1 MAKE_MOSAIC This task combines individual dirty images and beams corresponding to various pointing centers into a "mosaic" which is suited for further deconvolution using the MAPPING program. Mosaics are ensemble of overlapping fields, with typically half power primary beam overlap, and similar (but not identical) UV coverages for each field. Individual images for every field should be created with a common phase tracking center. The UV_SHIFT, MAP_RA and MAP_DEC variables in task UV_MAP must be used for this. The image names must derive from a generic name as follows (e.g. for a generic name MAP) MAP-1.LMV, MAP-2.LMV, ... MAP-N.LMV where N is the number of fields. For example LET MAPSIZE 256 512 LET MAPCELL 0.5 LET UVSHIFT YES LET MAPRA 20:39:10 LET MAPDEC 68:01:20 ! LET WCOL 1 FOR I 1 TO 10 LET NAME CONT-'I' GO UVMAP NEXT MAKE_MOSAIC produces a combined image (MAP.LMV), a data cube of primary beams (MAP.LOBE), a data cube of dirty beams (MAP.BEAM), and a weight image MAP.WEIGHT, which are required for cleaning. Two parameters are very important in the mosaic creation: the primary beam width (FWHM), and the truncation threshold of the primary beam. It is recommended to use a relatively high value for this threshold, 0.2 to 0.4, to avoid contaminating adjacent field in case of pointing errors. 2 FIELDS$ TASK\INTEGER "Number of fields" FIELDS$ The number of fields in the mosaic. 2 NAME$ TASK\CHARACTER "Generic file name (without extension)" NAME$ The generic name of the mosaic. The names of the individual field images is derived by appending the field number, e.g. map-1 map-2 etc.., when NAME$ = map. 2 BEAM$ TASK\REAL "Half-Power Primary Beam (in radians)" BEAM$ The half power primary beam of the antennas, expressed in radians. 2 BMIN$ TASK\REAL "Truncation Threshold" BMIN$ The minimum relative intensity under which the primary beam of the antennas should be set to zero. A value of 0.2 to 0.3 is recommended. END