This IDL function reads the number of maps and/or the pixel ordering of a FITS file containing a HEALPix map.
Location in HEALPix directory tree: src/idl/fits/getsize_fits.pro
- name of a FITS file containing the HEALPix map(s).
- contains on output the number of pixels stored in a map FITS file.
Each pixel is counted only once
(even if several information is stored on each of them, see nmaps).
Depending on the data storage format, result may be :
- equal or smaller to the number Npix of Healpix pixels available
over the sky for the given resolution (Npix =
- equal or larger to the number of non blank pixels
- contains on output the number of maps in the file
- contains on output the HEALPix resolution parameter
- contains on output the maximum multipole used to generate the map
- contains on output the pixel ordering
scheme: either 'RING' or 'NESTED'
- contains on output the number of non blanck pixels. It is set to -1 if it can not be determined from header
- Healpix/FITS file type
<0 : file not found, or not valid
0 : image only fits file, deprecated Healpix format
1 : ascii table, generally used for C(l) storage
2 : binary table : with implicit pixel indexing (full sky)
3 : binary table : with explicit pixel indexing (generally cut sky)
999 : unable to determine the type
- contains on output the FITS extension header
- extension unit to be read from FITS file:
either its 0-based ID number (ie, 0 for first extension after primary array)
or the case-insensitive value of its EXTNAME keyword.
- if set, an extensive help is displayed and no
file is read
getsize_fits gets the number of pixels in a FITS file. If the file
follows the HEALPix standard, the routine can also get the resolution
parameter Nside, the ordering scheme, ..., and can determine the type
of data set contained in the file.
This section lists the routines related to getsize_fits
- version 6.4 or more is necessary to run getsize_fits
- This HEALPix IDL facility can be used to read in maps
written by getsize_fits .
- This IDL routine (included in HEALPix package) can be used to update
or add FITS keywords to Header
- This HEALPix IDL routine can be used to reorder a map from
NESTED scheme to RING scheme and vice-versa.
- routine to write multi-column binary FITS table
Version 3.31, 2017-01-06