ERNE telemetry data are processed progressively into 'levels':

This is the raw telemetry received from the NASA ground segment.

Reconstructed ERNE data frames as sent from the ERNE onboard DPU.

Different measurement sets as separate files. Data are unpacked and some auxiliary information added. These are technical level data i.e., the spectral measurements are in raw counts.

Physical data files for the ERNE measurements and auxiliary data. The data are in physical units where applicable.

During the years the ERNE onboard processing program, Onboard Science Software (OSS), has seen various updates. Some of the modifications have affected the contents of the measurement data. The resulting telemetry frame versions are called formats. There are currently three major formats are:

f10

• In use in versions already before SOHO launch. Flight data from 1995-12-10 up to 2000-04-18. This time span covers Onboard Science Software versions OSS-2.13 - OSS-2.17 (Sabtech), and OSS-2.20 - OSS-2.24 (SEA).

f40

• From 2000-04-19 to 2001-07-02 (OSS-2.40)

f50

• From 2001-07-03 to present (OSS-2.50 - OSS-2.52).

• Format f20 has never existed, it is reserved for technical renaming of the current f10-data produced by the onboard science software versions developed in the 'new' SEA environment (OSS-2.20 up to and icluding OSS-2.24).

• Format f30 data exists for a couple of short time spans in the spring of 1998, mixed with the f10 periods. Due to some major problems with the counter logic the data is largely unusable and is not routinely processed to level-3. However the reader functions can handle level-3 f30 data if needed.

GED programs currently operate on level-2 and level-3 data.

NOTE: All the data for the levels are organized in daily-files, so one day is the basic access resolution.