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AVAS News &
Meetings |
A temporary change in AVAS leadership
Jim Konowitz has been an excellent president, and people who have attended the meetings are well aware that he explains things clearly, and finds interesting sights. However, he has suffered an injury to his shoulder, and cannot do much for the next several weeks. We all hope he makes a speedy and complete recovery.
In the interim, Sue and Frank Snively will conduct the meetings in February and March. They live at 429 Mill St. in Buena Vista. The background lights are more of a bother than at out of town locations, but some of the brighter sky objects will be well worth studying.
AVAS Will Meet at the Home of Harold Bristol on Friday evening
(NOTES:
(1) The current forecasts from NOAA and also from Accuweather both call for snow on Friday, extending into Saturday. It is entirely possible that we will have to cancel the meeting. If you have been thinking of attending the AVAS meeting, please call Frank & Sue Snively at (719)395-0605 or Harold and Susan Bristol at (719)395-8269.
(2) Frank Snively has just purchased a new Go-To for his eight inch Celestron, and he is reluctant to try to align it in a snowstorm! )
There (wixx) may be a meeting of the Arkansas Valley Astronomical Society at the home of Harold and Susan Bristol, starting at 7:15 PM MDT on Friday, March 19.
The Bristol residence is located at 326 South Pleasant Ave. in Buena Vista. If coming from the south, go on US 24 past City Market to Mill St. Turn left (west) on Mill St., and go through two stop signs, until you reach the end of Mill St, at Pleasant Ave. Turn right, and then left at the second driveway on Pleasant Ave. (yellow house), at the Bristol residence.
If coming from the north or west, turn south from west Main St., onto Pleasant Ave. Go south to the yellow house at 326 S. Pleasant Ave.
The meeting site was selected because Harold has an open horse pasture behind his house, which offers reasonable freedom from interfering street lights.
Hopefully, the snow will be melted off. However it cannot be guaranteed to be mud free, so don't wear your dress shoes. If snow remains on the ground, after the predicted storm on Thursday, we will have to make a decision - can the telescopes still be used? Probably, yes.
If there are questions, call the Bristols at (719)395-8269, or Frank and Sue Snively at (719)395-0605.
You can use our simple Contact Form to ask any questions about AVAS or to be added to our mailing list for notification of the time and location of our next opportunity for group stargazing.
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
