Chasing tiny celestial butterflies 11/17/08

Steve Gottlieb

Last Monday, when the November new moon window was just opening, I met Carter Scholz and Greg T. for a short evening (moonrise at 9:40) at Lake Sonoma. On the drive up 101 through Santa Rosa I was a bit concerned about the mix of streaky clouds criss-crossing the sky, but the weather cooperated and the skies cleaned up nicely as the darkness fell with the residual thin stuff drifting off to the east. Conditions were pretty ideal for mid-November – mild temperatures, no wind or dew and decent skies for a local bay area site (21.2 on my lens-type SQL).

A quick look at Jupiter, low in the southwest, confirmed the seeing was steady so I decided to focus on nearly stellar planetaries and pump up the power to resolve the disc and look for details. Most of these planetaries have a high surface brightness and are not difficult objects despite being missing from the NGC. The main reason they weren't picked up by the Herschels is their nearly stellar appearance – they were likely swept right over without noticing any unusual. But compact planetaries look odd to me in the field –they often stand out by their characteristic blue-green color and even if only 1" or 2" in diameter have a slightly soft or fuzzy appearance, like an out-of-focus star. Blinking with an OIII or narrowband filter confirmed the find, though generally this wasn't required on this night. Notes were taken using my 18-inch Starmaster with tracking at 175x, 450x and 807x.

Vyssotsky 1-1 = PN G118.0-08.6
00 18 42.2 +53 52 20, V = 12.6; Size ~5"
Russian born astronomer Alexander Vyssotsky accidentally discovered this compact planetary at the Leander-McCormick Observatory in Charlottesville, Virginia in 1942 on an objective prism plate.

I picked up Vy 1-1 at 175x (13mm Ethos) as a "soft" blue star. Very good contrast response by blinking with an OIII filter. The disc was easily resolved at 450x and at 800x the central star (listed at mag 14.2) was occasionally cleanly resolved within the high surface brightness glow. At other times, the planetary appeared to contain a brighter, quasi-stellar center.

Humason 1-1 = PN G119.6-06.7
00 28 15.6 +55 57 55, V = 12.4; Size 5"
Discovered by Milton Humason on Nov 9, 1920 at Mt Wilson on a spectrogram made with an objective prism using the 10-inch Cooke telescope. Edwin Hubble visually observed the planetary a month later with the 60-inch at Mt Wilson and described it as a "small disc about 5" in diameter, irregular in outline".

I immediately noticed Hu 1-1 at 175x as a very small, but distinctly non-stellar blue-grey disc, ~10" diameter. The OIII filter gave a large contrast gain. At 450x the surface brightness was irregular and at 807x there was a hint of annularity and a slightly brighter rim. The planetary is collinear with a 24" pair of mag 11.5-12 stars just 2' NW and a third fainter star is nearby. A mag 10 star located 8' NNW is at the NW end of a distinctive chain of stars to the north of the planetary.

Bohm-Vitense 5-2 = PN G121.6+00.0
00 40 21.6 +62 51 34, V = 15.4; Size ~20"
Discovered by Erika Böhm-Vitense at Lick Observatory in 1956 during a survey of extragalactic objects in the galactic plane.

At 175x and OIII filter BV 5-2 appeared as a very faint, roundish disc, ~15"-20" diameter but only visible ~30% of the time, so it was very difficult to see any structure or even the shape. Not visible unfiltered. Follows mag 8.6 HD 3529 by 10'.

IC 1747 = PN G130.2+01.3
01 57 35.7 +63 19 18, V = 12.0; Size 13"
Discovered by Willliamina Fleming in 1905 at Harvard College Observatory based on its spectrum.

Immediately picked up at 175x as a small, bluish disc, ~12" diameter. Situated within a distinctive 20' curving chain of stars that passes through much of the field. Very good contrast gain using an OIII filter. At 450x, the planetary is slightly elongated WNW-ESE, ~15"x12", and weakly annular. At 800x it appeared irregularly brighter along the rim with a knotty structure, particularly along the northern half. Located 30' SE of mag 3.4 Epsilon Cassiopeia.

Minkowski 1-4 = PK 147-2.1 = PN G147.4-02.3
03 41 43.4 +52 17 00, V = 13.6; Size 5"
Discovered by Rudolph Minkowski in 1947 at Mt Wilson. His first list includes 80 objects first found on objective-prism survey plates and verified on photographs takens with the 60-inch and 100-inch telescopes at Mr. Wilson.

Identified at 175x by blinking with an OIII filter. Visible unfiltered as a mag 13.5-13.8 "star" with perhaps a slightly soft appearance. At 450x, clearly visible as a uniform 3" disc with a crisp edge. At 800x the center is occasionally starlike, although I couldn't clearly resolve the central star (mag 16.7).

Minkowski 2-2 = PN G147.8+04.1
04 13 15.0 +56 56 58, V = 14.0; Size 12"x11"
Discovered by German-American astronomer Rudolph Minkowski in 1947 at Mt Wilson on searches for new planetaries and emission nebulae based on their spectrum.

Easily picked up unfiltered at 175x as a small, 12" disc of mag 13.5-14. Excellent contrast gain with an OIII filter. A mag 13 star lies 1' N and a brighter mag 11 star is 2.7' SE. A third mag 13 star 2.5' S forms a triangle with the planetary along the western side. At 450x and 800x a very faint central star was suspected.

IC 5117 = PN G089.8-05.1
21 32 31.0 +44 35 48, V = 11.5; Size 2"
Another Willamina Fleming discovery in 1905 at Harvard College Observatory. Picked up at 175x in a rich star field by blinking with an OIII filter (excellent contrast gain). Forms the fainter component (V = 11.5) of a "double star" with a mag 10 star 21" ENE, though with the filter the planetary dominates the star. There is similar double (Es 1339 = 10.8/11.5 at 24") in terms of separation and position angle just 3' NE! Without a filter at 175x, IC 5117 has a soft, bluish appearance and using 450x, a very small 2" disc was clearly visible.

Humason 1-2 = PN G086.5-08.8
21 33 08.3 +39 38 01, V = 11.8; Size 5"
Another discovery by Milton Humason. Hubble described it as a "small disc about 5" in diameter, nearly circular in outline" at the eyepiece of the 60-inch.

It was immediately picked up in my 18-inch at 175x as a small, elongated bluish object. At 450x, the planetary was clearly bipolar (size 10"x7") with two lobes oriented WSW-ENE, pinched in the center. At 800x, the planetary has an irregular knotty structure with subtle brightness variations along the length. In addition the planetary seemed to have an extremely faint outer envelope or "wings" (like the fainter portion of M27) that was most evident on the south side increasing the size to nearly 13"x10" and changing the major axis to NW-SE.

Merrill 2-2 = PN G100.0-08.7
22 31 43.7 +47 48 04, V = 11.5; Size <2"
Discovered on an objective-prism plate taken by William Miller in 1939 at Mt. Wilson. The discovery was announced by Paul Merrill in 1941.

I starhopped over to Me 2-2 from 4.4-magnitude 5 Lacertae, located 23' WSW. Identified by blinking with an OIII filter at 175x. Without a filter, this mag 11.5 planetary had a slightly soft appearance and a very pale, blue color. A good comparison star is located just 32" WNW. Me 2-2 is slightly brighter than this star unfiltered but up to 3 magnitudes brighter using the an OIII filter. A faint star is sandwiched midway betwseen the planetary and the star 32" WNW. No additional details were visible at 323x - just a soft bluish star, perhaps 1.5" diameter. Situated in a rich star field.

Vy 2-3 = PN G107.6-13.3
23 22 58.0 +46 53 58, V = 13.5; Size 5"
Discovered by William Miller at Mt Wilson in 1945. It was visible at 175x as a soft blue-grey mag 13.5 star. Good response to an OIII filter which increased the contrast, though not dramatically. Clearly nonstellar at 450x with a "starry" center or central star surrounded by a small, faint halo ~3" diameter. At 800x the halo appears elongated or irregular.

Hubble 12 = PN G111.8-02.8
23 26 14.8 +58 10 55
V = 11.8; Size 1"
Discovered by Edwin Hubble in 1920 at Mt Wilson Observatory. At 175x it appeared as a mag 12 "star" and was identified by blinking with an OIII filter. Forms a wide double with a mag 12.5 star 1' ENE. Although the listed size is only 1", at 450x a very faint, very small halo was resolved. Also a couple of fainter stars were visible between the planetary and the mag 12.5 star. At 800x the mag 13.8 central star was surrounded by a very small, faint 2" halo. The halo was verified by comparing the appearance of a nearby similar magnitude star.---

Observing Reports Observing Sites GSSP 2010, July 10 - 14
Frosty Acres Ranch
Adin, CA

OMG! Its full of stars.
Golden State Star Party
Join Mailing List
Mailing List Archives

Current Observing Intents

Click here
for more details.