by Steve Gottlieb
Although I missed Lassen, I spent five nights last week at the SF State's Sierra Nevada Field Campus near the Sierra Buttes (with not a single mosquito, Mark and Rashad) helping out with their astronony class. We had clear skies every night (7/15 - 7/19) but after coming home on Friday I drove back to Fiddletown on Sunday night where we had at least a half dozen observers/imagers. Here are some faint but interesting planetary nebulae observations -- I'll post some other interesting stuff I ran across soon.
| Abell 44 = PK 15-3.1 | 18 30 11.4 -16 45 28 | V = 15.8; Size 63"x39" |
|---|---|---|
| 17.5" (7/22/01): at 62x and OIII filter, extremely faint, fairly small, roundish, ~30" diameter. A mag 12.5 is involved at the western edge. Ill-defined and just glimpsed with averted at 64x and 104x using the OIII filter. Located 35' WNW of the rich open cluster N6645 (same low power field) and roughly two degrees ESE of the Swan Nebula! | ||
| Abell 50 = PK 78+18.1 = NGC 6742 | 18 59 19.7 +48 27 57 | V = 13.4; Size 31"x30" |
|
17.5" (7/22/01): moderately bright, fairly small, perfectly circular. Easily
picked by scanning region at 100x just 3.5' NE of mag 8.9 SAO 47978. Appears
unevenly lit at 280x, ~30" diameter with slightly enhanced regions along the
rim. A very faint star is off the NE edge.
17.5" (5/11/86): at 220x without filter appears fairly faint, round, fairly small. At 105x using an OIII filter the planetary is bright and compact with crisp round edges. | ||
| Abell 61 = PK 77+14.1 | 19 19 10.1 +46 14 36 | V = 13.5; Size 201" |
|
17.5" (7/22/01): at 62x and OIII filter appears faint, large, roundish, ~3'
diameter. Can hold continuously with a little effort. Low surface brightness
but crisp-edged in moments of better seeing and very nice disc embedded in a
rich star field!
17.5" (8/26/00): at 100x and OIII filter this large Abell PN is faint, round, 2.5'-3.0' diameter, irregularly lit. Could view continuously with concentration and fairly easy with averted vision although the surface brightness is quite low. The round halo had a fairly crisp edge at moments and was brighter along the northwest rim. Situated in a rich milky way field. 13" (8/17/85): at 79x and OIII filter appears as a large, round, extremely difficult glow. This planetary is near or at the visual threshold but definitely seen with extreme averted with an OIII filter. Located in a rich star field. This is one of the faintest large planetaries seen with the 13"! | ||
| PC 22 = PK 51-4.1 | 19 42 03.1 +13 50 39 | V = 13.3; Size ~15" |
|
17.5" (7/18/01): found at 220x (without filter) as a fairly faint oval,
elongated nearly 2:1 SW-NE, ~20"x12" with a mag 13 star at the NE end. At
380x, a very faint companion is just ENE of the mag 13 star with a brighter
mag 12 star 1' SE. This is an interesting PN at high power with a relatively
high surface brightness and unusual elongation.
17.5" (8/2/86): at 220x unfiltered a nice disc 10"-15" diameter is visible, estimate V = 13.0-13.5. Appears slightly elongated with a faint star at the E end. Located 6.2' E of mag 8.5 SAO 1405149 and 14' ENE of QS Aquilae (5.9-6.1). | ||
| Abell 66 = PK 19-23.1 | 19 57 31.5 -21 36 46 | Size 295"x241" |
|
17.5" (7/17/01): Viewed at 64x using an OIII filter. Required averted vision
to see a very large, round glow nearly 3' diameter with a mag 13 star at the
NE edge. Difficult to pick out initally but visible roughly 50% of the time
with averted. Occasionally the edge of the disc sharpened up and the
planetary was sharply defined, otherwise just appeared as a very low surface
brightness glow, similar to a unresolved milky way patch.
13" (8/17/85): at 79x with OIII filter; extremely faint (requires averted vision), large, round, unusually low surface brightness. Located 6' S of two mag 11 stars and a fainter mag 13 star is superimposed. Identified on the second attempt at this planetary and one of the dimmest planetaries observed with 13". | ||
| Abell 72 = PK 59-18.1 | 20 50 02.0 +13 33 28 | V = 13.8; Size 134"x121" |
|
17.5" (7/18/01): easily picked up at 64x and OIII filter as a fairly faint,
moderately large, round glow. Unusual setting with a mag 8 star just off the
WSW edge and two 11th mag and a 13th mag star off the E and SE side. At 140x
and a UHC filter the disc is fairly large and slightly elongated ~E-W, ~2'
diameter. Without the filter a couple of fainter stars are superimposed on
the disc.
17.5" (7/31/92): at 100x and OIII filter; fairly faint, large, 2' diameter, irregular shape without crisp edges. Striking location as mag 8.1 SAO 106544 is just off the the WSW edge 1.8' from the center! Mag 8.9 SAO 106547 lies 3.8' NNE and two mag 11 stars and a mag 13 star are just off the E and SE edges. A mag 13 star superimposed in the center is probably not the central star. Also viewed unfiltered at 220x although best view is at low power. 13" (7/20/85): faint, large, very diffuse. Several faint stars are superimposed and a mag 8 star is just off the western end! A mag 9 star is 4' N and three stars are off the E edge. | ||
| Abell 78 = PK 81-14.1 | 21 35 29.4 +31 41 45 | V = 13.4; Size 113"x88" |
|
17.5" (7/22/01): picked up at 64x with the OIII filter exactly midway
between
two mag 7/8 stars 8' NW and a similar distance SE. Appears as a faint,
fairly
large glow, ~1.5'-2' diameter, surrounding a mag 12.5 star (slightly SW of
center). At 144x and OIII filter, the disc does not quite reach mag 12 stars
close NW and NE. Still faint, but not difficult, with slightly irregular
surface brightness.
17.5" (8/26/00): easily picked up at 100x as the PN is at the midpoint of two mag 7.4 and 8.2 stars at 16' separation oriented NW-SE. Using an OIII filter it appeared as a fairly faint, moderately large glow surrounding a mag 12.5-13 star (apparently the central star). Appears ~90" diameter and fairly crisp-edged with averted vision. A mag 12.5 star is close NE. At 140x with the OIII filter, the halo and surface brightness seemed irregular and less well-defined as it gradually fades into the background. 13" (8/17/85): at 88x with OIII filter appears very faint, fairly small, round, best viewed with averted vision. Centered between mag 7.2 SAO 7.9' NW and mag 8.5 SAO 71500 8.0' SE. Appears fainter than computed magnitude V = 13.4. | ||