# SREM

## Product description

The SREM data files contain calibrated data for the different energy and particle species channels available in the SREM. Each data file contains 24 hours of data - from midnight to midnight UTC. (note this is not an Operational Day) - with the date covered by the file easily identifiable through the file name.

## Inputs

SREM calibrated data was produced from the SREM raw data acquired during the entire mission.

## Related products

Data for the SREM on board other ESA missions can be retrieved from the Paul Scherrer Institute [1]. In order to retrieve the data you will need to register first.

## Data files

The files containing the SREM calibrated data will have a name of the form SREMPlanck_PACC_YYYYMMDD.fits where PACC stands for Processed ACCumulated data and YYYYMMDD is the date the data in the file was acquired.

The SREM processed data can be downloaded from the PLA interface: "Ancillary data" tab of the "Time-ordered information" section.

A list of the files available can be found here.

### Data format

Each file contains three binary table extensions named CDFFITS1,CDFFITS2 and CDFFITS3. The first extension contains the accumulated counts data, the second extension the labels to identify the data in the first extension and the third extension the total radiation dosis. The contents of each extension are as follows.

CDFFITS1
Column Name Contents Format Unit
EPOCH vector containing 1 string with UTC for center of accumulation interval in ISO format (YYYY-MM-DDTHH:MM:SS.MMMZ) A24 NA
COUNTRATE vector containing 15 elements (1 for each channel) with counts for accumulation period identified in the EPOCH column E15.4 s$^{-1}$
ORBIT position (x,y,z) of the SREM in the ECI frame. Distance from center fo the Earth is $R=\sqrt(x^2+y^2+z^2)$ E15.4 km
ATTITUDE Not in use E15.4 -
PROT FITQUAL Not in use I1 NA
ODPF Not in use. E15.4 -
ODPFERR Not in use E15.4 -
ELEC FITQUAL Not in use I1 -
ODEF Not in use E15.4 -
ODEFERR Not in use E15.4 -
ANISOTROPY Not in use E15.4 -
TEMPERATURE 2 element vector containing temperature of the two detector heads at each EPOCH E15.4 $^\circ$C

CDFFITS2
Column Name Contents Format Unit
EPOCH this is a keyword NA UTC

CDFFITS3
Column Name Contents Format Unit
RADEPOCH this is a keyword A24 NA
RADFET Value proportional to the absorbed dose on a diode mounted on the surface of SREM E15.4 NA

Note: SREM calibrated data files where initially provided in the Common Data Format (cdf) format. This has traditionally been the preferred data format for SREM on board previous ESA missions. However, as cdf is not widely used in the astrophysics community it was later agreed with the provider that fits files should also be provided. This meant taking the original cdf format and converting it to fits. The original cdf files can be retrieved from the SREM site at the PSI.

Universal Time Coordinate(d)

European Space Agency

Planck Legacy Archive