Date Co-alignment for Ground-Based High-Resolution Solar Imaging

The multi-wavelength analysis is a well-spread method in solar physics studies, and the community increasingly relies on coordinated observations involving multiple instruments. The calibration of heliographic coordinates is therefore vital for the co-alignment of such multi-instrument, multi-wavelength data. However, this is particularly difficult for ground-based high-resolution observations because of the limited field of view. Manually co-aligning data with low-contrast features (e.g., photospheric observations of quiet Sun regions) between different telescopes requires exceptional efforts and patience. Here, we developed a technique to accurately determine coordinates of high-resolution images acquired by the Goode Solar Telescope (GST) at the Big Bear Solar Observatory. The technique employs a scale-invariant feature transform (SIFT) method, which performs without human interference. With this new approach, we co-aligned multi-wavelength GST data sets to the continuum intensity data from the Helioseismic and Magnetic Imager (HMI) precisely. The inferred heliographic coordinates are saved in each FITS file header, which is compatible with the common mapping methods available in the Solar SoftWare (SSW) package. GST data are fully open to the scientific community, and a substantial portion of observing time on the GST opens to the community as well.