HCO: Photographic Plate Collection Descriptions
  1. Patrol plates - filed by region
    • RH, RB, etc. - scale 390"/mm (roughly equal to SAO charts); limiting magnitude 14-15; roughly 100 plates of each region 1928-1952; mainly blue.
    • AC, AM, etc. - scale 600-700"/mm; 35 field; limiting magnitude 12 (some go fainter); several hundred plates of each region 1898-1954; mainly blue.
    • AI, BI, FA - scale 1200"/mm; 50 field; (of limited use.)
    • Damon (DN,DS) - scale 580"/mm; 35 field; limiting magnitude 14-15; 20-50 plates of each region 1965-1990; blue; a few yellow and red of limited use.
  2. Series plates - filed chronologically (see card catalogs filed by position)
    • Southern hemisphere: A (limiting magnitude 17), MF, B, ADH, etc.; earliest plates 1885.
    • Northern hemisphere: MC (limiting magnitude 17), MA, I, IR, J, etc.; earliest plates 1890's (MC from 1909).
  3. Other
    • Palomar sky survey (paper)
    • European Southern Observatory "Quick Blue" survey (glass)
  4. Available equipment
    • Blink microscope
    • Variable iris photometer (good to 0.04 mag on large scale with many grains per image)
    • Polaroid copying camera (fixed 3x enlargements)

Section Photo