Fig. 53

Fig. 54

PLATE XIX

N.G.C. 6790; 19h 17m9; +1° 19'

Exposures 10 to 1h 24m. B.D. +1° 3979; magn. 9.4. Indistinguishable from a star on the Crossley negatives, but shown to have a minute disk visually with the 36-inch refractor. Scale, 1 inch = 7.5.

N.G.C. 6803; 19h 26m6; +9° 51'

Exposures 10s to 1h 10m. Magn. 10. Probably has a central star of about magn. 13. A minute round disk, 5.5" in diameter, just distinguishable from a star; fades out a little at the edges. Bright; shows the nebular matter in 2 on S27. Rel. Exp. 0.3.

Fig. 56

Fig. 57

N.G.C. 6804; 19" 26m8; +9° 1'

Exposures 5 to 2h. Central star of magn. 12. An irregular ring 33" from N to S and 30" from E to W; brightest on north and south and fades out along an axis in p. a. 48°. The oval disk of much fainter matter outside is 63" X 50" in p. a. 0°, and stronger at western and southern edges. Rather faint; the ring just shows in 5m on S27. Rel. Exp. 25.

N.G.C. 6807; 19h 29m6; +5° 28'

Exposures 30 to 1h 10m. Magn. 10.4. Indistinguishable from a star on the Crossley negatives, but shown to have a minute disk visually with the 36-inch refractor. Scale, 1 inch = 7.5.

N.G.C. 6818; 19h 38m3; -14° 24'

Exposures 1 to 1" 40". Central star of magn. 14.

A rather irregular oval

ring 22" X 15" in p. a. 10°, fainter along and at the ends of the major axis.
A fainter narrow ring shows at east and west outside of the inner bright ring.
Fairly bright; the inner ring just shows in 1m on $27.
exposure; nebular matter within ring is fairly bright.

Drawing is for short

Exp. 0.7.

Fig. 58

Fig. 59

Fig. 61

Fig. 60

PLATE XX

N.G.C. 6826; 19h 42m1; +50° 17'

Exposures 30 to 2" 45". H.C.O. magn. 9.2. The central star of magn. 9 is surrounded by an oval disk of bright matter 27" X 24". Within this are rather obscure evidences of a brighter ring formation, the condensations at the ends of which are 22" apart in p. a. about 125°. Lantern-slide plates, relatively more sensitive in the violet, show interesting differences; the formation around the central star is more prominent, and the nebular disk appears to end inside the two condensations, instead of outside, as in the plates of greater speed. Very bright; the nebular matter shows in 30s on $23. Rel. Exp. 1.

N.G.C. 6833; 19h 46m9; +48° 42'

Exposures 20 to 32. H.C.O. magn. 10.2. Indistinguishable from a star on the Crossley negative, but shown to have a minute disk visually with the 36-inch refractor. Scale, 1 inch = 7.5.

N.G.C. 6879; 20h 5m9; +16° 38'

Exposures 10 to 50m. Magn. 10. Perhaps has a central star. A minute disk, 5" in diameter, just distinguishable from a star. Fades out slightly at the edges. Rel. Exp. 5.

Fig. 62

Fig. 63

Fig. 64

Fig. 65

Fig. 66

PLATE XXI

N.G.C. 6881; 20h 7m2; +37° 7'

Exposures 1 to 40m. Probably has a central star. Just distinguishable from a star; a minute disk 5" in diameter, with very faint ansae in 150-330° p. a. Shows in 5m on S23. Rel. Exp. 5?

N.G.C. 6884; 20h 7m2; +46° 10'

Exposures 10 to 1 30m. H.C.O. magn. 10.6; no central star can be distinguished. A minute, bright, round disk, of nearly equal brightness throughout, with a suggestion of an elongated brighter central portion in p. a. 135°; 7.5" in diameter in a 5" exposure. Quite bright; shows in 1m on S27. Rel. Exp. 0.5.

N.G.C. 6886; 20h 8m3; +19° 42'

Exposures 10s to 1". About magn. 10; no central star can be made out. A round disk 6" in diameter, of nearly equal brightness throughout, forms the central part. Two wings (of ring structure?) in p. a. 135-315° bring the total length to about 9". Quite bright; the central portion shows in 30% on $23. Rel. Exp. 1.

N.G.C. 6891; 20h 10m4; +12° 24'

Exposures 10s to 1". Central star of magn. 10 (Burnham 11.8 visual). A round disk 15" in diameter, of which the central 7" is considerably the brighter. From this brighter center extend indistinct traces of wings in p. a. about 135-315°. Quite bright; the parts immediately about the central star show in 30% on S23. Rel. Exp. 2.

N.G.C. 6894; 20h 12m4; +30° 16'

Exposure 2h. The Annular Nebula in Cygnus. The central star is about magn. 16. A very vague and indistinct ring, 44" in diameter along a major axis in p.a. 50°. Quite faint; the brightest patch is at the north, near the 14th magn. star involved in the ring. No structural details are visible, except for the very indistinct formations shown. Rel. Exp. 70.