# ERS-1 Mission Phase G

## Phase G parameters

*Phase G parameters*
- 35 day repeat cycle
- 501 orbits in one cycle
- 1784 orbits in phase

*Orbit number characteristics*

- First absolute orbit number is: 19248 on 21-mar-95 09:01:49.350 UTC

- First internal track: 222

- Last orbit number is:?????, 3-jun-96

*Orbit parameters*

- orbit eccentricity: 0.001165
- orbit inclination: 98.5421 deg
- asc. node Long.: 202.0497 deg
- semi-major axis: 7159495.96 m
- mean nodal period: 6035.928144 s
- mean anomaly: 270.1334 deg
- argument of perigee: 90 deg

## Formulas from Relative (track) to Absolute Orbit Numbers

ABS_ORB_NUM = REL_ORB_NUM + (CYCLE_NUM-144)*501 + 19026

CYCLE_NUM = INT[( ABS_ORB_NUM - 19027)/501] + 144

REL_ORB_NUM= ABS_ORB_NUM - 19026 - (CYCLE_NUM-144)*501

*Where:*

- the "Absolute Orbit Number" is counted from the beginning of the mission;
- the "Relative Orbit Number" (track), in a given cycle, is counted starting from the first orbit East of Greenwich;
- the "Cycle Number" is increased whenever the track 1 is rivisited (note that cycles can be uncomplete).

**This information was retrieved from ESA/ESRIN**