Field of view (dorado.scheduling.FOV)

class dorado.scheduling.FOV(representation)

Bases: object

The field of view of an instrument.

Examples

First, some imports:

>>> from astropy.coordinates import ICRS, SkyCoord
>>> from astropy import units as u
>>> from astropy_healpix import HEALPix

Now, get the footprint for the default pointing:

>>> fov = FOV.from_rectangle(50 * u.deg)
>>> fov.footprint().icrs
<SkyCoord (ICRS): (ra, dec) in deg
    [( 25.,  25.), ( 25., -25.), (335., -25.), (335.,  25.)]>

Get a footprint as HEALPix coordinates.

>>> hpx = HEALPix(nside=4, frame=ICRS())
>>> fov.footprint_healpix(hpx, SkyCoord(0*u.deg, 20*u.deg), 15*u.deg)
array([ 57,  41,  25,  24,  70,  55,  39,  38,  23, 120, 104, 105,  88,
        73, 119, 103, 102,  87,  72,  56,  71,  40])

Get the footprint for a grid of pointings:

>>> ra = np.arange(0, 360, 45) * u.deg
>>> dec = np.arange(-90, 91, 45) * u.deg
>>> roll = np.arange(0, 90, 15) * u.deg
>>> center = SkyCoord(ra[:, np.newaxis], dec[np.newaxis, :])
>>> footprints = fov.footprint(center[..., np.newaxis], roll)
>>> footprints.shape
(8, 5, 6, 4)

classmethod from_rectangle(width, height=None)

Create a rectangular field of view.

Parameters:

• width (astropy.units.Quantity) – The width of the rectangle.

• height (astropy.units.Quantity) – The height of the rectangle. If omitted, then the field of view is a square.

Return type:

FOV

footprint(center=<SkyCoord (ICRS): (ra, dec) in deg     (0., 0.)>, roll=<Quantity 0. deg>)

Get the footprint of the FOV at a given orientation.

Parameters:

• center (astropy.coordinates.SkyCoord) – The center of the field of view. If omitted, the default is RA=0°, Dec=0°.

• roll (astropy.coordinates.SkyCoord) – The roll of the field of view. If omitted, the default is 0°.

Returns:

vertices – The coordinates of the vertices of the field of view.

Return type:

astropy.coordinates.SkyCoord

footprint_healpix(healpix, *args, **kwargs)

Get the HEALPix footprint at a given orientation.

Parameters:

• center (astropy.coordinates.SkyCoord) – The center of the field of view.

• rotate (class:astropy.units.Quantity) – The position angle (optional, default 0 degrees).

Returns:

An array of HEALPix indices contained within the footprint.

Return type:

np.ndarray

footprint_healpix_grid(healpix, center, roll)

Calculate the HEALPix footprints of all pointings on the grid.

Returns:

A generator that yields the indices for each pointing center and for each roll.

Return type:

generator