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makethumbs (makethumbs-0.8) [xmmsas_20211130_0941-20.0.0]


Note on the processing speed

Generating GIF files itself with this task is reasonably quick. However, to read an external catalogue may not be so, in particular the given external catalogue is a large one, such as the 2XMM catalogue FITS file.

The least required (or desirable) columns for the external catalogue given to this task are listed in the following Section 2. If a user wants to give a large external catalogue as the input to this task, s/he is encouraged to trim (delete) the unnecessary columns in the catalogue before it is given to this task.

Unfortunately, it will take nevertheless 20 min or longer in the case of the catalogue based on the entire 2XMM catalogue, even if it is trimmed down to a minimised set of columns (in other words, it would take hours or longer if the raw 2XMM catalogue is given). The bottle neck is known to be in reading the column for the source names in the external catalogue. However, there is no plan that this problem will be fixed in the foreseeable future, because this problem is rooted in a technical reason in the SAS scheme for Fortran,

As the work-around for this problem, the task ingestsrcnames is provided in this package. With the task, users can ingest the all those parameters, which may be used in processing with this task, to the input source-list. Then, even though the process of ingesting takes as long time as this task would do, it is a one-off process, and once it is done, users can produce GIF files with this task makethumbs for any of the sources listed in the source list without waiting much, as the external catalogue is no longer given every time this task is run.

XMM-Newton SOC -- 2021-11-30