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=, Covariance_Matrix=, Dipole=, Monopole=, /NOREMOVE, NSIDE=, /ONLYMONOPOLE, ORDERING=, PIXEL=, /SILENT, UNITS=, /HELP]

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, map coordinate system (either 'Q' or 'C': equatorial, 'G': galactic or 'E': ecliptic; upper/lower case accepted)
default:'G' (galactic)

COORD_OUT =

string, coordinate system (see above) in which to output dipole vector in variable Dipole
default:same as coord_in

Covariance_Matrix =

OUTPUT, scalar (or symmetric 4x4 matrix),
covariance of the statistical errors made on monopole (and dipole) determination

Dipole=

OUTPUT, 3d vector,
coordinates of best fit dipole (done simultaneously with monopole), same units as input map

Monopole=

OUTPUT, scalar float,
value found for the best fit monopole (done simultaneously with dipole), same units as input map

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.

UNITS=

string, units of the input map

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

/HELP

if set, only display documentation header

/SILENT

if set, the routine works silently

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 6.4 or more is necessary to run remove_dipole.