Stellar spirit

Abell 33

Ghost of a dying star

In the western reaches of elongated Hydra, near the western border of Sextans you will find a ragged string of four stars ranging in magnitude from 6 to 8 aligned northeast to southwest located 1.7° south of 4th magnitude Iota Hydrae and 2.5° east of 5th magnitude Tau1 Hydrae (a fine, widely spaced double star). The third star from the west (and slightly out of line with the other three stars) is 7th magnitude HD 83535. This bluish-white star is superimposed on the edge of a ghostly planetary nebula known as Abell 33. My best view of this limpid pool of nebulosity was achieved with a 20mm Plössl (yielding a magnification of 45x) and an OIII filter. This setup revealed a small faint disk of tenuous nebulosity about 4½’ in diameter in contact with the 7th magnitude star on its southwest edge. The edges of the disk were reasonably sharp and the brightness faded gradually toward the darkened center. At other magnifications (both with and without the filter) the view was less distinct and the nebula became almost impossible to detect at magnifications above 60x. The 16th magnitude central star was not visible, but a trio of 13th magnitude stars (two of them a close pair) are perched on the northwestern edge of the nebula.

Abell 33 was discovered on Palomar Observatory Sky Survey plates by George O. Abell and published in the April 1966 Astrophysical Journal (Abell 1966). These nebulae, being very faint and of relatively large angular size are classified as ‘old’ or ‘evolved’ planetary nebulae. Observing the 86 objects in Abell’s catalogue constitutes one of the supreme observing challenges for amateur astronomers with large-aperture scopes; fortunately a few of them, including this one, are accessible in fairly modest equipment provided the observer has access to very dark skies and an OIII filter. Recent estimates place Abell 33 at a distance of about 1,100 light years from Earth (Phillips 2005), which implies an actual diameter of about 1.4 light years.

Subject: Abell 33 (PK 238+34.1)
Object Type: Planetary Nebula
Constellation: Hydra
Right Ascension (2000.0): 09h 39m 09.1s
Declination (2000.0): -02° 48′ 31″
Magnitude: 12.4n/15.7s
Diameter: 268″
Classification: 2b

Observer: Eric Graff
Location: Cuyamaca Mts., San Diego Co., California (4,000 ft. elevation)
Date & Time: 12 March 2007 at 04:30UT
Transparency: NELM 6.7, TLM ~14.1
Seeing: Pickering 5-6/10
Telescope: Parks Astrolight EQ6 (6″ f/6 Newtonian Reflector)
Eyepiece: 20mm Parks Gold Series Plössl (45x, 70′ TFoV)
Filter: Lumicon OIII Filter
Sketching Materials: #2 pencil, black ink, blending stump, 24# copy paper

Abell, George O. 1966. Properties of Some Old Planetary Nebulae. Astrophysical Journal. 144:259-279.
Philips, J.P. 2005. The distances of highly evolved planetary nebulae. Monthly Notices of the Royal Astronomical Society. 357:2:619-625.

A rose by any other name

Rosette Nebula

The Rossette nebula, NGC 2237-8, 46

Here is a challenging object. It was at the threshold of visibility for me and my gear. The nebulae was visible at a power of 12.5 (40mm EP) and at 19x (26mm EP). It vanished at any higher power!! The sketch was made with help of a lumicon UHC filter. But the most significant aid in detecting the ghostly glow was wobbling the scope left and right. The eye is more sensitive to moving ghosts than to steady
ones. As a result of the UHC filter, the fainter stars are lost. But I wanted to concentrate on the nebulae. The sketch was made in Photo-Paint, based on a raw pencil-sketch behind the scope. I hope you like the view.

Rony De Laet

Sketch data:

Date : March 9, 2007
Time : 21.00UT
Scope : Skywatcher 102/500
EP : 26mm SP
Power : 19x
FOV: 2.7°
Filter : Lumicon UHC
Seeing : 3/5
Transp. : 2.5/5
Sketch Orientation : N down, W left.

Famously floor fractured

Famously floor fractured

Lunar crater Petavius

The end of winter in the Midwest can sometimes produce cold, clear, wind free nights. On this particular night the waning gibbous Moon cleared the tall barren trees where I had set up my 10″ scope to observe and sketch. After examining the Moon awhile at low power I selected a target close to the terminator for sketching. Near the edge of the southeastern corner of the Sea of Fertility is the large ancient crater Petavius. Connected by a rampart to the west (just right of Petavius) is 57 km Wrottesley. To the east of Petavius buried deep in shadow is the Palitzsch Valley, asequence of overlapping craters that extends for nearly 112 km. The atmosphere was in such turmoil that much of the subtle detail was obscured at the time of this observation. The multiple mountain peaks on the floor of Petavius stood out as did the terraced walls and the 60 km long straight rille from the central peaks to the southwest rim. Even under conditions of poor seeing this is a rewarding crater to observe a couple of days past full Moon. If you missed it, try again 3 days past New Moon. From March to the end of spring the waxing crescent Moon is a great target in the Northern Hemisphere.

Frank McCabe

Sketch data:

For this sketch I used black Strathmore 400 Artagain paper 9″ x 12″, white and black Conte’ pastel pencils and a soft blending stump.

Telescope: 10 inch f/5.7 dobsonian and 6mm eyepiece

Date: 3-6-2007 2:45-3:30UT

Temperature: -6C (21 F) Clear Calm

Seeing: Antoniadi IV

Colongitude: 113.5 degrees

Lunation: 16.5 Days

Illumination: 95%

A dark horse

A dark horse

The Horsehead nebula is among the most photographed denizens of the deep-sky. But it is rarely the subject of a visual observation, much less a sketch. I made this observation the night of January 20, 2006, almost ten years to the day after my first observation of this ellusive object. Formally designated Barnard 33 (B33), the Horsehead is a dark nebula seen in the foreground of the delicate emission nebula IC 434. The contrast between IC 434 and the Horsehead is quite subtle; like a whisper in the night. But as long as the sky darkness and transparency are good, a 6-inch aperture is up to the task of seeing the famous Horsehead. On this night, the view in my 18-inch Obsession was truly stunning. Even unfiltered, the inky black form of B33 was obvious at 109X (22-mm Nagler Type 4 w/ Paracorr). My sketch represents a combination of two views. The first was unfiltered to reveal as many field stars as possible. The second was with a Lumicon hydrogen-beta (H-beta) filter in place to record the full glory of the B33/IC 434 complex. The Horsehead cuts into IC 434 along the nebula’s eastern edge. It is distinctively darker than the surrounding sky, having a genuine inky blackness as if someone has carelessly left the tip of their quill too long against the sky. The back of the horse’s neck, head, brow, and snout are all discerned. Some 60 stars frame the view.

I used HB and 2B Staedtler Mars Lumograph graphite pencils to make the drawing on a sheet of white printer paper. Gentle rubbing with the tip of my right index finger lended softness to the background nebulosity.

Bill Ferris
Flagstaff, Arizona