2 by direct comparison and extension, through objective-grating images on a plate taken with the 20-inch astrograph, with Special Selected Area 20 (Van Rhijn 1952). ... Many of the fainter stars in this heavily-obscured region around NGC 1999 are variable, and several comparison stars had to be discarded for ... The 20-inch astrograph plates especially have to be employed with caution because of their small scale (55aquot;/mm) and color-curve and low ultraviolet- transmission effects.
|Title||:||Mitteilungen der sternwarte|
|Author||:||Magyar Tudományos Akadémia. Csillagvizsgáló Intézet|