Each record contains one flag word by antenna, and one flag word by baseline. There may ultimately 32 flags in each word. As for now, both antenna and baseline flag words may contain one flag by subband (named CO1 to C06, and L01 to L06; in addition, the antenna flag words may contain flags LOCK, TSYS, POINTING, SHADOW, and DATA, while the baseline flagwords may contain flag DATA.
For instance, if subband flag C02 is present in baseline 23, subband C02 will be ignored for further processing of baseline 23 (in particular, it will be absent from plots). If present in antenna 1, baselines 12 and 13 will be affected. Other flags such as LOCK, TSYS, POINTING, SHADOW, and DATA will affect all subbands of the relevant baselines. Flags should normally be set by the real time system, or the real time calibration step in CLIC.
You may wish to use that data anyway, by masking them (command MASK). For instance use MASK C02 /BASELINE 23 if you feel that this subband was usable, but do not be surprised by the results !
You may also want to suppress temporarily some data channels from plots or from output tables, without modifying the data file itself. This is done by command MARK. Marked data channels will be ignored just as if they were flagged in the data.
On the opposite, you might have to flag some data yourself. There are several ways of doing this:
FIND /SCAN 5436 STORE FLAG DATA /BASELINE 12will flag baseline 12 for the whole duration of scan 5436. This is the best way to flag one or more complete scans.
IF DH_TOTAL.LT.10. THEN FLAG DATA /ANTENNA 2 GO WRITE ELSE GO ENDIFDo not forget to enable variables of group DATA_HEADER, before typing MODIFY DATA.
You may get a status of the flags in the data og the current index by issuing command LIST /FLAG.