To save space, you often see CSC maps which are simply single vectors
of numbers (temperatures, fluxes, etc.). How does one know what pixel
corresponds to what position on the sky? The answer is that the pixel
index actually holds this information. To extract the information, you
may need some of the following code written by the COBE team (and
modified a bit locally).
csc_conv.c
A set of subroutines for manipulating maps made with a CSC pixelation.
These were originally part of the COBE CGIS software distribution, but
have been modified to work without their original IDL wrappers. Other
modifications have also been made, so use with care if you are used to
using the originals from the COBE CGIS distribution.
csc_conv.h
A partial header file for use with csc_conv.c.
ll2pix.c
An example of how to use csc_conv.c to take a longitude and a
latitude (ll) and get the pixel number.
Compile this with a command something like
% gcc -o ll2pix ll2pix.c csc_conv.c -lm
pix2ll.c
An example of how to take a pixel number and find the lon./lat.
Compile this with a command something like