ObitPBUtil.c File Reference

ObitPBUtil function definitions. More...

#include "ObitPBUtil.h"
#include <math.h>

Functions
gfloat	ObitPBUtilPoly (gdouble Angle, gdouble Freq)
	Use polynomial beam shape - useful for VLA frequencies < 1.0 GHz.
gfloat	ObitPBUtilJinc (gdouble Angle, gdouble Freq, gfloat antSize)
	Use Jinc beam shape - useful for frequencies > 1.0 GHz.
gfloat	ObitPBUtilRelPB (gdouble Angle, gint nfreq, gdouble *Freq, gfloat antSize, gdouble refFreq)
	Function which returns relative primary beam correction.
gfloat	ObitPBUtilPntErr (gdouble Angle, gdouble AngleO, gfloat antSize, gdouble Freq)
	Function which returns pointing error amplitude correction.
ObitTableCC *	ObitPBUtilCCCor (ObitImage *image, glong inCCver, glong *outCCver, gint nfreq, gdouble *Freq, gfloat antSize, gdouble refFreq, glong *startCC, glong *endCC, ObitErr *err)
	Correct ObitTableCC for relative Primary Beam.
ObitFArray *	ObitPBUtilImageCor (ObitImage *inImage, gint *inPlane, gint nfreq, gdouble *Freq, gfloat antSize, gdouble refFreq, ObitErr *err)
	Correct Image for relative Primary Beam.

---

Detailed Description

ObitPBUtil function definitions.

Antenna primary beam shape utility class.

---

Function Documentation

ObitTableCC* ObitPBUtilCCCor (  ObitImage *  image, glong  inCCver, glong *  outCCver, gint  nfreq, gdouble *  Freq, gfloat  antSize, gdouble  refFreq, glong *  startCC, glong *  endCC, ObitErr *  err )

Correct ObitTableCC for relative Primary Beam. From the AIPSish $FOURMASS/SUB/PBUTIL.FOR PBFCCT Parameters: image  input image with input CC table inCCver  input CC table outCCver  Desired output CC table on image, if 0 then new value used returned. nfreq  number of frequencies in Freq Freq  Frequencies (Hz) of observations. antSize  Antenna diameter in meters. (defaults to 25.0) refFreq  Reference frequency (Hz) for which CC table is needed startCC  [in] the desired first CC number (1-rel) [out] the actual first CC number in returned table endCC  [in] the desired highest CC number, 0=> to end of table [out] the actual highest CC bumber in returned table err  Obit error/message object Returns: pointer to ObitCCtable, Unref when no longer needed.

ObitFArray* ObitPBUtilImageCor (  ObitImage *  inImage, gint *  inPlane, gint  nfreq, gdouble *  Freq, gfloat  antSize, gdouble  refFreq, ObitErr *  err )

Correct Image for relative Primary Beam. From the AIPSish $FOURMASS/SUB/PBUTIL.FOR PBFSCI Parameters: inImage  input image with inPlane  Desired plane in inImage, 1-rel pixel numbers on planes 3-7; ignored if memOnly nfreq  number of frequencies in Freq Freq  Frequencies (Hz) of observations. antSize  Antenna diameter in meters. (defaults to 25.0) refFreq  Reference frequency (Hz) for which CC table is needed err  Obit error/message object Returns: pointer to ObitFArray, Unref when no longer needed. NULL on error

gfloat ObitPBUtilJinc (  gdouble  Angle, gdouble  Freq, gfloat  antSize )

Use Jinc beam shape - useful for frequencies > 1.0 GHz. The power pattern is calculated from the pointing position and for observing frequency freq (Hz). The power pattern (2 * j1(x) / x) ** 2 of a uniformly illuminated circular aperture is used, since it fits the observations better than the standard PBCOR beam does. If the relative gain is less than pbmin = 0.05, it is set to pbmin. vscale is a measured constant inversely proportional to the VLA primary beamwidth, which is assumed to scale as 1./freq. vscale = 4.487e-9 corresponds to a 29.4 arcmin fwhm at 1.47 ghz. the actual scale is determined from the antenna size (antSize). xmax = value of x yielding pb = pbmin = 0.05, beyond which the series approximation loses accuracy. Note: this routine is probably only useful for the VLA but might be ok for a homogenous array of uniformly illuminated antennas where the beam scales from the VLA beam by the ratio of antenna diameters. From the AIPSish $FOURMASS/SUB/PBUTIL.FOR Parameters: Angle  Angle from the pointing position (deg) Freq  Frequency (Hz) of observations antSize  Antenna diameter in meters. (defaults to 25.0) Returns: Fractional antenna power [0.05, 1]

gfloat ObitPBUtilPntErr (  gdouble  Angle, gdouble  AngleO, gfloat  antSize, gdouble  Freq )

Function which returns pointing error amplitude correction. Note: this is the power pattern. Uses ObitPBUtilPoly (VLA assumed) for frequencies < 1 GHz and ObitPBUtilJinc at higher frequencies Adopted from the AIPSish $FOURMASS/SUB/PBUTIL.FOR PBFACT Parameters: Angle  Intended angle from the intended pointing position (deg) AngleO  Actual angle from the intended pointing position (deg) antSize  Antenna diameter in meters. (defaults to 25.0) Freq  Frequency (Hz) for which rel. gain is desired Returns: amplitude correction

gfloat ObitPBUtilPoly (  gdouble  Angle, gdouble  Freq )

Use polynomial beam shape - useful for VLA frequencies < 1.0 GHz. Parameters: Angle  Angle from the pointing position (deg) Freq  Frequency (Hz) of observations Returns: Fractional antenna power [0.01, 1]

gfloat ObitPBUtilRelPB (  gdouble  Angle, gint  nfreq, gdouble *  Freq, gfloat  antSize, gdouble  refFreq )

Function which returns relative primary beam correction. Uses ObitPBUtilPoly (VLA assumed) for frequencies < 1 GHz and ObitPBUtilJinc at higher frequencies Adopted from the AIPSish $FOURMASS/SUB/PBUTIL.FOR PBFACT Parameters: Angle  Angle from the pointing position (deg) nfreq  number of frequencies in Freq Freq  Frequencies (Hz) of observations. antSize  Antenna diameter in meters. (defaults to 25.0) refFreq  Reference frequency (Hz) for which rel. gain is desired Returns: Relative gain at freq refFreq wrt average of Freq.

---