NAME: APER PURPOSE: Procedure (adapted from DAOPHOT) to compute concentric aperture photometry. A separate sky value is determined for each source using specified inner and outer sky radii. CALLING SEQUENCE: aper, image, xc, yc, [ mags, errap, sky, skyerr, phpadu, apr, skyrad, badpix, TEXTOUT = , SILENT = ] INPUTS: IMAGE - input image array XC - vector of x coordinates. COORDINATE VALUES MUST BE IN IDL CONVENTION! (First pixel is 0 not 1!) YC - vector of y coordinates OPTIONAL INPUTS: PHPADU - Photons per Analog Digital Units, numeric scalar. Converts the data numbers in IMAGE to photon units. (APER assumes Poisson statistics.) APR - Vector of up to 12 REAL photometry aperture radii. SKYRAD - Two element vector giving the inner and outer radii to be used for the sky annulus BADPIX - Two element vector giving the minimum and maximum value of a good pix (Default [-32765,32767]) OPTIONAL KEYWORD INPUTS: TEXTOUT - Determines output device (see TEXTOPEN) textout=1 TERMINAL using /more option textout=2 TERMINAL without /more option textout=3.prt textout=4 laser.tmp textout=5 user must open file textout = filename (default extension of .prt) SILENT - If supplied and non-zero then no output is displayed to the terminal. OUTPUTS: MAGS - NAPER by NSTAR array giving the magnitude for each star in each aperture. (NAPER is the number of apertures, and NSTAR is the number of stars). A flux of 1 digital unit is assigned a zero point magnitude of 25. ERRAP - NAPER by NSTAR array giving error in magnitude for each star. If a magnitude could not be deter- mined then ERRAP = 9.99. SKY - NSTAR element vector giving sky value for each star SKYERR - NSTAR element vector giving error in sky values SYSTEM VARIABLES: If keyword textout is not used, the non-standard system variable !TEXTOUT will be used to determine the output device. PROCEDURES USED: MMM, TEXTOPEN, STRN REVISON HISTORY: Adapted to IDL from DAOPHOT June, 1989 B. Pfarr, STX Adapted for IDL Version 2, J. Isensee, July, 1990 Code, documentation spiffed up W. Landsman August 1991
(See /usr/local/idl/lib/zastron/daophot/aper.pro)
NAME: CNTRD PURPOSE: Compute centroid coordinates of a stellar object using the algorithm in the DAOPHOT FIND subroutine. CALLING SEQUENCE: CNTRD, img, x, y, xcen, ycen, [ fwhm , /SILENT, /DEBUG] INPUTS: IMG - Two dimensional image array X,Y - Scalar or vector integers giving approximate stellar center OPTIONAL INPUT: FWHM - floating scalar; Centroid is computed using a box of half width equal to 1.5 sigma = 0.637* FWHM. CNTRD will prompt for FWHM if not supplied OUTPUTS: XCEN - the computed X centroid position, same number of points as X YCEN - computed Y centroid position, same number of points as Y Values for XCEN and YCEN will not be computed if the computed centroid falls outside of the box, or if the computed derivatives are non-decreasing. If the centroid cannot be computed, then a message is displayed and XCEN and YCEN are set to -1. OPTIONAL OUTPUT KEYWORDS: SILENT - Normally CNTRD prints an error message if it is unable to compute the centroid. Set /SILENT to suppress this. DEBUG - If this keyword is set, then CNTRD will display the subarray it is using to compute the centroid. PROCEDURE: Maximum pixel within distance from input pixel X, Y determined from FHWM is found and used as the center of a square, within which the centroid is computed as the value (XCEN,YCEN) at which the derivatives of the partial sums of the input image over (y,x) with respect to (x,y) = 0. MODIFICATION HISTORY: Written 2/25/86, by J. K. Hill, S.A.S.C., following algorithm used by P. Stetson in DAOPHOT. Improved error checking W. Landsman August, 1991 Allowed input vectors G. Hennessy April, 1992 Fixed to prevent wrong answer if floating pt. X & Y supplied W. Landsman March, 1993
(See /usr/local/idl/lib/zastron/daophot/cntrd.pro)
NAME: DAOERF PURPOSE: Calulates the intensity of a 2 dimensional gaussian PSF at a pixel position x, by integrating between x-0.5 and x+0.5. It differs from ERF in 2 ways (to agree with DAOPHOT calls): (1) The number of output elements in F and PDER is identical with the number of elements in X and Y (2) The order of the parameter vector A is different CALLING SEQUENCE: DAOERF, XIN, YIN, A, F, [ PDER ] INPUTS: XIN - input scalar, vector or array, giving X coordinate values YIN - input scalar, vector or array, giving Y coordinate values, must have same number of elements as XIN. A - 5 element parameter array describing the gaussian A(0) - peak intensity A(1) - X position of peak intensity (centroid) A(2) - Y position of peak intensity (centroid) A(3) - X sigma of the gaussian (=FWHM/2.345) A(4) - Y sigma of gaussian OUTPUTS: F - array containing value of the function at each (XIN,YIN) OPTIONAL OUTPUTS: PDER - 2 dimensional array of size (NPTS,5) giving the analytic derivative at each value of F with respect to each parameter A. REVISION HISTORY: Written: W. Landsman October, 1987
(See /usr/local/idl/lib/zastron/daophot/daoerf.pro)
NAME:
DAO_VALUE
PURPOSE:
This function returns the value of a point-spread function at a
given point. The value of the point-spread function is the sum of a
two-dimensional integral under a bivariate Gaussian function, and
a value obtained by interpolation in a look-up table. DAO_VALUE will
optionally compute the derivatives wrt X and Y
CALLING SEQUENCE:
Result = DAO_VALUE( xx, yy, gauss, psf, [ dvdx, dvdy ] )
INPUTS:
XX,YY - the real coordinates of the desired point relative
to the centroid of the point-spread function.
GAUSS - 5 element vector describing the bivariate Gaussian
GAUSS(0)- the peak height of the best-fitting Gaussian profile.
GAUSS(1,2) - x and y offsets from the centroid of the point-spread
function to the center of the best-fitting Gaussian.
GAUSS(3,4) - the x and y sigmas of the best-fitting Gaussian.
PSF - a NPSF by NPSF array containing the look-up table.
OUTPUTS:
RESULT - the computed value of the point-spread function at
a position XX, YY relative to its centroid (which
coincides with the center of the central pixel of the
look-up table).
OPTIONAL OUTPUTS:
DVDX,DVDY - the first derivatives of the composite point-spread
function with respect to x and y.
NOTES
although the arguments XX,YY of the function DAO_VALUE
are relative to the centroid of the PSF, the function RINTER which
DAO_VALUE calls requires coordinates relative to the corner of the
array (see code).
REVISON HISTORY:
Adapted to IDL by B. Pfarr, STX, 11/17/87 from 1986 STSDAS version
of DAOPHOT
(See /usr/local/idl/lib/zastron/daophot/dao_value.pro)
NAME: FIND PURPOSE: Find positive brightness perturbations (i.e stars) in a 2 dimensional image and compute centroids, and shape parameters, Adapted from 1986 STSDAS version of DAOPHOT. CALLING SEQUENCE: find, image, [ x, y, flux, sharp, round, hmin, fwhm, roundlim, sharplim TEXTOUT = , /SILENT ] INPUTS: image - 2 dimensional image array (integer or real) for which one wishes to identify the stars present OPTIONAL INPUTS: FIND will prompt for these parameters if not supplied hmin - Threshold intensity for a point source - should generally be 3 or 4 sigma above background fwhm - FWHM to be used in the convolve filter sharplim - 2 element vector giving low and high cutoff for the sharpness statistic (Default: [0.2,1.0] ) roundlim - 2 element vector giving low and high cutoff for the roundness statistic (Default: [-1.0,1.0] ) OPTIONAL INPUT KEYWORDS: SILENT - Normally, FIND will write out each star that meets all selection criteria. If the SILENT keyword is set and non-zero, then this printout is suppressed. TEXTOUT - Controls output device (see the procedure TEXTOPEN) textout=1 TERMINAL using /more option textout=2 TERMINAL without /more option textout=3.prt textout=4 laser.tmp textout=5 user must open file textout = filename (default extension of .prt) OPTIONAL OUTPUTS: x - vector containing x position of all stars identified by FIND y- vector containing y position of all stars identified by FIND flux - vector containing flux of identified stars as determined by a gaussian fit. Fluxes are NOT converted to magnitudes. sharp - vector containing sharpness statistic for identified stars round - vector containing roundness statistic for identified stars SYSTEM VARIABLES: The non-standard system variable TEXTOUT determines the output device if the keyword TEXTOUT is not supplied. See TEXTOPEN for more info. REVISION HISTORY: Written W. Landsman, STX February, 1987 Keyword textout added, J. Isensee, July, 1990 ROUND now an internal function in V3.1 W. Landsman July 1993
(See /usr/local/idl/lib/zastron/daophot/find.pro)
NAME: GETPSF PURPOSE: To generate a point-spread function (PSF) from one or the sum of several stars. The PSF is represented as a 2-dimensional gaussian (integrated over each pixel) and a lookup table of residuals. The lookup table and gaussian parameters are output as an STSDAS (modified FITS) image file. The PSF file created by GETPSF can be read with the procedure RDPSF. Adapted from 1986 STSDAS version of DAOPHOT CALLING SEQUENCE: getpsf, image, xc, yc, apmag, sky, $ [ronois, phpadu, gauss, psf, idpsf, psfrad, fitrad, psfname] INPUTS: IMAGE - input image array XC - input vector of x coordinates (from FIND), these should be IDL (first pixel is (0,0)) convention. YC - input vector of y coordinates (from FIND) APMAG - vector of magnitudes (from APER), used for initial estimate of gaussian intensity. If APMAG is multidimensional, (more than 1 aperture was used in APER) then the first aperture is used. SKY - vector of sky values (from APER) OPTIONAL INPUTS: The user will be prompted for the following parameters if not supplied. RONOIS - readout noise per pixel, (in electrons, or equivalent photons) PHPADU - photons per analog digital unit, used to scale the data numbers in IMAGE into photon units IDPSF - vector of star id numbers from the list created by APER which will be used to define the PSF. Stars whose centroid does not fall within PSFRAD of the edge of the frame, or for which a gaussian fit requires more than 25 iterations, will be ignored when creating the final PSF. PSFRAD - the scalar radius, in pixels, of the circular area within which the PSF will be defined. This should be slightly larger than the radius of the brightest star that one will be interested in. FITRAD - the scalar radius, in pixels of the circular area used in the least-square star fits. Stetson suggest that FITRAD should approximately equal to the FWHM, slightly less for crowded fields. (FITRAD must be smaller than PSFRAD.) PSFNAME- Name of the STSDAS-disk file (modified FITS) that will contain the table of residuals, and the best-fit gaussian parameters. This file is subsequently required for use by NSTAR. OPTIONAL OUTPUTS: GAUSS - 5 element vector giving parameters of gaussian fit to the first PSF star GAUSS(0) - height of the gaussian (above sky) GAUSS(1) - the offset (in pixels) of the best fitting gaussian and the original X centroid GAUSS(2) - similiar offset from the Y centroid GAUSS(3) - Gaussian sigma in X GAUSS(4) - Gaussian sigma in Y PSF - 2-d array of PSF residuals after a gaussian fit. PROCEDURE: GETPSF fits a Gaussian profile to the core of the first PSF star and generates a look-up table of the residuals of the actual image data from the Gaussian fit. If desired, it will then fit this PSF to another star (using PKFIT) to determine its precise centroid, scale the same Gaussian to the new star's core, and add the differences between the actual data and the scaled Gaussian to the table of residuals. (In other words, the gaussian fit is performed only on the first star.) SYSTEM VARIABLES: Set !DEBUG = 1 to view each iteration of the least squares fit Subroutines called: RINTER, PKFIT, MAKE_2D, DAOERF, STRNUMBER, STRN REVISON HISTORY: Adapted from the 1986 version of DAOPHOT in STSDAS IDL Version 2 W Landsman November 1988
(See /usr/local/idl/lib/zastron/daophot/getpsf.pro)
NAME: GROUP PURPOSE: Procedure in DAOPHOT sequence to place stars with non-overlapping PSF profiles into distinct groups CALLING SEQUENCE: GROUP, X, Y, RCRIT, NGROUP INPUTS: X - vector, giving X coordinates of a set of stars. Y - vector, giving Y coordinates of a set of stars. RCRIT - scalar, giving minimum distance between stars of two distinct groups. Stars less than this distance from each other are always in the same group. Stetson suggests setting the critical distance equal to the PSF radius + the Fitting radius. OUTPUTS: NGROUP - integer vector, same number of elements as X and Y, giving a group number for each star position. Group numbering begins with 0. METHOD: Each position is initially given a unique group number. The distance of each star is computed against every other star. Those distances less than RCRIT are assigned the minimum group number of the set. A check is then made to see if any groups have merged together. PROCEDURES USED: REM_DUP REVISION HISTORY: Written W. Landsman STX April, 1988 Major revision to properly merge groups together W. Landsman Sep 1991
(See /usr/local/idl/lib/zastron/daophot/group.pro)
NAME:
MMM
PURPOSE:
Estimate the sky background, assuming that contaminated sky pixel
values overwhelmingly display POSITIVE departures from the true
value. Adapted from DAOPHOT routine of the same name.
CALLING SEQUENCE:
MMM, sky, [ skymde, sigma, skew, HIGHBAD = , DEBUG = ]
INPUTS:
SKY - Array or Vector containing sky values. This version of
MMM does not require SKY to be sorted beforehand. SKY
is unaltered by this program.
OPTIONAL OUTPUTS:
SKYMDE - Scalar giving estimated mode of the sky values
SIGMA - Scalar giving standard deviation of the peak in the sky
histogram. If for some reason it is impossible to derive
SKYMDE, then SIGMA = -1.0
SKEW - Scalar giving skewness of the peak in the sky histogram
If no output variables are supplied or if /DEBUG is set
then the values of SKYMDE, SIGMA and SKEW will be printed.
OPTIONAL KEYWORD INPUTS:
HIGHBAD - scalar value of the high "bad" pixel level (e.g. cosmic rays)
If not supplied, then there is assumed to be no high bad
pixels.
DEBUG - If this keyword is set and non-zero, then additional information
is displayed at the terminal.
RESTRICTIONS:
Program assumes that low "bad" pixels (e.g. bad CCD columns) have
already been deleted from the SKY vector.
METHOD:
The algorithm used by MMM consists of roughly two parts:
(1) The average and sigma of the sky pixels is computed. These values
are used to eliminate outliers, i.e. values with a low probability
given a gaussian with specified average and sigma. The average
and sigma are then recomputed and the process repeated up to 20
iterations:
(2) The amount of contamination by stars is estimated by comparing the
mean and median of the remaining sky pixels. If the mean is larger
than the median then the true sky value is estimated by
3*median - 2*mean
REVISION HISTORY:
Adapted to IDL from 1986 version of DAOPHOT in STSDAS,
W. Landsman, STX Feb 1987
Adapted for IDL Version 2, J. Isensee, STX, Sept 1990
Added HIGHBAD keyword, W. Landsman January, 1991
Fixed occasional problem with integer inputs W. Landsman Feb, 1994
(See /usr/local/idl/lib/zastron/daophot/mmm.pro)
NAME: NSTAR PURPOSE: Simultaneous point spread function fitting (adapted from DAOPHOT) CALLING SEQUENCE: nstar, image, id, xc, yc, mags, sky, group, [ phpadu, readns, psfname, magerr, iter, chisq, peak, PRINT= , SILENT= ] INPUTS: image - image array id - vector of stellar ID numbers given by FIND xc - vector containing X position centroids of stars (e.g. as found by FIND) yc - vector of Y position centroids mags - vector of aperture magnitudes (e.g. as found by APER) If 9 or more parameters are supplied then, upon output ID,XC,YC, and MAGS will be modified to contain the new values of these parameters as determined by NSTAR. Note that the number of output stars may be less than the number of input stars since stars may converge, or "disappear" because they are too faint. sky - vector of sky background values (e.g. as found by APER) group - vector containing group id's of stars as found by GROUP OPTIONAL INPUT: phpadu - numeric scalar giving number of photons per digital unit. Needed for computing Poisson error statistics. readns - readout noise per pixel, numeric scalar. If not supplied, NSTAR will try to read the values of READNS and PHPADU from the PSF header. If still not found, user will be prompted. psfname - name of of SDAS-type file containing point spread function as determined by GETPSF, scalar string. If omitted, NSTAR will prompt for PSFNAME. OPTIONAL OUTPUTS: MAGERR - vector of errors in the magnitudes found by NSTAR ITER - vector containing the number of iterations required for each output star. CHISQ- vector containing the chi square of the PSF fit for each output star. PEAK - vector containing the difference of the mean residual of the pixels in the outer half of the fitting circle and the mean residual of pixels in the inner half of the fitting circle OPTIONAL KEYWORD INPUTS: SILENT - if set and non-zero, then NSTAR will not display its results at the terminal PRINT - if set and non-zero then NSTAR will also write its results to a file NSTAR.PRT. One can specify the output file name by setting PRINT = 'filename'. PROCEDURES USED: DAO_VALUE, STRN, SXOPEN, SXREAD, SXPAR SYSTEM VARIABLES: Set !DEBUG=1 to see the results of each fitting iteration. REVISION HISTORY W. Landsman ST Systems Co. May, 1988 Adapted for IDL Version 2, J. Isensee, September, 1990
(See /usr/local/idl/lib/zastron/daophot/nstar.pro)
NAME: PKFIT PURPOSE: This procedure is called by GETPSF to perform the one-star least-squares fit in the DAOPHOT sequence CALLING SEQUENCE: PKFIT, f, scale, x, y, sky, radius, ronois, phpadu, gauss, psf, errmag, chi, sharp, Niter INPUTS: F - NX by NY array containing actual picture data. SCALE - the initial estimate of the brightness of the star, expressed as a fraction of the brightness of the PSF. Upon return, the final computed value of SCALE will be passed back to the calling routine. X, Y - the initial estimates of the centroid of the star relative to the corner (0,0) of the subarray. Upon return, the final computed values of X and Y will be passed back to the calling routine. SKY - the local sky brightness value, as obtained from APER RADIUS- the fitting radius-- only pixels within RADIUS of the instantaneous estimate of the star's centroid will be included in the fit, scalar RONOIS - readout noise per pixel, scalar PHPADU - photons per analog digital unit, scalar GAUSS - vector containing the values of the five parameters defining the analytic Gaussian which approximates the core of the PSF. PSF - an NPSF by NPSF look-up table containing corrections from the Gaussian approximation of the PSF to the true PSF. OUTPUTS: ERRMAG - the estimated standard error of the value of SCALE returned by this routine. CHI - the estimated goodness-of-fit statistic: the ratio of the observed pixel-to-pixel mean absolute deviation from the profile fit, to the value expected on the basis of the noise as determined from Poisson statistics and the readout noise. SHARP - a goodness-of-fit statistic describing how much broader the actual profile of the object appears than the profile of the PSF. NITER - the number of iterations the solution required to achieve convergence. If NITER = 25, the solution did not converge. If for some reason a singular matrix occurs during the least- squares solution, this will be flagged by setting NITER = -1. RESTRICTIONS: No parameter checking is performed REVISON HISTORY: Adapted from the official DAO version of 1985 January 25 Version 2.0 W. Landsman STX November 1988
(See /usr/local/idl/lib/zastron/daophot/pkfit.pro)
NAME: RDPSF PURPOSE: Read the STSDAS file created by GETPSF in the DAOPHOT sequence; combine the gaussian with the residuals to create an output PSF array. CALLING SEQUENCE: RDPSF, PSF, HPSF, [ PSFNAME] OPTIONAL INPUTS psfname - string giving the name of the SDAS file containing the PSF residuals OUTPUTS psf - array containing the actual PSF hpsf - header associated with psf REVISION HISTORY: Written W. Landsman December, 1988 Checked for IDL Version 2, J. Isensee & J. Hill, December, 1990
(See /usr/local/idl/lib/zastron/daophot/rdpsf.pro)
NAME: SKY PURPOSE: Determine the sky level in an image by applying the procedure MMM to approximately 4000 uniformly spaced pixels. Adapted from the DAOPHOT routine of the same name. CALLING SEQUENCE: SKY, image, [ skymode, skysig, CIRCLE = ,/SILENT ] INPUTS: IMAGE - One or two dimensional array OPTIONAL OUTPUT ARRAYS: SKYMODE - Scalar, giving the mode of the sky pixel values of the array IMAGE, as determined by the procedure MMM. SKYSIG - Scalar, giving standard deviation of sky brightness INPUT KEYWORD PARAMETERS: CIRCLERAD - Use the keyword to have SKY only select pixels within specified pixel radius of the center of the image. If CIRCLERAD = 1, then the radius is set equal to half the image width. For example, SILENT - If this keyword is supplied and non-zero, then SKY will not display the sky value and sigma at the terminal PROCEDURE: A regular grid of points, not exceeding 4000 in number, is extracted from the image array. The mode of these pixel values is determined by the procedure MMM. REVISION HISTORY: Written, W. Landsman STX Co. September, 1987 Changed INDGEN to LINDGEN January, 1994 Fixed display of # of points used March, 1994
(See /usr/local/idl/lib/zastron/daophot/sky.pro)
NAME: SUBSTAR PURPOSE: DAOPHOT procedure to subtract a scaled point spread function at specified star position(s). CALLING SEQUENCE: SUBSTAR, image, x, y, mag, [ id, psfname, /VERBOSE] INPUT-OUTPUT: IMAGE - On input, IMAGE is the original image array. A scaled PSF will be subtracted from IMAGE at specified star positions. Make a copy of IMAGE before calling SUBSTAR, if you want to keep a copy of the unsubtracted image array INPUTS: X - REAL Vector of X positions found by NSTAR (or FIND) Y - REAL Vector of Y positions found by NSTAR (or FIND) MAG - REAL Vector of stellar magnitudes found by NSTAR (or APER) Used to scale the PSF to match intensity at star position. OPTIONAL INPUTS: ID - Index vector indicating which stars are to be subtracted. If omitted, (or set equal to -1), then stars will be subtracted at all positions specified by the X and Y vectors. PSFNAME - Name of the STSDAS (modified FITS) file containing the PSF generated by GETPSF. SUBSTAR will prompt for this parameter if not supplied. OPTIONAL INPUT KEYWORD: VERBOSE - If this keyword is set and nonzero, then SUBSTAR will display the star that it is currently processing COMMON BLOCKS: The RINTER common block is used (see RINTER.PRO) to save time in the PSF calculations REVISION HISTORY: Written, W. Landsman August, 1988 Added VERBOSE keyword January, 1992
(See /usr/local/idl/lib/zastron/daophot/substar.pro)
NAME:
T_APER
PURPOSE:
Driver procedure (for APER) to compute concentric aperture photometry,
with I/O to FITS ASCII tables. Adapted from DAOPHOT.
CALLING SEQUENCE:
T_APER, image, h, tab, [ apr, skyrad, badpix, TEXTOUT=, SILENT = ]
INPUTS:
DATA - input data array
H,TAB - disk FITS table and header (from T_FIND). Must contain
the keywords 'X' and 'Y' giving the centroid of the source
positions in FORTRAN (first pixel is 1) convention.
OPTIONAL INPUTS:
User will be prompted for the following parameters if not supplied.
APR - Vector of up to 12 REAL photometry aperture radii.
SKYRAD - Two element vector giving the inner and outer radii
to be used for the sky annulus
BADPIX - Two element vector giving the minimum and maximum
value of a good pixel (Default [-32765,32767])
OPTIONAL KEYWORDS INPUTS:
TEXTOUT - If textout is set equal to 3 output will go to file aper.prt
If textout is not used, output will default to the screen.
SILENT - If this keyword is set and non-zero, then APER will not
display photometry results at the screen, and the results
will be automatically incorporated in the FITS table without
prompting the user
OUTPUTS:
H,TAB - FITS ASCII header and table array will be optionally updated
with photometry results from APER.
REVISON HISTORY:
Written W. Landsman ST Systems Co. May 1988
Store results as flux or magnitude August 1988
Added textout keywords, J. Isensee, October, 1990
Added SILENT keyword W. Landsman Sep. 1991
(See /usr/local/idl/lib/zastron/daophot/t_aper.pro)
NAME: T_FIND PURPOSE: Finds positive brightness perturbations (i.e stars) in a 2 dimensional image. Input and output are to FITS ASCII tables CALLING SEQUENCE: t_find, image, im_hdr, h, tab, [ hmin, fwhm, sharplim, roundlim, TEXTOUT = , SILENT = ] INPUTS: image - 2 dimensional image array (integer or real) for which one wishes to identify the stars present im_hdr - FITS or STSDAS header associated with image array OPTIONAL INPUTS: T_FIND will prompt for these parameters if not supplied fwhm - FWHM to be used in the convolving filter hmin - Threshold intensity for a point source - should generally be 3 or 4 sigma above background level sharplim - 2 element vector giving low and high limit for sharpness statistic (Default: [0.2,1.0] ) roundlim - 2 element vector giving low and high limit for roundness statistic (Default: [-1.0,1.0] ) OPTIONAL INPUT KEYWORD: TEXTOUT - Optional keyword to control output. See the procedure TEXTOPEN for more info. If not set, then the system variable TEXTOUT is used (default =1 ==> output to the screen.) SILENT - If this keyword is set and non-zero, then FIND will work silently, and not display each star found OUTPUTS: h - output FITS table header array tab - output FITS table array REVISION HISTORY: Written W. Landsman, STX May, 1988 Added detector and textout keywords, J. Isensee, STX, October, 1990 Added phpadu, J. Hill, STX, October, 1990
(See /usr/local/idl/lib/zastron/daophot/t_find.pro)
NAME: T_GETPSF PURPOSE: Generate a point-spread function from one or the sum of several isolated stars using FITS table I/O. Residuals are written to an STSDAS image file. CALLING SEQUENCE: t_getpsf, image, h, tab, [ idpsf, psfrad, fitrad, psfname ] INPUTS: IMAGE - image array H - header of FITS ASCII table created by T_APER TAB - FITS ASCII table array created by T_APER OPTIONAL INPUTS (GETPSF will prompt for these if not supplied.) IDPSF - vector of stellar ID numbers indicating which stars are to be used to create the PSF. Should be in IDL convention (first star number is 0.) PSFRAD - the radius for which the PSF will be defined FITRAD - fitting radius, always smaller than PSFRAD PSFNAME - name of STSDAS image file to contain PSF residuals, scalar string OUTPUTS: H,TAB - the field "PSF CODE" in the FITS ASCII table will be updated to indicate which stars were used for the PSF REVISION HISTORY: Written W. Landsman STX May, 1988
(See /usr/local/idl/lib/zastron/daophot/t_getpsf.pro)
NAME: T_GROUP PURPOSE: Procedure to place stars with non-overlapping PSF profiles into distinct groups. Input and output are to disk FITS tables CALLING SEQUENCE: t_group, h, tab, [ rmax, XPAR = , YPAR = ] INPUTS: h - header array for output table created by T_APER tab - table array created by T_APER OPTIONAL INPUTS: rmax - maximum allowable distance between stars in a single group OPTIONAL INPUT KEYWORDS: XPAR, YPAR - scalar strings giving the field name in the output table containing the X and Y coordinates. If not supplied, then the fields 'X' and 'Y' are read. REVISION HISTORY: Written, W. Landsman ST Sytems Co. May, 1988 Keyword variables xpar, ypar added by J. Hill Hughes STX April, 1992
(See /usr/local/idl/lib/zastron/daophot/t_group.pro)
NAME: T_NSTAR PURPOSE: Simultaneous point spread function fitting. Input and output are to FITS ASCII tables. CALLING SEQUENCE: T_NSTAR,IMAGE,H,TAB,[PSFNAME,GROUPSEL] INPUTS: IMAGE - image array H - FITS ASCII table header from T_APER TAB - FITS ASCII table array from T_APER OPTIONAL INPUTS: PSFNAME - Name of SDAS file created by T_GETPSF containing PSF residuals GROUPSEL - Scalar or vector listing the groups to process. For example, to process stars in groups 2 and 5 set GROUPSEL = [2,5]. If omitted, or set equal to -1, then NSTAR will process all groups. OUTPUTS: H,TAB - will be updated to contain the output of NSTAR OPTIONAL KEYWORD INPUTS: SILENT - if set and non-zero, then NSTAR will not display its results at the terminal PRINT - if set and non-zero then NSTAR will also write its results to a file NSTAR.PRT. One can specify the output file name by setting PRINT = 'filename'. REVISION HISTORY: Written W. Landsman STX Co. May, 1988
(See /usr/local/idl/lib/zastron/daophot/t_nstar.pro)
NAME:
UIT_FIND
PURPOSE:
Find positive brightness perturbations (i.e stars) in a
2 dimensional image and compute centroids, and shape parameters,
Adapted from DAOPHOT.
CALLING SEQUENCE:
UIT_FIND, image, [ x, y, flux, sharp, round, hmin, fwhm, roundlim,
sharplim, TEXTOUT = ,HMAX = , RCRIT = ]
INPUTS:
image - 2 dimensional image array (integer or real) for which one
wishes to identify the stars present
OPTIONAL INPUTS:
UIT_FIND will prompt for these parameters if not supplied
hmin - Threshold intensity for a point source - should generally
be 3 or 4 sigma above background
fwhm - FWHM to be used in the convolve filter
sharplim - 2 element vector giving low and high cutoff for the
sharpness statistic (Default: [0.2,1.0] )
roundlim - 2 element vector giving low and high cutoff for the
roundness statistic (Default: [-1.0,1.0] )
OPTIONAL OUTPUTS:
x - vector containing x position of all stars identified by UIT_FIND
y- vector containing y position of all stars identified by UIT_FIND
flux - vector containing flux of identified stars as determined
by a gaussian fit. Fluxes are NOT converted to magnitudes.
sharp - vector containing sharpness statistic for identified stars
round - vector containing roundness statistic for identified stars
OPTIONAL KEYWORD INPUTS:
TEXTOUT - Determines where output results will be printed (see
TEXTOPEN ) If not used, defaults to !TEXTOUT value.
HMAX - Maximum allowed intensity value for a valid source. If not
suppied, then hmax = 20000 to agree with BDR.
RCRIT - Scalar giving the maximum distance from the image center for
valid source. To agree with BDR the default value of RCRIT is
990 for 2048 x 2048 UIT images.
SYSTEM VARIABLES:
If !TEXTOUT=3 then an output file UIT_FIND.PRT will be created which
will contain a table of information on identified stars
REVISION HISTORY:
Written W. Landsman, STX February, 1987
Adapted for IDL Version 2, J. Isensee, STX, October, 1990
Added HMAX keyword W. Landsman STX August, 1991
(See /usr/local/idl/lib/zastron/daophot/uit_find.pro)