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: http://xmm.vilspa.esa.es/sas/7.0.0/documentation/threads/omsource.html
Дата изменения: Tue Oct 7 18:15:48 2003 Дата индексирования: Sat Dec 22 14:30:04 2007 Кодировка: Поисковые слова: earth's atmosphere |
1) Set things up: a) Before you can run task omsource properly, the environment variable for running SAS must be set. Please read SAS start-up thread at: http://xmm.vilspa.esa.es/external/xmm_sw_cal/sas_frame.shtml. If you can run OM pipeline chains 'omichain' or 'omfchain', that means that the environment variable has been set. b) The task omsource works on SAS processed image (after flatfield and mod8 corrections). This image file is included in the PPS product, and has file name PxxxxxxxxxxOMS*IMAG_*000.FIT (for example, P0158360201OMS012FIMAG_U000.FIT, corresponding to a full frame low resolution image)
2) start by typing the following command and pressing return - omsource imageset=P0158360201OMS012FIMAG_U000.FIT newsrclistset=slist.fit where: 'imageset' uses the image file PxxxxxxxxxxOMS*IMAG_X000.FIT in the PPS product. 'newsrclistset' is a new source-list file with an identical structure to that produced by the SAS task omatt, therefore it can be used as input file to the SAS task omsourcelistcomb. You can also add another parameter 'oldsrclistset', using an existing source-list file (for example, PXXXXXXXXXXOMSXXXSWSRLI*.FIT from PPS). The source stored in this source-list file are numbered in the image. This is useful to check the results from the PPS. The parameters 'imageset' and 'newsrclistset' are mandatory for SAS 5.4.1 or before, they can be omitted for a later SAS version (SAS 6.0). 3) select sources After typing the command in step 2), the main task window and the image will be displayed as below.![]()
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From the main task window, you have only two options ('Add sources' and 'Run omdetect'), either select sources from the image manually, or run the SAS task omdetect to locate sources on the image, by clicking the appropriate button. a) select sources from the image manually (if you are interested only on the main target or few sources on the image ) -- clicking the button 'add source', the task window is hidden and a small window appears as this Figure.-- You can select additional sources in the image by centering the cursor over the source and clicking the mouse button. -- When finished, press the 'Finished' button in the small window. -- The main window is shown again. The region for each source is displayed on the image as a yellow ellipse, and the top list box is loaded with parameters (RA, Dec, corrected count rates, instrumental mag) of each source. or b) run omdetect automatically (if you are interested in all sources on the image) -- Click the 'Run omdetect' button, a small dialog-box is displayed allowing you to change the parameters nsigma, minsignificance and detectextended.
-- The sources will be selected automatically when clicking 'OK' button in the small dialog-box. -- Each detected source is displayed on the image as a yellow ellipse and the top list box is loaded with the parameters of each source. -- Check the detected sources on the image, if the results are not satisfactory, click the 'delete list' button in the main window and then click the 'Run omdectect' again by changing the detecting parameters until the results are satisfying. 4) redo photometry for selected source a) the source has first to be selected -- In the Source selection control group click on the spin-box control to either increase or decrease the source-number. When the required source number (834 in following Figure ) is shown click the select button.
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b) Having selected the source, the source is then displayed by ds9 (see Figure 5). The region is displayed by a yellow ellipse and the photometry aperture, the inner and outer background radii, are indicated by blue circles.Figure 5
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c) Change the aperture radius and background annulus by clicking on the appropriate spin-box control. When the 'apply' button is clicked the photometry is recomputed using the selected aperture radius and background annulus. d) You can repeat step c) above by changing the aperture radius and background annulus. Each time the 'apply' button is clicked, the recomputed photometry parameters for the selected source, including the original value is stored in the 'logger table' in the lower part of the main task window. An average magnitude is computed from all the entries in the logger table and printed in the average magnitude table just below the logger table.