remove_dipole


This IDL facility provides a means to fit and remove the dipole and monopole from a HEALPix map.


Location in HEALPix directory tree: src/idl/misc/remove_dipole.pro


FORMAT

IDL> REMOVE_DIPOLE, Map [,Weight, BAD_DATA=, GAL_CUT=, COORD_IN=, COORD_OUT=, Dipole=, Monopole=, NOREMOVE=, NSIDE=, ONLYMONOPOLE=, ORDERING=, PIXEL=, UNITS=]


QUALIFIERS


Map
input and output, vector
map from which monopole and dipole are to be removed (also used for output). Assumed to be a full sky data set, unless PIXEL is set and has the same size as map
Weight
input, vector, optional
same size as map, describe weighting scheme to apply to each pixel for the fit
default:uniform weight
BAD_DATA =
scalar float, value given on input to bad pixels
default:!healpix.bad_value $\equiv -1.6375\ 10^{30}$.
GAL_CUT=
if set to a value larger than 0, the pixels with galactic latitude |b|<gal_cut degrees are not considered in the fit.
NB: the cut is really done in Galactic coordinates. If the input coordinates are different (see Coord_In), the map is rotated into galactic before applying the cut.
COORD_IN =
string, coordinate system (either 'Q' or 'C': equatorial, 'G': galactic or 'E': ecliptic)
default:'G' (galactic)
COORD_OUT =
string, coordinate system (see above) in which to output dipole vector in variable Dipole
default:same as coord_in
Dipole=
OUTPUT, scalar float,
value found for the best fit dipole (done simultaneously with monopole)
Monopole=
OUTPUT, scalar float,
value found for the best fit monopole (done simultaneously with dipole)
NSIDE=
scalar integer, healpix resolution parameter
ORDERING=
string, ordering scheme (either 'RING' or 'NESTED')
PIXEL=
input, vector, gives the Healpix index of the pixels whose temperature is actually given in map (for cut sky maps). If present, must match Map in size. If absent, it is assumed that the map covers the whole sky.


KEYWORDS


NOREMOVE=
if set, the best fit dipole and monopole are computed but not removed (ie, Map is unchanged)
ONLYMONOPOLE=
if set, fit (and remove) only the monopole


DESCRIPTION


remove_dipolemakes a simultaneous least square fit of the monopole and dipole on all the valid pixels of Map (those with a value different from BAD_DATA) with a galactic latitude larger in magnitude than GAL_CUT (in degrees). The position of the pixels on the sky is reconstructed from NSIDE and ORDERING. If Map does not cover the full sky, the actual indices of the concerned pixels should be given in PIXEL


RELATED ROUTINES

This section lists the routines related to remove_dipole


idl
version 5.0 or more is necessary to run remove_dipole.

Eric Hivon 2005-08-31