Index of /hsa/legacy/operations/moc/oem

	Name	Last modified	Size	Description
	Parent Directory		-
	archive/	2014-01-20 15:53	-
	data/	2016-11-10 09:05	-

Orbit (OEM) Files

This directory contains Herschel orbit files in CCSDS Orbit Ephemeris Message (OEM) format.

The OEM files were delivered by ESOC Flight Dynamics each week throughout the mission. Each delivery covered the whole duration of the mission, with a posteriori reconstructed ephemerides for the past and predicted value for the future. Consequently, the transition from reconstructed to predicted ephemerides advanced by a week with each delivery.

Mission planning worked with predicted values because it scheduled future observations. The daily processing of the data also used the predicted orbit because the reconstructed orbit was not yet available. However, the reconstructed orbit was available for later bulk reprocessing of the data.

The recommended file to use for data processing is H20130625_0002.LOE. This was the final end-of-mission orbit file containing the best a-posteriori knowledge of the orbit for the whole mission up to spacecraft switch-off on 2013-06-17.

At the end of operations, the spacecraft was placed in a Heliocentric orbit. The file H20140117_0002.LOE is a special orbit file containing a prediction up to the year 2050. This is included for interest but is not needed for data processing. It is identical to H20130625_0002.LOE up to spacecraft switch-off.

For completeness, the complete set of OEM file deliveries is included in directory "archive", starting with the pre-launch prediction H20090430_0001.LOE. These files may be of interest for comparing the orbit reconstruction with the predictions.

Contents

• data/H20130625_0002.LOE A posteriori orbit reconstruction up to 2013-06-17
• data/H20140117_0002.LOE Includes long-term prediction to the year 2050
• archive/*.LOE Archive of all OEM file deliveries

Format/ICD

• CCSDS OEM version 1.0
• Orbit Data Messages, CCSDS Blue Book CCSDS 502.0-B-1, Consultative Committee for Space Data Systems, September 2004.

Derived Products

• OrbitEphemeris product

Known Issues

• Version 0002 files are modified copies to move a comment line in the header. This was to work-around an issue that some of the delivered (version 0001) files had a comment line in the header in a different position. Although this was compliant with the CCSDS standard, it was rejected by the aux processor. The uplink software is able to use either version.