... ngas for file availability; qc_products for product file names and for ngams server names . ... You can download fits files or their headers only. ... use option -P for downloading any product header file . ... to download the header of a product file. Note: although you want to download a header, you must specify the fits file name since this is used in a query, and it is not possible to safely predict the name of a product fits file from its hdr name (it could have extension .fits or .tfits!) ...