Cumulative Release Notes for LET Level 1 data - Public data set. See http://www.srl.caltech.edu/STEREO/docs/LET_Level1.html for more LET Level 1 data documentation. October 6, 2022: There is a data gap from 2022-08-31T13:48 through 2022-09-02T14:32. The LET-ahead instrument was operational but not in science mode during this period. April 3, 2013: Important Update: Due to incorrect calculation of instrument livetimes in ground data processing, LET intensities at the peak of the July 23 2012 event were inaccurate. LET intensities during other periods of high peritcle intensities were also inaccurate to a lesser extent. We have corrected the livetime calculation, and a new version of the data has been released - Version 11. Dec 3, 2012: Important Update: Due to incorrect calculation of instrument livetimes in ground data processing, LET intensities at the peak of the July 23 2012 event are inaccurate. We are working on a correction to the livetime calculation, and expect to reprocess these data soon. April 16, 2012 The 15-21 MeV/nuc Carbon bin is not valid during high-rate periods (periods when the LET dynamic-threshold stats is >0). It is therefore set to "Fill data" for these periods. The instrument thresholds are higher during these periods, and particles in this species-energy bin fall below the raised thresholds in some cases. April 16, 2012 The total-energy calculation for particles that penetrate the instrument to Range 4 was found to be implemented incorrectly. The LET instruments on Ahead and Behind have been patched to correct the error. LET Ahead was patched on April 16, 2012. LET Behind was patched on April 18, 2012. Prior to these dates, the following species-energy bands are invalid. The LET data prior to the above patch dates are now reprocessed to replace the data in these bins with "FILL data". H: 12 - 15 * 4He: 12 - 15 C: 21 - 27 * C: 27 - 33 * N: 21 - 27 N: 27 - 33 * O: 27 - 33 * Ne: 27 - 33 * Ne: 33 - 40 * Mg: 33 - 40 * Mg: 40 - 52 * Si: 33 - 40 Si: 40 - 52 * Fe: 40 - 52 Fe: 52 - 70 * Note: the species-energy bands marked with "*" above were already suppressed in the Public data, for other reasons. So, this issue actually affects only 4 bands. October 14, 2011 The LET instruments on Ahead and Behind have been patched to correct the instrument response when the instrument is in its "dynamic thresholds" mode during high rate periods. LET Behind was patched on October 11, 2011 LET Ahead was patched on October 14, 2011. After these dates, the energy-bands for "heavies" that were invalid during high-rate periods are now usable and are no longer being excluded from public release. September 8, 2011 Due to unexpected changes in the LET instrument response when the instrument is in its "dynamic thresholds" mode during high rate periods, we have replaced with "FILL data" the data a subset of the energy-bands for for C, N, O, Ne, Na, Mg, AL, and Si, during high-rate periods (approximately when 1.8-3.6 MeV proton intensities exceeed ~150 counts/(cm^2 sr s MeV)). We expect to upload a flight-software fix for this issue soon. See Nov 11, 2010 note for more details of the issue. November 22, 2010 We made some changes to the species represented in the LET sectored rates. After Nov 22, 2010, the sectored rates are assigned as follows: 0 - 15: H 4-6 MeV/nuc 15 - 31: H 1.8-3.6 32 - 47: 4He 4-6 48 - 63: 4He 6-12 64 - 79: CNO 4-6 80 - 95: CNO 6-12 96 - 111: NeMgSi 4-6 112 - 127: NeMgSi 6-12 128 - 143: Fe 4-12 144 - 159: H 6-10 Prior to Nov 22, the rates were: 0 - 15: H 4-6 MeV/nuc 15 - 31: 3He 4-6 32 - 47: 4He 4-6 48 - 63: 4He 6-12 64 - 79: CNO 4-6 80 - 95: CNO 6-12 96 - 111: NeMgSi 4-6 112 - 127: NeMgSi 6-12 128 - 143: Fe 4-6 144 - 159: Fe 6-12 November 11, 2010 Recently we have discovered some unexpected changes in the LET instrument response when the instrument is in its "dynamic thresholds" mode during high rate periods. During such periods, calibration shifts have been found that cause some counts for some elements to be mislabeled as the neighboring elements. At present, only ~4-10 MeV/nuc C, N, O, and Ne on the Behind spacecraft have been affected, and only during two time intervals during the SEP events of 2-3 August 2010 (day of year 214 and 215). Rates for these elements are inaccurate by perhaps as much as a factor of ~2 from approximately 6:41 through 14:44 on day 214 and again from 4:29 through 9:07 on day 215 of 2010. Until we can develop and implement commands to fix the problem (which we are working on), these errors will also recur during any similar high rate periods (approximately when 1.8-3.6 MeV proton intensities exceed ~150 counts/(cm^2 sr s MeV)) on both spacecraft in the future. Note that this problem does NOT affect the data during the large SEP events of December 2006 since the instruments were in a different mode at that time. March 20, 2008 The geometry factors used to calculate intensities are under review. A new version of the LET Level 1 data will be released at some point in the future, using new geometry factors. The resulting changes from the current version will be on the order of 5%, or less. Sept 4 2007 LET Level 1 software version 09. Updated sectored geometry factors. July 31, 2007 LET Level 1 software version 08. First public data release. See http://www.srl.caltech.edu/STEREO/docs/LET_Level1.html for more LET Level 1 documentation. For the Public data set, we are currently flagging as bad the He data prior to March 29 2007, and the 3He data after March 29 2007. In addition, the following species/energy-bin channels are also flagged as bad in Public data set: All Protons prior to the March 29 software uploads. Protons below 4 MeV after the March 29 software uploads. All 3He, for all time periods. All 4He prior to the March 29 software uploads. Fe below 5 MeV prior to the March 29 software uploads. Fe below 4 MeV after the March 29 software uploads. One or two energy-bins at the low and/or high ends for many species. June 21 2007 LET Level 1 software version 08. Added sectored data files. June 14 2007 LET Level 1 software version 08. This version includes the following changes from the previous version: Added, Na, Al, S, Ar, Ca, Ni to output data files. Added elemental helium. After March 29, 2007, (at slightly different times on each spececraft) events identified as 3He onboard are treated like 4He for energy-binning (a mass-number equal to 4 is used). This allows the 3He and 4He boxes to be combined on the ground to obtain elemental helium (He) intensities. For data prior to the March 29 software uploads, the He data are FILL (-9999.9). For data after the March 29 software uploads, the 3He data are FILL. Improved software for reading in time-dependent factors files, and created new factors files for some time periods in Nov and Dec 2006 when the instruments were in funny states. Added capability to flag each species/energy-bin channel as either "good" or "bad" for any time period. Bad channels are set to FILL. The flags for different time periods are stored as external tables, and the tables are read as needed depending on the time-stamp of the data being processed. /home/stereo/LETL1Data/SRLonly/ Factors_files/ ReleaseNotes.txt ahead/ 2006/ 1Minute/ Sectored/ (contains 1Minute-averaged ahead sectored daily files for 2006) Standard/ (contains 1Minute ahead unsectored daily files for 2006) Summed/ (contains 1Minute ahead summed energy-bin daily files for 2006) 10Minute/ Sectored/ (contains 10Minute-averaged ahead sectored files for 2006, with a month of data in each file) Standard/ (contains 10Minute-averaged ahead unsectored files for 2006, with a month of data in each file) Summed/ (contains 10Minute-averaged ahead summed files for 2006, with a year of month in each file) Hourly/ Sectored/ (contains Hourly-averaged ahead sectored files for 2006, with a year of data in each file) Standard/ (contains Hourly-averaged ahead unsectored files for 2006, with a year of data in each file) Summed/ (contains Hourly-averaged ahead summed files for 2006, with a year of data in each file) Daily/ Sectored/ (contains Daily-averaged ahead sectored files for 2006, with a year of data in each file) Standard/ (contains Daily-averaged ahead unsectored files for 2006, with a year of data in each file) Summed/ (contains Daily-averaged ahead summed files for 2006, with a year of data in each file) 2007/ and so on... behind/ Same organization as for ahead