Last night (July 22) I joined Robert Leyland, Dick Flasck and David Silva at Lake Sonoma for comet viewing and a short night of deep sky viewing (moon up just after midnight). It was breezy as I arrived before sunset but the wind almost entirely died down by the time twilight ended. Skies were transparent (close to 6.5) and the seeing steady at 280x-380x. The only hassle was a constant stream of cars driving past the lot where we were set up in the park.
C/1999 S4 (LINEAR) did not disappoint - the comet was prominent in 10x50's along with an obvious tail. At 100x in my 17.5-inch the tail could be easily be seen out to 40' and traced to 50' with averted vision. As luck would it the head was passed very close to a star and the obvious motion of the comet past the star was mesmerizing.
Afterwards, I decided to take a look at several faint fuzzies which share the same field with a bright deep sky object: M13 and IC 4617 (14' NNE), M57 and IC 1296 (4' NW), NGC 6826 (Blinking Planetary) and CGCG 257-10 (11' W), M80 and IC 4596 (25' NW), IC 1295 and the stellar planetary K4-8 (5' WNW).
You probably wouldn't normally bother with these objects EXCEPT it's simple to identify the field, a challenge to pick out the faint glow and you have the bonus of observing a showpiece at the same time! I ended this very pleasant evening taking another look at some little-known planetaries (Minkowski 4-9, Minkowski 4-11, Abell 41) - some older notes from the mid-'80's are also included.
IC 4617
16 42.1 +36 42
Size 1.1x0.4; PA = 29d
Extremely faint, very small, slightly elongated SSW-NNE, cannot hold continuously with averted vision. Located 14' NNE of the core of M13 and 15' SW of N6207! A mag 14 star is close following 19" ESE of center and this star forms the SW vertex of a small parallelogram of mag 14 stars with sides approximately 1.5'x0.5'.
IC 1296 = U11374 = M+06-41-022 = Z201-040
18 53 18.8 +33 03 58
V = 14.0; Size 1.1x0.9; SB = 13.8; PA = 80d
Extremely faint, small, round, very low surface brightness. Situated just 4' NW of M57 along the north side of a small rhombus of mag 10.5/12/13.5/13.5 stars with sides of 1.5'.
CGCG 257-010
19 43 39.5 +50 32 32
B = 14.8
Faint, very small, elongated 3:2 N-S, 20"x14". A mag 12 star is attached at the SSE edge [20" from center], and the perception of elongation may be enhanced slightly by this star. Appears to have a smooth, surface brightness except a couple of times a very faint superimposed star or stellar nucleus was glimpsed with direct vision. Located 11' W of N6826, the Blinking Planetary in the same high power field!
IC 4596 = E516-009 = M-04-38-005
16 16 03.6 -22 37 31
Size 1.5x0.5; PA = 54d
Extremely faint, very small, elongated at least 2:1 SW-NE, ~20"x10", low even surface brightness. A mag 14 star is close north [37" from center] and a triangle of mag 12/13 stars lies 3' NNE. Located 25' NW of globular cluster M80!
K4-8 = PK 25-4.1
18 54 19.9 -08 47 32
V = 14.2; Size Stellar
17.5" (7/22/00): this stellar planetary is situated just 5' WNW of IC 1295! At 140x, visible as a mag 14.5 "star" in the middle of a shallow of arc of 4 stars, concave to the north with a slightly brighter star is at the east edge. Excellent contrast gain with OIII blinking and K4-8 appears to "turn on" and becomes brighter than the star on the east end.
17.5" (5/10/86): at 105x and 220x appears as a stellar planetary, estimate V = 13.5-14.0. Responds well to OIII and Daystar 300 filter. Located just 4.6' WNW of planetary IC 1295 and 22' SE of globular cluster N6712! Situated within a close arc of four similar faint stars.
13" (7/12/86): verified with UHC blink at 214x. Appears as third "star" in a close arc of four or five stars, estimate V = 14.0.
Minkowski 4-11 = PK 24-5.1
18 54 17 -10 05 13
V = 13.8; Size 22"x20"
17.5" (7/22/00): visible unfiltered at 220x as a fairly small disc, ~20" diameter with several faint stars nearby. Best view at 2x0x using a UHC filter; fairly faint, round, crisp-edge to disc, smooth surface brightness. Removing the filter, a faint star is at the south edge (with a companion close SE) and a dimmer star is at the east edge of the planetary. Located 1.25° south of IC 1295/K4-8.
13" (8/8/86): at 214x and UHC filter; fairly small disc visible, estimate 15"-20" diameter and V = 13.5-14.0. Visible without filter continuously with averted. Located by dropping 75' S of planetary IC 1295. This is the first known visual sighting along with Jack Marling.
Abell 41 = PK 9+10.1
17 29 02.0 -15 12 59
V = 15.6; Size 16"x7"
17.5" (7/22/00): picked up unfiltered at 220x as a very faint, small disc, ~15" diameter. Easier to view at 280x and could almost hold continuously. Appears to brighten towards the center and increase in size with averted vision. This low excitation PN gave no response to a UHC filter at 140x-280x or with a H-beta filter at 140x.
17.5" (7/21/90): at 220x without filter appears as a faint, small, round disc of low even surface brightness. Very unusual filtration response as dims with OIII and UHC filters! At 280x without filter, the disc is very evident.
Minkowski 4-9 = PK 24+5.1
18 14 18.5 -04 59 23
V = 14.1; Size 46"x38"
17.5" (7/22/00): picked up unfiltered at 220x as a 40" round glow. Could be held continuously at 280x. The surface brighness appears irregular and a faint star is embedded in the eastern edge. A slightly brighter star is off the NW side. Weak contrast improvement with UHC and OIII and preferred unfiltered view.
17.5" (7/5/86): at 105x a faint, fairly small disc is visible without a filter. Appears fairly faint using OIII filiter, slightly elongated with an even surface brightness. At 220x and Daystar 300 filter; fairly faint, fairly small, 30"-40" diameter, estimate V =14.0-14.3.
13" (7/12/86): at 79x with OIII filter a fairly small disc is visible about 30" diameter, can hold with direct vision, estimate V = 14.0. Visible at 166x without filter although very faint using averted vision. Easy at this magnification using UHC filter.