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SIERRA STAR GAZERS
Observation List for the September 9th Star Party
Site: Community Observatory - Placerville
Tonight we will have exclusive use of the observatory from 7:00pm until 10:00pm. Upon arrival at El
Dorado Center (see SSG event map) please pay $1.00 per vehicle to park in Lot B. It is a short walk up
the hill to the observatory. While personal scopes are welcome, please note that they must be carried
about 200 yards up the paved road. We will have use of several observatory scopes on site. Wise SSG
members will take advantage of them to observe the following objects.
Object
Type
Size
Distance
Coordinates
M11
OC
14’
6,000 LY
18h 51’ - 06 16’
M17
EN
11’
5,000 LY
18h 21’
-16 11’
M55
GC
19’
17,300 LY
19h 40’
-30 58’
M27
PN
8’
1,250 LY
19h 59’ +22 43’
NGC 7023**
OC/RN
18’
1,400 LY
21h 01’ +68 10’
NGC 7009*
PN
44”
1,400 LY
21h 04’
-11 22’
M15
GC
18’
33,600 LY
21h 30’ +12 10’
NGC7331**
Gal
11’
46,000,000 LY
22h 37’ +34 25’
M52
OC
65’
5,000 LY
23h 24’ +61 35’
NGC 7662*
PN
32”
3,200 LY
23h 26’ +42 32’
NGC 891**
Gal
12’
31,000,000 LY
02h 23’ +42 21’
Comet 103PHartley2 (See comet coordinate chart in observatory)
Jupiter (Jupiter will be at opposition on September 27th and is growing larger each evening)
Abbreviations:
MS = Multiple Star, EN = Emission Nebula, RN = Reflection Nebula, Gal = Galaxy, GC = Globular Cluster, LY = Light
Year, OC = Open cluster, PN = Planetary Nebula, SR = Supernova Remnant,
CS = Carbon Star, * = Video imaging optional, ** = Video imaging recommended
OBJECT DESCRIPTIONS
M11 Known as the Wild Duck cluster, this open cluster in the constellation Scutum, (SKEW-tum) is seen
best with the 4” refractor at low magnification. It contains more than 2900 stars and is estimated to be
about 250 million years old. M11 is receding from us at a speed of 27 km/s.
M17 The Omega, or Swan, Nebula in the constellation Sagittarius (Sah-jih-TAIR-ee-us ) is an emission
nebula caused to radiate by bright young stars imbedded within it. The total mass of gas making up the
Omega is roughly 800 times that of our sun. (For visual observing an Olll filter is ecommended)
M55 is a large, loosely constructed globular cluster in the constellation Sagittarius (Sah-jih-TAIR-ee-us)
sized about 2/3 the apparent diameter of The Moon. Having an overall visual brightness of 6.3
magnitude, the cluster has a total luminosity about 100,000 times that of our Sun. It boasts a mean
diameter of about 100 light years. Due to the southerly position of M55, the cluster is best observed in
late summer. Try observing M55 with the 4” refractor at medium magnification.
M27 The Dumbbell Nebula in the constellation Vulpecula (vul-PECK-u-la) was the first planetary nebula
discovered. Through the scope, the brightest sections resemble an hourglass. Averted vision may reveal
the outer gaseous regions that complete the spherical structure of the ejected gas bubble. The age is
uncertain, with estimates ranging from 3,000 to 48,000 years. (Use the Stellacam III or an Olll filter)
NGC 7023 is a reflection nebula in the constellation Cepheus (SEE-phee-us). Commonly known as the
Iris Nebula, the object is outstanding when seen through the 14” and StellaCam III. NGC 7023 is
physically associated with the 7th magnitude star, SAO 19158. Unlike gaseous emission nebulae,
reflection nebulae do not radiate light. Instead, motes of dust reflect the light of bright stars in the vicinity.
Would an OIII filter work on this object? Why?)
NGC 7009 In the constellation Aquarius (ah-QUAIR-ee-us) is commonly known as the Saturn Nebula
due to the extensions on opposite sides of the oblong disk. Discovered by William Herschel in 1782, this
magnitude 8 nebula is activated to emit by an 11.5 magnitude white dwarf in the center. (Use high
magnification and an OIII filter for best image)
M15 is a densely compacted globular cluster in the constellation Pegasus (PEG-uh-sus). This may be
the densest globular cluster in our galaxy. The accepted diameter of M15 is about 175 light years. The
globular cluster is thought by some to contain a supermassive black hole.
NGC7331 Discovered by William Herschel in 1784 in the constellation Pegasus (PEG-uh-sus), this is a
bright spiral galaxy viewed nearly edge-on. Despite this orientation, look for evidence of spiral structure.
M52 is an open cluster in the constellation Cassiopeia (Kas-ee-oh-PEE-ah). This is a young cluster with
an estimated age of 35 million years. It contains several hundred stars, spread across 19 light years,
that were born at roughly the same time. Note the red star that seems so out-of-place in the cluster. It is
actually a foreground star that is superimposed on the cluster.
NGC 7662 In the constellation Andromeda (an-DROM-eh-duh) is a planetary nebula. Commonly known
as the Blue Snowball Nebula, it has a distinctive bluish cast as seen by many observers
NGC 891 In the constellation Andromeda (an-DROM-eh-duh) It is either a type Sa or SBb (barred) spiral
galaxy seen nearly edge-on. Note the prominent perimeter dust lane that divides the disk. Thought to
have been discovered by Caroline Herschel in 1784, this galaxy is approximately 110,000 light years in
diameter and contains over 150 billion stars.
F. Lockhart
9/2010