Time and Position Transformation¶
New in version 0.2.
Time and position transform objects.
Time¶
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class
lsl.transform.
Time
(value, format='MJD', timesys='UTC')¶ Holds an absolute time value and can manipulate the value in various representations.
After creation, a particular time format and time system may be accessed using the appropriate instance member. If marked with ‘(S)’, the Time value may also be updated by setting the member to a new value.
utc_jd (S) - UTC standard Julian day utc_mjd (S) - UTC modified Julian day utc_timet (S) - UTC UNIX timet seconds utc_py_date (S) - UTC python datetime.datetime object utc_ln_date (S) - UTC libnova astro.date object utc_dp (S) - UTC DP samples at 196 MHz utc_mcs - UTC MCS MJD/MPM pair utc_str - UTC ISO8601 calendar string format
tai_jd (S) - TAI standard Julian day tai_mjd (S) - TAI modified Julian day tai_timet (S) - TAI UNIX timet seconds
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static
date_ln_to_py
(lnDate)¶ Convert libnova astro.date object into a python datetime.datetime object.
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static
date_py_to_ln
(pyDate)¶ Convert python datatime.datetime object into a libnova astro.date object.
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classmethod
from_system
()¶ Factory method to create a Time instance from current system clock value.
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property
tai_jd
¶ Time value formatted as TAI standard julian day (float).
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property
tai_mjd
¶ Time value formatted as TAI modified julian day (float).
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property
tai_timet
¶ Time value formatted as TAI UNIX timet seconds.
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property
utc_jd
¶ Time value formatted as UTC standard julian day (float).
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property
utc_ln_date
¶ Time value formatted as UTC calendar astro.date object.
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property
utc_mjd
¶ Time value formatted as UTC modified julian day (float).
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property
utc_py_date
¶ Time value formattes as UTC calendar datetime.datetime object.
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property
utc_str
¶ Time value formatted as UTC ISO 8601 calendar string.
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property
utc_timet
¶ Time value formatted as UTC UNIX timet seconds.
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static
Celstial Positions¶
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class
lsl.transform.
CelestialPosition
(value, format='EQU', epoch='J2000', name='')¶ Holds a celestial object position value and can manipulate the value in various representations.
After creation, the celestial coordinates may be accessed in different formats and epoch by using the appropriate instance member. If marked with ‘(S)’, the Time value may also be updated by setting the member to a new value.
j2000_equ (S) - J2000 equatorial coordinates j2000_gal (S) - J2000 galactic coordinates j2000_ecl (S) - J2000 ecliptic coordinates
b1950_equ (S) - B1950 equatorial coordinates
The instance methods apparent_equ() and apparent_ecl() may be used to get the apparent equatorial or ecliptic coordinates for a particular time.
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apparent_ecl
(time_)¶ Return position formatted as apparent ecliptic coordinates. The ‘time’ parameter should be set to a Time instance providing the time of interest. Return alue is object of type astro.ecl_posn.
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apparent_equ
(time_)¶ Return position formatted as apparent equatorial coordinates. The ‘time’ parameter should be set to a Time instance providing the time of interest. Return value is object of type astro.equ_posn.
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property
b1950_equ
¶ Position formatted as B1950 equatorial coordinates. Value is object of type astro.equ_posn.
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property
j2000_ecl
¶ Position formatted as J2000 ecliptic coordinates. Value is object of type astro.ecl_posn.
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property
j2000_equ
¶ Position formatted as J2000 equatorial coordinates. Value is object of type astro.equ_posn.
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property
j2000_gal
¶ Position formatted as J2000 galactic coordinates. Value is object of type astro.gal_posn.
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class
lsl.transform.
PlanetaryPosition
(name)¶ Holds a solar, lunar, or planetary position value and can manipulate the value in various representations.
The instance methods apparent_equ() and apparent_ecl() may be used to get the apparent equatorial or ecliptic coordinates for a particular time.
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class
lsl.transform.
SkyPosition
¶ Base abstract class for representing positions on the sky.
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class
lsl.transform.
PointingDirection
(source, site)¶ Represent a target source object pointing direction for a particular ground site location.
Each PointingDirection instance pairs a celestial position with a ground observation site position. Each instance contains a ‘source’ member reference of type CelestialPosition or PlanetaryPosition and a ‘site’ member reference of type GeographicalPosition.
The instance methods hrz() and dir_cos() may be called to get the pointing direction as horizontal coordinates or direction cosine components for a particular time of interest. The rst() method may be called to get the rise, set, and transit ephemeris times.
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dir_cos
(time_)¶ Return the pointing direction as three direction cosine components. The ‘time’ parameter should be set to a Time instance providing the time of interest. Return value is a tuple (l, m, n) of direction cosine components.
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Geographic Positions¶
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class
lsl.transform.
GeographicalPosition
(value, format='GEO', name='')¶ Holds a geographical position valuee and can manipulate the value in various representations.
After creation, the celestial coordinates may be accessed in different formats and epoch by using the appropriate instance member. If marked with ‘(S)’, the Time value may also be updated by setting the member to a new value.
geo (S) - longitude and latitude degrees, elevation meters ecef (S) - Earth centered rectilinear coordinates
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property
ecef
¶ Position formatted as ECEF rectagular coordinates. Value is object of type astro.rect_posn.
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property
geo
¶ Position formatted as geodedic longitude, latitude, elevation. Value is object of type astro.geo_posn.
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property