More solar observing experiments

I am continuing to experiment with my solar projector, which uses a hard disc platter as a heliostat mirror, and two Surplus Shed lenses, one positive with 2600mm focal length, and one negative with -800mm.  While I can see sunspots, I can't see almost any structure in them, and there is a lot of chromatic aberration.  A bit of experimenting suggests that most of the chromatic aberration is due to the negative lens, so I've ordered a -1000mm achromatic lens.  We'll see if that improves things.

While ordering from Surplus Shed, I also ordered a 15mm focal-length Hastings triplet.  If it does not make a good planetary eyepiece--I will certainly will try--I will have a nice 15X loupe, replacing my 15X plastic-lens loupe (which is usable, but only in the center of field).

Solar observing mishap

I was experimenting with solar projection with my 8" scope.  I first stopped up the aperture to about 3".  All was well.  Then I went for full aperture.  The images were sharper.

But then the images went foggy.  And I couldn't get them in focus.  And smoke started coming out.

I disconnected the Kellner and noticed the lens was fogged up.  Turns out that while the eyepiece housing was metal, as it should be for solar work, the eyepiece lenses had a plastic spacer.  Which melted.  The spacer is the black thing to the left of the lenses.

The lenses cleaned off fine with acetone.  But I wonder how I can find a metal replacement spacer.

So, that's a warning for solar work: don't assume that just because the eyepiece tube is metal, the inside is metal, too.

LunarMap 1.11 for Android

I just posted LunarMap HD and Lite 1.11 in the Android Market (or Google Play, as it is now awfully renamed).  Today's revisions

• Add satellite features (e.g., Plato B) [HD only]
• Adds astronaut-named features
• Improve memory handling
• Fix bug with selection of feature types
• Add a little more info about feature types

With this reversion, the HD version contains all official 9099 IAU named features.

I will upload to the Amazon Appstore on Monday if all is well.