$LastChangedDate: 27-Juil-2011 $

# CL_gm_lat2locTime

Satellite's local time at given latitude

## Calling Sequence

       [loctime_asc,loctime_desc]=CL_gm_lat2locTime(lat,inc,loctime_asc_node)

## Description

- Computes the satellite's local time at a given latitude.

  The satellite local time is computed from the local time of the ascending node (loctime_asc_node), the orbit's inclination (inc) and the satellite's latitude (lat).

  Two solutions exist, that correspond to the satellite latitude increasing (loctime_asc) or decreasing (loctime_desc).

- Notes:

  - A spherical planet is assumed.

  - The model used is Keplerian and the Sun direction is constant relative to the orbit plane.

  - The latitude in absolute value must be less than max(inclination, %pi-inclination).

  - A satellite local time equal to 12h means than the satellite's right ascension is equal to the Sun's right ascension.

  - "Local time" here means "true local time".

## Parameters

lat:

  Satellite latitude [rad] (1xN)

inc:

  Inclination [rad] (1xN)

loctime_asc_node:

  Local time of ascending node [hours] (1xN)

loctime_asc:

  Satellite local time (ascending path) [hours] (1xN)

loctime_desc:

  Satellite local time (descending path) [hours] (1xN)

## Authors

- CNES - DCT/SB

## Bibliography

- 1) Satellites orbites et missions - Michel Capderou

## Examples

    inc = CL_deg2rad(98.6);
    lat = CL_deg2rad(-90+9:1:90-9);
    loctime_asc_node=22;
    [lt_asc,lt_desc]=CL_gm_lat2locTime(lat,inc,loctime_asc_node);
    scf();
    plot(lt_asc,lat*%CL_rad2deg,".r",lt_desc,lat*%CL_rad2deg,".b")