EquatorialCoordinates¶

class sofia_redux.scan.coordinate_systems.equatorial_coordinates.EquatorialCoordinates(coordinates=None, unit='degree', copy=True, epoch=<sofia_redux.scan.coordinate_systems.epoch.epoch.JulianEpoch object>)[source]¶

Bases: PrecessingCoordinates

Initialize equatorial coordinates.

Equatorial coordinates are precessing celestial coordinates represented as spherical coordinates with the origin at the center of the Earth. The longitude (RA or right ascension) measure the angular distance of an object eastward along the celestial equator from the vernal equinox to the hour angle passing through the object. The latitude (DEC or declination) measures the angular distance of an object perpendicular to the celestial equator with north taken as positive.

Parameters:

coordinateslist or tuple or array-like or units.Quantity, optional: The coordinates used to populate the object during initialization. The first (0) value or index should represent longitudinal coordinates, and the second should represent latitude.
unitunits.Unit or str, optional: The angular unit for the spherical coordinates. The default is ‘degree’.
copybool, optional: Whether to explicitly perform a copy operation on the input coordinates when storing them into these coordinates. Note that it is extremely unlikely for the original coordinates to be passed in as a reference due to the significant checks performed on them.
epochEpoch or str or int or float or Time or fits.Header, optional: Information from which to set the epoch for these coordinates.

Attributes Summary

`EAST`
`NORTH`
`SOUTH`
`WEST`
`ZERO_LONGITUDE`
`dec`	Return the Declination coordinate(s).
`equatorial_pole`	Return an equatorial pole.
`fits_latitude_stem`	Return the string prefix for latitude (DEC).
`fits_longitude_stem`	Return the string prefix for longitude (RA).
`ra`	Return the Right Ascension coordinate(s).
`two_letter_code`	Return the two-letter code for the coordinate system.
`zero_longitude`	Return the zero longitude coordinate.

Methods Summary

`convert`(from_coordinates, to_coordinates)	Convert one type of coordinates to another.
`copy`()	Return a copy of the equatorial coordinates.
`edit_header`(header, key_stem[, alt])	Edit the header with equatorial coordinate information.
`from_equatorial`(coordinates)	Set the equatorial coordinates from those given.
`get_equatorial_pole`()	Return the equatorial pole.
`get_equatorial_position_angle`()	Return the equatorial position angle.
`get_parallactic_angle`(site, lst)	Return the parallactic angle for the coordinates.
`get_zero_longitude`()	Return the zero longitude coordinate.
`plot`(args, *kwargs)	Plot the coordinates.
`precess_to_epoch`(new_epoch)	Precess from one epoch to another.
`set_dec`(dec[, copy])	Set the Declination values.
`set_ra`(ra[, copy])	Set the Right Ascension values.
`setup_coordinate_system`()	Setup the system for the coordinates.
`to_equatorial`([coordinates])	Set the given coordinates to these equatorial coordinates.
`to_horizontal`(site, lst[, equatorial, ...])	Convert equatorial coordinates to horizontal coordinates.
`to_horizontal_offset`(offset, position_angle)	Convert an equatorial offset to a horizontal offset.

Attributes Documentation

EAST = -1¶

NORTH = 1¶

SOUTH = -1¶

WEST = 1¶

ZERO_LONGITUDE = <Quantity 0. deg>¶

dec¶

Return the Declination coordinate(s).

Returns:

declinationunits.Quantity

equatorial_pole¶

Return an equatorial pole.

Returns:

poleEquatorialCoordinates

fits_latitude_stem¶

Return the string prefix for latitude (DEC).

Returns:

str

fits_longitude_stem¶

Return the string prefix for longitude (RA).

Returns:

str

ra¶

Return the Right Ascension coordinate(s).

Returns:

right_ascensionunits.Quantity

two_letter_code¶

Return the two-letter code for the coordinate system.

Returns:

str

zero_longitude¶

Return the zero longitude coordinate.

Returns:

longitudeunits.Quantity

Methods Documentation

convert(from_coordinates, to_coordinates)[source]¶

Convert one type of coordinates to another.

The to_coordinates will be updated in-place.

Parameters:

from_coordinatesCelestialCoordinates
to_coordinatesCelestialCoordinates

Returns:

None

copy()[source]¶

Return a copy of the equatorial coordinates.

Returns:

EquatorialCoordinates

edit_header(header, key_stem, alt='')[source]¶

Edit the header with equatorial coordinate information.

Parameters:

headerfits.Header: The header to modify.
key_stemstr: The name of the header key to update.
altstr, optional: The alternative coordinate system.

Returns:

None

from_equatorial(coordinates)[source]¶

Set the equatorial coordinates from those given.

Parameters:

coordinatesEquatorialCoordinates

Returns:

None

classmethod get_equatorial_pole()[source]¶

Return the equatorial pole.

Returns:

poleEquatorialCoordinates

get_equatorial_position_angle()[source]¶

Return the equatorial position angle.

Returns:

position_angleunits.Quantity

get_parallactic_angle(site, lst)[source]¶

Return the parallactic angle for the coordinates.

Parameters:

siteGeodeticCoordinates: The site coordinates.
lstunits.Quantity: The local sidereal time.

Returns:

angleunits.Quantity

classmethod get_zero_longitude()[source]¶

Return the zero longitude coordinate.

Returns:

lonunits.Quantity (float)

plot(*args, **kwargs)[source]¶

Plot the coordinates.

Parameters:

argsvalues: Optional positional parameters to pass into pyplot.plot.
kwargsdict, optional: Optional keyword arguments.

Returns:

None

precess_to_epoch(new_epoch)[source]¶

Precess from one epoch to another.

Parameters:

new_epochEpoch

Returns:

None

set_dec(dec, copy=True)[source]¶

Set the Declination values.

Parameters:

decunits.Quantity
copybool, optional: If True, copy the coordinates.

Returns:

None

set_ra(ra, copy=True)[source]¶

Set the Right Ascension values.

Parameters:

raunits.Quantity
copybool, optional: If True, copy the coordinates.

Returns:

None

setup_coordinate_system()[source]¶

Setup the system for the coordinates.

Returns:

None

to_equatorial(coordinates=None)[source]¶

Set the given coordinates to these equatorial coordinates.

Parameters:

coordinatesEquatorialCoordinates, optional: The coordinates to convert. If not supplied, defaults to this.

Returns:

coordinatesEquatorialCoordinates

to_horizontal(site, lst, equatorial=None, horizontal=None)[source]¶

Convert equatorial coordinates to horizontal coordinates.

Parameters:

siteGeodeticCoordinates: The site coordinates.
lstunits.Quantity: The local sidereal time.
equatorialEquatorialCoordinates, optional: The equatorial coordinates to convert. The default are these coordinates.
horizontalHorizontalCoordinates, optional: The horizontal coordinates to convert to. The default is a fresh set of HorizontalCoordinates.

Returns:

horizontalHorizontalCoordinates: The equatorial coordinates as a horizontal representation.

classmethod to_horizontal_offset(offset, position_angle, in_place=True)[source]¶

Convert an equatorial offset to a horizontal offset.

Parameters:

offsetCoordinate2D: The 2-dimensional equatorial offsets to convert
position_angleunits.Quantity: The position angle as a scalar or shape (n,).
in_placebool, optional: If True, perform the conversion in-place. Otherwise, return a copy while leaving the original offset unchanged

Returns:

horizontal_offsetCoordinate2D: The (x, y) horizontal offsets.

Navigation

EquatorialCoordinates¶