Cluster orbit and event files
The Cluster Flight Dynamics team at ESOC produces a number of
files that contain information on the orbits of the four Cluster spacecraft
and the predicted times of various events for these spacecraft.
These files are copied to JSOC for use in Cluster science planning - and
are used by JSOC to generate data on the predicted
geometric and scientific positions of the four spacecraft and
to predict the occurence of scientific events (e.g. plasma boundary crossings
such the magnetopause, bow shock and tail neutral sheet).
JSOC also makes these files available to the broader scientific
community that is interested in the Cluster mission. Click on the links
below to see a directory listing of the available files for each of
the four types of orbit and event files:
Long Term Orbit Files (LTOF) - these contain
orbit data for a period of a year or more in advance. There is a separate
LTOF for each spacecraft.
Long Term Event Files (LTEF) - these contain
event data for a period of a year or more in advance. There is a separate
LTEF for each spacecraft.
Short Term Orbit Files (STOF) - these contain
orbit data for a period up to 3.5 months ahead. There is a separate
STOF for each spacecraft.
Short Term Event Files (STEF) - these contain
event data for a period up to 3.5 months ahead. There is a separate
STEF for each spacecraft.
The LTOF and LTEF are used by JSOC as the basis for long-term planning of
science operations (see Master Science Plan);
whereas the STOF and STEF are used by JSOC for detailed scheduling of the
PI commands to be sent to the instruments.
The file names in these directories take the form:
TTTT = file type (LTOF, LTEF, STOF or STEF)
yymmdd = date of generation as two-digit year, month and day
ss = spacecraft id (S1, S2, S3 and S4)
aaaa = first orbit number covered by the file
bbbb = last orbit number covered by the file
zzzz = file version number. There is a separate series of versions
for each file type and spacecraft id. This is useful is multiple files
are issued on one day.
The format and content of these four file types is defined in the
Cluster Data Delivery Interface Document (known as the "DDID"), which can
downloaded as a PDF file.
However, note that the files available from JSOC are plain ASCII files
conforming to the format given in Appendix F of the DDID.
Other Cluster systems may use a slightly different format, in which
each record of the orbit and event files is prefixed by a 14-byte
binary-format telemetry packet header as discussed in section 5 of the
Merged LTOF files
JSOC also maintains a set of
merged LTOF files (also known "Super-LTOF files")
which are derived by merging data from LTOF and STOF files in order:
to produce a continuous series of orbit data from launch
to include all available reconstituted orbit data
These files are produced using the merge_ltof software developed by Pat Daly, PI of the
This is run automatically when new STOF files arrive at JSOC.
Last updated by Mike
Hapgood ( email@example.com),
02 March 2022