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author | Joe Hunkeler <jhunkeler@gmail.com> | 2015-08-11 16:51:37 -0400 |
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committer | Joe Hunkeler <jhunkeler@gmail.com> | 2015-08-11 16:51:37 -0400 |
commit | 40e5a5811c6ffce9b0974e93cdd927cbcf60c157 (patch) | |
tree | 4464880c571602d54f6ae114729bf62a89518057 /noao/imred/specred/doc/msresp1d.hlp | |
download | iraf-osx-40e5a5811c6ffce9b0974e93cdd927cbcf60c157.tar.gz |
Repatch (from linux) of OSX IRAF
Diffstat (limited to 'noao/imred/specred/doc/msresp1d.hlp')
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diff --git a/noao/imred/specred/doc/msresp1d.hlp b/noao/imred/specred/doc/msresp1d.hlp new file mode 100644 index 00000000..cc3dfed2 --- /dev/null +++ b/noao/imred/specred/doc/msresp1d.hlp @@ -0,0 +1,191 @@ +.help msresp1d Feb92 noao.imred.specred +.ih +NAME +msresp1d -- Create 1D aperture response from flat and throughput data +.ih +USAGE +msresp1d flat throughput apreference response +.ih +PARAMETERS +.ls flat +Flat field image to extract and normalize to create a one dimensional +aperture response image. If no flat field is specified then a throughput +image or file must be specified and only a throughput correction will be +created. Note that the two dimensional unextracted image is specified. +If an extracted image of the same name with the ".ms" extension is present +it is used without reextraction though the unextracted image must also +be present. +.le +.ls throughput +Throughput file or image. If an image is specified, typically a blank sky +observation, the total flux through each aperture is used to correct for +the aperture throughput. If a file consisting of lines with the aperture +number and relative throughput is specified then the aperture throughput +will be generated by those values. If neither is specified but a flat +field image is given the flat field is used to compute the throughput. +Note that the image is a two dimensional unextracted image. If an +extracted image of the same name with the ".ms" extension is present +it is used without reextraction though the unextracted image must also +be present. +.le +.ls apreference +Aperture reference spectrum. If not specified the apertures are defined +using the flat field or throughput images. If only a throughput file +is used then an aperture reference spectrum must be specified to define +the apertures and dimensions of the final response image. +.le +.ls response +Response spectrum to be created. +.le + +.ls recenter = no +Recenter throughput image apertures? +.le +.ls edit = yes +Edit and review apertures? +.le +.ls trace = no +Trace spectra? +.le +.ls clean = no +Detect and replace bad pixels? +.le +.ls fitflat = yes +Fit and ratio flat field spectrum? +.le +.ls interactive = yes +Interactive flat field fit? +.le +.ls function = "spline3", order = 20 +Flat field fitting function and order. The functions may be one of +"chebyshev", "legendre", "spline1" (linear spline), or "spline3" (cubic spline). +The order is either the number of polynomial terms or the number of spline +pieces. +.le +.ih +OTHER PARAMETERS +The package parameters control logging of the operations performed and +the verbose option allows printing of some progress information. The +graphics use the device defined by the STDGRAPH variable and cursor +input is with the parameter \fIcl.gcur\fR. + +Aperture extraction is done using the task \fBapall\fR and any parameters +not overridden by task parameters will be used; for example the detector +noise parameters. +.ih +DESCRIPTION +For multiaperture or multifiber spectra a throughput aperture correction +must be applied to extracted object spectra. Also it is often better to +divide by a one dimensional flat field than a two dimensional one. This +is valid provided the pixels sampled by the flat field and object are +essentially the same. The advantages are that interspectrum pixels where +there is little signal are not used and small shifts (fractions of a pixel) +can be tolerated. The task \fBmsresp1d\fR creates a multiaperture image +containing one dimensional flat field and throughput corrections which +can be directly divided into extracted object spectra. + +If a one dimensional flat field is to be determined the flat field spectra +are extracted unless an extracted image having the specified flat field +name with the ".ms" extension is present. If the \fIfitflat\fR parameter +is set then all the spectra are averaged and a smooth function is fit to +this composite flat field spectrum. The smooth fit is divided into the +individual flat field spectra. This removes the mean flat field spectrum +shape, thus avoiding introducing the inverse of the flat field spectrum +into the object spectra and changing the approximate count levels in the +object. This procedure is recommended. Note that it does not matter if +the individual fibers have differing spectral shapes (such as might happen +with a combination of fibers with differing spectral throughput) because +only a common function is used. The fitting is done using the \fBfit1d\fR +task based on the \fBicfit\fR function fitting routines. When the +\fIinteractive\fR flag is set the fitting may be done interactively +allowing iteration on the fitting function and other fitting parameters. +Note that the function fit should follow the overall shape using a fairly +high order. + +If no throughput image or file is specified the relative strengths +of the flat field spectra define a throughput correction. If a +separate throughput image or file is given then the individual +flat field spectra are normalized to unity and then scaled by the +throughput determined from the image or file. + +If a throughput image, such as a blank sky observation, is specified it is +extracted if needed. The extracted sky spectra are divided by the flat +field which is not yet corrected for throughput variations. The total flux +through each aperture is then found to define the relative throughputs of +the apertures. If a flat field was also specified the throughput values +are multiplied into the normalized flat field otherwise the response image +will consist of constant spectra with the relative throughputs derived from +the image. + +If a throughput file is specified the throughput values for each aperture +are defined from this file. The file consists of lines with two columns, +the aperture number and the relative throughput. All apertures should +be represented. If a flat field was also specified the throughput values +are multiplied into the normalized flat field. If no flat field +is given then the aperture reference image must be specified and it +will be extracted, if necessary, to provide the template for the response +image having constant values for each aperture spectrum. + +It is an error unless one or both of the flat field and throughput +are specified. + +The last stage is to normalize of the response spectra over +all apertures to a global unit mean. Because of this step the throughput +values derived from the flat field, throughput image, or throughput +file need only be relative. Log information is recorded and printed +which includes the final relative throughputs values. + +Aperture extraction is done using the task \fBapall\fR and any parameters +not overridden by task parameters will be used; for example the detector +noise parameters. Task parmeters control whether recentering, +aperture review, and tracing are done. If no aperture reference is +specified the apertures will be defined as the task is run. +The aperture reference, if defined, is often the same as the flat field. +.ih +EXAMPLES +1. To make a flat field response and apply it to an extracted object: + +.nf + ms> msred.verbose=yes + ms> msresp1d flat005 "" "" resp005.ms + Extract flat field flat005 + Searching aperture database ... + Sep 7 14:36: DATABASE - 44 apertures read for flat005. + Resize apertures for flat005? (yes): n + Edit apertures for flat005? (yes): n + Extract aperture spectra for flat005? (yes): + Review extracted spectra from flat005? (yes): n + Extracting apertures ... + Sep 7 14:37: EXTRACT - Aperture 1 from flat005 --> flat005.ms + Sep 7 14:37: EXTRACT - Aperture 2 from flat005 --> flat005.ms + Sep 7 14:37: EXTRACT - Aperture 3 from flat005 --> flat005.ms + Sep 7 14:37: EXTRACT - Aperture 4 from flat005 --> flat005.ms + Sep 7 14:37: EXTRACT - Aperture 5 from flat005 --> flat005.ms + <etc> + Fit and ratio flat field flat005 + <Interactive fitting of average extracted flat field> + Create the normalized response resp005.ms + Sep 7 14:38 BSCALE: image = resp005.ms + bzero=0. bscale=1.0 mean=1.0 median=1.02386 mode=1.07141 + Average fiber response: + 1 0.8049859 + 2 0.6428247 + 3 0.9014022 + 4 0.7955039 + 5 0.9898984 + <etc> + ms> imarith obj006.ms / resp005.ms obj006.ms +.fi + +Of course the extracted object spectra must be the same in terms of apertures, +wavelength coverage, etc. + +2. To make only a throughput correction: + +.nf + ms> msresp1d "" obj005 "" resp005 +.fi +.ih +SEE ALSO +icfit, fit1d, apflatten, apnormalize, dofibers +.endhelp |