Observing Report: LSA 4/22-25

by Doug Hudgins

After what has seemed like an interminable string of new moon times punctuated by iffy to poor to downright awful weather, the gods in charge of such matters relented this month. April's new moon this past Monday was instead tucked into a string of pleasant and cloud-free (if not bone-dry) days and nights such as has not been seen 'round these parts in many moons (literally). I was not about to let the opportunity pass me by. Since commissioning my 24" f/5 Kriege-style Dobsonian last September, weather and other factors have conspired to allow only 3 - count 'em, 3 - nights of observing with the scope, and each of those was marked by mediocre-to-poor seeing. So it was with an anticipation approaching that of first light that I packed my gear in the Suburban Sunday afternoon and headed out for three night's observing at Lake San Antonio in southern Monterey County.

I arrived at the overflow campground to find my observing partner (who would not appreciate being identified) already setting up his scope. He had brought his magnificent 14.5" f/6 equatorially-mounted newtonian. This massive scope - sporting the classic white Parks fiberglass tube that was for many years an icon of amateur astronomy - is a bear to set up, but is optically one the finest I've ever had the privilege to look through. Superb contrast, razor-sharp star images - the views through this scope approach that of a high quality refractor. And my partner would know - he also has a 7" AP Starfire! I set up my scope, with its signature astroscan finder, nearby in the middle of the "baseball" diamond.

This was my third time out with the scope, so I have had the opportunity to "tweak" its design to optimize its performance. Most notably, I have added a simple, adjustable tube counterweight system to the secondary cage that allows me to fine-tune the balance of the scope. Now, at any elevation, I can go from my heaviest eyepiece (Alan Nelm's venerable TeleVue 20mm Nagler) to my lightest eyepiece with no drift of the tube. Other than that, the changes have all been small and purely cosmetic - a tribute to the sound engineering principles of the Kriege design. I am quite satisfied with the scope's operation now.

Observing conditions were good for this time of year, still struggling with the transition between rainy- and dry-season weather patterns. Daytime temperatures ranged from the mid-seventies when I arrived Sunday afternoon, to the mid-eighties by Tuesday afternoon. Nighttime temperatures were cool, but not unduly so - I estimate low- to mid-forties. Despite the dry weather pattern, dew was our constant companion all three nights. Nevertheless, while inconvenient, it never became so bad that it shut us down. There was no nighttime wind at all (hence the dew problem). Fog did impinge on us by about 3:00 AM on Sunday night, but the other nights were clear dusk-to-dawn. Overall, seeing varied from good to very good over the three nights, and transparency was good.

As is my wont, I spent most of my effort tracking down planetary nebulae. My constant companion in this endeavor is the beautiful and thorough tables of planetary nebula data compiled by Steve Gottlieb and Kent Wallace which I downloaded from Doug Snyder's www.blackskies.com web site. This resource is an absolute must for anyone who wants to get "off the beaten track" with planetary nebulae. If you have not been to the site, I highly recommend it. While I will not provide an exhaustive list of all the objects I observed over the three nights (largely because I didn't KEEP an exhaustive list of all the objects I observed over the three nights), I have included below some of my favorites...

NGC 2346, PK 215+03.1
position: RA 07 09.40 dec +00 38.6
constellation: Mon
eyepieces: 32 SWA (96x), 20 Nag (154x), 16.8 MV (183x), 13.8 SWA (223x), 10.5 MV (293x)
filter: OIII

visible, but unremarkable w/o filter in 32 SWA; improves nicely w/ OIII filter; stands magnification well; higher powers hint at associated structure, perhaps a halo of fainter nebulosity; central star (mag 11) easily seen.

Abell 20, PK 214+7.1
position: RA 07 22.99 dec +01 46.2
constellation: CMi
eyepieces: 32 SWA (96x), 20 Nag (154x), 16.8 MV (183x)
filter: UB, OIII

Very subtle; not seen w/o filter; seen best w/ 32 SWA/OIII combo and only with averted vision; OIII filter works best w/ this object; W/ highest power I get the impression of a somewhat irregular shape and/or structure.

K 1-11, Abell 22, PK 215+11.1
position: RA 07 36.11 dec +02 42.3
constellation: CMi
eyepieces: 32 SWA (96x), 20 Nag (154x), 16.8 MV (183x)
filter: UB, OIII

Very faint seen only with filter and averted vision; not detected w/o filter; star associated (not central star); maybe just the barest hint of structure glimpsed?

NGC 2610, PK 239+13.1
position: RA 08 33.39 dec -16 09.0
constellation: Hya
eyepieces: 32 SWA (96x), 24.5 SWA (125x), 20 Nag (154x), 24.5 SWA/2x barlow (250x)
filter: OIII

Attractive, smooth disk located in equilateral triangle of 8th mag stars; asymmetric brightness and apparent flaring along one limb gives nebula a "cometary" appearance.

NGC 2818, PK 261+08.1
position: RA 09 16.03 dec -36 37.8
constellation: Pyx
eyepieces: 32 SWA (96x), 20 Nag (154x), 16.8 MV (183x), 13.8 SWA (223x)
filter: OIII

seen both w/ and w/o filter in all eyepieces; mottled, oblong disk; distinct impression of ring structure; star associated with one limb came and went.

Abell 33, PK 238+34.1
position: RA 09 39.13 dec -02 47.6
constellation: Hya
eyepieces: 32 SWA (96x), 20 Nag (154x), 16.8 MV (183x)
filter: OIII

Not seen w/o filter in any eyepiece, but reasonably apparent w/ filter; assoc. with group of 7-8 mag stars, one on limb; somewhat oblong, mottled - perhaps annular - appearance.

NGC 3132, PK 272+12.1
position: RA 10 07.00 dec -41 26.7
constellation: Vel
eyepieces: 32 SWA (96x), 20 Nag (154x), 16.8 MV (183x), 13.8 SWA (223x), 10.5 MV (293x), 16.8 MV/2x barlow (366x)
filter: UB, OIII

Amazing object; easily apparent w/o filter in lowest power eyepiece; stands magnification well; best views w/ UB filter; exhibits wealth of structure, most notably a dark annulus w/in the diffuse brightness of this somewhat oblong nebula.

NGC 3242, PK 261+32.1, "Ghost of Jupiter"
position: RA 10 24.81 dec -18 38.2
constellation: Hya
eyepieces: 20 Nag (154x), 16.8 MV (183x), 10.5 MV (293x), 16.8 MV/2x barlow (366x)
filter: OIII

bright, distinctly bluish disk of uniform brightness with embedded brighter annulus and central star apparent; reminiscent of the Eskimo Nebula.

K 1-22, PK 283+25.1
position: RA 11 26.73 dec -34 22.2
constellation: Hya
eyepieces: 32 SWA (96x), 20 Nag (154x)
filter: OIII

Not seen without filter; seen confidently with filter and averted vision; large, irregular shape with hints of structure.

Abell 35, PK 303+40.1
position: RA 12 53.57 dec -22 52.3
constellation: Hya
eyepieces: 40 MV (77x), 32 SWA (96x), 20 Nag (154x)
filter: OIII

large, faint but clearly seen glow surrounding 9th mag star; not seen w/o filter; appears more or less circular and uniform; maybe just the barest hint of structure.

Haro 4-1, PK 049+88.1
position: RA 12 59.41 dec +27 37.8
constellation: Com
eyepieces: 32 SWA (96x), 16.8 MV (183x)
filter: UB, OIII

small, essentially stellar in appearance; found by comparison w/ and w/o filters; many galaxies mucking things up in region.

Lo8, PK 310+24.1
position: RA 13 25.62 dec -37 45.2
constellation: Cen
eyepieces: 32 SWA (96x), 20 Nag (154x), 16.8 MV (183x), 13.8 SWA (223x), 10.5 MV (293x)
filter: UB, OIII

???very tough object; with averted vision, I seem to get the impression of a patch of nebulosity associated with a star a about the correct position, but its only ~5 - 10% of the time and it does not seem to be perceptibly affected by either filter; a lot of "lumpy darkness" in the vicinity - interestingly, although this object is not plotted in Uranometria, it is mentioned in the entry for the galaxy NGC 5121 which lies just 11' SW. The note on Lo8 mentions, "other low surface brightness nebulae NE". Perhaps this is the source of the "lumpy darkness"??

[NOTE: upon returning to work, I looked up the image of Lo8 in Longmore's original paper. Indeed, IIRC, the nebula is associated with the star to which I refer above. However, the object is VERY subtle and I still have doubts as to whether I was actually seeing it.]

Abell 36, PK 318+41.1
position: RA 13 40.63 dec -19 53.2
constellation: Vir
eyepieces: 32 SWA (96x), 20 Nag (154x)
filter: OIII

not seen w/o filter; faint, roughly circular disk of nebulosity around mag 11 central star; mottling apparent, but not particularly annular.

IC 972, Abell 37, PK 326+42.1
position: RA 14 04.44 dec -17 15.3
constellation: Vir
eyepieces: 32 SWA (96x), 20 Nag (154x), 16.8 MV (183x), 10.5 MV (293x)
filter: UB, OIII

Oval, fairly smooth disk; some suggestion of mottling at highest power w/ filter; both filters work well with this object; some hint of brightening along one limb of nebula.

NGC 6058, PK 064+48.1
position: RA 16 04.42 dec +40 40.9
constellation: Her
eyepieces: 16.8 MV (183x), 16.8 MV/2x barlow (366x)
filter: UB, OIII

attractive, slightly oblong nebula with hint of annular structure at high power; central star (mag 13.6) seen w/ and w/o filters.

IC 4593, PK 025+40.1
position: RA 16 12.25 dec +12 04.4
constellation: Her
eyepieces: 32 SWA (96x), 20 Nag (154x), 16.8 MV (183x), 10.5 MV (293x), 10.5 MV/2x barlow (586x)
filter: OIII

small, bright nebula with distinct bluish color; oblong; central star (mag 11) easily seen; at high power, get the impression of a halo of fainter, irregular nebulosity (?) but power is really pushing the limits which the seeing allows.

Abell 39, PK 047+42.1
position: RA 16 27.52 dec +27 54.4
constellation: Her
eyepieces: 32 SWA (96x), 20 Nag (154x)
filter: OIII

large, faint oval with distinct annular appearance; invisible w/o filter, glimpsed with direct vision and held solid with averted using filter; very nice.

NGC 6210, PK 043+37.1
position: RA 16 44.50 dec +23 48.5
constellation: Her
eyepieces: 16.8 MV (183x), 10.5 MV (293x), 16.8 MV/2x barlow (366x)
filter: OIII

beautiful, bright blue/green oval; filter shows this oblong disk to be associated with a fainter halo having a complex, mottled appearance.

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