INNAME Input image name (name). INCLASS Input image name (class). INSEQ 0.0 9999.0 Input image name (seq. #). INDISK 0.0 9.0 Input image disk unit #. OUTNAME Output image name (name). OUTCLASS Output image name (class). OUTSEQ -1.0 9999.0 Output image name (seq. #). OUTDISK 0.0 9.0 Output image disk unit #. BLC Bottom left corner of input. TRC Top right corner of input. OPCODE Model types are: 'GAUS', 'DISK', 'RECT', 'SPHE', 'EXPD', 'POIN' NGAUS 1.0 4.0 Number components to add FMAX Peak of component (Jy/beam) no default FPOS -50.0 16434.0 (X,Y) position (pixels) no default FWIDTH (BMAJ, BMIN, PA) of comp. (pixels,pixels,deg) 0->Use clean beam FLUX Noise level FACTOR Multiplication factor. INLIST List of sources up to 9999

IMMOD Type: TASK Use: Modification of existing map images by addition of models. Adverbs: INNAME.....Input image name (name). Standard defaults. INCLASS....Input image name (class). Standard defaults. INSEQ......Input image name (seq. #). 0 => highest. INDISK.....Disk drive # of input image. 0 => any. OUTNAME....Output image name (name). Standard defaults. OUTCLASS...Output image name (class). Standard defaults. OUTSEQ.....Output image name (seq. #). 0 => highest unique. OUTDISK....Disk drive # of output image. 0 => highest number with sufficient space. BLC........Bottom right corner in input image of desired subimage. Default is entire image. TRC........Top right corner in input image of desired subimage. Default is entire image. OPCODE.....Operation code to determine the type of model. Any undefined OPCODE => Point. The available opcodes are 'POIN' => Point, 'GAUS' => Gaussian, 'DISK' => Solid Disk, 'RECT' => Solid Rectangle, 'SPHE' optically thin sphere, 'EXPD' => Exponential NGAUSS.....The number of components in the model (1 - 4). FMAX.......The peak value for each component. NO default. FPOS.......The position (X,Y) for components. The values are in pixels in the order (X1,Y1,X2,Y2,X3,Y3,X4,Y4). NO default. FWIDTH.....The major axis, minor axis and position of major axis for components. The values are pixels with degrees for position angle and the order is (MJ1,MN1,PA1,MJ2,MN2,PA2,...etc) If the major or the minor are <= 0, then the Clean beam is used. FLUX.......Noise level to be added (in the units of the image) FACTOR.....Factor by which the original data is multiplied before it is added to the model. 0 => drop original data. INLIST.....Set this blank unless you want an input components list. Text file containing one line per source, giving I, DX, DY, Maj, Min, PA blank separated free format and trailing zeros may be omitted. Used if INLIST not blank. The resulting NGAUS will be #lines in INLIST neglecting comments (start with # in col 1) and lines with format errors. Units are Jy/beam, pixels, pixels, pixels, pixels, degrees. The Clean beam is substituted if May and/or Min are 0 or missing. Limit 9999. The model type specified by OPCODE is used.

IMMOD: Task which modifies map images by scaling the existing map and adding a specific model (See also UVMOD). DOCUMENTOR: Eric R. Nelson NRAO/VLA/UNM DATE OF DOCUMENTATION: 14 JUNE 1983 RELATED PROGRAMS: UVMOD, APCLN, UVMAP, COMB VERSION 12june83 PURPOSE IMMOD modifes an already existing map image by the addition of one of four model types. The original map points may be scaled by a multiplicative factor, including negative values and zero, before they are added to the model. Random noise may also be added to the map. The four available models to choose from are 1) point source, 2) Gaussian, 3) solid disk, 4) solid rectangle, 5) optically thin sphere, 6) exponential disk.. The dimensions, offset and position angle are input by the user. COMMENTS OPCODE : The type model to be used can be selected by OPCODE. The allowed models, and their corresponding OPCODEs are listed below. 1) Point -> 'POIN' Only the specified point is altered. The position is determined by FPOS. The criterion for the point selection is Sqr(X^2 + Y^2) = 0 where (X,Y) is the current pixel location after correction for any offset. Parameters BMAJ, BMIN and BPA have no affect on this model. The value added is ZEROSP(1) * CBarea / Cellx / Celly where CBarea is the Clean beam area and Cellx and Celly are the x and y cell sizes. 2) Gaussian -> 'GAUS' The function ZEROSP(1) * (CBarea/NBarea) * EXP (-4Ln(2) * R**2) is added to the map where R = Sqrt(XX^2 + YY^2) with XX = (Y*Cos(BPA) + X*Sin(BPA))/BMAJ YY = (X*Cos(BPA) - Y*Sin(BPA))/BMIN where X and Y are the same as above, but in units of arcsec. NBarea is the new area defined by (1.1331 * BMAJ * BMIN) 3) Disk -> 'DISK' A solid disk is added to the map. The amplitude is ZEROSP(1) * BMarea / (Pi * BMAJ * BMIN / 4) 4) Rectangle -> 'RECT' A solid rectangle is added to the map. The amplitude is ZEROSP(1) * BMarea / (BMAJ * BMIN) 5) Sphere -> 'SPHE' A circular function is added to the map: ZEROSP(1) * BMarea / NBarea * sqrt (1-R*R) where R = sqrt (X*X + Y*Y) / BMAJ NBarea = 2.094 *BMAJ * BMAJ 6) Exponential The function ZEROSP(1) * (CBarea/NBarea) * EXP (-2ln(2) * R) is added to the map where R is defined above (in 2) and NBarea = 3.2699 * BMAJ * BMAJ BMAJ, BMIN, BPA (actually FWIDTH(1 through 3, i) for i'th component The dimensions of the resulting functions are determined by BMAJ, BMIN and BPA (position angle). For the Gaussian and exponential, the first two numbers are the FWHM of the two axes. For the disk and rectangle, the first two values are the absolute dimensions of the two available axes. For the sphere, only BMAJ is used and it is the diameter of the sphere. If either BMAJ or BMIN is zero, then all the models reduce to the point model. FACTOR : The FACTOR term allows one to add a scaled version of original data to the model. FACTOR is simply multiplied by the original data which is then added to the model. If FACTOR = 0 then only a map of the model will remain.