Important Announcements

	Our next meeting will be on Thursday, January 6th, at 8:00 PM at the Colts Neck Fire Company #2 on Conover Rd. in Colts Neck. Note the change in day of week, time, and location! Directions From Rt. 520, turn South onto Rt. 34. Conover Rd. is on the right, at the first light South of Rt. 520 (opposite Laird Rd. this is actually the 2nd Conover Rd. off of 34 south of 520, as Conover is a loop that begins and ends at Rt. 34). The fire house is on the right hand side, just past Heyers Mill Rd. Directions from Rt. 537, turn North onto Rt. 34. Conover Rd. is on the left, two lights North of Rt. 537 (opposite Laird Rd.). The fire house is on the right hand side, just past Heyers Mill Rd. The guest speaker will be Bill Murray (of AAAP), who will talk about CCD Astronomy in New Jersey. Anyone who's interested in astrophotography (and who isn't) should enjoy this talk.
	We need articles for the Spectrogram! Would you like to write one? See http://www.starastronomy.org/Library/Spectrogram/author.html for article submission guidelines, or ask Mike Lindner about it at the next meeting.
	One of the club's biggest expenses is printing and mailing this newsletter. If you have internet access and would like to save the club time and money (and save trees at the same time), send e-mail to mikel@att.net; I'll send you e-mail when the new Spectrogram is on-line, and you can read it at http://www.starastronomy.org/Library/Spectrogram.
	We need articles for the Spectrogram! Would you like to write one? See http://www.starastronomy.org/Library/Spectrogram/author.html for article submission guidelines, or ask Mike Lindner about it at the next meeting.

News & Events

	January 1, 2000 is the 75th anniversary of Hubble's announcement of the discovery that there are objects outside of our galaxy. It seems odd that most of the known universe was undiscovered until so recently.
	January 7 is the anniversary of the discovery of Jupiter's moons by Galileo in 1610. This was the first observational proof that the earth was not the center of the universe.
	January 11 at 8 PM, S*T*A*R vice president David Segelstein will give a presentation to the Amateur Astronomers' Association of Princeton in Peyton Hall on the Princeton campus. David's presentation will be entitled "A Day in the Life of a Struggling Amateur Astrophotographer." It will contain a few pretty pictures, and a lot of information about what was necessary to get those pictures, as well as a catalogue of photographic M-objects (where M stands for "Mistakes"). S*T*A*R members are welcome to attend, and hecklers will be tolerated (although all will be checked at the door for rotten fruit and other projectiles). David will give a similar presentation to S*T*A*R later in the year.
	January 20 lunar eclipse viewing at 10 PM at Phasor Video and Electronics, 47 Broad St. in Red Bank. All are welcome. Bring a scope and set up on the sidewalk! Contact Dan Pontone for details.
	January 31-February 5, Florida. The Winter Star Party at West Summerland Key in Florida. For more information contact Fred or Lucille Heinrich, WSP registrars, phone 904-362-5995 e-mail heinrich@alltel.net or see the web site http://www.scas.org/.

Notes from December

By Dave Hayden

Don Odegard gave a great description of his home-made 8'' Dobsonian scope. If you ever get a chance, take a look through this scope as it has some of the best optics in the club.

Don bought most of his materials at Home Depot, and his scope is a great example of how you can get a great instrument at very low cost.

For example, he uses three 30 W 1 watt resistors wired in series to loop around the eyepiece. This keeps it warm so it won't dew up. He has a similar arrangement on the finder. This probably cost less than the spare change in your pocket.

Don also built an equatorial platform. When the scope is on the platform, it tracks objects for an hour or so before the platform must be reset. It was so easy and cheap to build, that, as Don put it, if you build something like this and it doesn't work, you can just throw it away and start again.

David Segelstein spoke about the ``beginners night'' on November 13 at Dorbrook Park. There were about 20 people, including five or six beginners. The meeting pointed out the necessity of three accessories: star charts, dew removers, and warm boots! Dave recommends Sorel Dominators, which are rated to -100F. He's hoping to do something like this again at one of the darker sites.

Frank Loso spoke about variable star observing. The American Association of Variable Star Observers (AAVSO) has a web site at http://www.aavso.com which is a good place to start if you're interested. A variable star is one whose brightness changes. This can happen for many reasons such as eclipsing binary stars, pulsating stars, etc. This is one of the areas where amateur astronomers can make a real contribution to scientific knowledge because there aren't enough professional astronomers to keep up with observations of all the binaries. You can even observe from a light polluted site. Basically, you find the variable star and estimate it's magnitude by comparing it to nearby fixed magnitude stars. Talk to Frank if you're interested.

Mike Lindner spoke about the Amateur Telescope Making Special Interest Group (ATM SIG). Their next project will be to make solar filters. Contact Mike if you're interested. Materials will cost about $10 or so.

The speaker was Dr. Wil Van Der Veen who spoke about project AstroNova and late stage stellar evolution. AstroNova brings astronomers (professional and amateur) into 4th-9th grade classrooms about 4 times during the school year. It's been a big success. His talk on stellar evolution talked about the evolution of sun-like stars from the sun's current state to their end.

The meeting ended with some club business. Poricy Park has asked S*T*A*R to sign a contract or leave. The officers reviewed the proposed contract and cannot recommend its approval (all contracts must be approved by the members). So they spent some time looking at alternative meeting sites and recommend the Colts Neck Fire House. The cost will be $75 per night which is $25 more than Poricy, but the club has enough funds for us to finish out the year at Colts Neck, if necessary. One member suggested that the Hazlet Firehouse might be available for free.

A motion was made and seconded to move to the Colts Neck firehouse for the January meeting and to investigate the Hazlet Firehouse. The motion was passed unanimously. The club thanked Poricy Park for the use of their facility.

To Dew or Not to Dew: That's the question, dewed!

By Steve Walters

Earlier this year, I realized that combating dew has been a continuous saga in my astronomical pursuits for over 20 years and that I really did not understand dew in even a pseudo-scientific way. This prompted me to do some technical reading to learn more about dew and how to control it. I don't claim to be an authority, but this little article documents what I have learned about dew and its prevention. I hope it can help you enjoy dewless observing.

What Is Dew?

There are a lot of myths about dew floating around out there. Some people think that dew falls from the sky like rain. Others say it rises from the ground. Some astronomers swear by their dew caps while others swear at them. And, of course, the Kendrick Dew System is the legendary preventive but there are those who carry hair dryers around with their telescopes. Here are the simple facts about dew.

Air contains moisture. The amount of moisture the air can hold varies according to the air's temperature where warm air can hold more moisture than cold air. The moisture in the air and the air itself are at the same temperature. Let's call this T_air. The amount of moisture in the air is indicated by the Relative Humidity (RH) which can vary from 0% in completely dry air to 100% in completely saturated air. RH is a measure of how close air is to saturation.

A common myth is that dew cannot form when the air is warm. This is not so. Dew can form at any air temperature and at any relative humidity level other than zero. But, as we will see, it becomes easier to prevent dew when the humidity is low. So it's a good idea to learn about your observing climate and what it's like where you're going if you plan a trip to a remote location.

Now, let's introduce an object such as a telescope into this moist air. The scope is at some temperature, let's say T_scope, which for various reasons is not the same as the air. There is a temperature which is called the Dew Point (T_dew) at which invisible moisture in the air will condense into water droplets on any object that is at or below this temperature. If T_scope is at or below T_dew, water will materialize on the scope. So, there are three variables: T_air and RH (which allow us to determine T_dew) and T_scope. The Dew Point can be calculated using the formula:

where RH is in percent,and T_dew and T_air are in degrees Centigrade.

Attached is a table showing the dew point for various air temperatures and relative humidity levels. Take a look at the table. For example, at a RH of 50% and an air temperature of 40 degrees, the dew point is 23 degrees but if relative humidity rose to 90%, the dew point would be 37 degrees. If you examine the table, you can see that as RH approaches 100%, T_dew approaches T_air. This means at high humidity, the dew point is close to the air temperature. At low humidity, T_dew can be much lower than T_air. But at 100% RH, the dew point is the same as the air temperature and fog will occur.

An interesting fact that can be observed is that as night falls, the air temperature drops and the relative humidity rises. If we examine our table, we see that these tend to offset each other regarding the dew point. For example, at 50 degrees and 50% RH, the dew point is 32 degrees. If the temperature drops to 45 degrees while RH rises to 60%, the dew point remains constant at 32 degrees. In actuality, dew point does not usually remain constant as night falls, it can rise or fall depending on which parameter changes fastest but, in general, dew point will not change as fast as the air temperature due to this effect. For telescope users, this means that when the temperature drops, you have to watch your scope closely as it could quickly drop below the dew point.

Another common belief is that if you keep your scope just above the air temperature, dew will not form. This is true, however you may be keeping your optics much warmer than necessary which will lead to distortion, greater air currents in the tube and a wasted power leading to shorter battery life. Since moisture will condense on any object at or below T_dew so our goal is to never allow our optics to get below T_dew.

Dew Prevention

Now, let's understand what is going on with our telescope. The telescope is radiating heat into the night sky. The night sky is a terrific heat sink since it's at 3 degrees Kelvin which is nearly absolute zero. Your telescope is sending heat from its optics into space. The area of space seen by the optics depends on the telescope configuration. For example, an SCT corrector plate ``sees'' nearly the entire sky, a rather large area, while a dobsonian mirror ``sees'' only the area of its open tube. As heat leaves the optics, the optics' temperature will drop. When the temperature of the optics reaches T_dew, your observing is over. Moisture will form on the optical surface and you won't be able to see. This is why SCT owners frequently use dew caps. A dew cap limits the angle at which heat can be radiated so the cooling process will slow and it will take longer for dew to form. Sometimes, this can be enough for an observing session but eventually, moisture will condense on your corrector plate if the dew cap is your only cure. It will simply take longer. Another trick to delay dew formation is to point your scope at the ground or cover it when you're not using it. If dew forms on your optics, this can also help speed the recovery.

Next, enter the Kendrick Dew System, the Orion Dew Zapper and all those little homemade resistor ring beasties. These little gizmos all address the problem directly: they attempt to keep the optics above T_dew. Lots of folks get these things, strap them on and turn up the heat. Sure enough, they don't get any dew. They have solved one problem while creating two others. If the optics are over heated, they can produce distorted images. Pouring more heat into your optics than necessary also means shorter battery life. Incidentally, I really advise you NOT to power dew heaters from your car battery especially in remote locations like the Australian Outback unless you enjoy walking.

So, we would like to find a way to know how much power to put into the heaters to keep the optics just above T_dew but not to ``over dew it.'' Fortunately, there is a cheap easy way solution at your local Radio Shack store (for the record, I have no financial interests in Radio Shack). They sell a digital indoor/outdoor thermometer ($25) that also indicates relative humidity. By simply getting the outdoor sensor in good thermal contact with the optics (I made a metal block that encloses the sensor and is bolted to my corrector plate housing), you can know the temperature of the optics while the indoor” sensors show the air temperature and RH. By looking up T_dew in the table from the T_air and RH indicators, you can know whether to give the scope more or less heat. Often, you can delay for a considerable time before turning on your heaters. Professional observatories have systems which measure these parameters and decide when to heat and how much. You can do it too for only $25 but you have to be part of the system! Just don't cut it too close as the accuracy of these sensors is less than perfect.

Summary

Ok, here's the cheat sheet for your final exam:

1. Dew forms on any object with a temperature at or below the Dew Point.

2. Dew Point depends on air temperature and relative humidity and can be predicted

3. Dew Point gets closer to the air temperature as relative humidity rises

4. Dew caps simply delay the inevitable but sometimes this can be enough

5. Dew heaters can completely prevent dew

6. Dew heaters can be controlled to minimize distortion and maximize battery life

Never again should we find dew on a S*T*A*R member's scope! Be a dewless dewed from S*T*A*R! Clear Skies and dewless optics!

Kudos to Frank Loso for locating the formula for dew point and for reviewing this article. Thanks Frank!

Star Party U.

By Barlow Bob Godfrey

At star party university, class sizes range from thousands of amateur astronomers (at national "ivy league" star parties like Texas Star Party), to hundreds (at regional star parties, like Jersey StarQuest and Connecticut star party).

Classes are usually scheduled on a weekend with clear skies, from Friday night to Sunday morning. However, the Rockland Astronomy Club Summer Star Party is held over many days, guaranteeing clear skies.

There is a winter solstice recess from the late fall until early spring, The Winter Star party has classes in Florida during this recess.

Tuition at any star party is low. However, tuition only includes entrance, lodging and food. Students must pay for their own books, supplies, warm clothing and laboratory equipment.

At star party U., everyone is both a student and a teacher. Amateur astronomers exchange information on a variety of subjects. Some people are content being only a student; while others are born teachers, in search of a class.

You can observe through every commercial telescope on the market at most star parties. You can also use unique and large telescopes, created by amateur telescope makers.

People exchange eyepieces, telescopes, filters and other equipment, when observing together. This gives everyone the opportunity to test drive expensive toys for free before making a purchase. What a country! Commercial dealers selling astronomy equipment do not allow customers to try this equipment before buying.

Star parties attract many amateur astronomers of different levels of interest in our hobby, for a variety of reasons. Those who are planning to buy their first telescope attend seeking information and to test drive different telescopes. Always ask someone what they do not like about their equipment. You can learn much from their reply.

Others who have just purchased their first telescope attend to learn how to use their new toy. The most useful gift to give someone who has just discovered amateur astronomy is a star party. The above apprentice amateur astronomers attend not knowing what to expect. They leave with expert advice from the best amateur astronomy professors on this planet, worth far more than the cost of the star party.

People also attend star parties to: hear lectures, win door prizes, observe under dark skies, observe the sun through a hydrogen alpha solar filter, see creations of amateur telescope makers, take astrophotographs, buy directly from a dealer, exchange information with other amateur astronomers, meet people from different astronomy clubs, participate in planned observing programs, make new friendships and renew old ones from previous star parties.

People who have been amateur astronomers for many years usually attend their favorite star parties annually. Those people who attend all nine Connecticut star parties, for instance, consider the ninth star party to be the eighth reunion of the first one. About sixty people attended the first Connecticut star party. Over two hundred attended recently.

Think of a star party as a very large outdoor showroom of the ultimate dealership display of astronomy equipment. A showroom where you can kick the tripod or rockerbox, and take a free test drive along the dust lanes of the milky way.

Constellations for January

By Penny Fischer

Fairytale love stories often involve a frog who turns into a prince at the kiss of a princess.

In the story of Taurus, the Bull, we have a mythological god who takes on the form of a bull to win the love of his princess.

The god Jupiter, or Zeus, became enamored of the princess Europa. However, he knew that it would be hard to have the princess fall in love with him in his godly form. Wishing to disguise himself to her, he took the form of a bull. But he was not an ordinary bull. The mythology is in conflict with the usual representation of Taurus the bull in illustrations. His hide was white as snow and though his horns were short and small, they were polished and shining and jewel-like. The muscles on his neck stood out, and his head and eyes were said to be placid as he mingled with the other bulls on the plains, grazing on grass.

Europa fell in love with the placid bull as they played together on the beach. She was impressed with his gentleness, and he allowed her to climb onto his back. Then the bull swam with the princess across the sea to the island of Crete. It was on the island that the snowy white bull revealed his true self to her, Zeus, the King of the gods. It was also on Crete that the God Zeus won the love of Princess Europa.

The Alpha star, Aldebaran represents the bright red eye of the bull. It's a red giant star that has a diameter that is 36 times as large as our own sun. It's a relative neighbor at 68 light years away.

As Taurus is a zodiacal constellation, and lies on the ecliptic, there are chances throughout the year of lunar and planetary occultations. Lunar occultations of Aldebaran are scattered throughout most years and are an exciting event to watch either telescopically or through binoculars.

Taurus has a few very beautiful star clusters. The Hyades is great naked-eye cluster that comprises the stars in the bull's face. Further out, beyond the horns of the bull, is the Pleiades, a spectacular naked eye Messier object (M45) that is dazzling under low magnification. The Pleiades are also called the Seven Sisters in mythology, and there are many legends about this naked-eye cluster, including some Native American legends.

The Kiowa tribe's legend claims that the Great Spirit erected the Devil's Tower to protect seven indian maidens. The seven girls were being pursued by giant bears. After the pursuit, the maidens were immortalized in the heavens as the Seven Sisters. The vertical striations on the sides of Devil's Tower are the claw marks from the giant bears.

The cluster lies about 410 light years away. The cluster is relatively new. Under very dark skies and with some practice, it is possible to view about 13-14 stars naked-eye, with over 20 brighter than 6.5 magnitude!

The constellation Taurus also has several other interesting deep sky objects, including the infamous Crab Nebula, which is the result of a supernova that happened in 1054. The supernova was recorded by the Chinese as a "guest star" and was visible for several months during the day. The remnants have now faded to about 8.4 magnitude with a low surface brightness. The nebula is about a degree or so away from Zeta Tau, the tip of the bull's horn.

A bright nebula near the Hyades, Hind's Variable Nebula (NGC 1555) is unusual in that it changes in magnitude. When it was first discovered in the mid 1800's it was quite bright. The magnitude has continued to vary, and it almost faded completely from view before brightening considerably again.