Readme file for STEREO/IMPACT/SEPT level 2 ASCII data
IEAP, University of Kiel, Germany

Modified: August 10, 2011

Nominal data coverage starts January 17, 2007. Previous data should not be used for scientific analysis.
Before using the data, check the level1 data caveat: http://stereo.ssl.berkeley.edu/SEPT_Caveat.pdf. This document contains additional information about instrument status changes and data issues. 

Folder hierarchy:

level2
 |-spacecraft (ahead | behind)
 | |-time resolution (1min | 10min | 1h | 1d)
 |  |-year(YYYY)
 |   |-data files
 |-cat (concatenated files, without text header)
  
Filename format:

sept_s/c_particle_sensor_YYYY_DOY_resol_l2_v02.dat

where:
	s/c = ahead, behind (for STEREO A and STEREO B respectively)
	particle = ele, ion (for electrons and ions respectively)
	sensor = sun, asun, north, south, omni describes the pointing of the telescope: 
			sunward (along the nominal Parker spiral), 
			anti-sunward (along the nominal Parker spiral), 
			northward (perpendicular to the ecliptic), 
			southward (perpendicular to the ecliptic), 
			omnidirectional (mean of sun,asun,north,south)
	YYYY = four digits year 
	DOY = three digits day of year
	resol = 1min, 10min, 1h 1d (for 1 minute, 10 minute, 1 hour, 1 day)
		 "1 minute" corresponds to 59.954 seconds accumulation time and is the maximum time resolution available.
	vxx = version (currently v03)

The subdirectory "cat" contains concatenated yearly files with 10 minute, 1 hour and 1 day temporal resolutions (headers are removed). There are also some files with the full mission data (currently only 1 hour and 1 day resolution, filenames contain the string "alltime" instead of the year).

Text headers at the beginning of the ASCII datafiles provide a full description of the file format and additional information. Please note that the statistical errors for intensity equal zero are set to zero.

--
Version history

v01 (August 2009)
 First (preliminary) online version of level 2 ASCII files
 Uses constant geometric factors for electrons and protons: 0.13 and 0.17 cm^2 sr
 Efficiencies assumed equal 1 for all the energy bins
 Uses Differential non-linearity (DNL) correction

v02 (October 2010)
 File format changed for both, ions and electrons
 Uses energy-dependent electron geometric factors
 Bins 0,1 excluded. Bins 2,3 include efficiency correction
 Additional efficiency correction for STA sunward-looking electron telescope
 Uses Differential non-linearity (DNL) correction
 Ion energy windows improved (one significant digit added to the previous version)

v03 (February 2011)
 Efficiency values updated for STA south electron telescope (improved values using data from 2010 SEP events)
 The rest remains unchanged with respect to v02