Posts Made By: Steve Mathis

Hey all,

I decided I needed an artificial star to try to collimate my (pretty worthless) C130 Mak, and found plans on CN to build one. The one I made is a modified version of the one from the plans. I used an ultra-bright blue LED from Radio Shack, a 330 ohm resistor, a switch, and 9 V. battery for the source, and a 4 mm Plossl eyepiece for the optical component. The body of the device is made from 1/2" plywood. The idea is that the eyepiece is used to form a tiny real image of a small aperture located near the LED. In the same way that the image of the Moon in a scope is much smaller than the actual Moon, the image of the illuminated aperture is much smaller than the actual aperture. Using my dimensions, the image, which constitutes the "artificial star" is about 0.04 mm across. With the setup placed about 60 m from my scope, the size of the "star" is well below the resolving power of the scope.
The light from the LED has a very narrow bandwidth (not monochromatic, but almost!) so the diffraction pattern formed by the scope is very sharp. Bottom line, it works like a charm. (I was able to get the C130 Mak collimated to the best degree so far, but the process reveals some other issues with the optics.)

Anyway, it cost about $6 to make. I've attached a photo of the working end of the finished product, and a rough diagram of the construction.

Comments and questions are welcome!

Steve

Maybe? I found this in some landscaping river gravel. It is 21 grams, 2.7 g/cc density. I don't know how much can be determined from a photo. It is not attracted to a magnet at all...

Thanks for any input!

Steve

I am. Her church creeps me out. If you are not creeped out enough yet, watch the videos here:

http://www.alternet.org/blogs/peek/98698/palin%27s_%27heretical%27_church%3A_censored_video_the_mccain_campaign_doesn%27t_want_you_to_see%3A/#more

Yeah, it is from Alternet.

While this is not technically a CCD image...

I took this with a Canon Powershot G1 (point and shoot) afocally through a 17mm Hyperion eyepiece on my C11. This is a montage of 4 images, each a stack of 24 subs. Stacked with Registax, sharpened and stitched together with PS CS2. Thanks for looking, comments and criticism welcome!

Steve

Hey, everyone...Here is a mosaic of 25 frames in a 5x5 array of part of Cygnus. Each frame is a single 5 min. exposure at ISO 1600 through an older 200mm f/2.8 Nikkor ED telephoto on a D70. I subtracted the darks from each light frame with DSS, and stitched the mosaic together and did final tweaking with PS CS2. I took the 25 frames using the setting circles on my G11 mount, moving 12 min of RA each frame for the E-W displacement, and 5° of Dec. for the N-S...when stitching them together, it finally became clear why you have to rotate certain frames a bit to get them to fit together. The same amount of R.A. is skinnier at the top! Thanks for looking, comments are welcome!

Steve

Here is an image of the Helix taken with a Nikon D70 through an Orion 8" f/4.9 Newt. The exposure is 6 x 5 min, ISO 1600, stacked with DSS and adjusted with PS CS2. I posted this on the Nikon forum with some others from the same dark-sky trip. Thanks for looking!

There is a new sunspot emerging on the northeastern limb, described by SpaceWeather as "the biggest active region in months". I just came in from taking a peek (11:50 AM CDT), and the spot is easily visible in my 40mm PST. Go look!

Steve

This spot first appeared on 10-31-08, and is growing! It is easy to see through my 40mm PST, and is surrounded by some cool-looking activity (Sunday 10:40 AM CST). Go look!

What a great point! It may be a chance for a whole new market...fleets of trucks capable of delivering electrons/CNG/H2 to stranded, cell-phone enabled drivers. Of course, the emergency fuel will be enormously expensive!
Good post, Jim!

Here is my best lightning photo, taken years ago. This was shot on slide film, and digitized recently. Thanks for looking!