Description:
This routine takes a
chop throw and adds it on the supplied apparent RA/Dec centre position returning a new apparent
RA/Dec. Works with scan map and jiggle map but does not actually know the difference itself
(unless using SC chop). For EKH (SC) chopping we have to convert the scan ends to tangent
plane offsets from the reference centre before calculating the angle.
Invocation
CALL
SCULIB_ADD_CHOP(BEAM, RA_REF_CENTRE, DEC_REF_CENTRE, RA_CENTRE, DEC_CENTRE, CHOP_CRD,
CHOP_PA, CHOP_FUN, CHOP_THROW, LST, MJD, LAT_OBS, RA_START, RA_END, DEC_START,
DEC_END, OUT_RA_CEN, OUT_DEC_CEN, STATUS)
Arguments
BEAM = CHARACTER
()
(Given)
Beam name (’M’,’L’ or ’R’)
RA_REF_CENTRE = DOUBLE PRECISION
(Given)
Apparent RA of the map centre. This is the centre that scan map tangent plane
offsets are calculated from.
DEC_REF_CENTRE = DOUBLE PRECISION (Given)
Apparent dec of the map centre. This is the centre that scan map tangent plane offsets
are calculated from.
RA_CENTRE = DOUBLE PRECISION (Given)
the apparent RA
of the ‘centre’ of the array (radians)
DEC_CENTRE = DOUBLE PRECISION (Given)
the apparent dec of the ‘centre’ of the array (radians)
CHOP_CRD = CHARACTER
()
(Given)
Coordinate system of CHOP throw (SC,AZ,RB,RJ,GA)
CHOP_PA =
REAL (Given)
Position angle of chop (in radians)
CHOP_FUN = CHARACTER
()
(Given)
Chop function (CENTER, SQUARE, TRIPOS)
CHOP_THROW = REAL (Given)
Chop throw in radians
LST = DOUBLE PRECISION (Given)
the local sidereal time
(radians)
MJD = DOUBLE PRECISION (Given)
MJD of observation
LAT_OBS = DOUBLE
PRECISION (Given)
the latitude of the observatory (radians)
RA_START = REAL (Given)
RA
of start of scan (if SAMPLE_MODE=RASTER)
RA_END = REAL (Given)
RA of end
of scan (if SAMPLE_MODE=RASTER)
DEC_START = REAL (Given)
DEC of start of
scan (if SAMPLE_MODE=RASTER)
DEC_END = REAL (Given)
DEC of end of scan (if
SAMPLE_MODE=RASTER)
OUT_RA_CEN = DOUBLE (Returned)
New position with CHOP
OUT_DEC_CEN = DOUBLE (Returned)
New DEC with CHOP
STATUS = INTEGER (Given and
returned)
The global status
Notes:
It is assumed that the chop throw is divided by two
prior to calling this routine for scan map mode since the chop is effectively half a chop
either side of the middle. For jiggle modes the chop is effectively a full chop throw from the
centre since the 3-beam chopping is done by a combination of chopping and nodding.
-
This routine does not yet support TRIPOS chopping (I think)
-
AZ, LO and SC chopping are supported
-
The negative beam is always the ’left’ beam, the
ve
beam is the ’right’.
-
The chop tracking ’droopy’ beam problem should be dealt with in an earlier subroutine such that the
chop is converted from LO to AZ before calling this routine
Copyright
Copyright
©1995,1996,1997,1998,1999 Particle Physics and Astronomy Research Council. All Rights Reserved.