A Study of the FITS-IDI Format for the Chinese Spectral Radio Heliograph

Raw data observed with the Chinese Spectral Radio Heliograph (CSRH) will be recorded in a self-defined format. For convenient distribution and use it is necessary to convert CSRH data files to be of other standard formats such as the FITS-IDI. After an in-depth analysis of the FITS-IDI data format, we present a proposal of mandatory and optional FITS-IDI fields for the CSRH. We also discuss calculation equations of values of several data fields, including the UU, VV, and WW. A FITS-IDI data file converted from a raw-data file has been input into the CASA software package, successfully resulting in a CASA file of integrated Measurement Sets (MS). The generating and subsequent processing of the CASA file demonstrate the correctness of the proposed CSRH FITS-IDI format. Our study could effectively advance the CSRH project and provide useful references for further research of data storage for other astronomical instruments.