CALET on-orbit operations and data analysis system at the Waseda CALET Operations Center (WCOC)

Abstract

CALET is the long-term high energy cosmic ray observation mission on JEM-EF of the International Space Station. In order to extend measurements of electrons and gamma rays to the 10-20 TeV region and protons and nuclei to several hundred TeV, the CALET calorimeter (CAL) has a thickness of 30 radiation lengths. CAL is composed of a lead tungstate (PWO) Total AbSorption Calorimeter (TASC), a tungsten-scintillating fiber IMaging Calorimeter (IMC), and a plastic scintillator CHarge Detector (CHD). The data taken by CALET are passed to the ISS and sent to the ground immediately via NASA and JAXA data relay links. At JAXA’s Tsukuba Space Center, a ground operation system (JAXAGSE) then transmits the data to the Waseda CALET Operations Center (WCOC) at Waseda University. Monitoring of the instrument’s observation status has been performed since October 2015 at JAXA. Simultaneously, the CALET science team monitors the scientific mission and the data transmission on a 24-hour 7-day basis in WCOC. Monitoring at the WCOC is performed by Quick Look software developed at Waseda. When the Quick Look GUI detects observed values exceeding predetermined thresholds, an alarm is issued. In order to provide flexibility for the scientific operation, the CALET observing schedule is updated daily. In addition, the observation data file is processed for transmission to the science team. Raw (Level-0) data processed at JAXA-GSE are converted to engineering (Level-1) data for distribution to the international CALET collaboration. Finally, individual detector temperature dependences, time variations, etc. are included in the final (Level-2) data which are used for detailed science analysis.