A peculiar object in Serpens.

Abstract

This object, which appears to be a perfectly symmetrical planetary nebula, was discovered on a 75-minute Jewett Schmidt plate. A perfect halo, 17" in radius, surrounds a diffuse central image. Its position, ± 15h 15m0, δ +21° 46' (1950), l 358°, b+54° (1950), size and nucleus ( ~17 mpg, C. I. ~+ I.O) are not typical of the planetary nebulae. The halo, which is bluer than the nucleus, does not show in emission on an objective prism plate that records the central object. <P />As a most conservative alternative one might say that this is a new species among the "pathological" galaxies. Other ring-forming mechanisms such as a diffraction effect^1 or a gravitational lens system^2 are less probable explanations. The mass of the central object, in the latter case, would have to be of the order of 8 x 10^11 solar mass. <P />Since the object is unique, I suggest that a proper identification would be a worthwhile short-term project. <P />1.Struve, Ann. Astroph. I, 143, 1938. <P />2.Zwicky, Phys. Rev. 51, 290, 1937. <P />Harvard College Observatory,Cambridge, Mass.