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XMM-Newton Science Analysis System

rgsframes (rgsframes-3.16.1) [xmmsas_20060628_1801-7.0.0]

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Input to rgsframes are the RGS pixel files (R*SPE.FIT and R*HTE.FIT) and auxiliary file (R*AUX.FIT) in the ODF. From this it produces a single dataset per CCD which contains all the information needed for further processing. The PIXELS table contains the raw pixel data. The EXPOSURE table contains exposure relevant information per frame readout for the CCD.

The following corrections are applied to the pixel data:

  1. The pixel coordinates are transformed into CAL coordinates RAWX, RAWY. (In practice this means adding 1 to the values in the ODF) The same correction is applied to the keywords related to the windowing.

  2. Frame counter is corrected for 'wrap around problems' using saslib routine CorrectWrapAround()

  3. find and remove duplicate records by checking the following columns: FRAME, CCDNODE, RAWX, RAWY

  4. The SER column is replaced by a GRADE and SHAPE column. The algorithm for this depends on the version of the DPP software running on board. The DPP version number is obtained from the CAL (CAL_getMiscellaneousDataValue("DPPVERS")). SER values not listed in the table below will result in an fatal error.

              DPP version 16      DPP version 16.2 or 19.0
            -----------------    -----------------
             0     0      1       0     0      1
             1    null    2       1     1      4
             2    null    3       2     2      2
             3     1      4       3     3      2
                                  4     4      3
                                  5     5      3
                                  6     6      3
                                  7     7      3

    Note this is not applied for HTR processing.

For HTR now processing related to the Y-column data is performed.

The following processing is done on the frame data to create the EXPOSURE table:

  1. The table is sorted on increasing frame numbers.

  2. The frame time stamp is calculated using the OAL calls OAL_frameCounterToObt and OAL_obtToTimeTag. The value is written to a newly added column TIME

  3. The exposure times of each frame is calculated based on elapsed time since the previous readout of same sequence ID. Readout times are calculated from eoscoars and eosfine clock values. If no previous readout exists, the exposure time is set to the average exposure time estimated by also considering the position of the readout in the readout circle (thus producing the correct result for duplicate readouts). The first frame of every exposure has zero exposure time. Exposure times are written into the newly added column TIMEDEL

  4. find and remove duplicate records by checking the FRAME number

  5. Find missing frames by checking if the frame number and CCD sequence IDs match the the length of a readout sequence. The readout sequence is obtained from the RnAUX2 ($n=1,2$) table in the ODF AUX file.

  6. An optional column PIXELRATE is added which contains the number of pixels in the PIXELS table for each frame.

  7. Frames are flagged 'bad' in a FRAMEFLAG column according to a series of criteria. See below.

  8. corrections of the exposure time due to the number of pixels exceeding upper threshold are calculated by

    \begin{displaymath}{\tt FRACEXP} = 1 - \frac{\tt REJPIX}{{\tt WINDOWDX\times WINDOWDY}
- {\it uplinked_bad_pixels}} \end{displaymath}

    FRACEXP is calculated and stored per readout node. REJPIX is the number of pixels above upper threshold, and WINDOWDX/Y is the number of pixels read per node in CCD-X & CCD-Y.

Frames flagged 'bad' are excluded from the GTI (Good Time Interval).
Criteria for bad frames implemented at the moment are:

Finally a GTI table is produced based on the FRAMEFLAG column. If all frames are flagged bad a GTI table with zero rows is produced.

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XMM-Newton SOC/SSC -- 2006-06-28