Support for the Orbit Visualisation Tool (OVT)
This web page gives access to updates of various data files needed by
the Orbit Visualisation Tool for Cluster,
which has been developed by the Swedish Institute for Space
Physics, Uppsala and ESA.
The OVT code (currently version 3.0)
and documentation are
available from the OVT web site.
OVT supports the tracing of magnetic field lines within the magnetosphere. This tracing is based on various external and internal magnetic field models
International Geomagnetic Reference Field (the current IGRF model is version 13). To update this field model in OVT:
Download the updated data file igrf.d
Go to the mdata directory within your OVT installation (e.g. on a typical Windows 10 installation this is C:\Users\XXX\.ovt\3.0\mdata),where XXX is your user name. See figure below.
Rename the existing igrf.d file, e.g. as igrf_old.d
Copy the new igrf.d into the mdata directory
Re-start OVT to use the new file
ESOC has now produced a set of Cluster LTOFs extending to nominal re-entry of each spacecraft (August 2024 for C2, November 2025 for C1, and April 2026 for C3 and C4). However, IGRF13 is formally defined only to end of 2024. To ensure that OVT works with these LTOFs, the igrf.d file has been extended by linear extrapolation to end of 2029 (the IGRF code works in 5-year blocks). This is just a mathematical extension and is not, in any way, a future representation of IGRF - but is sufficient to enable use of OVT with any current Cluster orbit files.
Cluster orbit data
OVT can read the
Cluster orbit files provided by ESA. These files are available
from a variety of sources with varying lengths of time coverage. For comprehensive
coverage of the mission it is recommended to use the
Super-LTOF files compiled by JSOC.
These cover the whole period from launch to the end of mission.
They are updated weekly as new reconstituted data for the past mission becomes available.
They are also updated with new predicted data as ESOC implement the detailed plans developed by
the Cluster Science Operations Working Group. See below for
advice on how to check the provenance of a Cluster orbit file.
The Super-LTOFs include the latest good long-term predictions from ESOC. These include accurate predictions of the spacecraft configuration up to autumn 2011 and the subsequent orbit evolution to January 2015. Further release information
is as follows:
- The version available from 20 March 2009 to 7 May 2009 contained inaccurate data for December 2009 to December 2012.
- The version available
from 7 May 2009 contains accurate data for the period through to December 2012.
- This was extended to January 2015 in the version released
on 22 December 2009.
- A new version released on 26 March 2010 updates the orbits from 13 July 2009 through to January 2015.
- A new version released on 3 March 2011 updates the orbits from 20 July 2010 through to January 2015.
- A new version released on 28 October 2011 adds reconstituted data to 26 October 2011
and updates the predicted data through to 1 February 2017.
- A new version released on 12 December 2011 includes manoeuvres for the guest investigator formations now planned for 2012 and early 2013
and other changes agreed at or following the Nov 2011 SOWG at ESTEC. Orbits are then projected forward through to 2 January 2017.
- A new version released on 11 September 2012 includes updates to manoeuvres for the Foullon and Pu guest investigator formations planned for
November 2012 and February 2013. Orbits are then projected forward through to 2 January 2017.
- A new version released on 20 March 2013 includes updates to manoeuvres to refine the close configuration of C1, C3 and C4 in the inner magnetosphere during August-September 2013 and a preliminary planning of the Pitout guest investigator formation in November/December 2013. Orbits are then projected forward through to 3 January 2017.
- A new version released on 21 June 2013 includes updates to manoeuvres to refine the Pitout guest investigator formation in November/December 2013, to set up the ring current formation in spring 2014, and a draft planning for the tail formation in Autumn 2014. Orbits are then projected forward through to 3 January 2019.
- A new version released on 16 April 2014 includes changes from mid October 2014: (a) manoeuvres to a repetition of the Pitout guest investigator formation in October/November 2014, and(b) manoeuvres to set up a bow shock 5km formation in January 2015 (lasting at least till mid February 2015). Orbits are then projected forward by free drift propagation till end of 2019. The bow shock 5km formation 2015 is final for C3/C4. It might be changed for either C1 or C2 by shifting one satellite backwards by up to 20 minutes (to be decided in September 2014 at the SWT in Rhodes).
- A new version released on 17 October 2014 includes changes decided at the September 2014 SWT in Rhodes.
- A new version released on 06 March 2016 includes changes implemented by ESOC in August 2015 and February 2016. It now includes orbit data to January 2022.
- A new version released on 24 March 2017 includes changes implemented by ESOC in 04 January 2017. It now includes orbit data to January 2022.
- A new version released on 4 April 2018 includes orbit data now going up to Aug 2024 for C2 and end 2025 for C1, C3 and C4.
- A new version released on 7 August 2018 includes orbit data now going up to start of 2024. They cover the solar wind monitor formation in Spring 2019 and the tail formation in Autumn 2019. They include the manoeuvres planned for the associated formation changes between November 2018 and August 2019.
- A new version released on 19th February 2019 includes the LTOF files received from ESOC on 8th February. In these ESOC FD has implemented the proposed shifts of 4h by C1 and 1h by C3. The drift is started on 15th September 2019 and stopped on 10th December followed by a trim manoeuvre on 19th December 2019.
- A new version released on 1st August 2019 is unchanged up to 1st January 2024, but includes orbit data now going up to 31st Aug 2024 for C2, 6th November 2025 for C1 and up to 30th April 2026 for C3 and C4.
- A new version released on 15th August 2019 includes formations for the north hemisphere cusp crossing in Jan 2020, south hemisphere cusp in May 2020, looking at the sub-ion magnetic holes in the dipolarized plasma sheet Aug/Sep 2020, and a study of the magnetic reconnection at the Earth's magnetopause from end Nov 2020 onwards. Please note that the Aug/Sep 2020 formation implementation is still to be confirmed.
- A new version released on 15th October 2019 for Spacecraft 2 alone includes an update for manoeuvre optimisation and orbit prediction for the C2 manoeuvres on 22nd September and 13th November 2020. The new C2 LTEF/LTOF are practically identical to the previous ones except during 22nd September - 22nd November 2020 where the formation change manoeuvres take place. The maximum time difference is between four and five minutes along track.
- A new version released on 17th August 2020 for all spacecraft contains the 2021 manoeuvres for the hiss formation starting in June 2021. This update was contained in the LTEF and LTOF files received from ESOC on 7th August 2020. Manoeuvres to reach the formation will be performed between 29th March 2021 and 11th June 2021.
- A new version released on 4th August 2021 for spacecraft 3 implements the formation in April 2022, after the end of the short eclipse season, to measure the extent of high speed plasma jets in the magnetosheath. As only the SC.3 position changes along track, last years’ orbits of the other satellites remain valid and no new long-term orbit files are needed for the other spacecraft.
To update the Cluster orbit data in OVT, first download the updated orbit (SuperLTOF) files:
Then go to the odata directory within your OVT installation (e.g. on a typical Windows installation this is C:\Users\XXX\.ovt\3.0\odata),where XXX is your user name. See figure below.
Rename the existing orbit files, e.g. as Old_cluster1.ltof
Copy the new orbit files into the odata directory
Re-start OVT to use the new file
Double Star orbit data
Double Star orbit are also available as Super-LTOF files. To update these orbit data in OVT, first download the updated orbit files:
Double_Star_1.ltof (26 Mbytes)
Double_Star_2.ltof (32 Mbytes)
Then proceed as for Cluster orbit files
Checking the provenance of Cluster & Double Star orbit files
The Cluster & Double Star orbit files are divided into blocks where each block
specifies the spacecraft orbit for a particular period. Thus each orbit file is built
up of contiguous blocks in order to cover an extended period.
Each block is labelled with a data type (R for reconstituted and P for predicted) and
a generation time; these can be used as an indication of the provenance of
the orbit data.
To generate a list of orbit block provenance records, you may use the Unix script
orbit_block_list. This takes the orbit file name
as its only argument and lists records to standard output. Each record gives a data type,
generation time and the range of times covered by blocks with that provenance; this range will generally be more than one block.
This script runs under Solaris so you may need to adapt for other systems.
Swarm orbit data
Swarm orbit are available as both Super-LTOF files and as TLE-format files (see below). More details on the JSOC support page for
Other mission orbit data
OVT can also read orbit data in the
NORAD Two-Line Element (TLE) format. This is the recommended method by which OVT can
ingest and display orbit data for other magnetospheric missions, e.g. Polar, THEMIS. A number
of historical TLE datasets are available as part of the OVT installation kit. Additional
TLE data are available from a number of sources:
The official source of Two-Line Elements is the
Space Track web site run by the US Air Force. This requires a username/password for login and
the downloaded data are provided for your personal use only. Thus you are recommended to
apply for a personal account via the Space Track web site above.
Historical (1957-2004) elements are freely available via the
Celestrak web site together with a small amount of
more recent data. This web site also provides extensive information on the history and use of
To update other orbit data in OVT:
Obtain the Two-Line Elements as described above.
Go to the odata directory within your OVT installation (e.g. on a typical Windows installation this is C:\Users\XXX\.ovt\3.0\mdata),where XXX is your user name. See figure below.
Place the new TLE file in the odata directory with name xxxx.tle, where xxxx is a suitable description (no blanks)
Re-start OVT to use the new file
Caveat: Experience shows that OVT has problems in using some TLE datasets. These are being
investigated. Possible sources of problems are:
Missing checksums in TLE records - causes a read error in OVT
Large time gaps between TLE records
OVT directory structure and file installation
The figure below shows the standard OVT directory structure and
the location of the odata and mdata directories in which the files
above should be installed.
Important note: If you cannot save files directly from the web page to the relevant directory, it may be that you need to administrator privilege to load
files into these directories. If so it is recommended to save the files to an intermediate directory, then copy from there to the directories shown below,
confirming/supplying administrator privilege when prompted.
Last updated by Anne
Chadwick ( firstname.lastname@example.org), Yulia
Bogdanova ( email@example.com) and Mike
Hapgood ( firstname.lastname@example.org)
4th August 2021.