def __init__(self):
self.ims = ImagesQuery()
self.disc = DiscoveriesQuery()
self.bk = BlockQuery()
# pixel scale is symmetric, 0.1850 arcsec/pixel. Dectector is [1:23219,1:19354] pixels.
self.field_area = ((0.185 * 23219) / 3600.) * (
(0.185 * 19354) / 3600.) # sq. deg
