Tuesday, August 14, 2012

Galactic Night released

I've released Galactic Night, my night mode app for rooted Samsung Galaxy S2, S3 and Note.

Sunday, August 5, 2012

Progress on Samsung night mode

I have test code that works on my rooted S2 with GB and according to testers previous versions have worked partially (the night mode got disabled by power off/on) on an S3 with ICS and an S2 with ICS.  Anybody who wants to try it can get it from here. It definitely needs root.

Saturday, July 28, 2012

Samsung red mode

I am working on a better red night mode for rooted Samsung phones. The usual way to do red mode for rooted Android devices is to use ChainFire3D. However, ChainFire3D does red mode simply by dropping the green and blue components, and as psonice once pointed out to me, that's not the best way. After all, then, green and blue stuff on the screen is invisible.

The right way to do it is to combine the color components, using an RGB to grayscale conversion, and then use the red component.

I just managed to do it on my rooted Android 2.3 Epic 4G Touch using Samsung's MDNIE profiles (see screenshot) and some simple shell scripts. But I don't know if this will work on other Samsung phones, though I assume all Galaxy S2 family phones will work with my method.

A good rule of thumb is that a version of this hack should work on all rooted Samsung phones that have the Dynamic/Standard/Movie color mode switcher under Settings | Display | Screen mode.

If you want to help me with this project and have a rooted Samsung phone, there are some things you can do:

  1. (Easy, and you can do it even if your phone isn't rooted.) Go to Settings | Display | Screen mode and see if you have Dynamic/Standard/Movie switch. Tell me (either by email or by commenting) which phone and OS version you have, whether it has the switch, and whether it has these three or some other modes there.
  2. (A little more advanced and needs root.) Email me your /system/etc/mdnie_tune_movie_mode and /system/etc/mdnie_tune_ui_standard_mode files , also telling me which phone and OS version you have.

You can email me at arpruss at gmail dot com, with subject line "red".

The resulting switcher will be free and open source.

Tuesday, July 10, 2012

LunarMap HD USGS Geologic Map

I've added the 1971 USGS Geologic Map to LunarMap HD for Android (available in Google Play and Amazon Appstore (which will take a couple of days to update)).

Notice in the screenshot how the labels hard-printed on the map get combined with the yellow labels added by LunarMap, without any duplication of labels.

Tuesday, June 5, 2012

Transit of Venus

Here are some photos over the first 45 minutes or so. They are in sequence, but not evenly spaced in time.

This is from my 8" F/4.5 scope, stopped down to about 3", with photo taken hand-held with my Canon G7 camera off the projection funnel.

Here is the last photo in a larger size.  The sunspots were very nicely visible in the funnel (I counted about 15), and I could even see two without a telescope in the #14 welder's glass.  The photo doesn't do justice to the sunspots, especially the nice bright area that was just barely visible at the bottom of the disc.

Sunday, May 20, 2012


Here in central Texas, the sun set before the eclipse hit maximum.  But we had some lovely views of the moon gobbling up sunspots as the sun was setting over the lake.  Photos are taken by a Canon G7 camera, using a solar funnel for projection.  The scope is an 8" F/4.5.  For the first photo it was stopped down to about 3".  The second photo I think used the full aperture.

And for reference, here's the sun in the afternoon, before the eclipse:

Sunday, May 13, 2012

More sunspots

I still don't quite have the hang of photographing the projected solar image on my funnel--it's still sharper naked-eye--but the photos are improving. When the clouds aren't in the way.

Saturday, April 21, 2012

Sun funnel done

To get the size of sun funnel I wanted, I had to join two different funnels.  But it works!

Friday, April 20, 2012

More sunspots

I was handholding the projection screen material in front of my scope for a 4-5" image.  Wow!  Today's sunspots were really impressive.

I noticed that they were very much in pairs.  Apparently sunspots come in pairs with opposite magnetic polarity.

Tuesday, April 17, 2012

Sunspots today

A kind soul sent me a 25mm Kellner eyepiece for solar projection purposes for the cost of shipping.  A nice thing about this eyepiece is that the field stop extends quite far from the lens, and will dissipate any sunlight if the sun goes to the edge of the field.

I played with it today to see how far away from the eyepiece I'd need to get to have a 4" image in my 8" F/4.5 (stopped down to two 3" apertures).  Answer: ~26cm.  When I projected the sun on a piece of cardstock, at that size, I was blown away by the richness of the structure of the sunspots today.  And the sun was quite low, as it was shortly before sunset.  Here's today's LMSAL photo.  I saw the two larger groups but somehow missed the smaller group that's down from center.

It's time to build a sun funnel as soon as my projection material comes.

Thursday, April 5, 2012


Afocal, Coulter 8" F/4.5, TMB/BO Planetary 6mm eyepiece, with my son's Sony P100 camera.

Hard drive platter as flat mirror

Some time ago, I disassembled some old hard drives with the kids (including one that was donated to the cause by my employer's IT services), and extracted magnets (fun, as long as you're careful) and platters.  The platters gave me the impression of high quality first-surface mirrors, and I've been looking for a use for them.  I've put one into my so far not very successful solar projector project as a heliostat.

I was just playing with looking at stars reflected in this platter through my 15x70 binoculars, with only one eye.  There was some unidirectional glare from Venus, but stars looked pinpoint.  I was only hand-holding the binoculars, so the test isn't great.  And it would have been better if the central hole was blacked out.  This isn't a very demanding test, higher magnification would be much better, but it's a promising start.

Sunday, April 1, 2012


I've never done very well with Mars, and my best views--never that good--have been with an aperture mask.  With full aperture, I just get a red and white blob of chromatic aberration.

I had a 75mm single-hole aperture mask that I was planning to use in my 8" F/4.5 Coulter for solar projection, but tonight I added another hole to it.  Both holes miss the two-vane spider.  The views of Mars with the aperture mask and a 5mm ortho are great--best I've had.  Two dark areas (one was probably Mare Acidalium) and a bit of polar cap.  I don't know if they're better with two holes than with one--there may be better contrast with one--but they are a bit brighter with two, and I love the easy focusing (with the mask, you see double and you focus by merging the images).

Saturday, March 31, 2012

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).

Monday, March 26, 2012

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.

Saturday, March 10, 2012

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.

Saturday, February 25, 2012

Solar projection scope prototype

Warning: With solar observing, be very careful not to look into the optical train, or you are likely to go blind.  Do not leave the optics unattended.  Watch for children!  Don't let any critters walk into the optical path.  Remember that as you experiment with the device, the optical path may be unpredictable.

I got the following lenses from Surplus Shed:

  • 150mm diameter PMN, 2600mm focal length (stock L3855D, $25)
  • 68.7mm diameter NMN, -800mm focal length (stock L4380, $4)
I cut out holes in the shipping box and mounted the big lens to one side of it.

Next, I cut a hole in a piece of plywood, and mounted the small lens in it, using pieces of an old bike inner tube to hold it in place.  I added two pieces of wood to the bottom of the plywood for a stand.

I had some used hard drive platters.  I used a pair of cheap Harbor Freight helping hands to hold one of the platters as a heliostat mirror (using the alligator clip to hold the platter through a piece of cloth so it wouldn't mar the platter too much). 

I set up the optical train on the driveway.  After some experimenting, I got it working.  Hard drive platter reflects light into the big lens.  About 80 inches further, the small lens stands.  A couple of meters further away (I didn't measure; my calculations suggest 6.3 meters as the correct distance, but it seemed closer to me), in the shade, I have a box with a piece of card stock taped to the side as a projection screen.  

Aiming hard drive platter to reflect the sun was easier than I expected.  (At this point, the safety stuff becomes crucial--make sure the sunlight doesn't get focused in anybody's eyes.  Likewise, make sure no animal walks into the optical train.)  I could see a bright spot reflected from the platter.  I moved the spot onto the big lens.  I could then see an unfocused spot on the ground between the big lens and the small lens.  I centered that spot on the small lens, and put the screen box to catch the image.  I then moved the small lens to focus the image.

Result: Eight inch image of the sun.  Acceptable chromatic aberration along edges.  Moderately fuzzy.  One clear sunspot.  (Today's solar photo online showed a smaller sunspot near the larger one, and I did not see that.)  

It should work for the transit of Venus.  I hope it will get a bit sharper when I find a good way to collimate the setup, maybe with a laser.  Right now the collimation was all eyeballed (on the other hand, this is very long focal length work, since I am only using a small portion of the 150mm lens since the platter doesn't give much illumination, so it's less crucial.)  I also hope things will improve if align the optical train in such a way as to make the sun be closer to being at right angles to the mirror, which will increase the amount of the primary lens illuminated by the mirror.

At some point, I will try with a 3.5" diagonal instead of the platter, and if it makes a significant difference to quality, I may need to buy a mirror.

While one can no doubt be harmed if fairly well focused sunlight within the optical train hits the eye, it is worth noting that if the big lens is correctly pointed at the diverging lens, at no point in the optical train is there an image of the sun smaller than about 40mm, so the amount of heat concentration is not so great.

Tuesday, February 21, 2012

Shadows and light

I was just looking at Jupiter and Venus, both in the west.  Venus looked slightly gibbous and Jupiter had Io's shadow on it.  It was neat to see that the shadowed part on Venus and Io's shadow both pointed towards the below-horizon sun (after correcting for the upside-down field of view).

I hadn't done much astronomy lately.  I did notice lately that Venus was getting very far in the sky from the sun, and it was gratifying to see this coordinated with the slightly more than half-illuminated face of it.  I suppose it will now be getting closer to it, culminating in the transit this summer.

Monday, January 23, 2012

Solar projection telescope

I'm ordering lenses from Surplus Shed for my big solar projection scope.  The plan is a 150mm PNM objective lens with a 2600mm focal length, followed by a -800mm MNM lens spaced at 1890mm from it.  This should result in 202mm image of the sun approximately six meters away, for an effective focal length 23.1 meters!

I still don't know how I'll direct sunlight into the scope.  My first attempts will use a hard drive platter as a super-cheap mirror.

Sunday, January 22, 2012

Open Star Map for Android

I've compiled and made minor changes to the Google Sky Map application.  In particular, on devices like the Kindle Fire without a compass, it won't go into the auto mode which tracks the sky.  On devices that do have a compass, it should still track, but if you turn off the tracking (lower left corner icon), it will remember that setting (Google set it not to remember the setting, because of users who couldn't figure it out).  You can download the apk for the newly named Open Star Map.

There are a lot of unsatisfactory things about Open Star Map.  For instance, the night mode doesn't change everything.  For another, the catalogs are shallow.

Saturday, January 21, 2012

Google Sky Map now open source

Google has opened up Sky Map: announcement and source code.

Just built it with Eclipse. To build, download the source via svn. Then:

1. Import trunk/app as an existing-source Android 2.3.3 project.
2. In the Project Properties, go to Java Build Path and Libraries.
2.1. Press "Add JARs..." and select libGoogleAnalytics.jar from trunk/app/libs/libGoogleAnalytics.jar
2.2. Press "Add External JARs..." and select the two jars from trunk/tools/libs