Observer¶
- class astroplan.Observer(location=None, timezone='UTC', name=None, latitude=None, longitude=None, elevation=<Quantity 0. m>, pressure=None, relative_humidity=None, temperature=None, description=None)[source]¶
Bases:
object
A container class for information about an observer’s location and environment.
Examples
We can create an observer at Subaru Observatory in Hawaii two ways. First, locations for some observatories are stored in astroplan, and these can be accessed by name, like so:
>>> from astroplan import Observer >>> subaru = Observer.at_site("Subaru", timezone="US/Hawaii")
To find out which observatories can be accessed by name, check out
get_site_names
.Next, you can initialize an observer by specifying the location with
EarthLocation
:>>> from astropy.coordinates import EarthLocation >>> import astropy.units as u >>> location = EarthLocation.from_geodetic(-155.4761*u.deg, 19.825*u.deg, ... 4139*u.m) >>> subaru = Observer(location=location, name="Subaru", timezone="US/Hawaii")
You can also create an observer without an
EarthLocation
:>>> from astroplan import Observer >>> import astropy.units as u >>> subaru = Observer(longitude=-155.4761*u.deg, latitude=19.825*u.deg, ... elevation=0*u.m, name="Subaru", timezone="US/Hawaii")
- Parameters:
- location
EarthLocation
The location (latitude, longitude, elevation) of the observatory.
- timezonestr or
datetime.tzinfo
(optional) The local timezone to assume. If a string, it will be passed through
pytz.timezone()
to produce the timezone object.- namestr
A short name for the telescope, observatory or location.
- latitudefloat, str,
Quantity
(optional) The latitude of the observing location. Should be valid input for initializing a
Latitude
object.- longitudefloat, str,
Quantity
(optional) The longitude of the observing location. Should be valid input for initializing a
Longitude
object.- elevation
Quantity
(optional), default = 0 meters The elevation of the observing location, with respect to sea level. Defaults to sea level.
- pressure
Quantity
(optional) The ambient pressure. Defaults to zero (i.e. no atmosphere).
- relative_humidityfloat (optional)
The ambient relative humidity.
- temperature
Quantity
(optional) The ambient temperature.
- descriptionstr (optional)
A short description of the telescope, observatory or observing location.
- location
Attributes Summary
The elevation of the observing location with respect to sea level.
The latitude of the observing location, derived from the location.
The longitude of the observing location, derived from the location.
Methods Summary
altaz
(time[, target, obswl, grid_times_targets])Get an
AltAz
frame or coordinate.astropy_time_to_datetime
(astropy_time)Convert the
Time
objectastropy_time
to a localizeddatetime
object.at_site
(site_name, **kwargs)Initialize an
Observer
object with a site name.datetime_to_astropy_time
(date_time)is_night
(time[, horizon, obswl])Is the Sun below
horizon
attime
?local_sidereal_time
(time[, kind, model])Convert
time
to local sidereal time for observer.midnight
(time[, which, n_grid_points])Time at solar midnight.
moon_altaz
(time[, ephemeris])Returns the position of the moon in alt/az.
moon_illumination
(time)Calculate the illuminated fraction of the moon.
moon_phase
([time])Calculate lunar orbital phase.
moon_rise_time
(time[, which, horizon, ...])Returns the local moon rise time.
moon_set_time
(time[, which, horizon, ...])Returns the local moon set time.
noon
(time[, which, n_grid_points])Time at solar noon.
parallactic_angle
(time, target[, ...])Calculate the parallactic angle.
sun_altaz
(time)Returns the position of the Sun in alt/az.
sun_rise_time
(time[, which, horizon, ...])Time of sunrise.
sun_set_time
(time[, which, horizon, ...])Time of sunset.
target_hour_angle
(time, target[, ...])Calculate the local hour angle of
target
attime
.target_is_up
(time, target[, horizon, ...])Is
target
abovehorizon
at thistime
?target_meridian_antitransit_time
(time, target)Calculate time at the antitransit of the meridian.
target_meridian_transit_time
(time, target[, ...])Calculate time at the transit of the meridian.
target_rise_time
(time, target[, which, ...])Calculate rise time.
target_set_time
(time, target[, which, ...])Calculate set time.
tonight
([time, horizon, obswl])Return a time range corresponding to the nearest night
twilight_evening_astronomical
(time[, which, ...])Time at evening astronomical (-18 degree) twilight.
twilight_evening_civil
(time[, which, ...])Time at evening civil (-6 degree) twilight.
twilight_evening_nautical
(time[, which, ...])Time at evening nautical (-12 degree) twilight.
twilight_morning_astronomical
(time[, which, ...])Time at morning astronomical (-18 degree) twilight.
twilight_morning_civil
(time[, which, ...])Time at morning civil (-6 degree) twilight.
twilight_morning_nautical
(time[, which, ...])Time at morning nautical (-12 degree) twilight.
Attributes Documentation
- elevation¶
The elevation of the observing location with respect to sea level.
- latitude¶
The latitude of the observing location, derived from the location.
- longitude¶
The longitude of the observing location, derived from the location.
Methods Documentation
- altaz(time, target=None, obswl=None, grid_times_targets=False)[source]¶
Get an
AltAz
frame or coordinate.If
target
is None, generates an altitude/azimuth frame. Otherwise, calculates the transformation to that frame for the requestedtarget
.- Parameters:
- time
Time
or other (see below) The time at which the observation is taking place. Will be used as the
obstime
attribute in the resulting frame or coordinate. This will be passed in as the first argument to theTime
initializer, so it can be anything thatTime
will accept (including aTime
object)- target
FixedTarget
,SkyCoord
, or list (optional) Celestial object(s) of interest. If
target
isNone
, returns theAltAz
frame without coordinates.- obswl
Quantity
(optional) Wavelength of the observation used in the calculation.
- grid_times_targets: bool (optional)
If True, the target object will have extra dimensions packed onto the end, so that calculations with M targets and N times will return an (M, N) shaped result. Otherwise, we rely on broadcasting the shapes together using standard numpy rules. Useful for grid searches for rise/set times etc.
- time
- Returns:
Examples
Create an instance of the
AltAz
frame for an observer at Apache Point Observatory at a particular time:>>> from astroplan import Observer >>> from astropy.time import Time >>> from astropy.coordinates import SkyCoord >>> apo = Observer.at_site("APO") >>> time = Time('2001-02-03 04:05:06') >>> target = SkyCoord(0*u.deg, 0*u.deg) >>> altaz_frame = apo.altaz(time)
Now transform the target’s coordinates to the alt/az frame:
>>> target_altaz = target.transform_to(altaz_frame)
Alternatively, construct an alt/az frame and transform the target to that frame all in one step:
>>> target_altaz = apo.altaz(time, target)
- astropy_time_to_datetime(astropy_time)[source]¶
Convert the
Time
objectastropy_time
to a localizeddatetime
object.Timezones localized with pytz.
- Parameters:
- astropy_time
Time
Scalar or list-like.
- astropy_time
- Returns:
Examples
Convert an astropy time to a localized
datetime
:>>> from astroplan import Observer >>> from astropy.time import Time >>> subaru = Observer.at_site("Subaru", timezone="US/Hawaii") >>> astropy_time = Time('1999-12-31 06:00:00') >>> print(subaru.astropy_time_to_datetime(astropy_time)) 1999-12-30 20:00:00-10:00
- classmethod at_site(site_name, **kwargs)[source]¶
Initialize an
Observer
object with a site name.Extra keyword arguments are passed to the
Observer
constructor (seeObserver
for available keyword arguments).- Parameters:
- site_namestr
Observatory name, must be resolvable with
get_site_names
.
- Returns:
Observer
Observer object.
Examples
Initialize an observer at Kitt Peak National Observatory:
>>> from astroplan import Observer >>> import astropy.units as u >>> kpno_generic = Observer.at_site('kpno') >>> kpno_today = Observer.at_site('kpno', pressure=1*u.bar, temperature=0*u.deg_C)
- datetime_to_astropy_time(date_time)[source]¶
Convert the
datetime
objectdate_time
to aTime
object.Timezones localized with pytz. If the
date_time
is naive, the implied timezone is thetimezone
structure ofself
.- Parameters:
- date_time
datetime
or list-like
- date_time
- Returns:
Time
Astropy time object (no timezone information preserved).
Examples
Convert a localized
datetime
to aTime
object. Non-localized datetimes are assumed to be UTC. <Time object: scale=’utc’ format=’datetime’ value=1999-12-31 06:00:00>>>> from astroplan import Observer >>> import datetime >>> import pytz >>> subaru = Observer.at_site("Subaru", timezone="US/Hawaii") >>> hi_date_time = datetime.datetime(2005, 6, 21, 20, 0, 0, 0) >>> subaru.datetime_to_astropy_time(hi_date_time) <Time object: scale='utc' format='datetime' value=2005-06-22 06:00:00> >>> utc_date_time = datetime.datetime(2005, 6, 22, 6, 0, 0, 0, ... tzinfo=pytz.timezone("UTC")) >>> subaru.datetime_to_astropy_time(utc_date_time) <Time object: scale='utc' format='datetime' value=2005-06-22 06:00:00>
- is_night(time, horizon=<Quantity 0. deg>, obswl=None)[source]¶
Is the Sun below
horizon
attime
?- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- horizon
Quantity
(optional), default = zero degrees Degrees above/below actual horizon to use for calculating day/night (i.e., -6 deg horizon = civil twilight, etc.)
- obswl
Quantity
(optional) Wavelength of the observation used in the calculation
- time
- Returns:
Examples
Is it “nighttime” (i.e. is the Sun below
horizon
) at Apache Point Observatory at 2015-08-29 18:35 UTC?>>> from astroplan import Observer >>> from astropy.time import Time >>> apo = Observer.at_site("APO") >>> time = Time("2015-08-29 18:35") >>> apo.is_night(time) False
- local_sidereal_time(time, kind='apparent', model=None)[source]¶
Convert
time
to local sidereal time for observer.This is a thin wrapper around the
sidereal_time
method.- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- kind{‘mean’, ‘apparent’} (optional)
Passed to the
kind
argument ofsidereal_time
- modelstr or
None
; optional The precession/nutation model to assume - see
sidereal_time
for more details.
- time
- Returns:
Longitude
Local sidereal time.
- midnight(time, which='nearest', n_grid_points=150)[source]¶
Time at solar midnight.
- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- which{‘next’, ‘previous’, ‘nearest’}
Choose which noon relative to the present
time
would you like to calculate- n_grid_pointsint (optional)
The number of grid points on which to search for the horizon crossings of the target over a 24 hour period, default is 150 which yields midnight time precisions better than one minute.
- time
- Returns:
Time
Time at solar midnight
- moon_altaz(time, ephemeris=None)[source]¶
Returns the position of the moon in alt/az.
- Parameters:
- time
Time
or other (see below) This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object).- ephemerisstr, optional
Ephemeris to use. If not given, use the one set with
astropy.coordinates.solar_system_ephemeris.set
(which is set to ‘builtin’ by default).
- time
- Returns:
- altaz
SkyCoord
Position of the moon transformed to altitude and azimuth
- altaz
Examples
Calculate the altitude and azimuth of the moon at Apache Point Observatory:
>>> from astroplan import Observer >>> from astropy.time import Time >>> apo = Observer.at_site("APO") >>> time = Time("2015-08-29 18:35") >>> altaz_moon = apo.moon_altaz(time) >>> print("alt: {0.alt}, az: {0.az}".format(altaz_moon)) alt: -63.72706397691421 deg, az: 345.3640380598265 deg
- moon_illumination(time)[source]¶
Calculate the illuminated fraction of the moon.
- Parameters:
- Returns:
- float
Fraction of lunar surface illuminated
Examples
How much of the lunar surface is illuminated at 2015-08-29 18:35 UTC, which we happen to know is the time of a full moon?
>>> from astroplan import Observer >>> from astropy.time import Time >>> apo = Observer.at_site("APO") >>> time = Time("2015-08-29 18:35") >>> apo.moon_illumination(time) array([ 0.99972487])
- moon_phase(time=None)[source]¶
Calculate lunar orbital phase.
For example, phase=pi is “new”, phase=0 is “full”.
- Parameters:
- Returns:
- moon_phase_anglefloat
Orbital phase angle of the moon where pi corresponds to new moon, zero corresponds to full moon.
Examples
Calculate the phase of the moon at 2015-08-29 18:35 UTC. Near zero radians corresponds to a nearly full moon.
>>> from astroplan import Observer >>> from astropy.time import Time >>> apo = Observer.at_site('APO') >>> time = Time('2015-08-29 18:35') >>> apo.moon_phase(time) <Quantity [ 0.03317537] rad>
- moon_rise_time(time, which='nearest', horizon=<Quantity 0. deg>, n_grid_points=150)[source]¶
Returns the local moon rise time.
Compute time of the next/previous/nearest moon rise, where moon rise is defined as the time when the moon transitions from altitudes below
horizon
to abovehorizon
.- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- which{‘next’, ‘previous’, ‘nearest’}
Choose which moon rise relative to the present
time
would you like to calculate.- horizon
Quantity
(optional), default = zero degrees Degrees above/below actual horizon to use for calculating rise/set times (i.e., -6 deg horizon = civil twilight, etc.)
- n_grid_pointsint (optional)
The number of grid points on which to search for the horizon crossings of the target over a 24 hour period, default is 150 which yields rise time precisions better than one minute.
- time
- moon_set_time(time, which='nearest', horizon=<Quantity 0. deg>, n_grid_points=150)[source]¶
Returns the local moon set time.
Compute time of the next/previous/nearest moon set, where moon set is defined as the time when the moon transitions from altitudes below
horizon
to abovehorizon
.- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- which{‘next’, ‘previous’, ‘nearest’}
Choose which moon set relative to the present
time
would you like to calculate.- horizon
Quantity
(optional), default = zero degrees Degrees above/below actual horizon to use for calculating set/set times (i.e., -6 deg horizon = civil twilight, etc.)
- n_grid_pointsint (optional)
The number of grid points on which to search for the horizon crossings of the target over a 24 hour period, default is 150 which yields set time precisions better than one minute.
- time
- noon(time, which='nearest', n_grid_points=150)[source]¶
Time at solar noon.
- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- which{‘next’, ‘previous’, ‘nearest’}
Choose which noon relative to the present
time
would you like to calculate- n_grid_pointsint (optional)
The number of grid points on which to search for the horizon crossings of the target over a 24 hour period, default is 150 which yields noon time precisions better than one minute.
- time
- Returns:
Time
Time at solar noon
- parallactic_angle(time, target, grid_times_targets=False, kind='mean', model=None)[source]¶
Calculate the parallactic angle.
- Parameters:
- time
Time
Observation time.
- target
FixedTarget
orSkyCoord
or list Target celestial object(s).
- grid_times_targets: bool
If True, the target object will have extra dimensions packed onto the end, so that calculations with M targets and N times will return an (M, N) shaped result. Otherwise, we rely on broadcasting the shapes together using standard numpy rules.
- kindstr
Argument to the
sidereal_time
function, which may be either'mean'
or'apparent'
, i.e., accounting for precession only, or also for nutation.- modelstr or None; optional
Precession (and nutation) model to use in the call to
sidereal_time
, see docs for that method for details.
- time
- Returns:
Angle
Parallactic angle.
Notes
The parallactic angle is the angle between the great circle that intersects a celestial object and the zenith, and the object’s hour circle [1].
- sun_altaz(time)[source]¶
Returns the position of the Sun in alt/az.
- Parameters:
- time
Time
or other (see below) This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object).- ephemerisstr, optional
Ephemeris to use. If not given, use the one set with
astropy.coordinates.solar_system_ephemeris.set
(which is set to ‘builtin’ by default).
- time
- Returns:
- altaz
SkyCoord
Position of the sun transformed to altitude and azimuth
- altaz
- sun_rise_time(time, which='nearest', horizon=<Quantity 0. deg>, n_grid_points=150)[source]¶
Time of sunrise.
Compute time of the next/previous/nearest sunrise, where sunrise is defined as when the Sun transitions from altitudes below
horizon
to abovehorizon
.- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- which{‘next’, ‘previous’, ‘nearest’}
Choose which sunrise relative to the present
time
would you like to calculate.- horizon
Quantity
(optional), default = zero degrees Degrees above/below actual horizon to use for calculating rise/set times (i.e., -6 deg horizon = civil twilight, etc.)
- n_grid_pointsint (optional)
The number of grid points on which to search for the horizon crossings of the target over a 24 hour period, default is 150 which yields rise time precisions better than one minute.
- time
- Returns:
Time
Time of sunrise
Examples
Calculate the time of the previous sunrise at Apache Point Observatory:
>>> from astroplan import Observer >>> from astropy.time import Time >>> apo = Observer.at_site("APO") >>> time = Time('2001-02-03 04:05:06') >>> sun_rise = apo.sun_rise_time(time, which="previous") >>> print("ISO: {0.iso}, JD: {0.jd}".format(sun_rise)) ISO: 2001-02-02 14:02:50.554, JD: 2451943.08531
- sun_set_time(time, which='nearest', horizon=<Quantity 0. deg>, n_grid_points=150)[source]¶
Time of sunset.
Compute time of the next/previous/nearest sunset, where sunset is defined as when the Sun transitions from altitudes below
horizon
to abovehorizon
.- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- which{‘next’, ‘previous’, ‘nearest’}
Choose which sunset relative to the present
time
would you like to calculate- horizon
Quantity
(optional), default = zero degrees Degrees above/below actual horizon to use for calculating rise/set times (i.e., -6 deg horizon = civil twilight, etc.)
- n_grid_pointsint (optional)
The number of grid points on which to search for the horizon crossings of the target over a 24 hour period, default is 150 which yields set time precisions better than one minute.
- time
- Returns:
Time
Time of sunset
Examples
Calculate the time of the next sunset at Apache Point Observatory:
>>> from astroplan import Observer >>> from astropy.time import Time >>> apo = Observer.at_site("APO") >>> time = Time('2001-02-03 04:05:06') >>> sun_set = apo.sun_set_time(time, which="next") >>> print("ISO: {0.iso}, JD: {0.jd}".format(sun_set)) ISO: 2001-02-04 00:35:42.102, JD: 2451944.52479
- target_hour_angle(time, target, grid_times_targets=False)[source]¶
Calculate the local hour angle of
target
attime
.- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- target
SkyCoord
,FixedTarget
, or list Target celestial object(s)
- grid_times_targets: bool
If True, the target object will have extra dimensions packed onto the end, so that calculations with M targets and N times will return an (M, N) shaped result. Otherwise, we rely on broadcasting the shapes together using standard numpy rules.
- time
- Returns:
- hour_angle
Angle
The hour angle(s) of the target(s) at
time
- hour_angle
- target_is_up(time, target, horizon=<Quantity 0. deg>, return_altaz=False, grid_times_targets=False)[source]¶
Is
target
abovehorizon
at thistime
?- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- target
SkyCoord
,FixedTarget
, or list Target celestial object(s)
- horizon
Quantity
(optional), default = zero degrees Degrees above/below actual horizon to use for calculating rise/set times (i.e., -6 deg horizon = civil twilight, etc.)
- return_altazbool (optional)
Also return the ‘~astropy.coordinates.AltAz’ coordinate.
- grid_times_targets: bool
If True, the target object will have extra dimensions packed onto the end, so that calculations with M targets and N times will return an (M, N) shaped result. Otherwise, we rely on broadcasting the shapes together using standard numpy rules.
- time
- Returns:
- observableboolean or np.ndarray(bool)
True if
target
is abovehorizon
attime
, else False.
Examples
Are Aldebaran and Vega above the horizon at Apache Point Observatory at 2015-08-29 18:35 UTC?
>>> from astroplan import Observer, FixedTarget >>> from astropy.time import Time >>> apo = Observer.at_site("APO") >>> time = Time("2015-08-29 18:35") >>> aldebaran = FixedTarget.from_name("Aldebaran") >>> vega = FixedTarget.from_name("Vega") >>> apo.target_is_up(time, aldebaran) True >>> apo.target_is_up(time, [aldebaran, vega]) array([ True, False], dtype=bool)
- target_meridian_antitransit_time(time, target, which='nearest', grid_times_targets=False, n_grid_points=150)[source]¶
Calculate time at the antitransit of the meridian.
Compute time of the next/previous/nearest antitransit of the
target
object.- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- target
SkyCoord
,FixedTarget
, or list Target celestial object(s)
- which{‘next’, ‘previous’, ‘nearest’}
Choose which sunrise relative to the present
time
would you like to calculate- grid_times_targetsbool
If True, the target object will have extra dimensions packed onto the end, so that calculations with M targets and N times will return an (M, N) shaped result. Otherwise, we rely on broadcasting the shapes together using standard numpy rules.
- n_grid_pointsint (optional)
The number of grid points on which to search for the horizon crossings of the target over a 24 hour period, default is 150 which yields rise time precisions better than one minute.
- time
- Returns:
Time
Antitransit time of target
Examples
Calculate the meridian anti-transit time of Rigel at Keck Observatory:
>>> from astroplan import Observer, FixedTarget >>> from astropy.time import Time >>> time = Time("2001-02-03 04:05:06") >>> target = FixedTarget.from_name("Rigel") >>> keck = Observer.at_site("Keck") >>> rigel_antitransit_time = keck.target_meridian_antitransit_time( ... time, target, which="next") >>> print("ISO: {0.iso}, JD: {0.jd}".format(rigel_antitransit_time)) ISO: 2001-02-03 18:40:29.761, JD: 2451944.27812
- target_meridian_transit_time(time, target, which='nearest', grid_times_targets=False, n_grid_points=150)[source]¶
Calculate time at the transit of the meridian.
Compute time of the next/previous/nearest transit of the
target
object.- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- target
SkyCoord
,FixedTarget
, or list Target celestial object(s)
- which{‘next’, ‘previous’, ‘nearest’}
Choose which sunrise relative to the present
time
would you like to calculate- grid_times_targets: bool
If True, the target object will have extra dimensions packed onto the end, so that calculations with M targets and N times will return an (M, N) shaped result. Otherwise, we rely on broadcasting the shapes together using standard numpy rules.
- n_grid_pointsint (optional)
The number of grid points on which to search for the horizon crossings of the target over a 24 hour period, default is 150 which yields rise time precisions better than one minute.
- time
- Returns:
Time
Transit time of target
Examples
Calculate the meridian transit time of Rigel at Keck Observatory:
>>> from astroplan import Observer, FixedTarget >>> from astropy.time import Time >>> time = Time("2001-02-03 04:05:06") >>> target = FixedTarget.from_name("Rigel") >>> keck = Observer.at_site("Keck") >>> rigel_transit_time = keck.target_meridian_transit_time(time, target, ... which="next") >>> print("ISO: {0.iso}, JD: {0.jd}".format(rigel_transit_time)) ISO: 2001-02-03 06:42:26.863, JD: 2451943.77948
- target_rise_time(time, target, which='nearest', horizon=<Quantity 0. deg>, grid_times_targets=False, n_grid_points=150)[source]¶
Calculate rise time.
Compute time of the next/previous/nearest rise of the
target
object, where “rise” is defined as the time when thetarget
transitions from altitudes below thehorizon
to above thehorizon
.- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- target
SkyCoord
,FixedTarget
, or list Target celestial object(s)
- which{‘next’, ‘previous’, ‘nearest’}
Choose which sunrise relative to the present
time
would you like to calculate- horizon
Quantity
(optional), default = zero degrees Degrees above/below actual horizon to use for calculating rise/set times (i.e., -6 deg horizon = civil twilight, etc.)
- grid_times_targets: bool
If True, the target object will have extra dimensions packed onto the end, so that calculations with M targets and N times will return an (M, N) shaped result. Otherwise, we rely on broadcasting the shapes together using standard numpy rules.
- n_grid_pointsint (optional)
The number of grid points on which to search for the horizon crossings of the target over a 24 hour period, default is 150 which yields rise time precisions better than one minute.
- time
- Returns:
Time
Rise time of target
Examples
Calculate the rise time of Rigel at Keck Observatory:
>>> from astroplan import Observer, FixedTarget >>> from astropy.time import Time >>> time = Time("2001-02-03 04:05:06") >>> target = FixedTarget.from_name("Rigel") >>> keck = Observer.at_site("Keck") >>> rigel_rise_time = keck.target_rise_time(time, target, which="next") >>> print("ISO: {0.iso}, JD: {0.jd}".format(rigel_rise_time)) ISO: 2001-02-04 00:51:23.330, JD: 2451944.53569
- target_set_time(time, target, which='nearest', horizon=<Quantity 0. deg>, grid_times_targets=False, n_grid_points=150)[source]¶
Calculate set time.
Compute time of the next/previous/nearest set of
target
, where “set” is defined as when thetarget
transitions from altitudes abovehorizon
to belowhorizon
.- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- target
SkyCoord
,FixedTarget
, or list Target celestial object(s)
- which{‘next’, ‘previous’, ‘nearest’}
Choose which sunset relative to the present
time
would you like to calculate- horizon
Quantity
(optional), default = zero degrees Degrees above/below actual horizon to use for calculating rise/set times (i.e., -6 deg horizon = civil twilight, etc.)
- grid_times_targets: bool
If True, the target object will have extra dimensions packed onto the end, so that calculations with M targets and N times will return an (M, N) shaped result. Otherwise, we rely on broadcasting the shapes together using standard numpy rules.
- n_grid_pointsint (optional)
The number of grid points on which to search for the horizon crossings of the target over a 24 hour period, default is 150 which yields set time precisions better than one minute.
- time
- Returns:
Time
Set time of target.
Examples
Calculate the set time of Rigel at Keck Observatory:
>>> from astroplan import Observer, FixedTarget >>> from astropy.time import Time >>> time = Time("2001-02-03 04:05:06") >>> target = FixedTarget.from_name("Rigel") >>> keck = Observer.at_site("Keck") >>> rigel_set_time = keck.target_set_time(time, target, which="next") >>> print("ISO: {0.iso}, JD: {0.jd}".format(rigel_set_time)) ISO: 2001-02-03 12:29:34.768, JD: 2451944.02054
- tonight(time=None, horizon=<Quantity 0. deg>, obswl=None)[source]¶
Return a time range corresponding to the nearest night
This will return a range of
Time
corresponding to the beginning and ending of the night. If in the middle of a given night, return times fromnow
until the nearestsun_rise_time
- Parameters:
- time
Time
(optional), default =now
The start time for tonight, which is allowed to be arbitrary. See description above for behavior
- horizon
Quantity
(optional), default = zero degrees Degrees above/below actual horizon to use for calculating rise/set times (e.g., -6 deg horizon = civil twilight, etc.)
- obswl
Quantity
(optional) Wavelength of the observation used in the calculation
- time
- Returns:
- times
Time
A tuple of times corresponding to the start and end of current night
- times
- twilight_evening_astronomical(time, which='nearest', n_grid_points=150)[source]¶
Time at evening astronomical (-18 degree) twilight.
- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- which{‘next’, ‘previous’, ‘nearest’}
Choose which twilight relative to the present
time
would you like to calculate. Default is nearest.- n_grid_pointsint (optional)
The number of grid points on which to search for the horizon crossings of the target over a 24 hour period, default is 150 which yields twilight time precisions better than one minute.
- time
- Returns:
Time
Time of twilight
- twilight_evening_civil(time, which='nearest', n_grid_points=150)[source]¶
Time at evening civil (-6 degree) twilight.
- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- which{‘next’, ‘previous’, ‘nearest’}
Choose which twilight relative to the present
time
would you like to calculate. Default is nearest.- n_grid_pointsint (optional)
The number of grid points on which to search for the horizon crossings of the target over a 24 hour period, default is 150 which yields twilight time precisions better than one minute.
- time
- Returns:
Time
Time of twilight
- twilight_evening_nautical(time, which='nearest', n_grid_points=150)[source]¶
Time at evening nautical (-12 degree) twilight.
- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- which{‘next’, ‘previous’, ‘nearest’}
Choose which twilight relative to the present
time
would you like to calculate. Default is nearest.- n_grid_pointsint (optional)
The number of grid points on which to search for the horizon crossings of the target over a 24 hour period, default is 150 which yields twilight time precisions better than one minute.
- time
- Returns:
Time
Time of twilight
- twilight_morning_astronomical(time, which='nearest', n_grid_points=150)[source]¶
Time at morning astronomical (-18 degree) twilight.
- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- which{‘next’, ‘previous’, ‘nearest’}
Choose which twilight relative to the present
time
would you like to calculate- n_grid_pointsint (optional)
The number of grid points on which to search for the horizon crossings of the target over a 24 hour period, default is 150 which yields twilight time precisions better than one minute.
- time
- Returns:
Time
Time of twilight
- twilight_morning_civil(time, which='nearest', n_grid_points=150)[source]¶
Time at morning civil (-6 degree) twilight.
- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- which{‘next’, ‘previous’, ‘nearest’}
Choose which twilight relative to the present
time
would you like to calculate. Default is nearest.- n_grid_pointsint (optional)
The number of grid points on which to search for the horizon crossings of the target over a 24 hour period, default is 150 which yields twilight time precisions better than one minute.
- time
- Returns:
Time
Time of sunset
- twilight_morning_nautical(time, which='nearest', n_grid_points=150)[source]¶
Time at morning nautical (-12 degree) twilight.
- Parameters:
- time
Time
or other (see below) Time of observation. This will be passed in as the first argument to the
Time
initializer, so it can be anything thatTime
will accept (including aTime
object)- which{‘next’, ‘previous’, ‘nearest’}
Choose which twilight relative to the present
time
would you like to calculate. Default is nearest.- n_grid_pointsint (optional)
The number of grid points on which to search for the horizon crossings of the target over a 24 hour period, default is 150 which yields twilight time precisions better than one minute.
- time
- Returns:
Time
Time of twilight