The level 1 product contains data from the REPTile-2 detectors and energy channels as well as relevant spacecraft and telemetry information. It is formatted into netCDF, and each day where science data was recorded has its own netCDF file. Each file contains 25 variables that are formatted as arrays. All variables except ‘Epoch’ and ‘OffAng_timestamp’ are stored as 32-bit floating point arrays, or ‘float’. ‘Epoch’ and ‘OffAng_timestamp’ are stored as 64-bit floating point arrays, or ‘double’.

Each element in the array corresponds to a point in time. For all variables except ‘OffAng’ and ‘OffAng_timestamp’, the timestamp for each array element is the element with the same index in the ‘Epoch’ variable. For the ‘OffAng’ variable, the timestamp for each array element is the element with the same index in the ‘OffAng_timestamp’ variable. The timestamp format for ‘Epoch’ and ‘OffAng_timestamp’ is UTC seconds since 01/01/2000 00:00. Each variable is explained in the table below. A basic description of each variable is available in the netCDF metadata.

We acknowledge the use of the IRBEM library (4.4.0), the latest version of which can be found at https://doi.org/10.5281/zenodo.6867552.

Notes:

• The fill value (unwritten/bad data flag) for timestamp variables is -9.223372036854776e+18. For flag variables it is 999. For all other variables it is 9.9692100e+36.
• During all pointing modes, CIRBE’s regular pointing operations will be occasionally interrupted (usually ~4 times per day for a few minutes at a time) and the spacecraft will point at the ground for the purpose of uploading data or downloading instructions. Such periods are easily identifiable in the ‘OffAng’ variable.

Variable Name	Units	Description
‘Epoch’	s (UTC seconds since 01/01/2000 00:00)	Main timestamp for science data. Time format is UTC seconds since 01/01/2000 00:00.
‘Alt’	km (kilometers)	Altitude of CIRBE in kilometers.
‘Lat’	o (degrees)	Latitude of CIRBE in degrees. Negative values are degrees south, positive values degrees north.
‘Lon’	o (degrees)	Longitude of CIRBE in degrees. Negative values are degrees west, positive values degrees east.
‘L’	N/A	McIlwain L-parameter at location of CIRBE. Calculated via IRBEM (4.4.0).
‘MLT’	Decimal hours	Magnetic local time expressed as a decimal number from 0 to 24. Calculated via IRBEM (4.4.0).
‘MLAT’	o (degrees)	Magnetic latitude. Negative values are degrees south, positive values degrees north. Calculated via IRBEM (4.4.0.).
‘Pbins_RNG’	Counts	Event counts for each range proton channel (channels 1:50) over the integration period. Counts are shown for each channel for each Epoch timestamp.
‘Pbins_PEN’	Counts	Event counts for each penetrating proton channel (channels 51:60) over the integration period. Counts are shown for each channel for each Epoch timestamp.
‘Ebins_RNG’	Counts	Event counts for each range electron channel (channels 61:110) over the integration period. Counts are shown for each channel for each Epoch timestamp.
Ebins_PEN’	Counts	Event counts for each penetrating electron channel (channels 111:120) over the integration period. Counts are shown for each channel for each Epoch timestamp.
‘D1’	Counts	Count of events that trigger the first detector over the integration period. Corresponds to channel 121.
‘D2’	Counts	Count of events that trigger the second detector over the integration period. Corresponds to channel 122.
‘D3’	Counts	Count of events that trigger the third detector over the integration period. Corresponds to channel 123.
‘D4’	Counts	Count of events that trigger the fourth detector over the integration period. Corresponds to channel 124.
G’	Counts	Count of events that trigger the guard rings over the integration period. Corresponds to channel 129.
‘D12n’	Counts	Count of events that trigger the first detector but not the second over the integration period. Corresponds to channel 125.
‘D123n’	Counts	Count of events that trigger the first and second detectors but not the third detector over the integration period. Corresponds to channel 126.
‘D1234n’	Counts	Count of events that trigger the first, second, and third detectors but not the fourth detector over the integration period. Corresponds to channel 127.
‘D1234’	Counts	Count of events that trigger all detectors over the integration period. Corresponds to channel 128.
‘IntePrd’	ms (milliseconds)	Integration period for each ‘counts’ data point. The length of time in milliseconds over which the counted events occurred.
‘OffAng_timestamp’	s (UTC seconds since 01/01/2000 00:00)	Timestamp for ‘OffAng’. Time format is UTC seconds since 01/01/2000 00:00.
‘OffAng’	o (degrees)	Angle between REPTile-2’s pointing direction and the local magnetic field. Recorded separately from science data at regular, infrequent intervals or whenever the angle deviates from 90 degrees.
‘spacecraft_pointing_mode’	0 = nominal science mode 1 = sun-point static mode 2 = sun-point star-tracker mode	Shows what pointing mode REPTile-2 is in. Although the spacecraft is in its nominal pointing mode when this flag is set to 0, this does NOT mean that data are invalid when it is in other pointing modes. However, extra caution should be used and extra attention paid to the ‘OffAng’ variable during periods of other pointing modes as REPTile-2 may not be perpendicular to the local magnetic field. Nominal science mode is where CIRBE primarily points REPTile-2 perpendicular to the local magnetic field and secondarily points CIRBE’s solar panels towards the sun. Sun-point static mode is where CIRBE primarily points its solar panels towards the sun and otherwise remains static. Sun-point star-tracker mode is where CIRBE primarily points its solar panels towards the sun and secondarily points to the orbital nadir.
‘invalid_data_flag’	0 = data is valid 1 = data should be used with extreme caution	Shows whether the data of a certain timestamp has any major issues that impact its validity. The flag is active when the value is set to 1.

Contacts:

• Principal investigator: xinlin.li@lasp.colorado.edu
• Data processing code authors: david.brennan@lasp.colorado.edu, yang.mei@lasp.colorado.edu