Planetary maps

Contents:

Planetary mapping routines.

phi = 0 faces toward the observer phi = pi thus faces away from the observer theta=pi/2 is the z-axis or ‘north pole’ theta=-pi/2 is the ‘south pole’

maps.errseries(param, phi, theta, rangle, meas, err)[source]

Give the chi-squared to an input timeseries to get the wedge coefficients and inclination angle.

param – [inclination, phi0, wedge coefficients] phi,theta – from MAKEGRID rangle – rotation angles at which flux was measured meas – measured flux err – error on measurement (one-sigma)

Usage:
from scipy import optimize optimize.fmin(maps.errseries, guess, args=(...))
maps.makegrid(nphi, ntheta)[source]

Make grids of phi and theta values with the specified number of points in each direction. Phi ranges from 0 to 2pi, and theta ranges from -pi/2 to pi/2.

Returns (phi, theta)

maps.makespot(phi, theta, da=None, vmap=None, inc=None, rot=None, long=0, lat=0, siz=0.78539816339744828, plotalot=False)[source]

Make a spot-map.

EXAMPLE: import maps inc, rot = pi/2., 0. phi, theta = maps.makecoord(120,60) phi2, theta2 = maps.rotcoord(phi,theta,inc,rot) vmap = maps.visiblemap(phi,theta,inc,rot)

maps.makespot(phi,theta,inc=pi/2,rot=0.,lat=pi/4,long=1.*pi) maps.makespot(phi2,theta2,vmap=vmap,lat=pi/4,long=1.*pi)

maps.projarea(phi, theta)[source]

Return a 2D map of the projected area. Note that you need to determine for yourself which parts of the areal map are actually visible to the observer.

Assumes dA = cos(t) dt df (theta=t, phi=f)
and thus da = cos(f) cos(t)**2 dt df
EXAMPLE:
import maps, pylab phi, theta = maps.makegrid(300,240) vis = maps.visiblemap(phi,theta,pi/2,0) da = maps.projarea(phi,theta) pylab.imshow(da*vis) pylab.title(‘visible projected area sums to: %f (pi)’ % (da*vis).sum())
maps.rotcoord(phi, theta, iangle, rangle)[source]

rotate coordinate system from local (planetary) coordinates into observer-oriented coordinages. rangle and iangle are the rotation and inclination angles of the planet in radians.

returns (phi2,theta2)

phi2 will be in the range (0,2pi) and theta2 will be in the range (-pi/2,pi/2)

maps.visiblemap(phi, theta, iangle, rangle)[source]

Return a 2D boolean map that’s True for the planetary latitude, longitude values visible from an observer. For rangle (rotation angle) zero and iangle (inclination angle) equal to pi/2, phi=pi is toward the observer.

maps.wedgebasis(phi, theta, iangle, rangle, nwedge, phi0, fwedge=None)[source]

Return a set of basis functions for the flux from each wedge.

phi,theta are the observer-centered grids from MAPS.MAKEGRID iangle is the inclination of the system (0 = pole-on) rangle (seq.) is a sequence of (0,2pi) rotation values at which

the wedge-based flux is evaluated.

nwedge is the number of wedges phi0 defines the center of wedge zero.

fwedge – an optional sequence to set individual flux values for each wedge.

maps.wedgemap(phi, theta, phi0, phi1)[source]

Return a 2D boolean map that’s True for the latitude, longitude values in a given longitudinal planet ‘wedge’.

phi0,phi1 should be in the range (0,2*pi)

maps.wedgestack(phi, theta, nwedge, phi0)[source]

Return a stack of 2D boolean maps via wedgemap.

phi0 defines the center of wedge zero.

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