Category: open clusters

A Smoky Cascade

IC 1318(c)

IC 1318(c)
Sketch and Details by Eric Graff

Object Name: IC 1318(c) (West Extension)
Also Known As: LBN 236, LBN 240, LBN 241, DWB 52, GAL 077.7+03.4
Object Type: Emission Nebula
Constellation: Cygnus
Right Ascension (2000.0): 20h 17.1m
Declination (2000.0): +40° 50′
Magnitude: —
Size: 40′ x 25′

Date/Time: 27 July 2008 • 05:45 to 07:00 UT
Location: Oakzanita Springs, San Diego Co., California, USA
Telescope: Parks Astrolight EQ6 • 6″ f/6 Newtonian Reflector
Eyepiece/Magnification: Parks 20mm Gold Series Plössl • 45x • 70′ FoV
Filters: Lumicon OIII
Conditions: Clear, Calm, 64°F
Seeing: Pickering 6-7
Transparency: NELM 6.4; TLM 14.2

This cascade of stars shrouded in smoky wisps of nebulosity caught my attention as I made the star hop from Gamma Cygni to IC 1318(b). The cascade ends at the sparse open cluster Collinder 419, whose brightest star is a close pair known as Struve 2666 (6.0, 8.2; 2.6″; 245°). Just northeast of this cluster the narrow stream of nebulosity blossoms into a hazy morass of delicate nebulosity – this is IC 1318(c). Fifth magnitude HD 193092 blazes with a reddish-orange light to the south.

Sketch Info: Nebulosity sketched with graphite applied with artist chamois and blending stump on 24# paper in 7½” circle. Stars with pencil and ink, cleaned up digitally (and colorized) in Microsoft Picture It!

Binocular Treasure in Vulpecula

NGC 6940

NGC 6940
Sketch and Details by Rony De Laet

My first encounter with NGC 6940 was one of pure coincidence. I was sweeping with the binoculars along the rich Milky Way star clouds of Cygnus without any preparation. While trying to find the location of the Cirrus nebula, I stumbled upon an oval brightening in the sky, as large as the full moon. It was an enchanting, yet mysterious object. I did not know of such an object in the constellation Cygnus. This marvellous object turned out to be NGC 6940, an open cluster which belongs to the constellation Vulpecula. The easiest way to locate NGC 6940 is to start from … Cygnus, indeed. First locate Epsilon Cygni. Then move south to 52 Cygni, and a little west to 41 Cygni. Now move south until 41 Cygni borders the northern edge of the field of view. And voilà, there is NGC 6940. My 8×56 binoculars show a conspicuous, elliptical haze bordered with a handful of foreground stars. The lucida of this cluster is a mag 9 red giant. Therefore my binoculars don’t resolve many stars from the glowing haze. The cluster’s distance is about 2700 light years and its age is a respectable 800 million years. NGC 6940 is a very rewarding open cluster, and should be included in every tour of the summer constellations!

Site : Bütgenbach, Belgium
Date : June 28, 2008
Time : around 23.30UT
Binoculars : Bresser 8×56
FOV: 5.9°
Filter : none
Mount : Trico Machine Sky Window
Seeing : 2,5/5
Transp. : 4/5
Nelm : around 5.9
Sketch Orientation : N up, W right.
Digital sketch made with Photo Paint, based on a raw pencil sketch.

(Note: if the sketch does look too dark on your monitor, try to darken the room.)

Luminous Lagoon

M8

M8 – The Lagoon Nebula
Sketch and Details by Kiminori Ikebe

M8 (NGC 6523) Sgr diffuse nebula
Difficulty level 1
The Lagoon Nebula
Date of observation: 1998/05/27 03:20
Transparency/seeing/sky darkness: 3/3/4
Instruments: 32cm Dobsonian with XL21 at 70x and OIII Filter
Width of field: 0.9 degree

Complex structures are visible. There is the open cluster NGC 6530 near the center, which can be seen clearly even with the OIII filter. The brighter part of the nebula is divided into three regions. A triangular-shaped nebulosity in the southwest is the brightest with 9 Sgr (mag 6.1) shining at the center. There is a small, somewhat fainter region south of 9 Sgr. The second brightest region extend from the center to the south, which contains the open cluster NGC 6530. Between the brightest and next brightest regions lies a clear winding dark lane like a large river. The “banks of the river” is bright and a magnificent sight. At the southern end a sharp protrusion like a horn is visible. Although it is faint, the outline is sharp. North of the brightest region lies the third brightest region. It extends from the east to the west and the eastern half is bright providing a fine sight. With a close examination you can detect a faint nebulosity east of NGC 6530. It is large and looks like a very faint mist. In 10×42 binoculars, there are two bright spots side by side in the east-west direction within a narrow triangle. There is a double involving 7 Sgr at the western end of the triangle. There is a star near the center of the western part of the bright region. This star is 9 Sgr and the bright nebulosity surrounding it is clearly seen. The eastern part is rather elongated with the same orientation with NGC 6520. The globular cluster NGC 6544 is clearly seen in the southeast.

Forked Cluster

Trumpler 32

Trumpler 32
Sketch and Details by Eric Graff

Object Name: Trumpler 32
Also Known As: C1814-133, Harvard 19
Object Type: Open Cluster
Constellation: Serpens (Cauda)
Right Ascension (2000.0): 18h 17.2m
Declination (2000.0): –13° 21′
Magnitude: 12.2
Size: 4′

Date/Time: 4 July 2008 • 06:45 to 07:10 UT
Location: Oakzanita Springs (4,010 ft. elevation), San Diego Co., California, USA
Telescope: Parks Astrolight EQ6 • 6″ f/6 Newtonian Reflector
Eyepiece/Magnification: Parks 20mm Gold Series Plössl + 2x Barlow • 90x • 35′ FoV
Filters: None
Conditions: Clear, calm, 62°F
Seeing: Pickering 4-5
Transparency: NELM 6.3; TLM 14.0

Approximately ½° northwest of M16 you might notice a small delicate patch of mist strewn with faint stars. This is the open cluster known as Trumpler 32. The cluster is elongated north to south and I count about two dozen stars superimposed on a haze of fainter, unresolved members. A curious dark lane separates the southern third of the cluster from the rest of the group.

Foaming Starlight

M11

M11 – The Wild Duck Cluster
Sketch and Details by Carlos Hernandez

I was able to observe one of my favorite open clusters M11 (NGC 6705) in Scutum on August 9, 2008 (5:00 U.T.). This magnificent open cluster appears as an explosion of jewels in space. This spectacular collection of stars has an estimated 2,900 members of which 500 are brighter than 14th magnitude. It lies at an estimated distance of between 220 to 250 million light years. I made the observation using my 9-inch (23-cm) F/13.5 Maksutov-Cassegrain at 78x.

A digital image made using Photoshop CS3.

Links:
http://www.hawastsoc.org/deepsky/sct/index.html
http://apod.nasa.gov/apod/ap030122.html
http://www.maa.clell.de/Messier/E/m011.html

Carlos

Cassiopeia’s Sparkling Owl

NGC 457

NGC 457: The Owl Cluster
Sketch and Details by Frank McCabe

At a distance of 9,300 light years (2850 parsecs) this youthful open cluster is about the same age as the Perseus Double Cluster – eight million years old. NGC 457 in Cassiopeiae is composed of nearly 100 stars brighter than magnitude 13 and many fainter members. The cluster has several names including the Owl cluster, the E.T. cluster, the Phi Cas. cluster and others. The two brightest stars here, Phi Cas. and HD7902 may not actually be members of this open cluster but rather foreground stars. These two stars form the bright eyes of the owl. Phi Cas. is a magnitude 5 yellow star and HD 7902 is a magnitude 7 bluish star. If the brighter member is a cluster star at 9,000 light years it would have a luminosity of 275,000 suns. The integrated visual magnitude of this cluster is about 6.4 and it is 16’ across. This object was discovered by William Herschel in 1787. It can easily be found 2° south-southwest of delta Cas. (R. A. 1h. 22’, Dec. +58° 2’).

Sketching

Date and Time: 8-11-2008, 5:20-6:40 UT
Scope: 10” f/5.7 Dobsonian. 13mm eyepiece 111x
8”x11” white recycled sketching paper, 4B soft charcoal pencil, HB hard charcoal pencil, blending stump, scanned and inverted, some star magnitude adjustment made at the time of scanning.
Seeing: Pickering 5/10
Transparency: Average 3/5
Nelm: 4.2

Frank McCabe

Sting Like a Butterfly

M6

M6 – The Butterfly Cluster
Sketch and details by Rony De Laet

One of the binocular highlights of Scorpius is M6, the Butterfly Cluster. This bright open cluster forms a splendid duo with M7. These two bright – naked eye – clusters were known since antiquity. While they can be squeezed in a single field of view, I rather prefer to dedicate a single sketch to each one of this brilliant duo.

M6 can be found at the tail of the Scorpius at 5° north of Lambda Scorpii. In a pair of binoculars, the cluster appears 15’ wide. A dozen stars are visible with direct vision. Averted vision can reveal another 15 stars. The binocular low power does not make it easy to distinguish the individual stars in this dense packed cluster. So take all the time you need to study M6 in detail. The lucida of the cluster, at the edge of the eastern wing of the butterfly, is the orange variable BM Sco. Don’t be surprised that your observation does not match my sketch, because BM Sco can fluctuate between mag 5.8 and 8.0. The Butterfly Cluster is 1600 l-y away. Its true size is estimated at 14 l-y.

Site : Andratx, Mallorca, Spain
Date : July 25, 2008
Time : around 22.15UT
Binoculars : TS 15×70 Marine
FOV: 4.4°
Filter : none
Mount : Trico Machine Sky Window
Seeing : 2,5/5
Transp. : 4/5
Sky brightness : 21.00 magnitudes per square arc second near zenith (SQM reading).
Nelm : 6.4
Sketch Orientation : N up, W right.
Digital sketch made with Photo Paint, based on a raw pencil sketch.

(Note: if the sketch does look too dark on your monitor, try to darken the room.)

Bejeweled Ink Spot

NGC 6520 and Barnard 86

NGC 6520 and Barnard 86
Sketch and Details by Kiminori Ikebe

A dark nebula telescopically easy and an beautiful overlapping open cluster. A photograph taken by a 200mm lens shows a small dark nebula and a compact open cluster at the southern edge in addition to M8 and M20. At 110x B86 is quite clear. The field is lit up by the Milky Way stars but a dark triangular shape region to the west of NGC 6520 is quite conspicuous. It appears as if the area is literally painted black and is called the “Ink Spot.” A line of stars along the base of this triangle. A hint of a long dark nebula to the southwest of NGC 6520. This is not as conspicuous as B86; not visible with direct vision. NGC 6520 is beautiful, compact, and “lively.” Bright stars are scattered across. Faint stars are concentrated in some areas.

Milky Way Sights

Lagoon Nebula and Vicinity

Lagoon Nebula and Vicinity
Sketch and Details by Carlos Hernandez

My South Florida weather cleared temporarily on July 30, 2008 (04:00 U.T.) and allowed me to tour the Milky Way with my Oberwerk 11 x 56 binoculars. Many targets were visible but the Lagoon Nebula (M8) and Trifid Nebula (M20), as well as M21 and M28 caught my eye. The Lagoon Nebula (M8, NGC 6523) was visible as an elongated nebulosity which included clumps of stars (NGC 6530). The Trifid Nebula (M20, NGC 6514). The open cluster M21 was visible north of the Trifid Nebula and M28 towards the east (left).

A digital rendering made using Photoshop CS3.

Carlos