AIPS HELP file for HOLOG in 31DEC21
As of Sat Oct 23 20:55:37 2021
HOLOG: Task to read and process holography visibility data
Input data file name.
OUTNAME Output image name.
OUTDISK 0.0 9.0 Output disk number.
UVTAPER 0.0 Data tapering: (1) type,
(2) width in cells to 0.5
OPTYPE Telescope type: 'PFOC' prime
focus, 'SUBR' subreflector
'SURP' subreflector with
FACTOR 0.0 100.0 Magnification: 0 -> 13
OFFSET 0.0 100.0 Distance from prime focus to
bottom subreflector 0->0.512
REFREQ 0.0 Reference frequency in GHz
APARM Operating parameters.
1: Frequency (GHz).
2: Satellite elevation, deg.
Use 0 for sidereal obj.
3: Antenna diameter, m.
4: Unpaneled diameter, m.
(3,4) used to blank ant.
aperture phase data.
5: Focal length, m.
6: Slope in SURP 0 -> 0.65
9: 10000 * Ref ant. +
100 * target ant. + IF#.
10: Stokes (RR=1, LL=2)
(9) and (10) used only
if INFILE is not of form
CELLSIZE Cell size in asec for output
image type 1-3. Resets
BPARM Data reduction parameters.
1: Required map size, meters
or use CELLSIZE
2: No. of pixels on a side
of the output map (power
of 2, min=32, max=512).
0 => 128
3: Min. antenna scan angle
Units: inverse sine(ang)
0 => all data used.
4: Max. antenna scan angle
Units: inverse sine(ang)
0 => all data used.
<0 => radial (min, max).
5: Amplitude scaling factor
0 => 1
6: Fourier transform sign
0 => -1 (VLA convention)
7: Minimum antenna aperture
used for fit, in meters
< 0 => circular min.
0 => set by APARM(4)
8: Maximum antenna aperture
used for fit, in meters
< 0 => Circular max.
0 => set by APARM(3)
(7,8) used for focus and
9: Correction control flags:
read the HELP!
10: >0 => logarithmic ampl.
.LE. 0 => linear ampl.
default = linear
CPARM Parameters for the gridding
operation (see HELP).
NORMALIZ -1.0 1.0 > 0 => normalize outputs 1
and 2 below
DOVECT -1.0 1.0 > 0 write real/imaginary not
DPARM Output maps, >0 => Save this.
1,2: Regridded amplitude and
phase of the observed
antenna beam pattern.
3: Weights used in the
4,5: Derived amplitude and
phase of the antenna
6,7: Amplitude and phase of
the point-spread func.
8: Focus model corrections
9: Surface deviation map.
10: Antenna power pattern
and phase (See HELP!)
VPARM Use this model don't fit
1. Constant offset degrees
2. Phase ramp in X deg/cell
3. Phase ramp in Y deg/cell
4. Feed/subreflector offset
in X in mm
5. Subreflector/Feed offset
in Y in mm
6. Subreflector/Feed offset
in Z in mm (focus)
7. Subreflector X tilt deg
8. Subreflector Y tilt deg
9. Cassegrain feed offset
in X mm
10. Cassegrain feed offset
in Y mm
11. > 0 replace phase with
12. > 0 Replace amp with
average, value is clip
level (all below set 0)
Use: HOLOG processes holography data. It reads visibility data
from a file and Fourier transforms it to produce the
grading in the aperture plane of the antenna. Up to nine
different AIPS image files will be produced according to
the options specified in DPARM.
In the following description, (l,m) are the angular antenna
offsets, while (u,v) are distances in the antenna aperture
The input data format is four free format ASCII encoded
values per record:
1) Azimuth offset from source (degrees)
or true l (if APARM(2) <= 0)
2) Elevation offset from source (degrees)
or true m (if APARM(2) <= 0)
3) Amplitude (Volts or dB) or Real (Volts)
4) Phase (degrees) or Imaginary (Volts)
INFILE......Input visibility file name in the form AREA:FILE, where
AREA is a directory logical name or environment
variable, and FILE is an operating system specific file
name. If INFILE = 'ANT' or is blank, then INFILE will
be set to
where nn is the moving antenna number and mm is the
reference antenna number (= 0 if more than one reference
antenna is used), ss is the Stokes, and ii is the IF.
If INFILE contains only a logical name, as INFILE =
'AREA:', then 'AREA:HOLOnn-mmssii' will be used. The
values of nn, mm, ss, and ii come from APARMs (9) and
OUTNAME.....Output image name (12 characters). If the last 7
characters are blank, they are set to 'nn-mmss'.
OUTDISK.....Output disk number.
UVTAPER.....Tapering of data during the gridding process:
(1) Type: 1 Gaussian, 2 Exponential, 3 Linear
(2) Radius in cells for taper of 0.5. 0 => N/3.
(Remember that the max radius of the data must be
< N/2 just to avoid aliasing.)
OPTYPE......The model used for removing the effects of primary focus
offset. 'PFOC' = Prime Focus. 'SUBR' = Cassegrain
system. 'SURP' = Cassegrain system with reference
pointing - default SUBR
FACTOR......The magnification. Used only if OPTYPE = 'SUBR', 'SURP'
OFFSET......The distance between the prime focus and the bottom of the
subreflector in meters. Otherwise known as c-a where 2c
is the distance between the 2 hyperbolic foci and a is the
distance between the y-axis intercept of the upper
hyperboloid from the midpoint of the 2 foci in meters.
0 -> 0.522 appropriate for the VLA.
Used only with tilt parameters to display tilts in
degrees rather than physical offsets and only with
Operating parameters: all are required (NO defaults).
REFREQ......Use this as the reference frequency in GHz. If 0, use
the observing frequency found in the UVHOL output file
APARM(1)....Observing frequency (GHz). (ignored)
APARM(2)....Satellite elevation, degrees. Set = -1. for VLA data
(true l,m); set = +1. for sky az,el; set = actual
elevation for true az,el
APARM(3)....Antenna diameter, in meters. Used to blank antenna
surface phase map before applying models.
APARM(4)....Subreflector or unpaneled diameter, in meters. Used to
blank antenna phase map before models are applied.
APARM(5)....Focal length, in meters. This is used in correcting for
the focus and feed offset, and in computing the surface
APARM(6)....In SURP only, the slope applied to "q". 0 -> 0.65
APARM(9)....10000 * Reference antenna number + 100 * 2nd (moving)
antenna number + IF number. Used only for default names
(i.e., if INFILE = 'AREA:')
APARM(10)...Stokes ID (1 - 4 => RR, LL, RL, LR). Used only for
default names (i.e., if INFILE = 'AREA:')
Data reduction control parameters.
CELLSIZE....Cell size in asec for output image types 1, 2, and 3.
If > 0, BPARM(1) is reset to Lambda / (CELLSIZ(1) * AS2RAD)
BPARM(1)....Required map size, in meters. or use CELLSIZE
BPARM(2)....Number of pixels on a side of the output map
(power of 2, maximum 512).
BPARM(3,4)..Range of |l| and |m| (antenna scan angles) to use for
transform. Units are inverse sine(angle)
BPARM(5)....Scaling factor for the input amplitudes.
BPARM(6)....Fourier transform control. If negative, the phase read
from the data file is negated. If the absolute value is
2, a direct Fourier transform will be done, otherwise,
BPARM(7,8)..Range of |x| and |y| used in correcting for pointing,
focus, and feed offset. Negative values give (min, max)
of r = SQRT(u*u + v*v). See also BPARM(9).
BPARM(9)....Decimal encoded control parameters
1: If set, apply the subreflector tilt model.
10: Turn off phase slope model (pointing).
100: Inhibit local phase ambiguity correction in
the antenna aperture (V_PHA) plane.
1000: Turn off all model calculations.
2000: Turn off subreflector offset model.
4000: Turn off focus (z) model.
8000: Turn on Cassegrain feed offset model
BPARM(10)...Switch for logarithmic or linear data
>= 0 for logarithmic data (as for PKS)
< 0 for linear data (for the VLA).
CPARM(1)....Type of interpolation to apply in gridding 'l'.
1: Pillbox, (don't use for regularly sampled data)
5: Spheroidal (default).
NEGATE to obtain natural weighting. (default = uniform)
CPARM(2)....Support radius in u, in cells.
CPARM(3-5)..Parameters defining the interpolation function
Do HELP UVnTYPE for n=1,2,3,4,5.
CPARM(6-10).Corresponding parameters for 'm'.
Output option flags.
NORMALIZ....> 0 => amplitude and phase will be normalized, else no
normalization of amplitude and phase is done.
DOVECT......> 0 -> write real and imaginary rather than amplitude
and phase on DPARM(1,2)
The particular map will be stored if the associated DPARM is
> zero. If all are <= 0, DPARM(4,5) will both be set to 1.
AIPS task PANEL wants (4) for the mask and (9) for the deviations.
DPARM(1,2)..Regridded amplitude and phase of the observed antenna
beam voltage pattern (A_AMP, A_PHA).
DPARM(3)....Weights used in the regridding procedure (WGT) -
includes the weights for uniform (vs natural) weighting.
DPARM(4,5)..Derived amplitude and phase of the illumination of the
antenna aperture (V_AMP, V_PHA). The focus model, if
requested, will be removed from the phase image.
DPARM(6,7)..Amplitude and phase of the point-spread function. This
indicates the blurring in the derived grading map
DPARM(8)....Map of the phase corrections removed by the focus model
DPARM(9)....Map of the surface deviations of the antenna (V_DEV).
Units are in meters. The focus offset model, if
requested, will be removed.
DPARM(10)...The interpolated antenna power pattern (A_PWR). Set it
= to the desired interpolation factor, with anything >0
and < 2 => 2. Must be a power of 2 <= 2048 / NPIX,
where NPIX = BPARM(2). The phase image (A_PHS) is also
Compute a model rather than fitting one:
If any of VPARM(1) through VPARM(8) is not zero, then a model image is
computed from the parameters in VPARM rather than being fit to the
data in INFILE. Different models are computed for the 3 values of
VPARM(1)....Constant phase offset in degrees
VPARM(2)....Phase ramp in X in degrees/cell - equivalent to a
pointing error in X in arc minutes
VPARM(3)....Phase ramp in Y in degrees/cel - equivalent to a
pointing error in Y in arc minutes
VPARM(4)....Feed offset in X in mm for PFOC
Subreflector offset in X in mm for SUBR, SURP
VPARM(5)....Feed offset in Y in mm for PFOC
Subreflector offset in Y in mm for SUBR, SURP
VPARM(6)....Feed offset in Z in mm for PFOC
Subreflector offset in Z in mm for SUBR, SURP
VPARM(7)....Subreflector tilt in X in degrees
VPARM(8)....Subreflector tilt in Y in degrees
VPARM(9)....Cassegrain feed offset in X in mm
VPARM(10)...Cassegrain feed offset in Y in mm
VPARM(11)...> 0 => replace phase with model
VPARM(12)...> 0 => replace amplitude with average amplitude if
amplitude > VPARM(12), else set amplitude to 0. The
amplitude is a weighting function in the the determination
of rms, forward gain, and beam pattern.