Jeremy Perez – Page 149 – Astronomy Sketch of the Day

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.

A Brilliant Irony

Venus
Terrestrial Planet
By Eric Graff
Parks Astrolight EQ6 • 6″ f/6 Newtonian Reflector
7.5mm Parks Gold Series Plössl + 2x Barlow • 240x, 13′ FoV
30 September 2007 • 13:00-13:30 UT

It is somewhat ironic that the most brilliant planet in the sky is also the most challenging to observe. On 30 September 2007 Venus appears as a dazzling crescent (32% illuminated) in the morning sky, 42° west of the Sun and shining at magnitude –4.7.

This observation was made during morning twilight and the white cloud-tops of Venus displayed a fair amount of subtle, dusky shading, seemingly in a series of roughly parallel arcs curving northward. The shadings were most prominent toward the terminator, while the polar-regions were quite bright, particularly the southern cusp. In spite of the atmospheric subtlety, I found the observation of the large Venusian disk quite relaxing and relatively easy compared to the previous observation of the tiny Martian disk.

Holmes in a Spin

Comet 17/P Holmes
28th October 2007
18:40 UT Mag 2
Reflector FL 1200mm/8mm eyepiece/150X Pastel/Conte/Black Paper

Here is my sketch from October 28th, I got going early to avoid the predicted cloud cover. I had a long look into the halo around the nucleus. The material emanating from the pin point center seemed to be heading in a more southerly direction than I had observed in previous evenings. I could see darker areas fanning in the opposite direction in the inner halo. A star was visible just inside the outer halo. Because I could see a star through the out gassing then it must be very thin? The star was visually similar in size to the comet nucleus but a little dimmer. Sometimes the coma seemed to momentarily have transparent spaces within it. I have not seen a star in the area of the dark spaces, I wonder if these spaces are filled with dust?

All this was visible even though there was a 17 day moon rising almost directly under the icy action.

Deirdre Kelleghan
President
Irish Astronomical Society 1937 – 2007
Public Relations Officer IFAS
http://www.deirdrekelleghan.com/
http://homepage.eircom.net/~irishas/index.htm
http://www.irishastronomy.org/

Walther’s Ray of Sunshine

Sunset Ray on the Floor of Walther

Crater Walther (formerly known as Walter) lies on the southern lunar highland’s great peninsula facing almost directly toward the earth. This is an ancient land, high, heavily bombarded and Walther is a Necterian age, 145 kilometer member. This walled-plain crater has tall terraced walls that tower 4 kilometers above the crater floor. The off center central peak stands 1.6 kilometers above the surrounding floor. The ancient rim is heavily cratered and has several incisura along its circumference created by impacts. Before sunset and at just the right time light penetrates through a notch in the western rim and sprays light across the floor to the central peak and several floor crater rims beyond in an eastward direction. The remainder of the floor is completely dark creating the frozen searchlight view that I attempted to capture in this sketch. West of the notched wall is crater Deslandres W with its large rim blocks which separates it from the hellplain, Deslandres to the west. Walther also has a sunrise ray that can be seen beyond first quarter at just the right time.

The following webpage gives the times of lunar ray events for craters including Walther. http://www.lunar-occultations.com/rlo/rays/rays.htm

Sketching:

For this sketch I used: black Strathmore 400 Artagain paper, 8”x 8”, white and black Conte’pastel pencils and a blending stump. Brightness was slightly decreased after scanning.
Telescope: 10 inch f/ 5.7 Dobsonian and 6mm eyepiece 241x
Date: 11-2-2007 11:40-12:40 UT
Temperature: 0°C (32°F)
Clear, calm
Seeing: Antoniadi III
Co longitude: 115.4°
Lunation: 22.3 days
Illumination: 43.6 %

Frank McCabe

Note to visitors: Frank dedicated this stunning sketch to Rich Handy last week in the Cloudy Nights sketching forum. Thank you Frank. I’m sure we all echo your wish that Rich have a speedy rebuild and return home.

Jeremy