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NAME:
center
PURPOSE: (one line)
return a star center
DESCRIPTION:
return a star center
CATEGORY:
IMAGES
CALLING SEQUENCE:
center, d, xin, yin, xout, yout, method=method, nomax=nomax, $
miss=miss, ap=ap, skyin=skyin, skyout=skyout, count=counts,
skyval=skyval, fwhm=fwhm
INPUTS:
d : the two-dimensional image
xin, yin: initial guess at the star position
OPTIONAL INPUT PARAMETERS:
method: boxm, centrod, cntrd, or psf_1_gauss
[default = centrod]
nomax : don't begin by centering up on the local maximum
miss : allowable miss distance between xin,yin and the
x, y of maximum flux [default = 10]
ap :
boxm - not used
centrod - radius used for calculating the center of max
cntrd - size of box to use for calculating center
psf_1_gauss - radius of pixels to include
[default = 3]
skyin, skyout: inner and outer radii for calculating the
sky background [default = 10,20]
OUTPUTS:
xout, yout : calculated x,y position
boxm - location of the maximum (or passed xin,yin
if nomax=1
centrod - "center of mass" using Buie's centrod
cntrd - position where X and Y derivatives go to zero using
daophot's cntrd
psf_1_gauss - fit of an unweighted circular gaussian
OUTPUT KEYWORDS:
ckyval : value of the sky from the sky aperture
calculated using robomean
counts : counts in the star
boxm - the value at xout,yout
centrod - "mass" of the object in counts from buie's centrod
cntrd - aperture photometry using daophot's cntrd
psf_1_gauss - fit of an unweighted circular gaussian
returns mathematical total under the PSF, not just
from the center to ap
fwhm :
for psf_1_gauss, the fitted FWHM
SIDE EFFECTS:
EXAMPLE:
MODIFICATION HISTORY:
Written 14 Jun 2007 Leslie Ann Young SwRI
Modified 13 Sep 2007 LAY
Modified 07 Oct 2007 LAY set counts, fwhm if off frame
Modified 06 Sep 2010 LAY Fix error calling centrd where aper was
modifying the passes setskyval = sky
(See ../astrom/center.pro)
NAME:
centrod
PURPOSE: (one line)
Compute center of mass of an object aperture and errors.
DESCRIPTION:
CATEGORY:
CCD data processing
CALLING SEQUENCE:
centrod_err, image, image_err, xcen, ycen, $
radius, inradius, outradius, skyback, $
xbar, ybar, counts, xbarerr, ybarerr, countserr
INPUTS:
image : CCD image array.
image_err
xcen, ycen : Center of window.
radius : Radius of window.
inradius : Inner radius of sky annulus.
outradius : Outer radius of sky annulus.
skyback : Sky background in counts per pixel.
OPTIONAL INPUT PARAMETERS:
KEYWORD PARAMETERS:
ADDNEG : Flag, if set, the position is computed using both
the moments of counts above and below the background.
Default is to compute the position only using those
image values greater than the sky background.
OUTPUTS:
xbar, ybar : Position of center of mass.
counts : Mass of object in counts.
xbarerr, ybarerr : Error in position of center of mass.
countserr : Error in mass of object in counts.
COMMON BLOCKS:
SIDE EFFECTS:
RESTRICTIONS:
PROCEDURE:
MODIFICATION HISTORY:
Ported by Doug Loucks, Lowell Observatory, 1992 Oct, from the C-
language version written by Marc Buie.
4/1/93, DWL, Added argument validation (badpar).
99/08/31, MWB, added ADDNEG keyword.
2006 Jan 31 LAY Added errors (based on centrod)
(See ../astrom/centrod_err.pro)
NAME:
sumannerr
PURPOSE: (one line)
Integrate over an annulus.
DESCRIPTION:
This procedure computes the first two image moments of the pixels
contained within the input annulus AND THEIR ERRORS.
The position and inner and outer
radii define the annulus. Each pixel in the input image is then
assigned a weighting value which is its areal overlap between the pixel
and the annulus. This weight varies from 0 to 1 and is the precise
analytic area of overlap (computed by pixwt.pro). Of course, this
program doesn't do the computation for all pixels, only those near
the edge.
UNLIKE IN SUMANN, the moments are NOT into two components
CATEGORY:
CCD data processing
CALLING SEQUENCE:
Sumannerr, image, imageerr,xcen, ycen, $
inradius, outradius, back, backerr, totweight, $
sum, xmom, ymom, $
sumerr, xmomerr, ymomerr
INPUTS:
image : CCD image array.
imageerr : std deviation of image
xcen,ycen : Center of annulus.
inradius : Radius of inner circle.
outradius : Radius of outer circle.
back : Background to subtract from each pixel.
backerr : error in background
OPTIONAL INPUT PARAMETERS:
KEYWORD PARAMETERS:
OUTPUTS:
totweight : Area of annulus.
sum : Sums of positive and negative pixels.
xmomm : x moments relative to xcen.
ymom : y moments relative to ycen.
sumerr : formal error in sum
xmomerr : formal error in xmom
ymomerr : formal error in ymom
COMMON BLOCKS:
SIDE EFFECTS:
RESTRICTIONS:
PROCEDURE:
MODIFICATION HISTORY:
Ported by Doug Loucks, Lowell Observatory, 1992 Oct, from the
C-language version written by Marc Buie.
April, 1993. DWL. Replaced the inner FOR loop with vectors.
98/09/21, MWB, optimizations
98/09/29, MWB, fixed nasty bug introduced during optimization.
06/01/31, LAY, removed pos and neg sums, added errors, based on subann
(See ../astrom/sumannerr.pro)
NAME: wcstnx_rd2xy PURPOSE: (one line) World Coordinate System transformation DESCRIPTION: given ra and dec in radians calculate x and y (in IDL coordinates - 1st pixel centered on 0) CATEGORY: Astrometry CALLING SEQUENCE: wcstnx_rd2xy, ra, dec, wcs, xout, yout INPUTS: ra - right ascention in radians dec - declination in radians wcs - a structure containing astrometric info (see hdr2wcs) OPTIONAL INPUT PARAMETERS: KEYWORD INPUT PARAMETERS: KEYWORD OUTPUT PARAMETERS: xiast, etaast - 'astrometric' xi, eta xip, etap - the non-linear xi,eta OUTPUTS: x, y - IDL coordinates - 1st pixel centered on 0 COMMON BLOCKS: SIDE EFFECTS: RESTRICTIONS: PROCEDURE: MODIFICATION HISTORY: Written 2006 Feb, by Leslie Young, SwRI
(See ../astrom/wcstnx_rd2xy.pro)