November 4, 2021

e-POP Data Change Log


e-POP Data Change Log

This table details a summary of the latest changes made to e-POP data files.

SpacecraftCAS Ephemeris txt1.22022-06-10Minor bug fix in calculation of geodetic latitude and altitude. Fixes errors on the order of 0.001 degrees latitude and 0.01 km altitude.
SpacecraftAttitude Quaternions2.02024-01-24– Introduced the ‘Sun Vector Spin’ (SVS) frame to smooth out attitude interpolation for times when the spacecraft is spin stabilized (after December 2021)
– Updated the star sensor camera mounting quaternion information for improved attitude accuracy. The two camera sensors now agree to within 0.0281 degrees.
– Attitudes are now discarded if there are no data points within 3 minutes (down from 10 minutes), fixing issues with bad interpolation during spin stabilized attitudes
– Minor adjustments to discard less raw attitude data during processing
CERTEC zipn/a2013-09-13Initial version
FAIlv1 h5v5.02021-10-08– New format (hdf5)
– Image data is now in units of Rayleighs
– Files now include latitude and longitude of
projection of image onto the Earth at 110 km
(NIR) or 220 km (VIS) altitude
– Updated ephemeris and attitude data
– Now one file per pass rather than one file per
FAIlv1 h5v6.02023-03-08– Change camera source message in attributes from ‘Visible(630 nm)’ to ‘Visible (630 nm)’
– Fixed bug that allowed the projection of FAI image to clip through the earth
– Fixed bug that caused double ‘.preliminary’ file names
– Updated ephemeris library use to v1.2
– .png files now stored in an unzipped folder
GAPlv1 binaryv2.02018-06-22– Filenames now have a major and minor
version number
– Data files are now split after two minutes
of break rather than twenty
– Fixed bug that caused minor loss of data
at the end of some files
GAPlv1 binaryv3.12020-08-25Filename now supports the
major.minor.reprocessCount versioning standard
GAPLOS_TEC netCDFv2.12021-10-26Initial version of Line-of-sight TEC
GAPLOS_TEC netCDFv2.22023-08-31– Replaced cycle slip detection and correction algorithm based on Wide-Lane combination (Blewitt, 1990) with cycle slip detection and correction algorithm based on Melbourne-Wübbena and geometry-free combinations (Sanchez, 2016), which better distinguishes between cycle slips and outliers, and improves cycle slip detection in intervals of high noise and multipath.
– Increased threshold of multipath/noise combination (MP1/MP2; Stephens et al. 2011) from 1.5cm to 2.0cm.  Data intervals exceeding this threshold are discarded.
– Implemented an algorithm to detect and eliminate outliers based on the interquartile rule (
– Cumulatively, these modifications to the GPS LOSTEC data processing reduce the presence of noise, multipath, and outliers, and reduce the incidence rate of discarding useful data through an improved cycle slip detection algorithm. These changes also provide more accurate phase leveling and receiver differential code bias (DCB) estimation, resulting in more accurate TEC calibration.
Blewitt, 1990. An automated editing algorithm for GPS data. Geophysical Research Letters, 17(3),
Sanchez, 2016. Design and implementation of cycle-slip detectors for dual-frequency GNSS signals. Master’s Thesis, Universitat Politècnica de Catalunya Barcelonatech,
Stephens, P., Komjathy, A., Wilson, B., & Mannucci, A. (2011). New leveling and bias estimation algorithms for processing COSMIC/FORMOSAT-3 data for slant total electron content. Radio Science, 46, RS0D10.
IRMSSC h5v1.02021-10-08– Initial version of Sensor Skin Current (SSC) h5
– Note that this version supercedes the
IRM_skin_current lv1 data product which has now been retired.
IRMSSC h5v1.12022-04-20eclipse_status and attitude_quality attributes are now returned as lower case strings.
MGFlv1b CDFv02022022-05-25– New format (Swarm-like CDF)
– Complete overhaul of calibration
– Now includes flags and quality indicators
– Now includes attitude and ephemeris data
– Now includes CHAOS model magnetic field
RRIlv1 h5v11.02021-09-27Updated ephemeris and attitude data to
match the CAS_Orbit sp3 ephemeris files and
CAS_attQuat attitude data. ** THIS VERSION
DATA (times are off by up to one second) **
RRIlv1 h5v12.02021-10-29– Fixed incorrect radio data times
– GSM position values are now reported in km
RRIlv1 h5v13.02021-11-17Fixed creation of preliminary files for times when the orbit data is not available.
RRIlv1 h5v13.12023-22-02Implemented a fix for times when the RRI packet counter reports incorrectly for four packets, causing a timing error of 1.856 milliseconds in subsequent packets.

Data Processing Status

Full Mission ReprocessingCompleted2022-04-06Application of the new AttQuat v2.0 attitude solution to the entire mission of all instruments, excluding MGF. Correction of clock drift from 2023-06-22 to 2023-06-29.