Index of /group/cmb/data_release/map

[ICO]NameLast modifiedSizeDescription

[DIR]Parent Directory  -
[   ]maxima1_4det_pix8am_rescaled.idl30-Jan-2002 15:39 136M
[   ]combined_4det_beam31-Jan-2002 09:54 25K
[   ]maxima1_4det_pix8am_rescaled.fits07-Feb-2002 18:59 136M

This directory contains the MAXIMA-1 map and pixel-pixel noise
correlations.

Downloadable data:

	maxima1_4det_pix8am_rescale.fits - A portable FITS file
	containing the 4-detector MAXIMA-1 map, pixelized with 8
	arcminute resolution.

	maxima1_4det_pix8am_rescaled.idl - A portable IDL file
	containing the 4-detector MAXIMA-1 map, pixelized with 8
	arcminute resolution.  You will need IDL version 5.4 or later
	to use this file.

	combined_4det_beam - A text file of B_l, the beam window
	function, as it depends on the multipole l.  This is an
	effective beam function for the 4-detector combination.  To
	remove the affect of beam size from your analysis, divide the
	power spectrum by the square of these numbers.

Other available data:

	The 4-detector data are available by request at higher
	resolution and in different document formats.  Contact
	bahman@cosmology.berkeley.edu for more information.


MAXIMA pixelisation-projection scheme
----------------------------

Below follow some notes on the MAXIMA pixelisation to 
allow people familiarized with FITS jargon to visualize 
MAXIMA maps quickly.

MAXIMA-1 data maps are projected according to 
the pseudo-cylindrical Sanson-Flamsteed projection, 
an equal-area projection with projection law 
(Calabretta & Greisin 2001):

x=(alpha-alpha0) cos(delta)
y=delta

where x and y are the projected native coordinates.

1) To pass from celestial coordinates to pixel coordinates

x=(alpha-alpha0) cos(delta)
y=delta

ix= x/ CDELT1 + CRPIX1
iy= y/ CDELT2 + CRPIX2

where 
alpha          = right ascension 
delta          = declination 
alpha0         = right ascension of the meridian center of the map 
               = CRVAL1
CRPIX1, CRPIX2 = central reference pixels of the map
CDELT1, CDELT2 = angular pixel sizes (increments)
ix, iy         = pixel coordinates of the map

2) To pass from pixel coordinates to celestial coordinates 

x= (ix-CRPIX1)* CDELT1 
y= (iy-CRPIX2)* CDELT2

delta=y
alpha= x /cos(y) + alpha0

Note : since the reference point for the projection 
has alpha_p=alpha0, delta_p=0, the rotation of reference frame is 
equivalent to adding up alpha0 to the alpha coordinates (a consequence of 
setting up CRVAL2=0)

For these maps:
CDELT1, CDELT1 = 8 arcmin
alpha0 = 14.8 hours

(don't forget to put everything in the same angular units).

CRPIX1, CRPIX2 =  you choose, but it should correspond to the center point 
of your displayed array image.

References: "Representations of celestial coordinates in FITS", 2001, 
===========  M.Calabretta & E.W.Greisen, A&A draft 
            (http://www.atnf.csiro.au/people/mcalabre/index.html

[Domingos Barbosa 02/25/02]