globular – Page 15 – Astronomy Sketch of the Day

Globular Cluster M30

M30
Sketch and Details by Frank McCabe

Fall has arrived in my neighborhood and some of the Ash trees have begun dropping their golden leaves. On this evening the sky had cleared nicely and I took that opportunity to observe and sketch a favorite globular cluster in Capricornus. Globular cluster Messier 30 has for decades been a favorite to visit as it approaches the meridian. This cluster was discovered by Charles Messier on August 3, 1764. It is located less than 7° south of gamma Capricorni and when on my meridian is only 25° above the horizon. This object is 8 kiloparsecs (26,100 light years) from us and measures somewhere between 90 and 140 light years across. The visual magnitude of this cluster is 7.4 and is the deep sky showpiece of Capricornus. The small dense core is bright and noticeably ellipsoidal in shape. Most of the cluster stars that resolve well (mag.12) are to the north of the core. Two short chains of stars extending northward give this globular the appearance of legs in the inverted Newtonian telescope view. The brightest star in the field of the sketch is fifth magnitude 41 Capricorni. If you have a dark sky this is a fine target for a small telescope.

Location of M-30: R.A.21hrs. 40 min; Dec. -23° 11 min.

Sketching:

9”x11” white sketching paper; 2H, HB graphite pencils, black ink pen and a blending stump;
Scanned and inverted; brightness of some stars adjusted with MS Paint.
Scope: 18” f/5 Dobsonian: 12 mm wide field eyepiece 190x and 7.5 mm eyepiece 304x
Date and Time: 10-4-2008, 1:45-2:30 UT
Seeing: Pickering 5/10
Transparency: Average 3/5
NELM: 4.3

Frank McCabe

Sagitta’s Stellar Nexus

M71
Sketch and Details by Ernest Shekolyan

Hi!

That is my picture of M71 (globular cluster NGC 6838 in Sagitta 8.4m, 7.2′).
The sketch was done 27 July 2006 at village Ponizovka, South Crimea (Ukraine) under very dark sky (visual limit for naked eye was better 6.1m). 10″ 1:5.6 Dob, 6 mm UWA (Synta), 230x, FOV: 20 ang. minutes, graphite pencil, white paper, then photocopy + level correction, crop and inverting in ACDSee.

Sincerely yours, Ernest Shekolyan

Binoculars Along the Spine of the Scorpion

Antares, M4, and Rho Ophiuchi
Sketch and details by Michael Rosolina

Scorpius is well placed right now for northern hemisphere observers and holds many beautiful and interesting objects. Scanning the constellation with widefield binoculars can be particularly rewarding. I found that I could see this trio all at the same time with my 15×70 binoculars. They make an interesting combination: Antares, a red giant, Rho Ophiuchus, a bright binocular triple, and Messier 4, a globular cluster containing countless stars.

The sketch was done in the field with 2B and HB pencils and a stump loaded with 4B graphite for M4. I then scanned and inverted the sketch digitally, colorised Antares, and added a little blur (5%).

There are many images of this region–time exposures showing the stars embedded in glowing clouds of gas and dust. None of that can be seen visually, but the binocular view has its own beauty.

Michael Rosolina
Friars Hill, WV USA

Halo Wanderer

Globular Cluster, M62
Sketch and Details by Frank McCabe

Globular Cluster M-62 (NGC 6266)

In the halo of the Milky Way our home galaxy there are about 160 or so globular clusters orbiting the galactic center. Like life forms they are mostly alike but each is uniquely different in size, shape, density, chemistry, and the like. At 22,500 light years (l.y.) from us this globular is only 6100 l.y. from the galactic center. This cluster is also known to be distorted in shape from spherical due to tidal forces acting upon it by the galactic center. More than 200 RR Lyrae variable stars reside in this globular, a much higher number than most and in the spring of 2002 Chandra X-ray Observatory discovered a rich population of close X-ray emitting binary stars in this globular. M-62 is located on the Ophiuchus side of the constellation border with Scorpius. From my location near Chicago it never rises higher than 19° above the southern horizon. But even on an average night it is an impressive sight in a moderate telescope. This globular cluster was discovered by Charles Messier 237 years ago last month.

Other Features for M-62

R.A.17hrs. 1 min.; Dec. -30°7 min. Epoch 2000
Average distance between stars 0.25 l.y.
Diameter 100 l.y. across 14 arc minutes
Visual magnitude 6.5

Sketching:

9”x11” white sketching paper; 6B, 4B, HB graphite pencils and a blending stump;

Scanned and inverted; brightness of some stars adjusted with MS Paint.

Scope: 10” f/5.7 Dobsonian: 24 mm widefield eyepiece 60x and 12 mm eyepiece 121x

Date and Time: 7-2-2008, 4:00-4:40 UT

Seeing: Pickering 6/10

Transparency: Below average 2/5

NELM: 4.4

Frank McCabe

Above the Great Sand Sea of Namibia

47 Tucanae
Sketch and Details by Dave Riddle

It has been said that if we used all our senses to the fullest, we would stand in a constant state of amazement. Perhaps a telescope is merely a way to extend one of our senses — the gift of eyesight. I have come to appreciate how fortunate I have been to fulfill a few of childhood dreams. When the opportunity arose back in 2004 to visit Africa and take a five day road trip from Johannesburg, South Africa to the Great Sand Sea of Namibia, I jumped at the chance. I would spend eight weeks at the Sossusvlei Mountain Lodge under what must be some of the darkest skies found on our planet. The chance for daylight sightseeing combined with exploring the night skies of the southern hemisphere proved too much to resist…I’ll argue that the celestial wonders visible through a telescope are just as impressive as some of the other natural wonders seen along the way — the Augrabies Falls of S. Africa, the herds of elephants or the remarkable sand dunes of Sossusvlei. Submitted is a Photoshop rendering of 47 Tucanae, arguably the finest globular the heavens can offer. I used a 12″ Schmidt-Cassegrain at 250X to make the original graphite pencil and ink.

Dave Riddle

A Surprising GC

M92, a surprising globular cluster in Hercules
Sketch and Details by Jeremy Perez

I didn’t realize how nice this globular cluster would look. It stood up well to magnification, with stars resolving across the face of the cluster. It appeared noticeably elliptical in its outer reaches, pointing southwest to northeast. The core was soft but robust. It seemed that the core’s brightness was harder along the north side, and faded more softly to the south. I would estimate its dimensions at 6′ x 4′. Also, the core seemed to reside closer to the south-southeast side of the overall body of the cluster. A bright yellow star hung about 6′ to the east of the core. Overall, the cluster gave the offhand appearance of an elliptical galaxy.

Factoids:
M92 is a globular cluster about 26,000 light years away in the constellation Hercules. It is a bit more distant than it’s brighter, neighboring cluster M13. An age estimate of 16 billion years is being re-evaluated based on new distance scale information for the universe from the Hipparcos satellite, and so may be a bit younger. Its 14′ extension yields a diameter of 109 light years, and may have a mass of about 330,000 solar masses. It is approaching us at 112 km/sec. The precession of Earth’s axis will cause M92 to become our “North Cluster” or “Polarissima Borealis” in about 14,000 years, as it was previously, about 12,000 years ago.

Subject M56 (NGC 6341)
Classification Globular Cluster (Class IV)
Position* Hercules [RA: 17:17.1 / Dec: +43:08]
Size* 14.0′
Brightness* 6.4
Date/Time June 30, 2005 – 11:00 PM
(July, 2005 – 06:00 UT)
Observing Loc. Flagstaff, AZ – Home
Instrument Orion SVP 6LT Reflector (150 mm dia./1200 mm F/L)
Eyepieces/Mag. 10 mm (120X)
Conditions Clear, breezy, 68�F
Seeing 5-6/10
Transparency Mag 5.8 NELM
Sources SEDS
*Based on published data.

M13 by way of Binoculars

M13
Sketch and Details by Rony De Laet

The Great Globular in Hercules.

One of the finest globular clusters for northern hemisphere observers is undoubtedly M13 in Hercules. With a magnitude of 5.8, the cluster is a naked eye object under mag 6 skies. The cluster is also an easy to find object, even for novice observers. Just draw a line from Eta Herculis to Zeta Herculis and you’ll bump into M13. Just put Eta at the northern edge of the field of view, and M13 will appear centered in your view. Under dark skies, the Globular can be seen without optical aid as a tiny smudge of light.

While many globulars have a star like core, M13 appeared to me with a granular core. Its halo is very large compared to other globulars. I could detect a mag 10 star at the western border of the halo. The bright star at the top of the sketch is Eta Herculis.

With M13 riding high in the sky, try to compare it with other globulars like M3, M5, M10 and M12. At first, these globulars may all look alike. But with patience, each globular will show slightly different features!

Site : Bischofshofen, Austria
Date : May 3, 2008
Time : around 22.30UT
Binoculars : Bresser 8×56
FOV: 5.9°
Filter : none
Mount : Trico Machine Sky Window
Seeing : 3/5
Transp. : 4/5
Nelm : 6.0
Sketch Orientation : N up, W right.
Digital sketch made with Photo Paint, based on a raw pencil sketch.

Majestic Swarm

NGC 5139 (Omega Centauri)
Sketch and Details by Dave Riddle

My attempt to sketch Omega Centauri caused me to recall the trials faced by Frederick Catherwood, the famed British illustrator, while he tried to capture the Mayan “idols” found in Central America during the early 1800s. As recounted in C. W. Ceram’s “Gods, Graves, and Scholars”, Catherwood faced the daunting task of reproducing forms that were utterly different from any any thing he had experienced before and “for a time his crayon simply would not function.”

I spent an hour or so studying NGC 5139 before starting my sketch. Using a 12″ Schmidt-Cassegrain at 100X, prominent stars chains, clumps of stars and mysterious dark voids made their appearance. At first glance, Omega had appeared as a rather structureless oblate globe of stars.

My original graphite pencil and ink drawing was made on the evening of April 18, 2005 with rather poor seeing conditions and a waxing gibbous moon over the desert of Namibia. The submitted drawing is a Photoshop interpretation of the sketch.

Dave Riddle

Bisected Globular

M4
Sketch by Michael Vlasov

M4 lies about 7,200 light years away, and is one of the closest globular clusters. It displays a bar-like structure that runs through its center. The bar consists of 11th magnitude stars, is 2.5′ long and runs at a position angle of 12°. The cluster is obscured by interstellar matter, and so is dimmed greatly. Deep photography reveals a diameter of 36, equating to 75 light years, whereas its visual diameter has been estimated at 14′. At Class IX, it is one of the most open of globular clusters, with a half-mass radius of 3.65′ or 8 light years.

M4 was discovered by De Chéseaux in 1745-46 and subsequently catalogued by Messier in 1764 who resolved it into stars. It was the only one he could resolve, calling it a “cluster of very small stars”, and so was the first globular ever resolved into stars.

Source: SEDS.

Globular with a Wealth of Variables

M3
By Cyprien Pouzenc

Lying about 33,900 light years away in the constellation Canes Venatici, M3 is a globular cluster populated by about a half million stars. This cluster is notable for being rich in variable stars and also contains a relatively large number of Blue Stragglers. It provides a visual delight to the telescopic observer, as noted by Cyprien Pouzenc in this sketch from Southern France. Cyprien’s translated notes can be seen below:

Sketch done with graphite pencil on white paper.

Object : M 3
Nature : Globular Cluster
Constellation : CVn

RA : 13h 42′ 11,2″
Dec. : +28° 22′ 48″

– Date, hour, duration : 10-05-07, 22:35 TU, 9′
– Location, elevation : La Roque d’Anthéron (south of France), 175m

– No wind, T°16
– T1 (limit magnitude in UMi with naked eye : 6.17), P1 (light
pollution), S2/200x (Seeing) — all in 0 to 5 scale, 0 is the best.

– Reflector : Meade Lx90, 203/2000, F/10

Comments :
200x, H=73°; Circular cluster saw in direct vision, seemingly
fully resolved in beautiful dust of stars. A luminous central area
without important gradient is surrounded by a halo less luminous and by
a crown very grainy.

Web page of this object : http://cyprien.pouzenc.free.fr/M-3.htm
Web site : http://cyprien.pouzenc.free.fr

Clear Sky !

—
Cyp