29° 39' N, 8 2 ° 2 1 ' W

FirstLight Newsletter of the

Alachua Astronomy Club May 1997

Make your Own Telescope, Part I — Don Loftus

AAC Treasurer, Don Loftus, has agreed to share his experiences at telescope making. Those who have seen the results of his handiwork are impressed with the

quality of the craftmanship and optics both

Ihave had several requests to write about the telescope I've been making with my son Curtis and now

that I'm almost finished I can tell you about the project from beginning to end. You can see pictures of the scope on the AAC home page at:

http://www.aslio.Lit1.edii/~cohen/aac/profilOI html

I'm not sure exactly what got me interested in making my own telescope and mirror. I've always enjoyed working with my hands and building things so I guess this project was just a natural. 1 decided that a good reason to build a telescope was to make Curtis a Christmas present that he could help with. After all, when we finished he would have something that he helped craft from just raw materials and something that would last a life time that he could share with his kids (and besides we could make a better telescope than what we could buy).

I purchased the 6" mirror kit from William-Bell for about $80 and also bought Texereau's book "How to make

telescopes". 1 also got onto an Amateur Telescope Makers list serve on the Internet and have learned a lot from this source. In fact, without the ATM list, 1 might not have taken on this project. Reading the posts gave me the encouragement I needed. I knew I could make a minor myself. There are also a couple of glass pushers in the club, Gilbert Bernardo and Jan Sugalski, that I knew would help me if I got into a problem.

It really doesn't take all that long to make a 6" mirror...if you can manage to put some time into it. I started Curtis' mirror early in 1996 and here it is almost the middle of 1997! It's just that so many other things keep coming up...honest...it really doesn't take this long. I just realized that I had the telescope at the last Kanapaha and will have it at this recent one - six months of almost being done. My problem is the final figuring. I want the mirror to be as perfect as I can make it. Being the first minor, I'm learning a lot, but also taking wwww-aaaaaa-yyyyy too long.

FirstLight: Newsletter of the Alachua Astronomy Club Page 2

As for the actual project; we started by grinding the mirror outside in the backyard. Rough grinding is messy and doing it outside is a good idea. We used plenty of water between grits to keep contamination from becoming a problem. As you grind with finer and finer abrasives, if even one particle of a courser grit shows up, you get a scratch. To get rid of this scratch will erase many hours of labor and will add more hours backing up a couple of grits and starting over again. We were fortunate and only have one set of scratched that set us back about 2 or 3 hours.

When we got to the fine grinding stage, we moved indoors. I have a photographic darkroom with a large sink that was very convenient for

cleaning the mirror between grits. I made a grinding stand out of plywood and lumber so that Curtis could stand on a platform on one side (moving him up higher so he could work on the mirror easier), while I stood on the floor on the other side. His weight on the platform was my counter weight to keep the platform from moving and then we could take turns working the mirror. This is also one aspect of telescope making that slows things down; you have to make everything you need. It takes extra time. When you make your second mirror, everything you need is already made!

to be continued..

O

Upcoming Club Meetings and Events

April Club Meeting Date Tuesday, May 13th Time 7:30 p.m. Place Auditorium, Doyle Conner Building, 1911 SW 34th St. Speaker: Randy Palmer, AAC star party coordinator, will give some very practical advice on capturing the night sky on film in a talk titled: "Barn Door Photography." Included will be constructing the barn door drive, camera requirements, film types, and night time techniques. Weather permitting, actual exposures will be made from the parking lot.

Club Star Parties — dates & locations May 3 (Saturday Night); no rain date. This is a special combination picnic and star party at the Chiefland area star gaze site. See the enclosed map for particulars.

Chiefland v Hardeetown

SR 347 HJ

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SR 347 %

SR347. Turn right and travel west on SR347 3 the south. Turn left and travel south exactly rn. There is a row of mailboxes on the right, id with a small sign for LCR 434/NW 50th lickens in the road! Travel one city block west i right (north), NW 52 Court. Go to the end of here is a pole barn and a small building.

Notes from Melrose Chuck Broward April 16th 10 p.m. Earlier today I had run Satspy2 and it

showed that the Hubble Space Telescope would cross the face of the Moon at about 9:31 local time. At 9:25 my wrist watch alarm dutifully beeped and my teenage son and I pulled off the road at Highway 26 and the Windsor Road. Locals flashed us with their highbeams and yelled "watcherdoin?" I replied "lookin for deer!" At 9:30 we spotted HST, a fast moving star heading from Orion toward the Moon! It passed just north of the Moon, sped east, and then blinked out as it passed into the shadow of the Earth.

Arriving home I tweaked the program's ground location and discovered that just a few minutes change in latitude moved the path of the satellite north of the Moon. Satspy is fun, and I have found that it is useful for getting kids into looking at the sky. With Mir and HST in the news, children relate to seeing these objects charge across the sky.

Thoughts on Rosemary Hill That evening I had my Meade ETX, the Celestron C-8, and the Coulter 13.1 inch dobsonian side by side. I am elated with the Coulter dob-images are big, bright, and the scope is sooo steady! I'm hooked, but need a bigger vehicle! The C-8 (which is for sale) provided views almost as spectacular as the 13 inch, with the added advantage of the clock drive. I could for instance, almost see detail in M-51, good detail in the comet, and a bit of marking on Mars.

The Meade ETX grudgingly earned some respect by imaging Mars very nicely at 120 X. Its images of Mercury were good, while images of the comet and M-42 were OK, but one had to strain to pull detail out of the smallish images. I have a hunch the ETX will serve well for planets, the Moon, and objects like double stars. By the way, a Sam's Club coffee creamer bottle with the top and bottam cut out makes a great dew cap for the little scope!

I took the silly finder scope off the ETX and substituted a Celestron orange tube 6x30 finder—its longer length and greater eye relief is a lot easier to use that the Meade thing, which now rides in the glove compartment as a toy for the kids. The orange tube of the finder clashes nicely with the highly touted anodized black finish of the ETX.

The new-to-me Coulter Odessey is fun, but big and heavy. I am planning a series of modifications including adding wheels, a quick change mount for a 8 x 50 finder and Telrad, and a stop-down tube cap to see how the scope performs as a f-8 or f-10. I also plan to modify the mirror mount and add a internal mirror cover to protect the mirror during transport and storage. At present the mirror rides on the seat next to me! It is scary to cart it around like it is a dinner plate.

I have learned this past month that it really doesn't matter what kind of scope you own; there is enough in the sky to keep me occupied with a viariety of astro-scopes, binoculars, or just my eyes! Enjoy the sky!

For Sale, I want... Celestron C-8 for sale, black tube, tripod, solar filter, clock drive, 12 volt to 110 volt inverter and battery (with charger), manual, one or two eyepieces... $700 firm.

Photo guider and camera adapter for Celestron or Meade. $70

12 volt dew remover (hair dryer)....$17

2 inch diagonal (Meade) for Celestron or Meade Scope. $100 (with 1.25 inch adapter)

60 mm 2 inch Meade eyepiece... $200 (this on the C-8 makes for awesome views!)

(sold only with above diagonal)

Wanted—good quality 2 to 3x barlow, 2 inch focuser usable on the big dob scope. call Chuck at 392-1051 or 475-1014, or afn43753@afn.org

Chiefland Star Party Picnic 1997 May 3/4 (Saturday/Sunday)

Please use only dim parking lights if arrive at night

• Picnic begins 4:00 p.m.

• Bring a covered dish

• Plan to stay all night if you wish

• See heavens from a dark site with big scopes

• Directions - Two miles south of Chiefland, on US19-98. On right (west) side of highway about 2 miles and you will come to SR330 1 mile. GO SLOW so you do not miss the Just before the mailboxes, there is a dirt n Street. Go right (west) and try to miss the on the dirt road and take the first raod to tl the road, where Bill Dodd lives. On the lef

FirstLight: Newsletter of the Alachua Astronomy Club Page 3

Send In Your Astro Photographs — Howard Cohen

David Muir has volunteered to update the AAC photo web site

Mail your astro photos to David Muir at his home. David can scan them and then return the originals to sender. You should include all photo details, if possible, including:

l)Photographer's Name, Address (incl. email address if any), telephone number

2)Picture Title and/or Object Photographed

3)Day, Date, Time: (e.g., Monday, March 30, 1997, 7:50 p.m. EST)

4)Location: (e.g. 15 Gainesville, Florida)

miles NW of

5)Camera Type: (e.g., Pentax K1000 with Pentax 50mm fl.7 lens, at f/2.0)

6)Lens Used, focal length, f-ratio, f-ratio used for photo (e.g., Pentax 50mm f/1.7 lens, stopped down to f/2.0)

7)Telescope Used (if any), manufacturer, type, aperture and f-ratio or focal length, (e.g.. Meade 8" LX200 SCT, Diam.= 200 mmm, f/10, FL = 2000 mm)

8)Exposure Time (e.g., 20 seconds exposure at f/2.0)

9)Film Type and Speed (e.g., Kodak Tmax P3200 B/W)

10)Misc. (e.g., camera fixed on tripod, not tracking, etc.)

Send to:

David F. Muir, Ph.D. 7125 NW 47th Court Gainesville FL 32606

AAC meets every second Tuesday of each month, at 7:30 p.m., in the Doyle Conner Building, 1911 S.W. 34th Street, Gainesville, Alachua County, Florida, USA.

General public and beginning stargazers are invited to all meetings, star parties and club events. No equipment needed. Call a club officer (most area codes 352) for more information or e-mail fclpam@nersp.nerdc.ufl.edu

President

Vice-President

John Brandorff Gainesville (375-1043)

Howard L. Cohen Gainesville (376-5833)

Ryan and Don Loftus Alachua (904-462-1227)

Star Parties

FirstLight Editors

Publisher

Randy Palmer Bronson (528-9614)

Pamela Mydock and Duane Sandene Lochloosa (481-5238)

Chuck Broward

Treasurer

Secretary Bud Cridlin Gainesville (374-8599)

World Wide Web Home Page at URL http://www.astro.ufl.edu/~cohen/aac

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Astro Calendar (Times EDT) h m

08:00 ian Date 2,450,570.0 (12:00 UT)

19 Neptune (mag. +7.9) stationary 12 Saturn (mag.+0.8) 0.8° S of Moon 18 Eta-Aquarid Meteor Shower

(1/4 peak duration = 14 days, ZHR = 30) 12 Mercury (mag.+2.6) 1.2° N of Moon 16:46 New Moon 14 Mercury (mag.+2.2) stationary 10 Aldebaran (mag. +0.8) 0.6° S of Moon, occult. 05 Uranus (mag.+5.8) stationary 06:55 First Quarter Moon 12 Mars (mag. -0.1) 2° N of Moon 04 Venus (mag. -3.9) 6° N of Aldebaran 05:13 Full Moon 19 Mercury (mag. +0.6) at greatest elong W

(25°) 06 Pluto (mag. +13.7) at opposition 02 Jupiter (mag. -2.4) 4° S of Moon

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