Monday, November 29, 2010

Amateur astronomy information from 1894

This is really neat. I really like the descriptions of what can be seen with what size of telescope.

Sunday, November 28, 2010

open 2sky release

2sky is a full-featured planetarium application for PalmOS devices. It should work on both the newest PalmOS devices (TX, Centro, Treo) as well as older devices as far back as PalmOS 3.1 and maybe even 2.0. Open 2sky supports standard square screens, as well as the extended non-square screens of just about all devices.

Thanks to Kevin S. Polk's generosity in releasing 2sky to me under the GPL, I am happy to announce that 2sky for PalmOS is now officially released, free of charge. Click on "Download" at:

I think the interface of 2sky is a model of elegance. The features include:

  • star catalogs up to magnitude 11 (and smaller catalogs for devices with more limited memory)
  • NGC/IC catalog
  • Solar System objects including Sun, moon, planets, Pluto, moons of Jupiter, major asteroids, bright comets, and meteor shower radiants

This release of open 2sky is essentially the same as the last paid release of 2sky (3.0.2), except that I've:

  • updated US/Canada/Mexico daylight savings rules which had changed in the meanwhile
  • refreshed the asteroid and comet databases
  • added support for Handera and Dana Alphasmart non-standard screen sizes
  • removed the white border around the screen on the TX and some other newer devices
  • rewritten code that wasn't GPL-compatible and made the code-base compile with prc-tools rather than Codewarrior
  • added Waco and Turner Research Station to the locations :-)

The resulting binaries are actually slightly smaller than the last paid release.

Wednesday, November 24, 2010

open 2sky alpha test

After a number of hours of converting code from CodeWarrior to prc-tools and rewriting GPL-incompatible code, I have an alpha test release of open 2sky. USE AT YOUR OWN RISK and please send me or post any bug reports.

The database building tools are not yet running (actually, Kevin hasn't sent them all to me yet). The Comets and Asteroids databases thus are out of date. However, all of the star databases, up to magnitude 11 are included.

Note 1: The app by default reassigns all the four hardware keys when it runs. This is a problem on devices like newer Treos which need one of the keys for the home button. So, when you first run 2sky on such devices, just unassign your home button when you get to the screen for assigning buttons (to unassign it, tap on the icon for it, and then choose a blank square).

Note 2: I haven't succeeded in running this under a PalmOS 3.0 emulator (dragging doesn't work, and that's crucial), but I have succeeded in running it under a PalmOS 3.3 emulator. Open 2sky works best under PalmOS 5.x. It should support Palm, Tapwave, Garmin and Sony non-square screen devices. It may support Handera ones. The next release will support Dana Alphasmart.

Monday, November 22, 2010


Kevin S. Polk, the author of the excellent but now alas defunct 2sky for PalmOS, has agreed to have me release it freely under the GPL.  I will be working on converting the code to prc-tools, as well as replacing the GPL-incompatible CollapseUtils-derived code with PalmResize.

Isn't the screenshot beautiful?

Wednesday, November 17, 2010


I was playing with my 5mm ortho eyepiece on my 13" last night, looking at the moon and Jupiter, but the seeing wasn't good enough.  But I did take a picture of Clavius with my Canon G7 through my Hyperion 13mm.  Not as sharp as I'd like.

Friday, November 12, 2010

In praise of hard fiber washers

I got a pack of a hundred 3/8" ID 1" OD hard fiber washers from Amazon's Industrial and Scientific sale on sale for under a dollar as an experiment (the regular price is about $16).  A significant portion of my do it yourself budget seems to be washers, so I thought it was worth trying these.  They're great.  The ones I got are black and not glossy so they're suitable for use inside a telescope without painting.  They are a bit thicker than steel washers and a bit thinner than nylon.  They are super-hard, lighter than steel and of course don't corrode.  I know this post sounds like an ad, and to alleviate that impression, I'm not linking.  But search for "fiber washer" in the Industrial and Scientific store, and sort by price from low to high.

Thursday, November 11, 2010

Home-made fine-tuning rings for Hyperion eyepieces

The Baader Hyperion eyepieces accept fine-tuning rings which increase the magnification.  One unscrews the lens group at the bottom, screws in one or more fine-tuning rings, and screws the lens group onto that.  One can buy the fine-tuning rings, of course, for a modest price.  But cheap as I am, I decided to save.  Instead, I purchased two bunches of 48mm camera filters on ebay.  The latest bunch was a lot of ten Niko skylight filters for $13 shipped.  One then removes the glass from the filters, and screws the filter housings into a tube.  The tube is very rigid.  (Removing the glass destructively is easy.  Put filter in some thick bag, hit with hammer or screwdriver or handle of butter knife through the bag.  If the glass breaks, it is easily removed from the housing, though of course one should wear some kind of safety gloves and be careful not to let the glass out of the bag.  Eye protection and a breathing mask are a good idea.  Surprisingly, a number of the Nikos had the glass survive the procedure.)

The ten Nikos add up to 43mm total, and the three Gemkos I have from an earlier purchase give me 14mm.  I could control the length of the fine-tuning tube in increments of about 4.5mm by adding and subtracting one filter housing at a time.

For a total extra price of about $20, my single 13mm Hyperion varies in increments of under a millimeter of focal length between 13mm and about 7.5mm.  The views are really good, though the focus has to be close in with all 57mm of rings attached.  The apparent field of view increases very significantly, which is nice (at full extension, I need to press the eye into the eyeguard to see the whole field of view).  I guess this is because the field stop doesn't increase.  The eyepiece becomes absurdly long, and maybe some focusers won't be happy with the added torque.  I suppose for added fun, I could put in a Barlow, but then the magnification would be more than I can really use.

Friday, November 5, 2010

Astronomy gear and microscopy

I wanted to show the kids the grooves on a CD.  With the medium magnification objective on our microscope, one could just see shimmering graininess.  And I couldn't get the highest magnification objective to focus in on the graininess.  I think the problem may have been that the condenser light couldn't go through the CD, and so I was lighting it with a hand-held flashlight, and that objective has to go so close to the object that blocked the light.  So I got out my 6mm TMB/BO planetary eyepiece (equivalent to about 40X as a microscope eyepiece), popped it in a 1.25" - microscope adapter, and went back to the medium magnification eyepiece, and while we couldn't see it too well, it was obvious that there were pits, and that they were arranged in a line-by-line pattern.

That "1.25" - microscope adapter" is home-made, of course. I cut a 1" segment of 1.25" poplar dowel. I then drilled out the inner 1" of it with a Forstner bit, making a wooden tube with 1/8" walls. I cut a 1.5" segment of some 1.25" ID aluminum tubing (well, actually, a little less than 1.25" ID--I had to sand it out). I then nested the two, with the wooden tube sticking out of the bottom of the aluminum tube, and the aluminum tube extending on top about 1/2" past the top of the wooden tube. (See diagram: gray is aluminum and brown is wood.) They fit snugly, but I put in a couple of drops of CA glue for safety.

The whole assembly then fits around the focuser tube of the microscope, with the top of the wooden tube being flush with the top of the microscope's focuser tube. Eyepieces then fit in the aluminum collar that sticks out on top. The nice thing about making the adapter fit around the focuser tube instead of the more obvious inside is that it doesn't contribute any vignetting.

Of course, it would have looked a bit neater to make the inner tube of aluminum. But ordering an aluminum tube would cost about $8, while a dowel cost $4, plus I wanted the dowel for another project. Moreover, there is an advantage to using a wood inner tube--it won't scratch the outside of the microscope focuser tube as much as metal would. I suppose PVC could have worked as well, but the closest I could find in PVC was 1.29" OD, and I didn't relish the thought of sanding that down to 1.25" OD to fit inside the aluminum tube.