Eye of the Raven

Object Name: NGC 4361
Also Known As: H.I.65, PK 294+43 1, PN G294.1+43.6, VV 62
Object Type: Planetary Nebula
Constellation: Corvus
Right Ascension (2000.0): 12h 24m 30.8s
Declination (2000.0): –18° 47′ 05″
Magnitude: 10.3n/13.2s
Diameter: 45″/110″
Voronstov-Velyaminov Type: 3a+2
Distance: 2,600 light years
Discovery: William Herschel on 7 February 1785 with 18.7-inch reflector
NGC Description: vB, L, R, vsmbMN, r

Telescope: Parks Astrolight EQ6 • 6″ f/6 Newtonian Reflector
Eyepiece/Magnification: 7.5mm Parks Gold Series Plössl • 120x • 26′ Field of View
Filter: None
Date/Time: 30 April 2011 • 05:00-05:45 UT
Observing Location: Oakzanita Springs, Descanso, San Diego Co., California, USA
Transparency: NELM 6.2; TLM 14.1
Seeing: Pickering 7-8
Conditions: Clear, calm, cold, humid

I found this bright planetary nebula easily by sweeping 5° due east of my previous target, NGC 4038/9. If you are seeking this object out on its own, it lies in the northern portion of the keystone-like shape of the Crow, and forms a right triangle with Delta (δ) and Gamma (γ) Corvi. As the brightest deep-sky object in Corvus, it is faintly visible in 10×50 binoculars under a dark sky.

At 30x magnification, NGC 4361 appears as a small circular patch of colorless nebulosity with a brighter center in a field sprinkled with bright and faint stars. The central concentration, while prominent, could not clearly be resolved as the central star.

At 60x magnification NGC 4361 displays a bright inner ellipse in position angle 115° surrounded by a fainter outer halo. The central star is intermittently visible as a stellering in the center of the ellipse. Variations in brightness are suspected in the outer shell. At 120x magnification the central star is clearly and steadily visible, even with direct vision. The inner shell appears slightly brighter in its NE half, and faint spiral “arms” can be traced through the outer halo. The nebula remains colorless (or “white”) at each of these magnifications. In many ways this object looks a lot more like a galaxy than a planetary nebula through the eyepiece. At 240x magnification NGC 4361 appeared dim and very diffuse, with the 13th-magnitude central star blazing through the fog. This lack of definition prompted me to back the magnification down to 120x for the sketch.

At 120x magnification, most of the prominent stars visible in the low-power view have been pushed out of the field of view. Only TYC 6105-1027-1, yellow-orange, 8.7′ NE, and TYC 6105-1204-1, blue-white, 10′ NNW, both 11th-magnitude are bright enough to rival NGC 4361. The remaining field stars range from 12th down to 14th magnitude.

The sketch presented here depicts the view at high magnification (120x). The sketch has been rotated so that north is up and west is to the right. The sketch was produced with a No. 2 mechanical pencil with 0.5 mm lead, and three blending stumps (8948B, 8943B, and 8941B) on 100 lb. white card stock. The original drawing measures 7½ inches across.

This observation was made from a reasonably dark site (borderline blue-green on LP maps) at an elevation above 4,000 feet. The NELM was estimated at 6.2, the TLM at 14.1 in the vicinity of the target. The seeing conditions were above average (Pickering 7-8), but the humidity was quite high and care had to be taken to prevent dew from accumulating on optics and sketching materials. The temperature was 37°F. The air was very still and the high magnification views very steady.

Eric Graff


New Active Region

2011 05 09, 1429UT-1550UT
Solar NOAA 11203, 11204, ??, 11209, 11208

www.pcwobservatory.com

PCW Memorial Observatory, Zanesville, Ohio USA – Erika Rix
DS 60mm Maxscope, LXD75, 21-7mm Zhumell, ETX70 AT w/tilt plate and white light glass filter.

All sketches done scopeside and flipped in Photoshop to match standard orientation. H-alpha sketch created with black Strathmore Artagain paper, white Conte’ crayon and pencil, Derwent charcoal pencil, black oil pencil. White light sketch created on photocopy paper with 0.5mm mechanical pencil and #2 pencil.

Transparency made it nearly impossible to view prominences at the start of the session with the thin layer of cirrus creating a milky white sky. There were small breaks that allowed me to sketch in some of the detail on a western prominence, that later as the transparency improved, showed an abundance of thin whispy structure that wasn’t captured on paper. By that time, I was already working on a full disk sketch in h-alpha. Seeing was terrific until I started on the white light observation, but had I set up the ETX at the beginning of the session to let the scope adjust to the warmth, it would have been much better by the time I observed with it. As it was, I observed in the observatory for protection of the wind as I view with a shade attached to the objective and wanted to avoid vibration.

There is a possible new active region between 1209 and 1208 that, while observing in white light, had several little spots forming an elliptical shape with pointed ends like a football. I noticed facula around 1208, but the seeing was so bad that I couldn’t make out a definite shape. The umbra of the preceding spot in that region was displaced, as was the preceding spot in 1203. I didn’t notice any sunspots in 1209 during my observation, but that may have been the result of the seeing.

The band of active regions is still putting on a nice show in h-alpha with more-defined plage around them.


Well Tuned Antennae

Object Name: NGC 4038/9
Also Known As: H.IV.28, Arp 244, the Antennae, Ring Tail Galaxies
Object Type: Interacting Galaxy Pair
Constellation: Corvus
Right Ascension (2000.0): 12h 01m 53.2s
Declination (2000.0): –18° 52′ 38″
Magnitude: 10.7
Dimensions: 4.5′ x 3.6′
Hubble Class: S?/pec
Distance: 63 million light years
Discovery: William Herschel on 7 February 1785 with 18.7-inch reflector
NGC Description: 4038 – pB, cL, R, vgbM; 4039 – pF, pL

Telescope: Parks Astrolight EQ6 • 6″ f/6 Newtonian Reflector
Eyepiece/Magnification: 7.5mm Parks Gold Series Plössl • 120x • 26′ Field of View
Filter: None
Date/Time: 30 April 2011 • 04:15-05:00 UT
Observing Location: Oakzanita Springs, Descanso, San Diego Co., California, USA
Transparency: NELM 6.2; TLM 14.2
Seeing: Pickering 7-8
Conditions: Clear, calm, cold, humid

This interacting galaxy pair is best located about 50 arc minutes NNE of the fifth magnitude star HD 104337, the brightest star on the western border of Corvus. While you are in the area you might do well to look for NGC 4027 30′ NW of HD 104337 and NGC 3981 68′ WSW of that star. The Antennae would be a challenging target for binocular observers.

At 30x magnification, this galaxy pair appears as a soft asymmetric patch of nebulosity, larger and brighter toward the north, smaller and fainter toward the south, but with no other details readily visible. Another soft, featureless patch of nebulosity may be glimpsed in the same field of view, 42′ away to the SW; this is NGC 4027, an 11th magnitude barred spiral galaxy and a fine target in its own right.

At 60x magnification, the Antennae or Ringtail galaxies are clearly resolved as two separate (though attached) objects. Together they look like a lopsided heart or a bloated “V”, with occasional glimpses of mottling across the face of the nebulosity. At 120x magnification the western rim (shaped like a backward “S”) of the pair is clearly brighter and more distinct than the rest of the object. During moments of good seeing this bright rim breaks into several distinct knots. The central region of NGC 4038 appears almost hollow by comparison; perhaps this is why Herschel catalogued this object as a planetary nebula. Averted vision revealed occasional glimpses of the base of the southern tail.

At 120x magnification NGC 4038 and NGC 4039 share the 26′ field of view with 9th-magnitude TYC 6097-326-1, white, about 6.5′ NW, 10th-magnitude TYC 6097-415-1, orange-red, about 9.5′ S, 11th-magnitude TYC 6097-619-1, yellow-white, about 10.8′ NE, 11th-magnitude TYC 6097-288-1, yellow-orange, about 13′ NNW, and 11th-magnitude TYC 6097-629-1, yellow, about 12.5′ NW. The remaining field stars are in the 12-14 magnitude range.

The sketch presented here depicts the view at high magnification (120x). The sketch has been rotated so that north is up and west is to the right. The sketch was executed with a No. 2 mechanical pencil with 0.5 mm lead, and two blending stumps (8948B, 8941B) on 100 lb. white card stock. The original drawing measures 7½ inches across.

This observation was made from a reasonably dark site (borderline blue-green on LP maps) at an elevation above 4,000 feet. The NELM was estimated at 6.2, the TLM at 14.2 in the vicinity of the target. The seeing conditions were above average (Pickering 7-8), but the humidity was quite high and care had to be taken to prevent dew from accumulating on optics and sketching materials. The temperature was 37°F. The air was very still and the high magnification views very steady.