Документ взят из кэша поисковой машины. Адрес оригинального документа : http://xmm.vilspa.esa.es/sas/7.1.0/doc/ecubechip2sky.ps.gz Дата изменения: Mon Jul 9 06:48:28 2007 Дата индексирования: Tue Oct 2 12:05:44 2012 Кодировка: Поисковые слова: trees

XMM-Newton Science Analysis System Page: 1
ecubechip2sky
July 9, 2007
Abstract
The task takes a list of CHIPCOORD images and replots them onto a single image
in sky coordinates.
1 Instruments/Modes
Instrument Mode
EPIC mos or PN Imaging
2 Use
pipeline processing maybe
interactive analysis yes
3 Description
The present task is exactly the same as eimchip2sky, except that the input CCD images are in the form
of chip cubes as dened in the task documentation for the chipcube library. I'll direct you to that task
rather than repeating the same description. All the remaining sections are given in full however.
Why separate the two tasks? Originally there was just one task, with the option to supply the CCD
images as 2-d images, 1 per chip, or as chip cubes. However, mainly because of dierences in the way
GTI extensions are present in the two formats, the resulting parameter tree became tangled and clunky.
Separating the tasks has led to a lot of simplication. Of course, shared processing is all performed by
common library functions - there is little actual duplication of code.
4 Parameters
This section documents the parameters recognized by this task (if any).
Parameter Mand Type Default Constraints
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templateset yes dataset
The name of the input template image. This supplies information about the projection plane and pixel
size (via WCS keywords) and pixel dimensions (via the array dimensions) of the output image.
chipcubesets yes dataset
list
A list of names of input chip cubes (see the denition in the documentation for chipcube).
outsets no dataset
list
outset.ds
The list of output images (in sky coordinates). See the documentation for eimchip2sky for a description
of how they match up with the input cubes.
withindices no bool no
Whether to read the indices parameter.
indices yes integer
list
1
See the documentation for eimchip2sky for a description of how they work.
attstyle no string template binnedset|template|user
As described in the documentation for eimchip2sky, in general the attitude (ie, pointing direction and
roll angle) of the spacecraft doesn't stay xed during the course of an exposure. This `wandering' of
the attitude can be approximated by sampling the attitude at a series of times during the exposure. A
separate coordinate transform is computed for each attitude sample and the output image is build up
of appropriately weighted contributions from each transform. The present parameter allows the user to
choose whether to supply such a list of attitude samples (attstyle=`binnedset') or to simply compute
a single coordinate transform for the whole exposure, either at an attitude read from the PNT key-
words of the templateset (attstyle=`template', the default) or at an attitude submitted by the user
(attstyle=`user').
binnedatttab yes table
This parameter is read (and only mandatory) if attstyle=`binnedset'. The parameter should give the
name of a dataset plus table (eg: `mySet.ds:ATT TAB'). The table should contain samples of the XMM
spacecraft attitude in time bins (see the task binned att documentation for a description of the format).
weightstyle no string gti none|binnedset|gti
This parameter is read if attstyle=`binnedset'. A series of attitude samples is supplied; it remains to
decide how to calculate the weight for each sample. weightstyle=`none' is only valid if there is only 1
attitude sample: the task will fail with an error otherwise. For weightstyle=`binnedset', the task will
seek for weights in a column named WEIGHTS in the binnedatttab table. If weightstyle=`gti', the task
attempts to obtain a list of Good Time Intervals (GTIs), the exact way these are supplied being dictated
via the parameter gtistyle; these GTIs are ANDed with the attitude time bins; the net GTI in each
bin provides the weight.
gtistyle no string fromimages user|kwd|fromcubes|gtitablist
This parameter is read if weightstyle=`gti'. In this case the task attempts to obtain a list of Good Time
Intervals (GTIs); these GTIs are ANDed with the attitude time bins; the net GTI in each bin provides
the weight. Note that matters are complicated by the fact that dierent CCDs usually have dierent
sets of GTIs. Parameter gtistyle species the way in which GTIs are supplied. If gtistyle=`user', the
task obtains a single, simple GTI for all chip images from the parameters tstart and tstop. The same
is true if gtistyle=`kwd', except that the task expects to the start and stop times in keywords TSTART
and TSTOP, (or whatever alternates are specied via parameters tstartkwd and tstopkwd), in the FITS
table specied by the parameter kwdtab. The alternate gtistyle=`fromcubes' tells the task to look for
GTI extensions (via the KEY2IMGS table, see documentation for chipcube) in the cube sets. The nal
alternate, gtistyle=`gtitablist', aords the most general and exible specication of GTIs. In this case
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the task looks for a list of GTI tables in the parameter gtitablist. Note that this parameter must have
the same number of elements as chipcubesets.
tstart yes real
This parameter is read if gtistyle=`user'. Species the start of the single, universal GTI.
tstop yes real
This parameter is read if gtistyle=`user'. Species the end of the single, universal GTI.
kwdtab yes table
This parameter is read if gtistyle=`kwd'. It gives the FITS table description in which to nd the GTI
start and stop keywords.
tstartkwd no string TSTART
This parameter is read if gtistyle=`kwd'. Name of the keyword in kwdtab which species the start of
the single, universal GTI.
tstopkwd no string TSTOP
This parameter is read if gtistyle=`kwd'. Name of the keyword in kwdtab which species the end of
the single, universal GTI.
gtitablist yes table
This parameter is read if gtistyle=`gtitablist'. A list of FITS table descriptions, 1 per input image,
which should contain GTI lists.
ra yes real
This parameter is read (and only mandatory) if attstyle=`user'.
dec yes real
This parameter is read (and only mandatory) if attstyle=`user'.
apos yes real
This parameter is read (and only mandatory) if attstyle=`user'.
usefast no bool yes
Whether to use a fast, approximate or slow and accurate regridding algorithm.
conserve ux no bool yes
A CCD pixel covers, in general, a dierent amount of sky to a sky-image pixel. With some sorts of
quantities (eg background rate per pixel) this change of area matters; for others (eg exposure time) it
does not. In the former case you should set conserveflux to `yes', in the latter, `no'.
withnormalize no bool no
I am no longer sure what this is about. Best to leave it at default!
tempset no dataset tempset.ds
Name of a temporary dataset. If you are running more than 1 invocation of the task in the same working
directory, you should name this uniquely for each invocation, to avoid crosstalk.
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5 Errors
This section documents warnings and errors generated by this task (if any). Note that warnings and
errors can also be generated in the SAS infrastructure libraries, in which case they would not be docu-
mented here. Refer to the index of all errors and warnings available in the HTML version of the SAS
documentation.
badAttStyle (error)
The value of attstyle was not recognized.
badGtiStyle (error)
The value of gtistyle was not recognized.
badNumIndices (error)
The number of elements in indices must equal the number in chipcubesets.
badNumberGtiTabNames (error)
The number of elements in gtitablist must equal the number in chipcubesets.
badWeightStyle (error)
The value of weightstyle was not recognized.
duplicateCcds (error)
More than one CCD was found with the same combination of instrument, CCD number and
indices value.
noWeightColumn (error)
You set weightstyle to `binnedset', but no WEIGHT column was found in the binned attitude
set.
tooManyAttBins (error)
You set weightstyle to `none', but this can't work because there is more than one row in
the binned-attitude le.
noGtiBlock (warning)
corrective action: this is the corrective action
6 Input Files
1. A template image. Its array header must contain WCS keywords (see [?] for a recent
description of these). The output image(s) will be the same size as the template image and
projected onto the same celestial projection plane. Note that the data contained in the
template image are not read by ecubechip2sky.
If attstyle=`template', the template image array header must also contain RA PNT, DEC PNT
and PA PNT keywords.
2. A list of FITS chip-cube datasets (see format description in chipcube). These images are
supplied via the chipcubesets parameter.
3. If attstyle=`binnedset': a dataset containing a table of samples of the spacecraft attitude.
The table format is described in the documentation to sas library binned att.
4. If attstyle=`binnedset', weightstyle=`gti' and gtistyle=`kwd': A dataset+table which
contains tstartkwd and tstopkwd keywords.
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5. If attstyle=`binnedset', weightstyle=`gti' and gtistyle=`gtitablist': a list of datasets,
1 per input image, each of which which contains a GTI table.
7 Output Files
1. Each output le contains an image array, which has the same pixel size and dimensions, and
is projected onto the same plane, as the input template image. The data type of the output
image is 4-byte real. The output image contains a copy of all the keywords in the template
image.
See documentation of task eimchip2sky for a description of how multiple output images
match up with the input images.
References
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