Astronomy Sketch of the Day – Page 267 – Drawings and sketches of an astronomical nature

The Astounding Geometry of Clavius

Clavius Crater and Craterlets
By Serge Vieillard

Clavius is the 3rd largest crater on the earth-facing side of the moon (225 km in diameter), and was formed during the Nectarian period about 4 billion years ago. It is most famous for the arc of craterlets arrayed across its floor in counterclockwise order of descending size.

Serge created this sketch on August 14, 2006, during a trip to Southern Italy. He observed the moon with his Strock 250, plotting finer details during brief moments of steadier seeing.

A Brooch in the Horns of the Bull

NGC 1647
By Jeremy Perez

Observation Notes:
I first noticed NGC 1647 between the horns of Taurus in a wide-field astro photo I shot of the area in November 2005. I had been meaning to observe and sketch it since then. At 37.5X magnification, the cluster appeared large, bright and sparse. Two colorful yellow and yellow-orange stars rested at the south side of the cluster. I noted several doubles within. The diameter of the main body of the cluster appeared to be about 30 arc minutes. Several bright Orionids graced the sky and caught my attention during the observation and sketch.

Object Information
NGC 654 was discovered by Friedrich Wilhelm Herschel in 1784. According to Catalogue of open cluster parameters from UBV-data. (Loktin+, 1994), the cluster is about 509 parsecs distant (1,660 light years). Star Clusters and Associations, Selected Data (Alter+ 1970) lists a distance of 550 parsecs (1,790 ly). The cluster is also catalogued as Cr 54, Mel 26, OCL 457, Lund 139, H VIII-8, GC 896.

Tuttle’s Steady March

Comet 8P/Tuttle
By Martin Mc Kenna

8P/Tuttle Sketch on Dec 10/11th 2007 using a 8.5″ F/7 reflector with 32mm 1.25″ eyepiece. Tuttle was very high in the circumpolar sky within Cepheus approximately 1.5 degrees from Gamma Cephei – the naked eye star which marks the ‘roof’ of this house-shaped constellation. This sketch shows the position of Tuttle with respect to a triangle of bright field stars at 18.20, 20.13 and 21.55 UT. The comets rapid NE motion is very obvious. This is slow compared to how fast it will be moving when closest to the Earth during late December when it will be a faint naked eye object. The comet is a short period object with prograde motion meaning it moves around the Sun in its orbit in the same direction as the planets and main belt asteroids. The icy nucleus of this comet is several kilometers in diameter. If it hit the Earth it would most likely cause a near extinction event!.
Martin Mc Kenna

Grucian Propeller

NGC 7496
By Eiji Kato

NGC 7496 is an 11th magnitude Seyfert Galaxy in Grus that displays a barred spiral structure. It is a member of the IC 1459 Grus Group and weighs in at about 80 Billion Solar Masses. This galaxy was discovered by Sir John Herschel in 1834 at the Cape of Good Hope with an 18-inch f/13 speculum telescope.

Sources:
The Deepsky Observer’s Companion Website
Gas dynamics in barred spiral galaxies. II – NGC 7496 and 289
NGCIC.org

Solar Cornucopia

Solar Observation – November 23, 2007
PCW Memorial Observatory
By Erika Rix

Well the new active region doesn’t appear to have a designation yet (or even if it will), but I was able to make it outside for a few hours to observe. It was only scattered clouds during the observation and a little windy and chilly. But with the Sun at a very low altitude of approximately 27 degrees, it was still a struggle against time to observe in both h-alpha and white light before the trees obscured by view.

Paul opened up the observatory for me and by the time I got my scopes switched on the LXD, he was coming in with a cup of hot tea for me and Riser was curled up in a ball at my feet on his blanket.

The first thing I noticed in the Maxscope was a small bright plage area almost dead center in the solar disk. Bumping up the magnification, I found that it was actually broken off into two sections with fainter “arms” reaching to the east and west of it. There were hints of two darkened spots on either side of it, but I couldn’t confirm it in that bandwidth.

There were three areas of prominences on the Eastern limb, two that are included in the close-up sketches. On the western limb, there were just a few very tiny areas that looked like little spikes.

Just north of the prominence at approximately 90 degrees was a bright patch of plage, almost oblong with the western edge outlined a slightly darker hue. A very thin line of filament branched inward from the limb just north of the 90 degree mark, but could not see it extend outward off the limb against the dark background.

The prominence on the 140 degree mark had a fairly broad sectioned filament running north to south about 15 degrees inside the limb. It was broken into three obvious sections as well as a few very thin lines of filament in the same area.

After a brief few moments enjoying the countryside view from the drop down southern wall of the observatory, I grabbed my clipboard, a few pencils, my empty cup of tea and marched off to the house in my slippers and knitted hat, with Riser following close behind.

The ETX is stored in the house for a few reasons. The observatory isn’t quite big enough to house all the scopes plus it’s easy access for white light viewing to just drag the already set up scope outside from the living room.

Within minutes, I was sat behind the ETX with my sketchpad on my knee, recording what the new active region looked like in white light. There were two dominant smaller spots with an additional fainter spot just off of the larger one. Then, reaching out to the other side of the spots were long thin faint lines. I didn’t notice faculae, but I imagine the dark lines may have been the contrast of border from faculae.

The views were slightly softened today, so it was difficult to view granulation, but limb darkening was very noticeable.

h-alpha sketch media: black Strathmore Artagain paper, white Conte’ and Prang pencils, white Conte’ crayon for disk surface

white light media: copy paper, number 2 and .5mm mechanical pencils

Wolf-Rayet in Vela

Gamma Velorum
By Rogerio Eirado

The brilliant Gamma Velorum system is composed of at least 6 stars. The primary star of this system is actually a spectroscopic binary that has been dubbed the Spectral Gem of the Southern Skies because its exotic spectrum is dominated by bright emission lines rather than dark absorption lines. It is composed of an O9 blue giant and a massive Wolf-Rayet star that are separated by 1 AU and orbit with a period of 78.5 days. The Wolf-Rayet star probably started its life at around 40 solar masses, but has blown most of that mass away and is now probably closer to 10 solar masses. Both stars in this pair have extremely powerful winds, and as these winds collide they produce X-Ray emissions. The Wolf-Rayet star is likely in the last stages of its path toward exploding as a Supernova. It’s companion will eventually follow suit. The B component seen in Rogerio’s sketch is a B-class subgiant and the C and D components (lined up above the A and B components in the sketch) are white A-class stars. The D component itself has a much fainter and challenging 13th magnitude companion separated from it by 1.8 arc seconds (the 6th star in the system).

Rogerio sketched this beautiful multiple star using pencil on white paper. The sketch was then scanned, inverted to a positive image, and digital methods were used to enhance and add observed color to the stars. His sketch gallery can be found here: A vida, o universo e tudo o mais.

Sources: Burnham’s Celestial Handbook, Jim Kaler’s ‘Regor’, Wikipedia

Sculptor’s Reticulated Showpiece

NGC 55
Edge-on Barred Magellanic Galaxy in Sculptor
By Eric Graff

Parks Astrolight EQ6 • 6″ f/6 Newtonian Reflector
15mm Parks Gold Series Plössl • 60x, 52′ Field of View
11 October 2007 • 05:30-06:30 UT

The late Walter Scott Houston wrote, “Some deep-sky objects offer beautiful, breathtaking visual experiences. NGC 55 is one such object.” Christian Luginbuhl and Brian Skiff call this galaxy “one of the most interesting and detailed in the sky.” Stephen James O’Meara named it “one of the night sky’s finest wonders.” Clearly, this galaxy has something of a reputation. As I slewed my scope toward 2nd-magnitude Alpha (α) Phoenicis (my guide star for this particular object), I wondered if the view would live up to the high praise these respected observers offered up to this edge-on Magellanic-type galaxy on the southern border of Sculptor.

Centering the golden giant Alpha Phe in my 30mm eyepiece, I quickly located NGC 55 by offsetting my scope 2° west of Alpha and sweeping a little over 3° north. Star-hoppers may wish to follow a ragged line of 6th-7th magnitude stars northward from Alpha Phe and then west toward the galaxy.

Despite its southerly declination (culminating only 18° above my southern horizon), NGC 55 is indeed a stunning sight in the eyepiece. This large, bright galaxy displays a fascinating degree of detail including its three “nuclei”, extensive mottling (particularly in the bright, central region), and a reticulated network of dark lanes.

James Dunlop discovered NGC 55 on August 4, 1826. Distance estimates range from 4.2 million light-years upward toward 7 million light-years (with the smaller distance estimates being more current). Most astronomers place NGC 55 in the Sculptor Group of galaxies, but some have suggested that NGC 55 (together with NGC 300) are foreground objects and members of our own Local Group of galaxies.

Information provided by Eric Graff

A Feast in the Martian Desert

Mars
By Sol Robbins

In describing his sketching technique for recent Mars sketches, Sol noted:

It occurs to me that there is a bit of a change taking place in my sketches. One change is in regard to the paper I am using which is very smooth. It is from Office Depot, Super White Platinum Series. That’s in concert with using just a 2H pencil.

Seems like I can get a range of gray tones that are pretty close to each other. These tones are evident in that last couple of Mars sketches which shows my newer ability to render details in light and dark albedo features with more subtlety. This paper accepts and holds on to graphite in a very controllable way.

It holds up well to rubbing when working up details which helps a lot in allowing a wider range of lifting or erasing graphite quickly. Blends smoothly too. Gray tones can be worked up faster.

I guess all of the above just adds up to being able to have a perceivable/scanable depth or richness when working on computer print out paper with a simple pencil. Blending stumps work very well on this paper too.

Its a 20 lb paper and acid free.

Walled Plain Neighbors

Hecataeus and Humboldt
By Frank McCabe

At nightfall a beautiful orange waning gibbous moon just a day past full was rising at the early summer sunrise point on the northeastern horizon. The cold atmosphere was nearly saturated with water and ice creating some ice fog and reduced transparency. By 11:30 pm local time the moon was high enough in the sky for a close up view, although the temperature had plunged to well below freezing. The telescope was completely covered with thick hoar frost at the beginning of my sketching interval. I used extended time on this sketch to go indoors to warm my fingers. My sketching target was crater Humboldt and its smaller neighbor Hecataeus. Upper Imbrium era Humboldt is a large floor fractured, walled plain formation, 207 kilometers across. High on the convex floor a line of central peaks and craters can be seen in the foreshortened view. Just as seen in nearby Petavius (not visible in the sketch) dark pyroclastic deposites were visible at the corners of the floor. Floor fractures here and on neighboring Hecataeus to the left could not be detected visually at the eyepiece because of less than ideal seeing. Hecataeus at 130 kilometers in diameter and slightly older than Humboldt was showing off a substantial wall line on its floor just proximal to crater Humboldt.

Sketching:

For this sketch I used: black Strathmore 400 Artagain paper, 9”x 9”, 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: 11-25-2007 5:30-7:00 UT
Temperature: -3°C (27°F)
ice fog, calm
Seeing: Antoniadi III
Co longitude: 95.9°
Lunation: 15.3 days
Illumination: 99.4 %

Frank McCabe

Parabolic Leviathan in Perseus

Comet 17P/Holmes
By Michael Rosolina

This is a recent view of the incredible, expanding, and ever-changing comet C17P/Holmes. Holmes is best viewed at low power so the observer can take in the entire coma, now greater in diameter than the Sun.

The outburst which produced this expansion may have a second act–the 1892 apparition had two outbursts about 75 days apart–so Holmes continues to be a worthwhile target for the amateur observer. It is best seen in a moonless sky, although the view holds up amazingly well even when Luna is present.

The sketch was done at the eyepiece with an HB graphite pencil, a blending stump, and a kneadable eraser on Strathmore 400 series 60 pound paper and inverted digitally after scanning.

Michael Rosolina
Friars Hill, WV USA