The Association Table

The second step is to inspect the data, to define a set of criteria to select the science frames and their associated calibration frames, and to use the MIDAS Data Organizer to do the selection and to create the Association Table. Typically, the Association Table looks as displayed in Table 3.1. Depending on available exposure types and on the selection, like for the bias exposure additional columns for darks and flats can be present in the table. The ... represent the three dimensional character of the Association Table, where in this case, the single bias frames are stored in the third dimension of column BIAS.

 

Table 3.1: Example of an Association Table

SCI	BIAS	...	QUAL_BIAS	BIAS_MASTER
susi0097.bdf	susi0124.bdf	...		susi_124_125.bdf
susi0098.bdf	susi0124.bdf	...		susi_124_125.bdf
susi0099.bdf	susi0126.bdf	...		susi_124_125_126.bdf
susi0100.bdf	susi0124.bdf	...		susi_125_126_127.bdf

 

After inspecting the master calibration frame, the user may decide that this is not what (s)he wants and that using another master calibration frame would be better. For example, one can require that in the calibration process of frame susi0099.bdf the master bias susi_124_125.bdf is to be used, i.e. the bias frames associated with the science frames susi0097.bdf and susi0098.bdf. The change can either be made by running the DO package once more with slightly different selection rules, or by using the command EDIT/TABLE.

In addition to the standard naming convention three other input formats can be used in the Association Table. The first one is the use of non-standard name(s) (i.e. frame names that are not related to a data set), e.g. stdbias.bdf instead of susi_124_125.bdf. In this case the system requires that the master bias stdbias.bdf already exists. A second possibility is to have an asterisk *, indicating that all single raw calibration frame associated with a particular science frame are to be combined. In that case the names of the single frames will be retrieved for the Association Table. The third possibility is to store constants in the Association Table, e.g. 294 instead of susi_124_125.bdf.

An example of these three input possibilities is given in Table 3.2. Here, for the reduction of the frame susi0097.bdf a constant bias value of 294 is used while the frame susi0099.bdf will be calibrated using all available single bias frames associated with that science frame. Frame susi0100.bdf will be reduced with the standard bias frame stdbias.bdf that is assumed to be present in the working directory.

 

Table 3.2: Example of a manually modified Association Table

SCI	BIAS	...	QUAL_BIAS	BIAS_MASTER
susi0097.bdf	susi0124.bdf	...		295
susi0098.bdf	susi0124.bdf	...		susi_124_125.bdf
susi0099.bdf	susi0126.bdf	...		*
susi0100.bdf	susi0124.bdf	...		stdbias.bdf