Annual Report of the FGM Experiment for the 8th Operations Review of the Cluster Active Archive (CAA) Chris Carr, Leah-Nani Alconcel, Patrick Brown, Tim Oddy, Peter Fox, Barry Whiteside Imperial College London June 2013

Introduction In the last year: Data delivery rate has increased - May 2011–April 2012 and June, July 2012 delivered - Additional files delivered to fill-in gaps on CAA New software developed last year now in routine use - provide checking of spin-axis offset spread in solar wind - improve speed of range jump correction step Long term trends in calibration parameters have been investigated further, with the results to be provided in a paper for CAA special issue New server hardware has been installed to improve reliability and provide redundancy of data-storage September and October 2012 also now delivered

Management (status and changes) Funding support from STFC finished at the end of December 2010. ESA funds (routed via UKSA and STFC) are now in place until end of December 2013. -1.5 FTE (Full-Time Equivalent) of staff effort plus some travel and equipment/consumables. Technical Assistance contract directly from ESA (in place until end of November 2013) -0.5 FTE The team is configured as follows: Chris Carr (PI following Elizabeth Lucek) Leah-Nani Alconcel is Archive Engineer (50%) Patrick Brown is Operations and Data-Processing Manager (25%) Tim Oddy is software, calibration and instrument analyst (50%) Peter Fox calibration (50%) Barry Whiteside helps out with calibration since September 2012 (25%)

(activities since June 2012) Software development (activities since June 2012) A program has been developed to check the evolution in spread of the spin-axis offsets over a month immediately after the solar wind calibration step. This check reduces the possibility of having to repeat the calibration process due to offset errors found at the validation stage The range jump correction software has been thoroughly overhauled, and the range jump step is much faster as a consequence New server hardware has been installed. Data processing is now carried out on a pair of redundant servers, reducing the likelihood of disruption to the calibration schedule because of hardware failure

Calibration/cross-calibration (status and activities since June 2012) The FGM calibration procedure is described in the FGM Calibration Report Issue 5 and in Gloag et al, 2008. The main procedure has not changed in the last year however smaller changes have been incorporated: Checking of spin-axis offset spread over the entire month is now performed immediately after the solar wind calibration step. The range jump correction step is now much faster No new work on cross-calibration of FGM with EDI, WHISPER or STAFF has been led by FGM in the past year. Over the summer, we plan to revisit the FGM/EDI comparison as part of an investigation into range jump corrections.

Range Jumps Currently, spin plane range jumps are corrected by making an Offset correction to the upper range Gain correction to the lower range If gain correction for higher-range changes is large, it can result in a jump at lower range changes This is undesirable!

Range Jumps (Example) R23 jump before R23 range jump correction is applied. Same jump after R23 range jump correction is applied. Same jump after R34 range jump correction is applied.

Range Jumps Other corrections are possible e.g. making offset and gain correction to the upper range only This would prevent higher range changes from influencing lower range changes However, this would lead to larger corrections in high range data We plan to investigate different options over the summer, using B-field magnitude from EDI for comparison

Status of dataset delivery Datasets Delivered interval Comments FGM magnetic field data: FULL, 5VPS, SPIN – V01 Jan 2001–April 2012 and June, July 2012. Preparation of these core datasets was our highest priority. FGM supporting data: GAPF and VALF files These files are prepared routinely along with the core data sets. FGM calibration files: CALF Detached headers (required in order for these non-CEF data files to be ingested) have been submitted to the CAA. FGM caveat files: CAVF Files are prepared to highlight periods where problems with data occur that cannot be calibrated out. FGM calibration accuracy files: CALA Feb 2001 – Dec 2006, files prepared for all orbits CALA files have been superseded by CAVF files.

Guest Investigator Data In addition to regular calibration for the CAA, data for November 2012, January and February 2013 have been calibrated ‘out of sequence’ for two GI campaigns. These data will be supplied the CAA after the GI embargo period of 1 year.

Dataset delivery plan The long term plan is to deliver: all 2012 data by the middle of Summer 2013 (excluding GI data) all 2013 data by the 8th Operations Review (June 2014).

Documentation (Summary since June 2012) FGM ICD Version 5 of the FGM ICD was submitted to the CAA in May 2013. minor changes to update contact details FGM User Guide Issue 5 of the FGM User Guide was submitted to the CAA in May 2013. Updated relative accuracy estimate (between spacecraft) Table of contents is now hyper-linked to the sections of the document FGM Calibration Report Issue 5 of the FGM Calibration Report was submitted to the CAA in May 2013. The long term offset trend plots have been updated Estimated phase difference between STAFF and FGM included

Replies to the 7th Operations Review OR7-R1: The board notes that the delivery schedule requires that all teams should have provided data up to and including December 2011 by the time of the review. We commend those teams that are up-to-date in their delivery. We require that all other teams speed up their delivery to be compliant with the current and future delivery schedule. Data delivery is continuing at a steady rate with calibration also being done for guest investigators. We have made excellent progress into the routine calibration activities, the team is now fully-staffed and we do not anticipate any schedule problems. OR7-R2: The board recommends that all teams ensure that they have provided detailed information to the CAA regarding the pointing of instrument sensors relative to the spacecraft reference frame (e.g. sun-sensor or spacecraft Y-axis). Relevant FGM instrument information, e.g. physical information, coordinates etc. is given in the FGM data processing handbook, which will be archived on the CAA/CFA in due course. This handbook is maintained by TU Braunschweig.

Replies to the 7th Operations Review OR7-R3: The board recommends that instrument teams provide information regarding “special operations”, e.g. special modes, solar wind operations, guest investigator campaigns, etc., including their description and time of operation. The CAA is to coordinate this activity and to make the information available through their web-pages. FGM will be happy to assist in efforts by the CAA in this regard.

Replies to the 6th Operations Review OR6-R2: We note that the cross-calibration exercises between many of the instruments have been very successful in ensuring high quality data products. We encourage the CAA and instrument teams to identify those cross-calibration efforts which have been most useful and to disseminate them to the community, preferably in the peer-reviewed literature. CAA-OR6-R6: FGM data are a key data-set for the mission and for the processing of data from other instruments. The board notes that delivery of FGM products has caught up significantly, but encourages the team to accelerate delivery as it is essential for the delivery of other instrument data sets. The board also notes that some sub-nT calibration problems have been identified in magnetotail measurements and the board encourages FGM to work with EDI to resolve this issue if possible. Further work on the FGM/EDI comparison is scheduled for this summer.

Replies to the 5th Operations Review OR5-R16: The board notes that the CAA lacks observations from the commissioning phase and recommends delivery of observations particularly from January 2001 (which have already been used for many publications) and December 2000 (when there are interesting interference campaigns). Data from January 2001 have been supplied to the CAA. See also action items CC8-AI-13 and FGM09-AI-5 below.

Status of Action Items Open actions from the 17th Cross-Calibration meeting CC17-AI-1: Use a new monthly reports template (see CrossCal17-Annex03.doc) OPEN: Completed FGM has been using the new monthly reports template from March 2013. CC17-AI-2: to investigate how to implement the time glitch information described in ESOC anomaly report (CLU AR-214, see CrossCal17-Annex05.pdf) in the instrument processing software OPEN We are investigating the frequency at which this glitch has occurred, to establish whether it has any significance for FGM.

Status of Action Items Open actions from the 2012 FGM Progress Meeting FGM12-AI-01: To investigate why the content of the three science datasets were not identical, i.e., one or more had data why the others did not (see e.g., C1: Nov’01, Sep’06, Dec’06, Nov’07; C2: Nov’02, Jun’07, Apr’08, May’08, Dec’08, Jun’10; C3: May’08, Oct’10; C4: Sep’02, Oct’02, Apr’04, Jun’10) OPEN: Completed All data gaps have been identified and have been filled in with new data files supplied to the CAA. FGM12-AI-08: To update the UG, CR, and ICD according to the suggestions given during the PM The documents have been updated in line with the suggestions and supplied to the CAA.

Status of Action Items Open actions from the 8th Cross-Calibration meeting CC8-AI-13: Teams to investigate whether it is feasible to produce data for the commissioning phase. OPEN Data have been produced for January 2001 using the full calibration pipeline (see FGM09-AI-5 below). It is feasible in principle to prepare data from the remainder of the commissioning phase, but it is not straightforward. If these data are prepared, then it is likely that they would be calibrated using a cut-down calibration pipeline. We have listed this previously as a low to medium priority task and will be done if resources allow.   FGM09-AI-5: to consider producing the FGM files for January 2001 using the calibration files of Feb 2001: OPEN: Completed Data for January 7th-30th 2001 have been calibrated using the full FGM calibration pipeline, and the data have been uploaded to the CAA. Data for January 1st-6th were not calibrated as during this period Cluster 4 was operating the inboard FGM sensor, for which no in-flight calibration currently exists.

Problems and Open Issues Bursty Spin Noise on Spacecraft 4 Seen since September 2010 (possibly earlier) and has continued No progress has been made in finding the source of the problem There appears to be no correlation with FGM commanding or platform commanding. We are continuing to caveat the Cluster 4 range 2 and 3 data.