National Radio
Astronomy Observatory

2.3.4.3 The timerange Parameter

The time strings in the following (T0, T1 and dT) can be specified as YYYY/MM/DD/HH:MM:SS.FF. The time fields (i.e., YYYY, MM, DD, HH, MM, SS and FF), starting from left to right, may be omitted and they will be replaced by context sensitive defaults as explained below.

Some examples:

1. timerange=’T0~T1’: Select all time stamps from T0 to T1. For example:
     timerange = ’2007/10/09/00:40:00 ~ 2007/10/09/03:30:00’

   Note that fields missing in T0 are replaced by the fields in the time stamp of the first valid row in the MS. For example,

     timerange = ’09/00:40:00 ~ 09/03:30:00’

   where the YY/MM/ part of the selection has been defaulted to the start of the MS.

   Fields missing in T1, such as the date part of the string, are replaced by the corresponding fields of T0 (after its defaults are set). For example:

     timerange = ’2007/10/09/22:40:00 ~ 03:30:00’

   does the same thing as above.

2. timerange=’T0’: Select all time stamps that are within an integration time of T0. For example,
     timerange = ’2007/10/09/23:41:00’

   Integration time is determined from the first valid row (more rigorously, an average integration time should be computed). Default settings for the missing fields of T0 are as in (1).

3. timerange=’T0+dT’: Select all time stamps starting from T0 and ending with time stamp T0+dT. For example,
     timerange = ’23:41:00+01:00:00’

   picks an hour-long chunk of time.

   Defaults of T0 are set as usual. Defaults for dT are set from the time corresponding to MJD=0. Thus, dT is a specification of length of time from the assumed nominal ”start of time”.

4. timerange=’>T0’: Select all times greater than T0. For example,
     timerange = ’>2007/10/09/23:41:00’  
     timerange = ’>23:41:00’                # Same thing without day specification

   Default settings for T0 are as above.

5. timerange=’<T1’: Select all times less than T1. For example,
     timerange = ’<2007/10/09/23:41:00’

   Default settings for T1 are as above.

An ultra-conservative selection might be:

which would choose all possible data!

More information about CASA may be found at the CASA web page

Copyright © 2010 Associated Universities Inc., Washington, D.C.

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