projected_size

sbpy.units.projected_size(eph: sbpy.data.ephem.Ephem)[source]

Angular size and projected linear size equivalency.

Based on the tangent formula:

length = delta * tan(angle)

Parameters
ephQuantity, dict-like, sbpy.data.Ephem

Distance to the object as a quantity or the field 'delta'.

Returns
eqivlist

List of equivalencies

Examples

>>> import astropy.units as u
>>> import sbpy.units as sbu
>>> (1 * u.arcsec).to('km', sbu.projected_size(1 * u.au))
... # doctest: +FLOAT_CMP
<Quantity [725.27094381] km>
>>> (725.27 * u.km).to('arcsec', sbu.projected_size(1 * u.au))
... # doctest: +FLOAT_CMP
<Quantity [1.00] arcsec>