AIPS HELP file for BLC in 31DEC20
As of Sat Feb 22 16:00:21 2020
Type: Adverb (Real array, 7 elements)
Use: The array subscripts of the pixel at the Bottom Left
Corner of the desired subarray of the image. The first
value in BLC gives the column number of the pixel; the
second value in BLC gives the row number of the pixel.
The array may contain up to 7 dimensions.
Null value: 7*0
Null value is usually assigned to (1,1,...), the bottom
left corner of the entire image.