Gyrate
发表于 2025-3-28 15:45:52
https://doi.org/10.1007/978-1-4471-0145-1CCD; Corona; Solar; Sun; Sunspot; astronomy; instruments; observational; observing techniques
使满足
发表于 2025-3-28 20:53:10
General Telescopic Observing Techniques, blankets, aluminised helium balloons, potato crisp packets, floppy disks, smoked plastic, crossed Polaroid filters, sunglasses, mirrors, medical X-rays or almost any other of the items that may be suggested from time to time as a substitute for the filters discussed below, to act as a reliable filter.