another weekday dark sky

Once again, a dark sky window opened on a Tuesday night.  By luck my work schedule was clear Tuesday afternoon, for the drive down, and Wednesday morning, for the drive back.  I went back to the "tranquility base" site, arriving at 7pm.  This time I brought my 4-/8-inch combo refractor, ready to be more productive in my observing.  After setting up I had my picnic dinner, and watched the day-old moon, fresh off its eclipse the day before, setting behind a nearby rocky ridge.  Its earthshine shown in the darkening dusk, and I had the privilege to watch first the thin bright crescent, then the moonshined sphere itself, set behind the ridge.  

After it being more fully dark, I quickly swept up Pons-Brooks near Jupiter in both the 4-inch and 8-inch.  It had a stumpy, broad fan shaped tail, but I did not see any long extensions coming off it.

I didn't have a set observing plan, though I did use my atlas to find different objects in various parts of the sky.  First up:

NGC 2354: An open cluster in Canis Major, which was a large rich round cluster with a pretty curved main stream delineated by a N-S lack of stars.  10 bright stars and numerous, easily 100, faint stars.   This picture shows a view similar to the low power 4-inch's field, with night vision -- the cluster is just right of center.

ESO 428-29: A small, bright elliptical galaxy close to Eta CMi.  Picked up easily in the 4-inch.

After checking out M46 & M47:

Cluster of open clusters, within the same field in the 4-inch: 

Ru 151: Fairly large, round and faint cluster, well separated, fairly rich with faint stars, with a bright star dominating the center

NGC 2428: Tight group of several bright stars in the middle of a large, round cluster, well defined, backed by another 50 or so fainter stars.

NGC 2430: fainter and smaller than the other two, still well seen and fairly well separated from the rich Milky Way field, it is fairly concentrated and probably 30-40 stars.

I tried once more for the Procyon Nebula.  Knowing it was to the east of Procyon, I held the bright star out of the field and used both 4- and 8-inch and flipped through my filters.  I consistently saw a patchy contrast change from the background sky in the 7nm & 3nm Ha filters, vaguely fan shaped and extending roughly 1-degree from Procyon.  But when I pan around the area, I notice other wispy patches of contrast change, which I believe are part of the Orion-Eridanus Super Bubble.  So I am not really sure if I saw it -- since the nebula is depicted in Finkbeiner as being quite bright.  I contacted Kevin Jardine, who runs the Galaxy Map site, and he said not to read too much into Finkbeiner's low-resolution composite.  There are several other bright stars which have nebula showing up around them, so I'm not sure how to understand this: is it sensor artifacts, or a very localized ionization of hydrogen and not an HII region per se?  

I skipped a lot of objects because they were too small to be enjoyed with my scopes.  I really must do something about the image scale, or get a large aperture dob for dark sky outings.  I did, however, return to some of the nebula I had observed at 1x the week before for a closer look:

RCW 19 = Gum 10, & RCW 20: Finally, a nebula I could explore with more certainty!  This was pretty bright and showed well in the 3nm filter in both the 4-inch and especially the 8-inch.  There is a bright and nearly round patch at the NE end of this long nebula, which in the 8-inch reveals two dark nebula / elephant trunk structures intruding into it from the north.  These were still small scale, but very clear.  The rest of the nebula trailed off to the SE and was generally diffuse and heavily mottled, though the nebula expanded again into a large puffy cloud at the SE end (RCW 20).  Galaxy Map says RCW 19 "is part of a 200 thousand solar mass giant molecular cloud related to the Pup OB3 association and the O7f III giant star HD 69464. This image shows only the bright rim of the larger RCW 19 complex.  Avedisova adds the O9.5 III giant CD -35 4412 as a second ionizing star. She places RCW 19 in the star formation region SFR 253.75-0.50 with the molecular cloud [MAB97] 253.63+0.00 (this may be the cloud mentioned above) and the reflection nebulae Bran 124b, Bran 125b and VdBH 9.

NGC 2467: This very exiting nebula immediately impressed with its two large butterfly-like wings.  The bright concentration is the NGC itself, a round bright nebula centered over a star (Haffner 19 a compact cluster containing a Strömgren sphere which is ionized by a hot B0 V-type star).  From there a bright thick fountain of nebula forms one wing, and a brittle dark lane separated it from the other wing sprouts from a bright knot (Haffner 18, which contains a very young star, FM3060a, that has just come into existence and still surrounded by its birth cocoon of gas).  The rest of this wind is fainter, more diffuse and with a dark nebula running the main length, but larger, especially the top of the wing which trails off quite a distance and tapers.

RCW 27: A fine nebula in the large, loose open cluster Ru64, which consists of 10 brighter and countless fainter stars over a 1-degree area.  With Ha, the nebula is larger than the OC, overall round, thick doughnut shaped with crenellated edges, with a brighter quadrant to the SE.  It appears to be shot through with finger-like dark nebula, especially separating the SE and eastern segments (dark nebula SL 1).  It is very reminiscent of the Rosette nebula, but smaller and fainter.  The bluish, non-stellar glow in the lower right of this astro-photo is the reflection nebula NGC 2626.  I did not notice it in NV (which doesn't do well with reflection nebula with blue wavelengths generally).  Galaxy Map notes "RCW 27 lies in the same direction as the reflection nebula association Puppis R2 in the Vela molecular ridge. A major contributor to the ionization of RCW 27 comes from the O star HD 73882. (SIMBAD gives an O9 III class for this star.) The reflection nebula NGC 2626 is part of the same complex."

Gum 15 & Gum 17: Gum 15 is smaller than RCW 27, but brighter.  It is a mostly round puff centered on a bright star, heavily mottled with dark nebula, and with some viewing appears like a cave lit within by a fire -- the bright star clearing gas and dust from around itself.  It looks like a smaller version of the Trifid Nebula.  There are faint nebulous streams wafting faintly from Gum 15 to the NE.  Wikipedia says "located in the constellation of Vela, Gum 15 is about 3,000 light-years from Earth.  It is shaped by aggressive winds flowing from the stars within and around it. The bright star in the center of the nebula is HD 74804, a double star."

To the SE is Gum 17, more than 2x larger but more diffuse and fainter.  It is also round and mottled, with very faint dark nebula crackling through it.  

NGC 2658: Open cluster in Pyxis, it is small, round, rather faint and slightly difficult to separate from it surroundings, moderately rich. 

I moved on to view galaxies.  I used the 685nm filter the most, and sometimes unfiltered.  I took a tour of the Virgo Cluster, and of course found that NV at the relatively small aperture 8-inch, would show me galaxies just fine (as well as I remember my 20-inch in dark sky showed visually), but they are on a small image scale and not easy to appreciate.  I did change my afocal set-up from 67mm to 40mm, but the smaller exit pupil dimmed the sky so much I lost view of some galaxies.  I tried the Hydra cluster, and I could easily see NGC 3309 and NGC 3311 in a brighter clump between two stars, but the other galaxies were small faint imperfections in the sky darkness: I knew they were galaxies, but they were unsatisfying to look at.  The only way to have more image scale is to use more aperture.  I wish the Challenger scope was easier to use; otherwise, I need to beg others' time to observe on their large dobs or go and buy one for myself.  As it was, I stuck with the brighter, larger objects, knowing it' the most I could get out of the equipment at hand.

One good thing about NV and galaxies is it really helps with edge-on flat galaxies.  In flat galaxies, the dust has blocked blue wavelengths and red predominates, and red is more visible in NV.  I will plan my next spring outing on flat galaxies and globular clusters, and hopefully have a more enjoyable experience.

NGC 2997: Small bright core, diffuse halo, seems slightly inclined -- it's a face-on spiral with strong arms on either side, making it appear inclined to me at low magnification.

IC 2469: Gorgeous, ghostly near edge-on, NE-SW, bright nucleus, fairly bright halo is very long tapers to thin points, is a very rich field.  A faint star is next to the nucleus on the SW side.

A trio of flat galaxies, in a line NE-SW, about equally spaced from each other, look in the field like three tossed coins.  NGC 4216: The largest of the three, in the center of them, it has a bright core, well elongated and thin edge on, NNE-SSW, mottled along the edge especially to the NNE side.  To its SW is NGC 4206, very faint, emerges from the dark, about half the size of NGC 4216, it stands nearly N-S and has a bright nucleus and thin tapering tips.  NGC 4222 is to the NE, the smallest of the three, faint, very elongated NE-SW, close to a fairly bright star to its east.  Really beautiful scene with these three flat galaxies.

NGC 3109: Difficult large faint flat galaxy, very long, 4:1 NE-SW, weak core, it seems to melt into the background.

NGC 3087: Small elliptical with a bright core in a triangle of similar magnitude stars

M61: Bright core, round and diffuse halo which is cut off sharply along the SE side.  Did not notice spiral arms.

M58: fairly large round halo and bright core.  NGC 4567 and NGC 4568, both inclined, elongated galaxies, of similar brightness and size, nearly touch the outer edge of their halos, form an arrow shape.  Very small round non-stellar glow nearby is NGC 4564.

NGC 4927: Elongated, pretty bright, small.  Nearby in a 90-degree difference in position angle is NGC 4536, smaller and fainter (I didn't notice the round halo of this face-on spiral).

NGC 4037: Nice, elongated galaxy, bright nucleus, diffuse 3:1 halo N-S.

M83: Bright nucleus, comparatively large round halo with some hints of spiral structure on the NW side.  I think this would look better with even moderate aperture with glass.

NGC 5102, Iota (Centauri)'s Ghost: A slightly elongated elliptical with fairly bright core near the very bright star.

Omega Centauri filled the 8-inch's 2-degree field, and looked pretty good despite some haze which had built up on the low horizon.  

I tried pretty hard to see ESO 270-17, Fourcade-Figuerora Object, but could not.  It's a galaxy "shred," the remnants of a galaxy which merged with Centaurus A and appears similar to a flat galaxy.  I could see Centaurus A, and its distinctive dark lane, just fine.

I then switched to visual (!) observing.  Using the 8-inch, I found

Abell 35: Weak partial C-shaped glow, with OIII.  Of course what I saw was only the brightest, thickest portion of the nebula.  

NGC 4517: Beautiful, very long flat galaxy, ENE-WSW, very subtly mottled halo, bright nucleus.  A star, brighter than the nucleus, touches the northern edge of the halo.  

NGC 4565: "The Needle": Gorgeous flat galaxy running most of the field SE-NW, clear dark lane splitting the mottled halo which tapers to sharp tips, bright round nucleus.