21 August 2005

I got a firm price quote on the plastic for my solar filter yesterday. The price went up to $20 per piece. It may be that I told them I sent the inside piece of plastic and not just the ring so am taking away ore square inches of plastic. I also added a few small square tabs that will be extra laser positionings and cuts. It may also be that I was dealing with a different person. In any case I went down there and they had it cut within 90 minutes.

Item	Quantity	Unit Price	Cost
Laser cut per computer file of 1/8" green fluorescent	2	20.00	40.00
1/4" x 1/2" x 6' strip	1	4.30	4.30
2" x 2" square 1/8" frosted	1	N/C	N/C
Subtotal			44.30
Tax			3.71
Total			$48.01

The square of frosted plastic is for use in the sun finder.

Canal Plastics Center didn't have the little plastic beads I like to use as feet so I had to go around the corner to T&T Plastic Land and get three of them at $0.18 each for a total of $0.59.

I bought a bag of six s-hooks Friday at Home Depot for $0.88 anticipating using at least that many on these two projects.

I have plenty of 1/8" #6-32 screws but none long enough to go through the plastic so this morning I went to Radio Shack to get a bag of them.

So my total cost for the project is going to come in under $50.00. I can buy a filter already mounted in a cell from several sources for $~65.00. But as soon as I get it I will have to modify it so that it will accommodate the secondary spider screws and maybe the rail shoe and finder shoe. And it would be silver or white rather than the flamboyant fluorescent green that is going to light up when the sun its it. And because I made this cell myself I will be able to replace the filter film when it becomes damaged or substitute wratten filters for star/planet/nebula observing. And I designed and built it myself.

This morning I woke up early and have basically finished constructing the cell. I still need to get a few miscellaneous parts and correct a few design errors but it is nearly ready for use.

I have identified three design flaws - so far. The first, which I saw before I had the plastic cut but couldn't correct due to my newest computer problem, was that my proposed sun finder will be in the way of the filter or the filter will be in the way of the finder. If the finder works I will have to cut a notch out of the side of the cell so it will fit around the finder's tube.

The second flaw was in my placement of one of the little tabs that will be used to keep the cell from falling off of the secondary cage. I was being careful to mount things where they would not get away of bumps on the secondary cage and thought I had everything accounted for but when I went to attach the s-hooks I found that I had placed one of the tabs right under the eyepiece drawtube and that it hits the tube and keeps the cage from getting into the cell. Of course that piece is attached so solidly that there is no way of getting it off. I am going to have to take the Dremel and cut it off. I have another idea in mind for securing the dell at the top of the secondary.

And I just discovered that I hadn't thought about the bar possibly having to extend out beyond the front of the secondary to bring the scope to focus. I am going to have to cut a notch in the bottom of the cell so it will fit over the bar.

my plastics suppliers were

Canal Plastics Center	T & T Plastic Land Inc
345 Canal St	315 Church St
New York, NY 10013	New York, NY 10013
212-925-1666	212-925-6376
http://www.canalplasticscenter.com
canalplastics@gmail.com

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Observing Location	TotL
Observational Period	2015-0045 EDT
Atmospheric Conditions	The temperature was nice and there was a little breeze. Clouds kept drifting through and transparency was not that great. Peter commented about seeing not being good either but I didn't observe it. Transparency Fair Seeing
Instruments	Canon 15x50 Image Stabilized binocular - Charlie Coulter CT-100 - Charlie Tacahashi 102 - Peter Fujinon 7x50 binocular - Peter
Observing Party	Charlie Ridgway Peter Tagatac

I bunch of new asteroidal occultation predictions had been posted and I spent the day making maps for them and wasn't aware of the weather at all. In the early evening I got an email from Peter asking if anyone was going to TotL and checked to see nice blue sky. I should have gone out for a sunspot count but only had time to run up and grab a slice of pizza before rushing down to the park. There was a bright satellite pass at 2030 and an Iridium flare at 2039 that I wanted to catch.

I had Some Assembly Required with me and my major activity for the night was performing a drift test on the finder.

Drift Test
Test 1	Acrturus	286 sec
Test 2	Arcturus	254 sec
Average		270
Declination of Arcturus		19.2°
FoV = T * 0.2507 * Cos(Dec) FoV = 270 * 0.2507 * Cos(19.2) FoV = 270 * .0257 * 0.9444		6.55
Field of View		6.6°
Test 3	Antares ?	244 sec

My theory of performing the drift test multiple times and averaging the results was sound but I didn't do it right. On reading the instructions in Astronomy Hacks I find that you need t know the declination of the target star and I used two different stars in different parts of the sky and don't even know what the second star was for sure so had to discard my last test. Calculating the FoV based on the single probable Antares observation I come up with 5.6° so feel comfortable saying the Field of View of the finder is 6°.

We noted a lot of colllimation problems with the scope tonight. Everything looked like a comet with a double tail.

Target	Iridium 46
Constellation	Cam
Category	Satellite
Time	21Aug05, 2039 EDT
Comments	This satellite flared at Mag -3. I was expecting that it would appear to the right of the compass heading listed but it appeared right around where they said it would so I can't figure out if they are listing degrees True or degrees Magnetic on Heavens-Above.com since sometimes they are where I expect them and sometimes they are not.

Target	Meteor
Constellation	Cas
Category
Time	21Aug05, 2328 EDT
Comments	I saw a bright meteor going NE to SW (up) parallel to Cas. It was likely a Perseid. It appeared fat and yellow and moved quickly.

Target	Moon
Constellation	Psc
Category	Lunar
Time	21Aug05, ~2330 EDT
Comments	We moved around the top of the Lawn a little bit to the west to make the Moon rise above the trees a little earlier. The terminator ran down through Mare Serenitatis and then through a line of four prominent craters [Theophilus, Cyrillus and Catharina - there is no 4th crater there]. The next to the last crater in the line [Theophilus] had a central peak in daylight but its floor was in shadow. [I think I am mixing up my direct view with my inverted view here. I appear to be describing the relationship of the string of craters to Mare Serenitatis as direct view, but the location of the crater with the central peak in relation to the others in the chain as inverted view.]