distanceModulus¶

utilipy.astro.distanceModulus(arg, A=<Quantity 0. mag>, obs=True, *, unit: typing.Optional[astropy.units.core.Unit] = None, to_value: bool = False, equivalencies: typing.Sequence = [], decompose: typing.Union[bool, typing.Sequence] = False, assumed_units: dict = {'A': Unit("mag")}, _skip_decorator: bool = False, **kw) → Any[source]¶

Distance Modulus.

\[DM = 5 log10(d / 10) + A\]

Parameters

d: array_like, optional: no units to parsecs
A: Quantity array_like, optional: extinction in magnitudes (default \(0 \rm{mag}\))
obs: bool: (default True goes to \(mobs - M\)) whether to return (\(mobs - M\)) or (\(mtrue - M\)) .. note:: don’t change unless specifically required

Returns

DM: Quantity array_like: default MAG

Other Parameters

unitastropy Unit or Quantity or str

sets the unit for the function evaluation. (default None) must be astropy-compatible unit specification. equivalent to func(*args, **kw).to(unit) if None, skips unit conversion. function arguments override decorator and function annotation arguments

to_valuebool

whether to return .to_value(unit) (default False) see astropy.units.Quantity.to_value function arguments override decorator and function annotation arguments

equivalencieslist

equivalencies for any units provided (default []) used by .to() and .to_value() function arguments override decorator and function annotation arguments

decomposebool or list

Decompose the unit into base units, can provide base as list. (default []) function arguments override decorator and function annotation arguments if bool, then do/don’t decompose if list, bases for .decompose(bases=[]) will first decompose, then apply unit, to_value, equivalencies

Decomposing then converting wastes time, since to(unit, equivalencies) internally does conversions. The only use for combining decompose with other params is with:

unit=None, to_value=True, equivalencies=[], decompose=[bases]

since this will decompose to desired bases then return the value

Note

for things which are not (u.Unit, u.core.IrreducibleUnit), tries wrapping in Unit() this allows things such as:

>>> x = 10 * u.km * u.s
>>> bases = [u.Unit(2 * u.km), u.s]
>>> x.decompose(bases=bases) 
<Quantity 5. 2 km s>

(this would normally return an error)

assumed_units: dict

dictionary of default units (default {})

>>> from utilipy.units.decorators import QuantityInputOutput
>>> dfu = {'x': u.km}
>>> x = 10
>>> y = 20*u.km
>>> @QuantityInputOutput.as_decorator(assumed_units=dfu)
... def add(x, y):
...     return x + y
>>> add(x, y) 
<Quantity 30.0 km>

Notes

\(mtrue - M = 5 log10(d / 10)\) if there is line-of-sight extinction \(mobs = mtrue + A\) \(mobs - M = 5 log10(d / 10) + A\) \(true - M = 5 log10(d / 10) - A\)

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distanceModulus¶