  The gamma-ray detectors (GRDs) of GECAM-C onborad SATech-01 satellite is
designed to monitor gamma-ray transients all over the sky from 6 keV to 6 MeV.
The energy response matrix is the key to do spectral measurements of bursts,
which is usually generated from GEANT4 simulation and partially verified by the
ground calibration. In this work, energy response matrix of GECAM-C GRD is
cross-calibrated with Fermi/GBM and Swift/BAT using a sample of Gamma-Ray
Bursts (GRBs) and Soft Gamma-Ray Repeaters (SGRs). The calibration results show
there is a good agreement between GECAM-C and other reasonably well calibrated
instrument (i.e. Fermi/GBM and Swift/BAT). We also find that different GRD
detectors of GECAM-C also show consistency with each other. All these results
indicate that GECAM-C GRD can provide reliable spectral measurements.
