Документ взят из кэша поисковой машины. Адрес оригинального документа : http://xmm.vilspa.esa.es/sas/8.0.0/doc/omdetect/node15.html
Дата изменения: Wed Oct 22 17:31:26 2008
Дата индексирования: Tue Aug 18 14:53:38 2009
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Поисковые слова: comet tail

XMM-Newton Science Analysis System


omdetect (omdetect-5.14.2) [???]

Meta Index / Home Page / SourceListFile / QUALITY FLAGS

Short-comings

Comprehensive source-flagging was introduced into SAS 6.5 in 2005, and things can occasionally go wrong- when problems are found the cause is identified and improvements made. Iit is expected that all problems will be eliminated within the next 10,000 years).

Here is a list of known shortcomings/problems-

1. Mod-8 pattern- occasionally a source that does not have any obvious mod-8 pattern around it gets flagged and vice versa.
2. Smoke ring - Occasionally one or more sources may clearly to be seen to be near or within a smoke-ring, but not flagged. This seems to be due to the predicted position of the smoke-ring being completely wrong, and is being investigated.
3. Source lies near to a bright source - Occasionally a source near to a bright source may not be flagged, when you expect it to be. Ways of making this more reliable are being investigated.

4. Source within central enhancement region Currently omdetect uses a circular region with a fixed radius to flag sources. This means that occasionally some sources will not get flagged when they are clearly affected by the central light, and some may get flagged unnecessarily.
5. SOURCE ON STAR SPIKE Occasionally some sources may not be flagged when they clearly should be.

For example, a source with a bad pixel and lying on or close to a read-out streak would have bits 0 and 1 set and thus have a quality flag of 3.