Because the point-source extraction program generates detections in a variety of quality classes (tagged by a detection “status” parameter), the project has felt that a capability may be needed to prevent certain classes from being mixed together by the bandmerging process. Therefore, a detection must qualify for consideration as a bandmerge partner with any given candidate, and vice versa. The status classes are as follows, where “mapping” refers to an internal status assigned during initialization.

 

Status   description             mapping

 

  -3     “no more dof”              5

  -2     “converged”                3

  -1     “exceeded”                 4

   0     “no fitting performed”     6

  +1     “previous success”         2

  +2     “new success, converged”   1

  +3     “new success, exceeded”    0

 

The status parameter, however, has not been declared mandatory; hence if it does not exist in the input detection files, then all detections are treated as qualified to mix with all others in different bands, and the control parameters Status_Check_Flag and Status_Threshold (see §4.2) are pointless to specify. Assuming that the status parameters are present in all bands, then the following rules for mixing and matching are in effect:

 

Status_Check_Flag is initialized to zero. It may be set to 1 or 2 (as well as 0) by including the Status_Check_Flag parameters in the namelist file. Any other values will be ignored and a WARNING message will be printed.

 

Status_Threshold is also initialized to zero. It may be set to 0-6 by including the Status_Threshold parameter in the namelist file. Any other values will be ignored and a WARNING message will be printed.

 

If Status_Check_Flag is equal to zero, both Status_Check_Flag and Status_Threshold (as well as the optional input value “status”) are ignored in the processing (but if “status” has been included as an optional input column in the namelist file, this value will always be read from the input source detection tables and copied verbatim to the output bandmerged file).

 

A Status_Check_Flag value of 1 or 2 means that in the Cross-Band Linkage processing (see §2.1.1), all seed candidate pairs that pass the coarse windows tests will have the Status_Check_Flag checked.

 

If Status_Check_Flag is equal to 2, the function status_check is called with the seed and the potential candidate information. The status values for the seed and the candidate should be in the range -3 to +3.; these are mapped as shown in the table above to the range 0-6. The absolute value of the difference between the two mapped status values is returned (i.e. a value between 0 and 6) unless an error occurs, in which case -1 is returned. If Status_Check_Flag is equal to 1, the function status_check is called twice, first with the seed information, and second with the potential candidate information. In each case, the status value (originally in the range -3 to +3) is mapped to the range 0-6. This value is returned (unless an error occurs, in which case -1 is returned).

 

For both cases 1 and 2, the returned value is checked. If the returned value is negative (i.e. -1) then the processing is terminated with an error message. Otherwise, the returned value is compared to the Status_Threshold value. If the returned value is greater than the Status_Threshold value, chi-square for this seed-candidate combination is computed, etc. If the return value is less than or equal to the Status_Threshold value, this seed-candidate combination is rejected, and processing continues with another seed-candidate combination (assuming more exist).