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Help on vishead task:
List, summary, get, and put metadata in a measurement set This task allows the user to manipulate some meta-data parameters in a measurement set. The mode='list' shows those keywords that are presently implemented, with their values. The contents associated with the keywords can be obtained (get) and changed (put). The modes that are available are: list --- List all keywords that are recognized, and list the value(s) for each. Only these keywords can be obtained (get) or changed (put) summary --- Equivalent to running taskname='listobs'; verbose=F get --- Get the specified keyword value(s) from the ms put --- Put the specified keyword value(s) into the ms Parameters currently implemented are (June 1, 2009): cal_grp field Field names fld_code Field Observing codes freq_group_name log observer Observer name project Project name ptcs Phase tracking centers for each field release_date schedule schedule_type spw_name Spectral parameters? source_name Source Names (=Field Names?) telescope Telescope Name Keyword arguments: vis --- Name of input visibility file default: none, example: vis='my.ms' mode --- Mode of operation for vishead default = 'list'; example: mode='get' hdkey--- keyword to get or put from the ms (used in get/put mode only) ex: hdkey='telescope' hdindex--- index (counting from 0) if keyword is an array (used in get/put mode only) hdkey--- keyword to get or put from the ms (used in get/put mode only) ex: hdkey='telescope' hdindex--- index (counting from 0) if keyword is an array (used in get/put mode only) ex: hdindex='2'; hdindex=''->put/get full array; hdvalue --- value to be put in the MS (used in put mode only) ex: hdvalue=array(['MyTelescope']) Examples: To transfer the parameters to useful python items requires some care. taskname = 'vishead' default() vis = '3C84C.ms' mode = 'get' to get a field name (string), hdkey = 'field'; hdindex = '2'; hdvalue=vishead(); print hdvalue = the name for field='2' to get an phase center (number) hdkey = 'ptcs'; hdindex = '1'; hdvalue = vishead(); hdvalue gives the ra, hdvalue gives the dec in field '1' taskname = 'vishead' default() vis = '3C84C.ms' mode = 'put' To change a string, hdkey = 'field'; hdindex = '2'; hdvalue = 'junk'; vishead() field='2' is renamed 'junk' To change a number, (egs. ra of field=1 to 0.5 radian) is too complicated to figure out!