diff options
Diffstat (limited to 'noao/digiphot/daophot/doc/substar.hlp')
| -rw-r--r-- | noao/digiphot/daophot/doc/substar.hlp | 323 |
1 files changed, 323 insertions, 0 deletions
diff --git a/noao/digiphot/daophot/doc/substar.hlp b/noao/digiphot/daophot/doc/substar.hlp new file mode 100644 index 00000000..5de81b85 --- /dev/null +++ b/noao/digiphot/daophot/doc/substar.hlp @@ -0,0 +1,323 @@ +.help substar May00 noao.digiphot.daophot +.ih +NAME +substar -- subtract photometry results from an image +.ih +USAGE +substar image photfile exfile psfimage subimage +.ih +PARAMETERS +.ls image +The list of images from which to subtract the scaled and shifted PSF. +.le +.ls photfile +The list of PSF fitted photometry files. There must be one photometry file +for every input image. If photfile is "default", "dir$default", or a directory +specification, SUBSTAR will look for a file called image.nst.? where the +question mark stands for the highest existing version number. Photfile is +usually the output of the NSTAR task but may also be the output of the PEAK +and ALLSTAR tasks or even the PHOT task. Photfile may be an APPHOT/DAOPHOT text +database or an STSDAS table. +.le +.ls exfile +The list of photometry files containing the ids of stars to be excluded +from the subtraction. Exfile must be undefined or contain one exclude file +for every input image. If exfile is "default", "dir$default", or a directory +specification, SUBSTAR will look for a file called image.pst.? where the ? +mark stands for the highest existing version number. Exfile is usually the +output of the PSTSELECT task but may also be the output of the PEAK, NSTAR and +ALLSTAR tasks or even the PHOT task. Exfile may be an APPHOT/DAOPHOT text +database or an STSDAS table. +.le +.ls psfimage +The list of images containing the PSF models computed by the DAOPHOT PSF task. +The number of PSF images must be equal to the number of input images. If +psfimage is "default", "dir$default", or a directory specification, +then PEAK will look for an image with the name image.psf.?, where +? is the highest existing version number. +.le +.ls subimage +The list of output subtracted images. There must be one output subtracted +image for every input image. If subimage is "default", "dir$default", or a +directory specification, then SUBSTAR will write an image called image.sub.? +where question mark stands for the next available version number. +.le +.ls datapars = "" +The name of the file containing the data dependent parameters. The parameters +\fIscale\fR, \fIdatamin\fR, and \fIdatamax\fR are located here. If datapars +is undefined then the default parameter set in uparm directory +.le +.ls daopars = "" +The name of the file containing the daophot fitting parameters. The parameters +\fIpsfrad\fR and \fIfitrad\fR are located here. If \fIdaopars\fR is undefined +then the default parameter set in uparm directory is used. +.le +.ls wcsin = ")_.wcsin", wcsout = ")_.wcsout", wcspsf = ")_.wcspsf" +The coordinate system of the input coordinates read from \fIphotfile\fR, of the +psf model \fIpsfimage\fR, and of the output coordinates written to +the standard output if \fIverbose\fR = "yes". The image header coordinate +system is used to transform from the input coordinate system to the "logical" +pixel coordinate system used internally, from the internal logical system to +the PSF model system, and from the internal "logical" pixel coordinate system +to the output coordinate system. The input coordinate system options are +"logical", "tv", "physical", and "world". The PSF model and output coordinate +system options are "logical", "tv", and "physical". The image cursor coordinate +system is assumed to be the "tv" system. +.ls logical +Logical coordinates are pixel coordinates relative to the current image. +The logical coordinate system is the coordinate system used by the image +input/output routines to access the image data on disk. In the logical +coordinate system the coordinates of the first pixel of a 2D image, e.g. +dev$ypix and a 2D image section, e.g. dev$ypix[200:300,200:300] are +always (1,1). +.le +.ls tv +Tv coordinates are the pixel coordinates used by the display servers. Tv +coordinates include the effects of any input image section, but do not +include the effects of previous linear transformations. If the input +image name does not include an image section, then tv coordinates are +identical to logical coordinates. If the input image name does include a +section, and the input image has not been linearly transformed or copied from +a parent image, tv coordinates are identical to physical coordinates. +In the tv coordinate system the coordinates of the first pixel of a +2D image, e.g. dev$ypix and a 2D image section, e.g. dev$ypix[200:300,200:300] +are (1,1) and (200,200) respectively. +.le +.ls physical +Physical coordinates are pixel coordinates invariant with respect to linear +transformations of the physical image data. For example, if the current image +was created by extracting a section of another image, the physical +coordinates of an object in the current image will be equal to the physical +coordinates of the same object in the parent image, although the logical +coordinates will be different. In the physical coordinate system the +coordinates of the first pixel of a 2D image, e.g. dev$ypix and a 2D +image section, e.g. dev$ypix[200:300,200:300] are (1,1) and (200,200) +respectively. +.le +.ls world +World coordinates are image coordinates in any units which are invariant +with respect to linear transformations of the physical image data. For +example, the ra and dec of an object will always be the same no matter +how the image is linearly transformed. The units of input world coordinates +must be the same as those expected by the image header wcs, e. g. +degrees and degrees for celestial coordinate systems. +.le +The wcsin, wcspsf, and wcsout parameters default to the values of the package +parameters of the same name. The default values of the package parameters +wcsin, wcspsf, and wcsout are "logical", "physical" and "logical" respectively. +.le +.ls cache = ")_.cache" +Cache the image pixels in memory. Cache may be set to the value of the apphot +package parameter (the default), "yes", or "no". By default caching is +disabled. +.le +.ls verify = ")_.verify" +Verify the critical SUBSTAR task parameters? Verify can be set to the DAOPHOT +package parameter value (the default), "yes", or "no". +.le +.ls update = ")_update" +Update the SUBSTAR task parameters if \fIverify\fR is "yes"? Update can be +set to the default daophot package parameter value, "yes", or "no". +.le +.ls verbose = ")_.verbose" +Print messages about the progress of the task ? Verbose can be set to the +DAOPHOT package parameter value (the default), "yes", or "no". +.le + +.ih +DESCRIPTION +SUBSTAR task takes an input photometry list \fIphotfile\fR containing +the fitted coordinates and magnitudes, and an input PSF \fIpsfimage\fR, and +for each star in the photometry list scales and shifts the PSF and subtracts +it from the input image \fIimage\fR. The final subtracted image is saved in the +output image \fIsubimage\fR. + +The input photometry list can be the output from of the PEAK, NSTAR or ALLSTAR +tasks or even the PHOT task although most people would not want to use the PHOT +output for this purpose. + +Selected stars may be omitted from the subtraction by supplying their ids in +the file \fIexfile\fR. \fIExfile\fR is normally the output the PSTSELECT task +and is used to tell SUBSTAR to subtract the PSF star neighbors, but not the +PSF stars themselves. + +The coordinates read from \fIphotfile\fR are assumed to be in coordinate +system defined by \fIwcsin\fR. The options are "logical", "tv", "physical", +and "world" and the transformation from the input coordinate system to the +internal "logical" system is defined by the image coordinate system. The +simplest default is the "logical" pixel system. Users working on with image +sections but importing pixel coordinate lists generated from the parent image +must use the "tv" or "physical" input coordinate systems. + +The coordinate system of the PSF model is the coordinate system defined by the +\fIwcspsf\fR parameter. Normally the PSF model was derived from the input image +and this parameter default to "logical". However if the PSF model was derived +from a larger image which is a "parent" of the input image, then wcspsf should +be set to "tv" or "physical" depending on the circumstances. + +The coordinates written to the standard output if \fIverbose\fR = yes are in the +coordinate system defined by \fIwcsout\fR. The options are "logical", "tv", +and "physical". The simplest default is the "logical" system. Users wishing to +correlate the output coordinates of objects measured in image sections or +mosaic pieces with coordinates in the parent image must use the "tv" or +"physical" coordinate systems. + +If \fIcache\fR is yes and the host machine physical memory and working set size +are large enough the input and output image pixels are cached in memory. If +caching is enabled and SUBSTAR is run interactively the first subtraction +will appear to take a long time as the entire image must be read in before +the measurement is actually made. All subsequent measurements will be very +fast because SUBSTAR is accessing memory not disk. The point of caching is +to speed up random image access by making the internal image i/o buffers the +same size as the image itself. However if the input object lists are sorted +in row order which SUBSTAR does internally and are sparse caching may +actually worsen not improve the execution time. Also at present there is no +point in enabling caching for images that are less than or equal to 524288 +bytes, i.e. the size of the test image dev$ypix, as the default image i/o +buffer is exactly that size. However if the size of dev$ypix is doubled by +converting it to a real image with the chpixtype task then the effect of +caching in interactive is can be quite noticeable if measurements +of objects in the top and bottom halves of the image are alternated. + + +The SUBSTAR task is most commonly used to check on the quality of the PSF +fitting produced by PEAK and NSTAR, to search for non-stellar objects and close +binary stars, to generate an improved PSF in crowded fields, and to remove +neighbors from bright stars which are to be used to determine aperture +corrections. + +.ih +EXAMPLES + +1. Subtract the NSTAR photometry results for the test image dev$ypix from the +image dev$ypix. + +.nf + da> datapars.epadu = 14.0 + da> datapars.readnoise = 75.0 + + ... set the gain and readout noise for the detector + + da> daofind dev$ypix default fwhmpsf=2.5 sigma=5.0 threshold=20.0 + + ... answer verify prompts + + ... find stars in the image + + ... answer will appear in ypix.coo.1 + + da> phot dev$ypix default default annulus=10. dannulus=5. \ + apertures = 3.0 + + ... answer verify prompts + + ... do aperture photometry on the detected stars + + ... answer will appear in ypix.mag.1 + + da> display dev$ypix 1 + + da> psf dev$ypix default "" default default default psfrad=11.0 \ + fitrad=3.0 mkstars=yes display=imdr + + ... verify the critical parameters + + ... move the image cursor to a candidate star and hit the a key, + a plot of the stellar data appears + + ... type ? for a listing of the graphics cursor menu + + ... type a to accept the star, d to reject it + + ... move to the next candidate stars and repeat the previous + steps + + ... type l to list all the psf stars + + ... type f to fit the psf + + ... move cursor to first psf star and type s to see residuals, + repeat for all the psf stars + + ... type w to save the PSF model + + ... type q to quit, and q again to confirm + + ... the output will appear in ypix.psf.1.imh, ypix.pst.1 and + ypix.psg.1 + + da> group dev$ypix default default default + + ... verify the prompts + + ... the output will appear in ypix.grp.1 + + da> nstar dev$ypix default default default default + + ... verify the prompts + + ... the results will appear in ypix.nst.1 and ypix.nrj.1 + + da> pdump ypix.nst.1 sharpness,chi yes | graph + + ... plot chi versus sharpness, the stars should cluster around + sharpness = 0.0 and chi = 1.0, note that the frame does + not have a lot of stars + + da> substar dev$ypix default "" default default + + ... subtract the fitted stars + + da> display ypix.sub.1 2 + + ... note that the psf stars subtract reasonably well but other + objects which are not stars don't +.fi + + +2. Rerun the previous example on a section of the test image using the group +file and PSF model derived in example 1 for the parent image and writing the +results in the coordinate system of the parent image. + +.nf + da> nstar dev$ypix[150:450,150:450] default default default default \ + wcsin=tv wcspsf=tv wcsout=tv + + ... answer the verify prompts + + ... fit the stars + + ... the results will appear in ypix.nst.2 and ypix.nst.2 + + da> display dev$ypix[150:450,150:450] 1 + + ... display the image + + da> pdump ypix.nst.2 xc,yc yes | tvmark 1 STDIN col=204 + + ... mark the stars + + da> substar dev$ypix ypix.nst.2 "" default default + + ... subtract stars from parent image + + ... the output images is ypix.sub.2 + + + da> substar dev$ypix[150:450,150:450] ypix.nst.2 "" default default \ + wcsin=tv wcspsf=tv wcsout=tv + + ... subtract stars from the nstarinput image + + ... the output images is ypix.sub.3 + +.fi + +.ih +TIME REQUIREMENTS +.ih +BUGS +.ih +SEE ALSO +datapars,daopars,nstar,peak +.endhelp |