be
applied that would bring the maps in line. This is a shift in the output coordinate frame.
WEIGHT = REAL (Read)
This parameter does nothing in
calcsky. It must be present
when using text file input. Any value is allowed.