Astrometry detection4/6/2023 Then source crossĬorrelation will be performed and the computed offsets will be added to theĭerived coordinates of the sources. A subset of USNO catalogue can be provided optionally. The celestial positions are added as two new columns to the SWSRLI.FITįile. This new method provides a better attitude reconstruction. Raw Attitude File (*RAS.ASC) instead of the Attitude History File (*ATS.FIT). Since SAS 12, the attitude is obtained by default from the so-called History file, the instrument boresight file and the OM filter distortion It converts detector position from pixelĬoordinates into RA/Dec positions based on information from the attitude Image generated by ommodmap and reads the source list file generated by The sensitivity limit of the specific exposure The output is added as extra column to the source The task requires input from the source listįile SWSRLI. The corrected count rates are converted into The detector is computed for the epoch of the observationĪnd the count rates are corrected for this effect.įor the UV filters, the PSF is extrapolated to account for Count rates are corrected forĭetector deadtime. Stored pixel quality information to assign quality flags to the previously In order to find fainter, previously undetected sources. Since SAS v9.0, omdetect can be used on final mosaiced or stacked images Coincidence loss correction is applied by considering Received in an elliptical area and the background is measured in an annulus,Īs for point sources. The photometry of an extended source is made by adding all the counts It is used by theĮxtended sources are also identified if the parameter detectextended is The region file describes theĪrea associated with each identified source in the image. Name defined by the parameter regionfile. Coincidence loss correction is also applied to theĬount rates of the sources and the background.Īn optional output file, called the region file, can be generated with a In absolute detector pixel and the calculated sources and backgroundĬount rates (cts/sec). The output is a source list (SWSRLI) which contains the source positions The point spread function (PSF) of OM is taken into ![]() Then the algorithm looks for sources matching theĬriteria defined by the task parameters. The task omdetect applies a sourceĭetection algorithm to find the sources present in the image. It will be usedįor additional source detection in mosaiced or stacked images. Pixel quality information is carried onĪnd assigned to detected sources through quality flags. ![]() 4 Source detection, astrometry and photometry Next: 6.2.5 Final combined results Up: 6.2 Description of the OM image data processing chain omichain Previous: 6.2.3 Handling of corrections applied to image mode dataĦ.
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