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AVAS News &
Meetings |
Next AVAS Stargazing Opportunity
The September meeting of AVAS is still being planned but will likely be either Friday, Sept. 10th or Saturday, Sept. 11th. Check back closer to that time for an update.
If you are not already on our mailing list you can use our simple Contact Form to ask any questions about AVAS or to be added to it for notification of the time and location of our next opportunity for group stargazing.
Everyone of all ages and knowledge levels is always welcome to join in stargazing with AVAS. Meetings are informal and are held to provide a group stargazing opportunity. Telescopes will be set up for everyone to enjoy our mid-summer night sky and members will provide descriptions and interesting facts about the celestial wonders being viewed.
The highlights for August include:
The Perseid Meteor Shower the night of the 12th and early morning of the 13th. The peak is estimated to be around 60 per hour. The shower is so named because the radiant (apparent point of origin) is in the constellation Perseus. The best viewing should be after midnight toward the northeast.
Saturn is getting farther from us every day as we outrun it going around the Sun. This month will be the last “decent” chance to see it in the evening until next Spring.
The brilliant, brightest of the evening and second brightest of all stars we see in the northern hemisphere, the orange star Arcturus will be high overhead. Vega, second only to Arcturus will be high in the east and along with Deneb (the top of the Northern Cross) and Altair make up the Summer Triangle. The blue giant star, Spica, will be in the southwest. These stars provide contrasting color examples of the hot, blue stars compared with the cooler, orange and red stars.
Low in the south is the supergiant red star, Antares, in the constellation Scorpius. Antares is about 700 times bigger than our Sun. If it was placed in our solar system it would engulf the orbit of Mars and Jupiter would be about the distance from it that Earth is from our sun. Antares is about 10,000 times more luminous than our Sun. Looking with binoculars just west of Antares is M4 – a dim, fuzzy ball that is a globular cluster located outside the plane of the Milky way.
This is a good time of year to locate the Little Dipper. After sunset each evening it is standing on its handle with the end of the handle being Polaris, the North Star. Polaris can be located using the “pointer stars” of the Big Dipper which are the two stars that form the end of the cup. Follow those stars to the north and you see Polaris almost alone as a moderately bright star directly north. The Little Dipper extends up from Polaris with the cup toward overhead and the top of the cup toward the northwest.
To our west will be the planets Venus, Saturn and Mars clustered together within a 6 degree diameter circle. On August 12th a sliver of the crescent moon will join them.
The Lagoon Nebula (M8) in Sagittarius, the brightest nebula (glowing cloud of inter-stellar gas and dust) in our summer sky is at a more favorable position to see this month. It is only 1 of 2 star forming nebulae visible with the naked eye for us – the other being the Great Orion Nebula visible in winter. Even at its distance of around 5,000 light years (30,000,000,000,000,000 miles) it appears dazzling in a small telescope.
The Summer Triangle will be bright and high overhead. The northeast corner of the Triangle, the star Deneb, is the top of the Northern Cross in the constellation Cygnus. The remainder of the cross extends to the south ending with the beautiful double star Alberio.
Alberio, sometimes referred to as the “Bronco” Star is actually 2 stars that can be easily separated into a larger orange/yellow star and a smaller blue star. These two show a distinct presentation of the color contrast with which stars can shine.
The open star cluster, the Wild Duck Cluster (M11), will be high in the southeast. It is one of the more compact open clusters composed of an estimated 2,900 stars of which many can be seen in a small telescope.
Almost directly overhead is the constellation Hercules containing the Great Globular Cluster in Hercules (M13), the brightest globular cluster in the northern sky made up of several hundred thousand stars.
To our south we will gaze toward the center of our galaxy, the Milky Way with an assortment of deep sky, fascinating objects.
About Arkansas Valley Astronomical Society Meetings
Arkansas Valley Astronomical Society monthly meetings are always open to the public. Weather permitting, we typically meet once a month on the Friday or Saturday closest to the new moon. This strategy allows for a dark sky and some predictability of when each meeting might be scheduled.
This year we will add some evenings for lunar (moon) viewing too. Check back (or join the mailing list) for when these opportunities are planned.
If you or someone you know received a telescope or one of the newest stargazing instruments as a gift, or even if you have had one tucked away in a closet unsure about taking it out, bring it along! Our meetings provide a great opportunity to come out and get an orientation of our wondrous night sky. We will gladly try to help you get started with your new scope if we can.
If you would like to have an opportunity to learn how to use a telescope that is new to you before the next meeting contact Jim Konowitz at (719) 539-6839 to discuss a possible meet. Orientations are usually best conducted in a lit (daytime or indoors) environment. If your new scope is a Go To or computerized model it is always helpful to bring your scope's manual. If you do not have a manual copy check on the web to see if you can get a version.
All ages and knowledge levels are welcome from the novice to the advanced. We always have one or more telescopes set up for everyone to do some stargazing.
In the more comfortable weather months meetings are usually held at the Arkansas Headwaters Recreation Site of Stone Bridge located off CO Hwy 291 just southeast of US Hwy 285. In the colder months we typically meet at someone’s home, using their outdoor area for stargazing, while also using their home for a respite to warm up.
Community Star Parties
We welcome inquiries from schools, community organizations and groups who may have an interest in our assisting you in conducting a “star party” as part of your activities. Feel free to contact us using our Contact Form for more information.
The Time of Twilights
When we plan a stargazing session we obviously need to especially consider when the sky will be dark. Between sunset and maximum darkness we have 3 categories of twilight. Horizon in these cases is 90 degrees from zenith (directly overhead) and not the mountains to our west.
Civil Twilight is the time between sunset and the point where the sun is below the horizon 6 degrees. This is the period most of us consider to be twilight. At our latitude, Civil Twilight usually ends about 30 minutes after sunset and is referred to as Civil Dusk. When reasonable, this is the period we use for setting up our telescopes with some natural light still available.
Nautical Twilight is the time between the Civil Dusk (the sun is 6 degrees below the horizon) and the point where the sun is below the horizon 12 degrees. It is called "nautical" twilight because during this time most of the brighter, navigation stars become visible. Nautical Twilight ends about 1 hour after sunset with Nautical Dusk.
Finally we have Astronomical Twilight that starts with Nautical Dusk (the sun is 12 degrees below the horizon) and ends when the sun is 18 degrees below the horizon with Astronomical Dusk. At this point the sun is no longer effectively illuminating the atmosphere above us, or about 1.5 hours after sunset.
Typically we can start viewing the brightest objects such as the planets and brightest stars during Nautical Twilight. We have to be later into Nautical Twilight to begin viewing dimmer objects such as open star clusters. The dimmest objects like globular star clusters and nebulae generally need Astronomical Twilight to really be appreciated.
A convenient web site that provides the twilight times along with other related information is at Custom Sunrise Sunset Calendar - Colorado Location Selection.
What constitutes a "good" viewing night?
Of course, there is no exact answer to the question. However, there are some things that will help you see the heavens more clearly. And some simple checks you can make. If you want to see, photograph, or just explore the sky, there are some nights that are better than others. That is especially true if you are looking for faint objects, or if you would like to do some photography.
First, it should be dark. That means that the moon, especially if it is nearly full, should not be up. Many of us have to tolerate street lights, signs or fearful neighbors who feel better with the yard brightly lit. Those things are bad, but if the moon is shining also, almost everything else can be wiped out.
There are three technical terms astronomers use to describe the quality of conditions in the night sky. These are darkness, seeing and transparency. Darkness is just as it sounds. For instance, the moon or city lights degrade darkness. Seeing refers to how still the air is from the ground to the top of the atmosphere. Turbulent air makes for degraded seeing. Finally there is transparency. This refers to how clear the air is. Smoke and haze are some of the causes of degraded transparency.
AVAS is listed with a web site called the Clear Sky Chart. Our summer meeting site at Stone Bridge has been registered. The site not only goes into much greater detail about these terms, but also provides a chart of what the conditions are predicted to be at Stone Bridge. You can visit the Stone Bridge Clear Sky Chart at http://cleardarksky.com/c/StnBrCOkey.html?1 or by clicking =>Stone Bridge Clear Sky Chart.
There are a couple quick checks I use:
First, the stars should not be twinkling very much. Stars low in the sky may twinkle, but those higher up generally should not. If wind or rising warm air are stirring the atmosphere, the images will "dance", and you will not be able to see close star pairs, any detail of a planet or diffuse objects.
Second, the two stars that make the inside of the bowl of the Little Dipper, which are dimmer than 4'th magnitude, should be visible. Another clue is the nucleus of the Andromeda Galaxy, should be visible if someone shows you where to look (it is also 4'th magnitude, but is more difficult to see, since it is a diffuse patch, not a sharp point).
And What to do if There is Haze, Light Pollution, and Such?
There are still things to do unless it is clouded over. The bright planets, namely Venus, Jupiter and Saturn are worth looking at, if you can see them at all. Venus is always a bit of a washout since it is completely shrouded in clouds. But, what you can see is that it has phases -- a thin crescent when it is close to the earth, an almost full disk when it nears opposition (i.e. the other side of the sun), and everything in between. Jupiter and Saturn put on a good show almost any time you can see them.
A personal anecdote from our past President, Frank Snively: I didn't do much star gazing until I went out to California to attend graduate school. A friend of mine who knew his way around campus (he had been an undergraduate at Caltech, also) asked me, one evening, "What's that bright thing in the sky?" "I dunno." "Let's take a look", he said.
Like most graduates of Caltech, he had a collection of keys, and we went to the 1/10 scale model of the Palomar telescope, which had been built to support detail design of such things as the pointing and tracking system. It was always used as a Cassegrain, since only 20 inches diameter would not support a built-in observer's cage at prime focus.
Using the spotter scope, which needed cleaning badly, we located the bright object and looked in the main scope. There, with the rings glowing nicely, was Saturn. I still remember the thrill. And with the collecting area that comes with 20 inch diameter, it was quite bright. In later years, with lesser telescopes (my own is 8 inch diameter) I have also looked at Jupiter on many occasions.
And the moon is well worth looking at, as well. That is especially true several days before or after full moon. The craters near the terminator (i.e. the shadow line) are thrown into sharp relief by the sun which is close to the local horizon. Most of the larger ones have been named, and you can look at a diagram of the moon's surface to try to answer the question "What's that one called?" Of course, a good many smaller ones remain nameless.
A good many people stick a dark filter into the eyepiece of their scope when they are looking at the moon. It enhances the contrast, especially when the moon is nearly full. Note well, however, that there is no danger of actually harming your eye. The actual surface brightness of the moon is about the same as that of old worn pavement with the sun shining on it.
Something well worth watching
There is a very interesting web site you can take a look at. Dr John Dubinski, a professor at U. of Toronto, happens to have the largest "supercomputer" in Canada, and has used the facility to model the dynamic behavior of galaxies. No, he can't analyze all the hundred billion stars in something like our Milky Way or Andromeda, but he can track the behavior of, perhaps, several hundred thousand stars as they interact through gravity with each other. He has several simulations of colliding galaxies - note that the average separation of stars is so large that the galaxies pass through each other - and then "bounce" and ultimately form giant elliptical galaxies.
It is quite wonderful to watch.
The URL for the visual treats is:
http://www.galaxydynamics.org/gravitas.html
Rather than feel bad about inclement weather, and doing something desperate like watching TV, it is well worth using the computer for a look at several of the dynamic simulations.
The Sloan Digital Sky Survey Is Available
You might be interested in looking at a bit of the data from the Sloan Sky Survey. The data from the Sky Survey is processed at Fermilab in Illinois, and is available to the public. There is far too data much for any single astronomer or group to study in detail. The reduced data are available On Line, for public access. The URL is
http://www.sdss.org
There is a good bit of information on the web site which is accessable to the "normal" Mac and Windows users, which is most of us. I was personally reluctant to try to get into the UNIX oriented data files, since they would tie up a "home use" broadband connection (I use a cable modem, myself), and rapidly exceed the capacity of my Hard Drives. Maybe some day..
It would be nice to find something worth publishing in "Astrophysical Journal". The data are there. All we need is a dedicated (fast) home computer and plenty of storage capacity. Well a 1000 baseT Ethernet connection would be handy, also.
Two AVAS Astronomy Articles!
Frank Snively, past President of AVAS, discusses how we know if the color in a photo taken from space is accurate. Also, Jeff Beaty presents an interactive panorama of the surface of Mars as seen from the Spirit rover. Check out the Astronomy Articles Page.
A New Observatory Has Arrived In A Valley Near You
The Gunnison Valley Observatory is operational and open to the public!
The primary mirror of the telescope (about 30 inches diameter) is ground from a disk of low expansion glass, and is carefully mounted for vibration isolation and thermal isolation. The Cassegrain reflector is mounted on a number of steel posts which extend from the primary support. It is interesting to note that the Cassegrain position has a motor control - necessary because the thermal expansion of the support is quite different from that of the mirrors, and the telescope would go out of focus as the temperature changes.
The local promoters have made arrangements with a faculty member at the University of Dallas to procure CCD imaging and spectroscopic equipment, which will make the telescope useful for a variety of research programs.
For more information, use the link on the AVAS home page, to go to "coloradoskies.org" or click =>Gunnison Valley Observatory.
A Caution Regarding Arkansas Headwaters Recreation Area Sites
The Stone Bridge site near Salida, and the Railroad Bridge site north of Buena Vista are both excellent for viewing. We will continue to use them but it will cost us.
With the tremendous budgetary squeeze on all public institutions in Colorado, it is mandatory that everyone pay the required fee to events at Arkansas Headwaters Recreation Area sites so that they can continue to keep them open.
As stated on the AHRA web site:
Vehicle Pass: (Self Serve): $6 per vehicle per day for all vehicles entering an AHRA fee site and includes all passengers in the vehicle. Good at all AHRA sites until noon the following day.
Daily Individual Pass: (Walk-In, Self Serve): $3 per person per day, age 16 and over for visitors entering a site by means other than a motor vehicle (i.e., bicycle, boat, hiking, etc.).
Various annual passes are available through the Colorado State Parks offices and web site along with the AHRA office in Salida.
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Buena Vista Area Sky Chart
