Astronomy Sketch of the Day – Page 270 – Drawings and sketches of an astronomical nature

The Water Bearer’s Spiral

NGC 7293 – The Helix Nebula
By Eiji Kato

The Helix Nebula lies roughly 450 light years away, making it one of the closest planetary nebulae (distance estimates range from 85 to 590 light years). With a diameter of 16′ for the main portion of the nebula and an outer halo diameter of 28′ its apparent size is among the largest known planetary nebulae. Although the nebula is intrinsically bright, its large size makes it a difficult target for visual observation under less than ideal sky conditions. It was discovered by Karl Ludwig Harding before 1824.

More of Eiji’s deep sky and comet sketches can be found in his gallery.

A Trio of Isolated Prominences

Solar Prominences
By Erika Rix

Seeing today was terrible and I tried my best to hang in there for a few good moments to see anything on the other half of the Sun. There was a small prominence, but I just wasn’t able to catch the fainter large one that others were able to see.

I did have some nice views by playing with the Etalon. There were some hairline filaments, or perhaps just darkened lines, scattered about on the disk. And three areas of proms on the eastern half of the Sun can be shown in the sketch.

Sketch done on black Strathmore Artagain paper with Conte’ and Prang white pencils. The graphic on the upper right is from Les’ Tilting Sun program. Some areas blended slightly with fingertip.

Early Details of a Golden Comet

17P/Holmes
Periodic Comet
By Eric Graff

Parks Astrolight EQ6 • 6″ f/6 Newtonian Reflector
7.5mm Parks Gold Series Plössl • 120x, 26′ Field of View
26 October 2007 • 09:45-10:15 UT

On the 23-24th of October, 2007 Comet 17P/Holmes experienced a major outburst, increasing its brightness 1 million times in just a few short hours, rising from 17th to 2nd magnitude. Such events are usually caused by the sudden release of gas and/or dust particles from the comet (the yellow color suggests the latter, in this case). During the early morning hours of October 26, the smoke from the Southern California fires had cleared sufficiently to make this observation. To the unaided eye, 17P rivaled the brightest “star” in the constellation Perseus – appearing only slightly less prominent than magnitude 1.8 Alpha (α) Persei (Mirfak). In 10×50 binoculars it had a bright yellow hue and looked slightly fuzzy or unfocused.

Through the eyepiece of my telescope the golden hue was striking as was its brilliance, near-perfect circular symmetry, and sharp stellar pseudo-nucleus. It resembled a huge, bright, yellow planetary nebula about 4′ in diameter. At high magnifications (120x, 240x) the central regions of the comet displayed considerable detail. A bright arc of material extends from the nucleus from south to west, with three prominent streamers involved in and extending from this arc. The circular coma has a somewhat annular appearance. Beyond the bright circular coma, two faint plumes of material, one to the northwest (elongated) and the other to the south-southeast (very broad and diffuse) could be detected by gently rocking the scope from side to side.

This comet was discovered by British astronomer Edwin Holmes on November 6, 1892 while conducting observations of the Andromeda Galaxy (M31). The entirety of its 6.88 year orbit is spent between the orbits of Mars and Jupiter.

Crater Burg and the Lake of Death

Crater Burg and Lacus Mortis

By Frank McCabe

Crater Burg is a young, sharp rimmed crater formed less than 900,000 years ago and can be seen resting at the east center of the ancient Lake of Death or Lacus Mortis. This 40 km. crater with its central peak and well defined ejecta apron is in stark contrast to the old pre-Imbrium crater, Lacus Mortis which embraces it. Interesting terracing can be seen clearly in the low sunlight.
The Lake of Death crater is a large one as craters go, nearly 160 km. in diameter. Its features include rilles across the floor, a few of which are fairly long. Perhaps these floor fractures are from doming of the floor as some lava entered from below. The central bulge of this crater can be seen in grazing sunlight much like crater Petavius. Ridges emanating from the northwest and southwest outer walls of Burg can be seen crossing the lake floor all the way to the rim of the Lake of Death. Just to the west of the south ridge of Burg is a straight scarp that continues as a rille as it nears the lake center. It appears much like Rupes Recta. The east face is brightly illuminated by the setting sun near the southern wall of the lake and it is much taller than the more famous straight wall.
Further west on the lava floor is Rima Burg a 100km. long slump in the floor. It is nearly in line with a shadowed valley seen in the hills beyond the boundaries of Lacus Mortis.
Other craters to the east of Burg are superimposed on the old destroyed rim of Lacus Mortis. They are Plana (45 km.) with a central peak sticking up above the lava flooded flat floor and Mason (43 km.) the other crater to the north which is nearly a twin without the central mountain.

Sketching:

For this sketch I used: black Strathmore 400 Artagain paper, 9”x12”, white and black Conte’pastel pencils and a blending stump. Brightness was slightly decreased after scanning.

Telescope: 18 inch f/5 Dobsonian and 9mm eyepiece 222x
Date: 10-30-2007 6:05-7:00 UT
Temperature: 11°C (52°F)
Clear, calm
Seeing: Antoniadi III
Co longitude: 142.8°
Lunation: 19.3 days
Illumination: 75.1 %

Frank McCabe

A Calculating Cluster

NGC 2169 – The 37 Cluster

By Wade V. Corbei

NGC 2169 is an open cluster located near the apex of Orion’s raised eastern arm. It has become known for an asterism of stars within it that appear form an angular representation of the number 37. NGC 2169 lies 3600 light years away and is receding at about 16 km/sec.*

*Source: SEDS

Triangulum’s Spectacular Spiral

M33 and HII Regions

By Kiminori Ikebe

From the English translation at Mr. Ikebe’s website:

M33 (NGC 598) Triangulum Galaxy – Difficulty Level: 2/5
NGC 588 Tri Star Cloud – Level: 5/5
NGC 592 Tri Diffuse nebula – Level: 4/5
NGC 595 Tri Diffuse nebula – Level: 4/5
NGC 604 Tri Diffuse nebula – Level: 3/5
Date of observation: 1998/11/14 21:55
Observing site: Makinoto
Transparency: 3/5
Seeing: 4/5
Sky darkness: 4/5
Instruments: 32cm Dobsonian and Pentax XL14
Magnification: 110x
Width of field: 0.6 degreeThis is a galaxy with a dynamic spiral arm.
The haze around the core is very faint and requires dark adaptation to see its extent. Once your eye is fully adapted, you will be surprised how extensive the haze is. NGC 604 is bright and located in the northeast of this galaxy. If you spend enough time, you will be able to detect this galaxy’s magnificent spiral structures as well as star clusters and nebulae such as NGC 588, NGC 592, and NGC 595 within the galaxy. The core is compact and elongated. At its center lies a small shining nucleus. There are two arms visible, one in the south and the other in the north; both are spiraled counter-clock-wise. The southern arm is divided into three regions. The northern arm is thin and broken off at places while embedded in haze. Other regions of the galaxy appear as faint haze.

NGC 604: Almost circular and small, but as bright as the center of M33.
NGC 595: A small faint object located near where the northern arm starts. The center of this object appears stellar surrounded by fuzzy nebulosity.
NGC 592: This object looks like a faint small spot.
NGC 588: It is located far from the center of M33 and easily missed. It is a much smaller spot than NGC 592.

Mr. Ikebe uses white pencil and “poster color” on black drawing paper. An extensive collection of his sketches can be found on the English section of his website. A larger collection can be found at the Japanese language site.

Checkmark LONEOS

C/2007 F1 (LONEOS)
By Martin Mc Kenna

Observation notes from Martin’s website entry:

Despite a poor sky with cloud, haze and chimney smoke along with a developing frost the sky cleared from the west on Oct 17/18th and I found the comet extremely quickly at 19.10 BST to the west and slightly south of Arcturus in the darkening evening twilight.

The coma was thin, compact, very well condensed with clearly defined edges where the coma meets the sky. It was wrapped tightly around a large white disk-like central condensation with a tear drop appendage from which a long spine ran into the tail. The coma was elongated away from the Sun and sported several fanning streamers similar in profile to a ‘shuttle cock’. The coma was a white-grey tone however no green could be seen.

The ion tail was blue, very straight, extending for 1 degree to the W of N and broadened with distance away from the Sun. Delicate long blue streamers could be glimpsed in fleeting moments of good clarity. I suspect the tail is MUCH longer than this. I was able to confirm something I have suspected since the morning of the 16th – a faint dust tail visible to the E of N leaving at a shallow angle from the coma perhaps 5′ long. The leading sunward edge of this tail is the brightest component. It will be interesting to watch its development. This is my best evening view of the comet to date.

Lost the comet to cloud so I did a little deep sky work then watched the waxing crescent Moon with earthshine set over the mountains with compact orange corona and long but faint pillar. For icing on the cake a V-shaped formation of geese flow overhead calling as they headed to the NE with bellies and wings lit orange from the town lights!.

Mag+ 6.0 Dia: 3′ D.C: 7/

Martin’s gallery of comet sketches can be found here:
Nightsky Hunter – Comet Sketches

A Mystery Wrapped in a Riddle Covered to the Brim in Lava

Wargentin and Environs
By Richard Handy

Immediately south west of Schickard near the South West limb, lies a crater that can truly be regarded as one of the Moon’s most unusual and enigmatic features. Eighty four kilometer Nectarian aged Wargentin is a cup filled to the brim with ancient mare lavas. Its relatively smooth and flat floor has a series of gently sloped branches from it’s central wrinkle ridge, yet beyond this gentle relief it is almost flush with the crater rim, creating a plateau fully 450 meters higher than the surrounding mare. The maria like surface shows significant albedo (shades of grey tone) differences. There is a coating of light material that appears in patches and sheets most probably of Orientale origin, the last remnants of the skirt of fluidized flow fronts settling out over this region.

There are a few smaller or partial versions of this “filled to the rim” crater phenomena on the lunar surface, however nothing of this size appears anywhere else on the Moon. What special conditions must be satisfied to allow for the creation of this bizarre lunar plateau? We can be assured that the inner crater walls did not have many faults or openings that would have allowed the mare lavas to escape. A close look at the exterior wall shows that it remains relatively free of large secondaries or craterlets. This obvious lack of wall destruction certainly must have played a role in the continued embayment of the lavas over time.

An element that may have been a factor was that Wargentin appears have excavated a deep crater in pre-existing mare units. Hypothetically these denser basalt rims could more effectively embay lavas than the rims of craters in plains or highland areas because of their more compact stratification. Rim material would therefore be much more likely to hold the magma within the inner walls, as the floor slowly crept higher and higher on each new inundation.

The third element is perhaps the least well understood. How did its magma channels, cracks or fissures deep beneath the crater bowl itself, feed this unique crater? In other words what kind of plumbing was required to allow this “bathtub” of a crater to fill to overflowing? There must be a reason that the crater continued to fill up over the millions of years required to lay down such a volume of lava. Or alternately did it fill up, at least partially, in a relatively short time span of tens of thousands of years while still a young feature, perhaps after the impact penetrated into liquid magma filled channels or chambers? Nearby Schickard shows evidence that some mare lava flooding occurred after the dusting by the Orientale impact and therefore argues for a gradual buildup over many tens of millions of years.

Lunar geological research will undoubtedly uncover some of the reasons this remarkable and puzzling feature exists, yet its enigmatic and singular nature may well have to wait for a more sophisticated understanding of the early lunar crust and mantle.

Sketch details

Subject: Wargentin and environs
Date: 3-2-07 (UT) Julian date: 3-1-07
Session Start 6:32 UT End 8.00 UT
Seeing: Antoniadi II-III Weather clear
Lunation 1041, 12.51 days Phase: 20.1 deg Illumination 96.9%
Colongitude: 65.0 deg
Lib in Lat: -02 deg 19 min Lib. in Long: +4 deg 52 min
Telescope: Meade 12” SCT f/10
Meade Star diagonal
Binoviewer: W.O. Bino –P with 1.6X nosepiece
Eyepieces: 12.4 mm Meade Super Plossls
Magnification: 393X
Sketch medium: White Conte’ Crayon on black textured Strathmore paper
Sketch size: 18” x 24”

Tuning in to a Cloven Galaxy

Fifteen million light years away in the constellation Centaurus lies the nearest radio galaxy, NGC 5128. Also known as Centaurus-A, it is categorized as an intermediate galaxy type, with qualities of both an elliptical (which describes its main body) and spiral galaxy (due to the prominent dust band encircling it). Loads of information about this fascinating galaxy can be found at the solstation website. This galaxy’s beautiful and unusual structure has been made famous through astro photographs, but it is also accessible to astronomical sketchers.

This sketch of NGC 5128 by Eiji Kato, was made at the Twinstar Guesthouse Observatory in Queensland, Australia. He notes: “As for my sketch of NGC 5128, it was made at Ballandean using my new 18″ f/4.5 (Galaxy Optics) mirror at 290x (Naglar 7mm eyepiece). It was drawn on white paper with black graphite, and then inverted after scanning. I am still working on this object for further refinement, but have to wait until next season as it is too low now.”

More of Eiji’s deep sky and comet sketches can be found in his gallery. (Note that a few of the links are broken, but don’t let that discourage you from viewing his excellent work.)

Pillars and Threads of Plasma

Solar Prominences and Filaments
By Erika Rix

Erika’s composite solar H-Alpha sketch from October 29, 2007, features prominences along the eastern limb as well as delicate filaments on the solar disc itself. Material used: black Strathmore Artagain paper with a combination of white Conte’ pencil for the brighter, more dramatic areas and white Prang pencil for the fainter areas.