Time¶
caldate_to_jd(year, month, day, hour=0, minute=0, second=0.0)
¶
Convert a calendar date to Julian Date.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
year
|
ArrayLike
|
Year of the calendar date. |
required |
month
|
ArrayLike
|
Month of the calendar date. |
required |
day
|
ArrayLike
|
Day of the calendar date. |
required |
hour
|
ArrayLike
|
Hour of the calendar date. Default: |
0
|
minute
|
ArrayLike
|
Minute of the calendar date. Default: |
0
|
second
|
ArrayLike
|
Second of the calendar date. Default: |
0.0
|
Returns:
| Type | Description |
|---|---|
Array
|
Julian Date. |
References:
1. Montenbruck, O., & Gill, E. (2012). *Satellite Orbits: Models, Methods and Applications*. Springer Science & Business Media.
caldate_to_mjd(year, month, day, hour=0, minute=0, second=0.0)
¶
Convert a calendar date to Modified Julian Date. Algorithm is only valid from year 1583 onward.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
year
|
ArrayLike
|
Year of the calendar date. |
required |
month
|
ArrayLike
|
Month of the calendar date. |
required |
day
|
ArrayLike
|
Day of the calendar date. |
required |
hour
|
ArrayLike
|
Hour of the calendar date. Default: |
0
|
minute
|
ArrayLike
|
Minute of the calendar date. Default: |
0
|
second
|
ArrayLike
|
Second of the calendar date. Default: |
0.0
|
Returns:
| Type | Description |
|---|---|
Array
|
Modified Julian Date. |
References:
1. Montenbruck, O., & Gill, E. (2012). *Satellite Orbits: Models, Methods and Applications*. Springer Science & Business Media.
jd_to_caldate(jd)
¶
Convert Julian Date to calendar date.
Uses the algorithm from Montenbruck & Gill for Gregorian calendar dates.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
jd
|
ArrayLike
|
Julian Date. |
required |
Returns:
| Type | Description |
|---|---|
tuple[Array, Array, Array, Array, Array, Array]
|
tuple[jax.Array, ...]: (year, month, day, hour, minute, second) where year/month/day/hour/minute are int32 and second is configurable float dtype. |
References:
1. O. Montenbruck, and E. Gill, *Satellite Orbits: Models, Methods and
Applications*, 2012, p. 322.
jd_to_mjd(jd)
¶
Convert Julian Date to Modified Julian Date.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
jd
|
ArrayLike
|
Julian Date. |
required |
Returns:
| Type | Description |
|---|---|
Array
|
Modified Julian Date. |
References:
1. Montenbruck, O., & Gill, E. (2012). *Satellite Orbits: Models, Methods and Applications*. Springer Science & Business Media.
leap_seconds_tai_utc(mjd)
¶
Return TAI-UTC (cumulative leap seconds) for a given MJD.
Uses a hardcoded step-function lookup table covering 1972-01-01 through 2017-01-01. For dates before 1972, returns 10.0; for dates after the last entry, returns the most recent value (37.0).
JIT-compatible: uses jnp.searchsorted for O(log n) lookup.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
mjd
|
ArrayLike
|
Modified Julian Date (UTC), scalar or array. |
required |
Returns:
| Type | Description |
|---|---|
Array
|
TAI-UTC in seconds. |
mjd_to_caldate(mjd)
¶
Convert Modified Julian Date to calendar date.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
mjd
|
ArrayLike
|
Modified Julian Date. |
required |
Returns:
| Type | Description |
|---|---|
tuple[Array, Array, Array, Array, Array, Array]
|
tuple[jax.Array, ...]: (year, month, day, hour, minute, second) where year/month/day/hour/minute are int32 and second is configurable float dtype. |
References:
1. O. Montenbruck, and E. Gill, *Satellite Orbits: Models, Methods and
Applications*, 2012.
mjd_to_jd(mjd)
¶
Convert Modified Julian Date to Julian Date.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
mjd
|
ArrayLike
|
Modified Julian Date. |
required |
Returns:
| Type | Description |
|---|---|
Array
|
Julian Date. |
References:
1. Montenbruck, O., & Gill, E. (2012). *Satellite Orbits: Models, Methods and Applications*. Springer Science & Business Media.