As of Wed Jan 17 6:12:54 2018

TDEPEND: Procedures to do time-dependent imaging


          ******** see TDSTEP3 and TDSTEP5 for adverbs *********


Type:  Process
 Use:  TDEPEND is a process involving some procedures which you may
       use plus some steps which you are left to do in your favorite
       way.  To compile the procedures, enter RUN TDEPEND, a command
       you need enter only once.  The process consists of 3
       preliminary steps, plus a pait of steps which may be iterated.
       The preliminary process is:

       1. Run task SPLIT on your data to create a fully calibrated and
       editied single-source data set.  Set INNAME, INCLASS, INSEQ,
       and INDISK to point at this output data set for inputs to the
       later steps.

       2. Prepare adverb TD_TIMES which is a list of times in days
       indicating the time ranges to be used in breaking up your data.
       Thus the I'th time range is from td_times(i) to td_times(i+1).
       The procedure TD_SSCANS(i,j) will read the index table and find
       all scans of source i.  It will make j time intervals within
       each scan, filling the TD_TIMES adverb.  TD_SCANS(i) does the
       same with simple breaks between scans.

       3. TDSTEP3 loops over the time ranges doing:
            a. SPLIT to make 'ISPLIT' containing all data for time
               range (i)
            b. IMAGR of NFIELDS+1 where NFIELDS is the number of
               facets required to image the full area and facet
               NFIELDS+1 is centered on the time-variable target
               source.  BOXFILE must include all NFIELDS+1 facets and
               should do an UNClean box on the target source wherever
               it occurs in facets numbered <= NFIELDS and should do
               UNClean boxes surrounding the source in facet
               NFIELDS+1.  The latter is really only required if you
               do auto-boxing.
            c. UVSUB subtracts facet NFIELDS+1 from ISPLIT and appends
               the data in a file with class 'APPEND'
            d. It then deletes ISPLIT and all images and beams.

       The iterative process includes:

       4. Iterate over:
            a. ZAP any previous images from this step
            b. IMAGR on APPEND with NFIELDS and the UNClean box
               surrounding the time variable source.  Use an OUTNAME
               to differentiate the output images from those of
               TDSTEP1 and TDSTEP3.
            c. CALIB on APPEND with these images - always use APPEND
               as the input data set since we need to build a total
               correction SN table.
            d. Flag as needed
          Then TACOP the final net SN table to the single-source
          input file created in step 1.  TAPPE the final FG table to
          the previous FG table of the single-source file.

       5. TDSTEP5 initially deletes the APPEND file if needed and any
          target image files with class 'TRGT*'.  It then loops over
          the time ranges doing:
            a. SPLIT to make 'ISPLIT' containing all data for time
               range (i)
            b. UVSUB the final model produced in step 4 (and contained
               in adverbs NMAPS and IN2NAME, IN2CLASS, etc.) to make
               ISOURC containing only the target source visibilities
            c. IMAGR on the target source, making NGAUSS images of a
               single facet.
            d. UVSUB the model found in (c) from ISPLIT and append the
               result to APPEND, a data set containing all sources
               except the target.
            e. Rename the target images from ICL0nn to TRGTnn.
            f. It then deletes IUVSUB, ISPLIT, ISOURC, and all beams.

        Repeat 4 and 5 until done.  Result is 1 set of images of the
        time independent full field, plus 1 set of target source
        images as a function of time.