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Дата изменения: Fri Feb 23 12:58:15 1996 Дата индексирования: Tue Oct 2 17:16:06 2012 Кодировка: Поисковые слова: ancient observatory |
The CCD package is based on so-called data sets. A data set contains a science frame, all its associated raw calibration frames and the master calibration frames created by combining and processing the raw calibration frames. Depending on the processing to be done on the science frame one or more master calibration frames are to be created.
Basically, the creation of a master calibration frame can be done in two ways. Either one creates a MIDAS catalogue which contains the names of all single calibration frames to be combined in to the master frame, or, in the case of pipe line reduction, one use the Association Table. Since the first method is straightforward we concentrate on the use of the Association Table.
In order to archieve a maximum of efficiency and to interface the package with the Data Organizer, the naming convention for master calibration frames is identical to the naming convention for the naming of the master calibration frames in the latter package. Here the name of a master calibration frame is a composition of the generic prefix and all frame numbers of the calibration frames to be used and therefore selection in the DO context. E.g. the master calibration frame susi_12_123_1245 is a combination of the frames susi0012, susi0123, and susi1245.
After the association process by the DO, the name of the master calibration frame is stored in a separate column in the Association Table. The name of this frame is defined as described above. The names of single calibration frames are however also available in the Association Table. This obviously offers the possibility of simply combining all single raw calibration frames in a master one. To execute this brute force combining the column for the master frame should contain a asterisk *. The name of the master will then be a composition of the name of the science frame to which the master calibration frame is associated plus the postfix _exp. Here, exp is the exposure type, stored in a MIDAS frame descriptor ( EXP_TYPE), and the name of the column with this exposure type in the Association Table and containing the names of the raw calibration frames. E.g. the master calibration frame susi0100_bias is created by combining all bias frames associated to the science frame susi0100 and stored in the Association Table.
Currently, the following exposure types are supported:
Other calibration frames that can be used in the calibration process are:
*** WARNING ***
In principle, the CCD package allows the use of any name for the calibration frames. However, to make the reduction of CCD frames as easy as possible it is recommended to use the above described naming scheme. It is highly recommended to use it. Using different names may, under particular circumstances, lead to complications, in particular in the case of pipe line reduction.