STEREO SEP Suite Telemetry Data

These directories contain Level 0 telemetry data from the
two STEREO spacecraft ("ahead" and "behind").

Data files are binary files containing raw telemetry packets in Payload
Telemetry Packet (PTP) format. There are separate files for each day.

Data files will remain available on the ftp site for 60 days.

For each day:
   Packets are extracted from IMPACT Level 0 data files and sorted into
   smaller files for each SEP instrument.
   In addition, the following packets are included in all files:
	SEP Housekeeping packet (apid 0x241)
	SEP Command Response packet (apid 0x240)
	IMPACT Beacon packet (apid 0x270)
   The above three packet-types are also available on their own,
   in a separate (MISC) file.
   In addition, a single file is provided containing all the SEP science,
   Housekeeping, CmdResponse and Beacon packets.

******** See below for file version and filename extension information ********

The directory structure is laid out as follows:

Level0
   |
   ---ahead: data from the Ahead spacecraft
   |    |
   |	---SEP: files containing all the SEP-suite science packets,
   |    |       plus Housekeeping, CmdResponse and Beacon packets
   |	|
   |	---HET: files containing all the HET science packets,
   |    |       plus Housekeeping, CmdResponse and Beacon packets
   |	|
   |	---LET: files containing all the LET science packets,
   |    |       plus Housekeeping, CmdResponse and Beacon packets
   |	|
   |	---SEPT: files containing all the SEPT science packets,
   |    |        plus Housekeeping, CmdResponse and Beacon packets
   |	|
   |    ---SIT: files containing all the SIT science packets,
   |    |       plus Housekeeping, CmdResponse and Beacon packets,
   |    |       plus files containing hex dumps of same
   |    |
   |	---MISC: files containing just the Housekeeping, CmdResponse
   |            and Beacon packets
   |
   ---behind: data from the Behind spacecraft
   |    |
   |	---SEP: as above
   |	|
   |	---HET: as above
   |	|
   |	---LET: as above
   |	|
   |	---SEPT: as above
   |	|
   |    ---SIT: as above
   |    |
   |	---MISC: as above
   |
Ancillary: attitude/orbit data, to be described later
   |
Quicklook: Beacon data in PTP format, received in near-real-time from NOAA
           tracking stations, via the SSC


File Versioning and Filename Extension Information
--------------------------------------------------
During normal operations after launch, the MOC will release several versions
of the Level 0 data for each day, all in the same Payload Telemetry Packet
(PTP) format.

All file versions except the final version will have the .ptp extension.  The
final/definitive Level 0 data file (which will be released at least several
days later) for each day will have the .fin extension. But otherwise this file
is in exactly the same format as the earlier files.

The names of the instrument-specific Level 0 files that are provided on the
website preserve the version number and filename extension of the original
IMPACT Level 0 file from which they were generated. This applies also to the
IDL-structured files are provided locally for LET.

Filenames are constructed as follows:

III_SSSSS_YYYY_DDD_V_VV.XXX

	III	3- or 4-character Identifier (HET, LET, SEPT, SIT, SEP, or MISC) 
	SSSSS	5- or 6-character spacecraft identifier (ahead or behind)
	YYYY	4-digit year
	DDD	3-digit day-of-year
	V_VV	Version (from original IMPACT Level 0 data file)
	.XXX	Filename extension (.xxx or .fin)

Note that even if an instrument HET (for example) is off for a given day, a
HET level 0 file is still generated for that day. However, the file will only
contain HK, CMdResponse, and Beacon packets.

The processing scripts currently do not remove the old versions from the site
when new versions become available. Thus, several versions may be present for
the same day.  We intend to implement a "Cleanup" script that periodically
purges the old versions from the website, perhaps once per week...

It is up to each instrument team to figure out how to handle the
processing/archiving of these multiple versions of the Level 0 data at their
end.