Creation of Position Grid Table

 

In order to create a maximum likelihood image a user list in the form of a position grid table has to be created. This can be done with the command

 CREATE/GRID_TABLE gritab refima xstrt,ystrt xstep,ystep nx,ny

 

• gritab is the name of the grid table (user_list input for ML)
• refima is the name of a reference image. This image is used to get the pointing direction reference (in RA, DEC).
• xstrt,ystrt are the x,y start values of the lower left corner of the grid (in sky pixels)
• xstep,ystep are the x,y step values of the grid (in sky pixels)
• nx,ny are the number of grid pixels in x,y direction (1 nx 512 and 1 ny 512)

The xstep and ystep size should be adjusted to the size of the point spread function (FWHM). A recommended range of values may be

Examples:

CREATE/GRID_TABLE gritab refima -2400.,2400. 30.,-30. 160,160