Comparison of Line-of-sight Magnetic Field Observed by ASO-S/FMG, SDO/HMI and HSOS/SMAT

The Full-disk MagnetoGraph (FMG) onboard the Advanced Space based Solar Observatory (ASO-S) has obtained a series of Line-of-Sight (LOS) magnetic field since it launched in October 2022. It is important to compare its observational data with other existing solar telescopes. In this paper, we make a detail data comparison of 4 active regions and a pore region simultaneously observed by FMG, SDO/HMI (Helioseismic and Magnetic Imager onboard Solar Dynamic Observatory) and HSOS/SMAT (Solar Magnetism and Activity Telescope at the Huairou Solar Observing Station). The magnetic field structure and spatial distribution are found basically consistent among these three instruments, and the initial correlation coefficient of magnetic field is approximately 0.90. They slightly increase when sunspot umbra region was removed, and they significant increase in penumbra region, up to 0.98. The magnetic field observed by FMG tends to smaller than the HMI in strength in sunspot umbra due to saturation effect, whereas larger outside sunspot. The differences probably come from the affections of noise, the seeing condition (SMAT is affected by the Earth's atmosphere), and observational and calibration methods.