Michael A. Covington    Michael A. Covington, Ph.D.
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Daily Notebook

Popular topics on this page:
Rainbow continued in mist kicked up by car
How I fight mosquitoes and chiggers (redbugs)
Handy hint for users of DioptRx astigmatism corrector
Barlow lens vs. telecentric focal extender
Is Pluto still a planet?
Tracking down a computer crash
Cheap red astronomy flashlight
Not joining the anti-pipe-organ movement
Right-to-left languages in Unicode and Windows
RichTextBox right-to-left language bug
Bring back missing TortoiseSvn icon overlays
Windows 10 install discs, and other handy hints
Venus and Jupiter close together
Many more...
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Windows 10 install discs, and other handy hints

Since Windows 10 arrives by download, how do you get an installation disc? By using Microsoft's download utility, here.

You'll also need a product key (the serial number, consisting mostly of letters, that you type in). If you got the free upgrade, your product key is the same as before. But if your computer came preinstalled with Windows 8, 8.1, or 10, the product key isn't on a sticker on the computer; it's hidden in the BIOS. Retrieve it with this handy program, and print it out, and keep the printout. If nothing else, you'll need it if you ever replace the motherboard.

If your software refuses to install on Windows 10 even though it worked under Vista or Windows 7 or 8, tell it to install in compatibility mode for some earlier version. What's happening is that the installer is asking Windows what version it is, and, getting the number 10, concludes that's something strange and unsuitable. So you tell Windows to lie to it.

Now, why is it Windows 10 rather than 9? Several reasons have been advanced:

  • There is software that looks for "Windows 9" in the operating system name and concludes it's Windows 95 or 98. Bad idea — that's not the right way to check the version number — but some klutzy programmers do it.
  • To signify a clean break from Windows 7 and 8.
  • To get version numbers in sync with Macintosh OS X.

The internal version number of Windows 10 actually is 10, as opposed to Windows 8.1, 8, 7, and Vista, which were 6.3, 6.2, 6.1, and 6.0 respectively. (Right, 7 and 8 were not 7 and 8.) But there is reportedly an elaborate internal mechanism to keep programs from knowing they're in a version of Windows later than Vista unless their manifest says they require it. I haven't explored this, but don't blame Microsoft — some commercial software asks Windows what version it is, and refuses to run in the "wrong" one even if it would have worked perfectly well.

Did Windows (Vista, 7, 8, 10) break my software?
Or was it 32- versus 64-bit?

It has dawned on me why so many people think Windows 10 might not run their software, even though in fact, anything that follows Microsoft's recommendations since the late 1990s will run with no problems (and I run plenty of older software).

It's that a lot of people don't realize when they've switched from a 32-bit to a 64-bit operating system. All recent versions of Windows come in both kinds.

The 64-bit version requires a 64-bit CPU, addresses more than 4 GB of RAM, and is generally faster. But it won't run some older software. It does run normal 32-bit Windows software as well as newer 64-bit software. I don't have the details at hand, but Win16 programs (from as long ago as Windows 3.1) will run in newer 32-bit but not 64-bit versions of Windows. Here is an erudite technical discussion.

64-bit and 32-bit editions of recent versions of Windows look just alike. To find out which you have, right-click on "Computer" or "This PC" in File Explorer and choose Properties.

I think a lot of people are clinging to Windows XP because they want to do things that actually would work fine (and be safer) in 32-bit Windows Vista, 7, 8, or 10. But I would want to experiment to be sure.


Bringing back missing TortoiseSVN icon overlays

Windows 10 update at bottom.

I use TortoiseSVN on my PCs, in conjunction with a CollabNet Subversion server on my home network, to store current and past versions of all my work in minimum space. ("Subversion" because it keeps track of versions and sub-versions, and you can always revert a file to any earlier state.) Besides version control, it's also good for keeping a desktop and two laptops in sync. Both TortoiseSVN and CollabNet Subversion are free.

TortoiseSVN normally uses icon overlays to show you which files and folders are up to date. Here the "Hodierna" folder contains a file that has been changed since I last downloaded it, so the changes need to be uploaded. The other folders are current.

Notoriously, these icon overlays sometimes fail to appear. On Philothea, with a newly installed setup, they were obstinately absent.

The problem is that Windows supports only a limited number of icon overlays, and other software may have claimed too many of them. Reportedly, 11 are available for user software, or maybe fewer. Windows uses a few internally to mark such things as shortcuts. Dropbox (which I have) wants a large number of them. And so on.

The solution? Take away some of the other applications' icon overlays. This can be done by editing the Registry, but it's much easier and safer to use the free Autoruns utility from Microsoft. Launch Autoruns with administrator privileges, and then search under Explorer until you find two lists of icon overlays, 64-bit and 32-bit:

I chose to give Dropbox only its first three (which are the most important) and then give TortoiseSVN its full set. Presto — the icon overlays are back.

Windows 10 update: Under Windows 10, OneDrive takes up 5 icon overlays and cannot be uninstalled, nor can Autoruns see them or uncheck them. (A matter of registry permissions.) Note that both Dropbox and OneDrive have key names that begin with blanks in order to make them come first in alphabetical order.

What worked: I had to go into the Registry (HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\ShellIconOverlayIdentifiers) and rename the first three Tortoise overlays so that they have spaces at the beginning (thus "1TortoiseNormal" became " 1TortoiseNormal" and so on). Now those three are the first in alphabetical order; then Dropbox's three; then Windows loads what it can of OneDrive's five.

They work just fine after the renaming, and the ones that come first in alphabetical order win out.

33rd anniversary: Dishwasher

Silver for the 25th, gold for the 50th when it comes, a dishwasher for the 33rd. Our new Bosch dishwasher arrived today, and it is quiet. The racks are completely different than on our old Maytag — instead of a place for every dish and every dish in its place, the Bosch has the same low, angled tines everywhere, cleverly designed so you can put plates, bowls, or glasses anywhere.


Activation servers, rental software, and other modern problems

[Revised for conciseness.]

Activation servers are today what copy-protected diskettes were in 1987: something that sounds like a good idea but causes unforeseen difficulty.

Copy-protected diskettes died a sudden and well-deserved death in 1987, when IBM switched from 5.25-inch to 3.5-inch diskettes. All of a sudden, people had to copy their diskettes into the other format in order to use them.

Today's potential problem is software that has to connect to an activation server at the time of installation. That's a good way to keep one person from installing 1000 machines from a single copy. But what if somebody needs to do an installation of an older piece of software and the activation server is no longer there?

I ran into that moving Adobe Audition 3.0 to Philothea last night. Adobe's activation server doesn't work any more. To their credit, they have released an alternative version of Audition 3.0 (along with the other CS2 products) that I could download and install without an activation server.

Both Microsoft and Adobe are trying to move toward software-by-subscription, otherwise known as software rental. It is the alternative to permanent licensing for a one-time fee (software purchasing). In the days of mainframes, both methods were fairly common, and there was also a surprising amount of software that was free or came with the machine.

With the rise of personal computing, manufacturers wanted to market their software as objects that could be bought in stores, by purchase rather than subscription. The industry boomed.

We live in a different world now, and the gorilla in the room is that software doesn't necessarily become obsolete in five or ten or even twenty years. We're past the era where all software was primitive and poorly built, or severely constrained by small, early computers, or both. They can't sell us a new version every couple of years.

Manufacturers are moving to software-by-subscription because they want continuing income. Fortunately, the subscriptions are often surprisingly affordable in the short term and are often accompanied by generous free-trial periods.

The awkward thing is that software is not just a tool that we use; it's intimately combined with the things we make with it. Rent a table saw and build a floor and give the table saw back; you still have the full use of the floor. But rent a word processor and write some documents, then give it back, and you can no longer edit your own documents!

That is the problem with software-by-subscription, at least until a much bigger interoperability problem is solved so that software really does work more like rented tools. I can edit the same .TIF file with Photoshop one day and Pixinsight another day; I don't have to keep Photoshop in order to keep working with the file. If other kinds of data worked like that, software-as-a-service would make a lot more sense.


Happy anniversary, Melody!

I hereby incorporate by reference all that I've said to you in the Daily Notebook on previous anniversaries. Thank you for 33 great years!

‭"‮שָׁלוֹם!‏‬" Right-to-left languages in Unicode and Windows‬

Hebrew, Arabic, and some other languages are written right-to-left, not left-to-right like English. Here is a summary of how Unicode handles them.

  • Characters and words in the file are stored in logical order (in order of time — the order in which they would be read out or pronounced). That is, Hebrew is not stored "backward." The characters are in first-to-last order in the file.
  • Characters are designated left-to-right (like English letters), right-to-left (like Hebrew letters), or neutral (like punctuation marks and spaces).
  • Neutral characters inherit their directionality from the characters on either side of them.
  • There is also a default directionality, which applies when nothing else makes the directionality clear. For example, if you were to output "!?:" (three neutral characters) at the beginning of a document, they would appear left-to-right on a computer whose default is left-to-right (the usual case in English-speaking countries). The default directionality also controls whether paragraphs are aligned against the left margin or the right margin.
  • There are special characters you can use to further specify directionality. The most important one is hex 200F, the "right-to-left mark" (RLM). It is an invisible right-to-left character that can be used to continue a right-to-left context. For example, suppose you have a Hebrew word, a punctuation mark, and an English word. Which one should the punctuation mark inherit its directionality from? By adding a 200F, you can arrange for it to be flanked by right-to-left characters, and thus printed right-to-left.

There is a lot more, which you can read here. But let's look at how it works.

Here's a subtle example, which I am going to write into a WPF RichTextBox with the following method calls:

richTextBox1.AppendText("Did you say,\"");  // this part is left-to-right
richTextBox1.AppendText(" ");
richTextBox1.AppendText(" ");
richTextBox1.AppendText("\"?");  // back to left-to-right script

Note that the Hebrew sentence ends with '!' and the English sentence that surrounds it ends with '?'.

And here's how it comes out:

You see that the right-to-left passage is in the right order, complete with the exclamation mark at the end. (The 200F after the exclamation mark makes it stick with the Hebrew right-to-left type.) It continues to work this way if you insert the parts of the string in more elaborate ways, such as by creating Run objects with different colors and fonts.

Hebrew scholars will recognize the words as the inscription on Ben Gurion Airport.

WinForms RichTextBox right-to-left language bug

I did that neat example in WPF. With WinForms (System.Windows.Forms), the older .NET windowing system, the picture is not so pretty.

First the good news: If you send bidirectional text to the RichTextBox as a single string, it comes out OK:

richTextBox1.AppendText("Did you say,\"" +
                        "ברוכים" +
                        " " + 
                        "הבאים" +
                        " " +
                        "לישראל" +
                        "!" +
                        "\u200F" +

That's the only thing that works right. I quickly discovered that some "neutral" characters aren't handled properly as neutral. For example, Unicode 25C4, a black triangle that I was going to use to mark words, disrupts the right-to-left order even though it is officially a neutral character.

richTextBox1.AppendText("Did you say,\"" +
                        "ברוכים" +
                        " " +
                        "הבאים" +
                        " " +
                        "\u25C4" +
                        "לישראל" +
                        "!" +
                        "\u200F" +

More seriously, even without any unfamiliar characters, WinForms RichTextBox loses track of its directionality after each AppendText. Here is a simple example, but as you can imagine, a program that appends the text in small pieces can easily make a big mess.

richTextBox1.AppendText("Did you say,\"" +
                        "ברוכים" +
                        " " +

richTextBox1.AppendText(" " +
                        "לישראל" +
                        "!" +
                        "\u200F" +

Among other things, this precludes changing colors or fonts while sending bidirectional output to the RichTextBox. Every string that involves bidirectionality must arrive as a single, uninterrupted unit. Setting the RichTextBox.RightToLeft property (to change the default) doesn't seem to be powerful enough to fix it.

I have been in touch with Microsoft about this. I'm blogging it here so that others will at least know it's a known problem (still present as of .NET 4.6).


Meet Philothea the new computer

After taking Sharon to a 7:45 a.m. doctor's appointment in Atlanta (and hearing my high school friend Richard Dasher interviewed on Sirius Channel 111 during the drive back), I spent the latter part of the day doing some tidying up of Athena, my desktop computer (the Asus Essentio from the fall of 2009).

Sensibly, before doing a lot of software work, I decided to inspect the hardware carefully.

I found a capacitor on the motherboard that was bulging like the one on the video card that recently failed.

That made the decision for me. Athena runs fine now but is going to need major repairs soon. Since Athena is six years old, it's time for a new computer.

So Melody and I betook ourselves to the local Best Buy store and scored a deal on a just-returned, locally-refurbished Dell Inspiron 3847 for $519. This is the least I've ever spent on my main work computer. The most was $5500 on an IBM PS/2 Model 70 back in 1991.

We've named the new computer Philothea, continuing my series of naming computers for saints (instead of goddesses, mostly variations on the goddess Athena — a system started by Cathy and Sharon a long time ago).

I wonder if both Athena's video card and Athena's motherboard were pushed over the edge by the overheating event last month.

Main technical discovery so far: If you want to install an aftermarket video card in a new Windows 8 machine, you have to turn off Secure Boot in the BIOS. When I first transplanted the Athena's (newly replaced) dual-monitor video card into Philothea, Philothea refused to boot. The reason? The video card contains some BIOS extensions, and Secure Boot didn't trust them.

Right now Philothea is eating her fill of Windows updates. Software installation will proceed over the next few days.


Not joining the anti-pipe-organ movement

This Notebook entry is addressed mainly to my fellow Christians, but others may find it interesting.

I've recently learned that one of the shibboleths of the "megachurch" or "church growth" movement is that you're supposed to dislike pipe organs.

Count me out. Admittedly, some people have never developed a taste for organ music. They are often the same ones asking me to develop a taste for loud rock music.

I've found a major source of the anti-pipe-organ movement. In The Purpose-Driven Church, Rick Warren has this to say:

We invite the unchurched to come and sit on seventeenth-century chairs (which we call pews), sing eighteenth-century songs (which we call hymns), and listen to a nineteenth-century instrument (a pipe organ), and then we wonder why they think we're out of date!

Well... We also read a Bible, parts of which are well over two thousand years old. If that doesn't make us out of date, nothing will!

Rick Warren goes on for a few pages about the need to turn church music, basically, into popular music or rock music in order to attract the unchurched. Reportedly, in speeches, he takes it for granted that people "hate" the pipe organ.

I have to tread a thin line here. Yes, we should sing newer music as well as old music, provided it's good. Yes, we should use modern musical instruments appropriately. In my opinion that does not mean adopting the esthetics and values of a rock concert, but it does mean using things like electronic keyboards effectively.

In fact, in general, if a church doesn't have a pipe organ, I wouldn't be strongly agitating to buy one. The purpose of a pipe organ is to provide great versatility with just one musician. It was the ultimate one-man orchestra. There are other ways to get versatility now that electronic instruments have been invented. But if the organ is there, use it.

What I don't buy is that we're obligated to throw out everything that isn't from the present century and replace it with contemporary entertainment. As I said, that would mean throwing out the Bible.

It would also mean losing our connection with our predecessors. Surely people come to church for something of enduring value, not for the latest episode of this week's hot fashionableness. In fact, if you ask them, they say they want the church to give them a connection with the past. Even to the point of using a pipe organ.

And it would mean catering to provinciality and undeveloped tastes. Must a church refrain from using any kind of music that is not already familiar to its audience, er, I mean congregation? A church music program is not a dance band. Its purpose is to edify, not to entertain. And that may mean helping people expand their tastes in order to appreciate music and other arts that have glorified God in an enduring way.

Evangelical culture has a problem with inverse snobbery and I suspect the move to "modernize" (i.e., dumb down) the music is part of this. What we have to beware of is becoming something popular that is no longer a church. Rock concerts draw more people than church services — so church services should become rock concerts? Where does it end? Churches turning into Disneyland?

You can read the rest of Warren's passage here. It was published in 1995, so the advice is already 20 years old. On other points, he gives very good advice, but I think that on this point, he has taken a partially good idea way too far.

We have to remember that what worked for Rick Warren, in the particularly shallow, traditionless, history-unaware culture of Southern California, might not work everywhere.

And you can only attract people with novelty for so long, and then then get tired of it and want something enduring.

Follow-up: A friend who is an experienced church worker writes: "When you plan your worship style and content with the unbeliever as your primary focus, you are effectively allowing unbelievers to plan the worship of Almighty God. Worship is primarily for believers. Frankly, I think unbelievers should feel different in a genuine worship service. If worship is familiar and comfortable for them, will they be open to the idea that they need to make a change?"

We want to lead people to God, not make them comfortable in their own culture.


Tracking down a computer crash

Over the past few days I resumed using my upstairs computer, Athena, at its own keyboard and two screens, rather than just by remote access. And it started crashing. About four times in six hours of use, the screens suddenly froze with a fine crosshatch pattern superimposed on the display, the music from the sound card turned into a constant droning noise, and the computer was unresponsive to everything except the power switch.

Step 1 was to open up the computer and re-seat the video card and the RAM. I also found a ventilation problem (there since the factory) and improved the ventilation.

That didn't fix it. Next step: remove the aftermarket video card and use the video system on the motherboard (with only one screen).

I haven't run the computer this way enough yet to know whether the crashes are cured. But I found something suspicious on the video card — a bulging electrolytic capacitor, doubtless containing an intermittent short circuit that is influenced by temperature. The bulge shows that the capacitor has conducted too much current and overheated. (It's the brownish cylinder near the top of the picture. Compare it to the one at the bottom, whose top doesn't bulge.)

That is a very believable explanation for the crashes. A shorted capacitor can pull down supply voltages and freeze the CPU. The location of this one would explain why the crashes started when I started exercising the video system, making the video card heat up. And I've had a similar problem before.

This one, I can probably fix with a soldering iron, making this the first time since the 1980s that I've fixed a PC at the component level.

A cheap red flashlight for astronomy

Take one of the white LED flashlights that are cheap or even free at Harbor Freight, a bit of vinyl tape, and the cap from a 2-liter Coke bottle, and what do you have?

A red flashlight for astronomy.

The only problem is that it's not red enough for critical astronomers. Some whitish or purplish light gets through. This might be fixed by a bit of red tape on the inside of the cap.

But it's a lot better than an unfiltered flashlight, and the price is right.

This isn't entirely my own idea; someone on Cloudy Nights Forums mentioned it. A more elegant solution would be to change all the white LEDs to red, but I haven't found a nondestructive way to take the flashlight apart in order to do that. Has anyone?


Here's Saturn with my 8-inch f/10 telescope and Explore Scientific telecentric 2× extender, giving f/20 and a much brighter image than the previous setup, which gave about f/30. (More than twice as bright, but only 2/3 as big.)

The camera was my Canon 60Da DSLR in "movie crop" mode, using the central part of the sensor at full resolution. I took 2 minutes of video (7200 frames) and stacked the best 80% of them with AutoStakkert, enlarging them 1.5× as I did so, and then enhanced the image with RegiStax.

This convinces me the Canon is satisfactory for serious planetary work. Whatever is lost from its image compression can be made up by taking a larger number of frames. A stack of over 6000 frames, not underexposed, gives a practically grainless image.


Is Pluto still a planet?

New Horizons is sending back fascinating discoveries about Pluto, and many people want to reopen the question: Is Pluto a planet?

The question is difficult for two reasons:

  • There seems to be no good classification that will give us exactly the list of nine planets we learned in school. If Pluto is a planet, so is Eris and maybe Ceres. If Pluto isn't a planet, maybe neither is Mercury.
  • Some classifications are natural (like bird vs. mammal) and others are artificial (like rock weighing more than a ton vs. rock weighing less than a ton). Only the first kind are of real scientific interest.

When Pluto was "demoted" to "dwarf planet" (a different category, not a type of planet) in 2006, it was because it did not meet all three of the following conditions:

  • It must be held in a round shape by its gravity (hydrostatic equilibrium).
  • It must orbit the sun.
  • It must contain the bulk of the matter that is in its orbit; that is, it must not share its orbit with a substantial amount of other matter.

The third criterion is what Pluto fails. Like Eris (a recently discovered object similar to Pluto but farther out), Pluto is part of the Kuiper Belt of distant asteroids.

That criterion has been questioned because it is not about the object itself, but rather its surroundings. Should the same object be a planet, or not be a planet, depending on what happens to be near it?

I think that's a valid objection. What if some orbital encounter had moved Pluto into a region where there were no asteroids? Would that change its nature?

But consider also the second criterion. Must a planet orbit the sun (or another star)? That's not a question about the nature of the object. The largest satellites of Jupiter and Saturn, and even our moon, are quite planet-like except that they orbit other planets. Mercury and our moon are so similar that pictures of one can easily be mistaken for the other. (This one is Mercury.) Of the two, Mercury is only 40% larger. So — are they really different kinds of objects?

I won't press the point, because classifying objects by what they orbit is time-honored astronomical practice. But I propose that we drop the third criterion, about not sharing the orbit. One day, in some stellar system, we're going to encounter two perfectly normal planets that share an orbit at the Lagrange equilibrium points. They may be the size of Jupiter. We won't want to demote them to "dwarf planets" just because there are two of them.

The way I see it, Pluto is a planet, and so are Eris, Ceres, and other planetary bodies that are big enough to hold themselves in a round shape.

We can no longer have nine planets, but maybe we can have more than ten. In the 1800s, astronomy books classified the asteroids (Ceres, Eros, etc.) as planets, pure and simple, until it became evident that there were more than just a few.

The only reason for wanting to hold to a list of 9 planets is human tradition — not very long-established tradition; we've had that list for less than a century. If we want to follow human tradition, maybe we should go back to the five ancient planets: Mercury, Venus, Mars, Jupiter, and Saturn. The ancients didn't know Earth was a planet and, of course, didn't know of Uranus, Neptune, or Pluto.


Although it is not yet clear whether and to what extent a foreign power was behind it, we hasten to express our shock and dismay over the terroristic attack that happened today in Chattanooga, and our appreciation to the soldiers who so unexpectedly died for their country.


For "3× Barlow" read "3× extender" throughout my notes:
Barlow lenses vs. telecentric focal extenders

I've just had my consciousness raised about an important optical distinction.

I've taken lots of planetary images using various telescopes plus either my 2× Celestron Barlow lens or my 3× Meade focal extender to magnify the image. Until the other day I was under the impression that they were both Barlow lenses. The latter one isn't. I was calling it by the wrong name.

The difference is important in photography because the magnification of a Barlow depends on the distance to the focal plane, but the magnification of a focal extender doesn't, at least not to a great degree.

So, when combined with a deep Canon camera body, my 2× Barlow was magnifying more than 3× when I photographed Saturn the other day — but the 3× Meade TeleXtender was also magnifying 3×

Here's a diagram that shows how they work. Note that the lens arrangements are not exact.

The light cones come out of the telecentric focal extender more or less parallel, as if they were coming from a telescope objective of very long focal length. (That's what telecentric means.) That is better for the eyepiece and camera than if they came out diverging, as they do from a Barlow. It also makes the magnification relatively insensitive to focal plane position.

You can recognize a telecentric focal extender because you can pick it up, look through the small end, and use it as a Galilean telescope. It may be a bit out of focus, but it definitely magnifies distant objects. (And not if you look through the big end.) A Barlow lens makes objects look smaller no matter which end you look through.

With all this in mind, I've just bought an Explore Scientific 2× focal extender and am going to try photographing Saturn with it.

I hear great things about the price-performance ratio of Explore Scientific. What I'm sure of already is that they have the spiffiest product packaging in the business. That box has magnetic clasps!


Saturn, two ways

Despite the hot weather, we've had rather steady air in the evenings recently, and I've had good views of Saturn.

The purpose of these pictures, taken July 9 and 10 respectively, was to compare a dedicated planetary camera to a Canon 60Da DSLR in movie mode.

The first picture was taken with a DFK planetary camera, recording 7.5 frames per second of uncompressed video, using the 8-inch telescope and Meade 3× focal extender.

The second was taken with the Canon 60Da, recording 60 frames per second (it can't do any less) with a much shorter exposure (1/60 second, to be precise) and a Celestron 2× Barlow lens (actually magnifying 3.3×, which is much more than ideal, due to the extra space introduced by the depth of the camera body).

The two pictures are nearly equal in quality, but what you don't see is that the Canon DSLR picture was trickier to process. It was actually downsampled from its original size and despeckled in Photoshop at the last step.

The dimness of Saturn worked against me, as did the high f-ratio with the Canon. (I didn't realize until late in the session that my 2× Barlow was giving me 3.3×, effectively f/33 with my telescope, nor could I do anything about it.)

The planetary camera had an easy time because it could take long exposures. I exposed for two minutes (the maximum set by the rotation of Saturn) and stacked the best 80% of 900 frames with AutoStakkert and enhanced them with RegiStax. Everything worked as intended. Exposures of 125 milliseconds are not too long in this situation.

The Canon had to be turned up to ISO 4000 (surely its highest true speed, although the settings go higher) and still produced underexposed images. Because it was recording compressed video, I (correctly) felt the need for an ample number of images; fortunately, in about two minutes I got almost 7,200. Stacking and processing were done the same way, with more fiddling with the adjustments. AutoStakkert corrected the underexposure as best it could.

I don't think video compression worked against me; not with over 7,000 frames. But the Barlow lens did. I need to right a way to get a magnification of about 2×, probably through positive projection with a Plössl or orthoscopic eyepiece.

Improving the ergonomics of a DioptRx astigmatism corrector

Here's the right way to solve the orientation problem for an eyepiece with a Tele Vue DioptRx astigmatism corrector on it. Last month I proposed a method that didn't quite work.

The corrector lens has to be rotated into the right position to match the astigmatism in your eye, and as the telescope tilts and twists to reach different parts of the sky, you have to keep turning the DioptRx into the right position.

If the astigmatism correction that you require is fairly subtle (like 1.00 with a 2-millimeter exit pupil), orienting the DioptRx can be tricky and may even require you to defocus the stars to see if they look round. What we want is a way to keep the lens oriented without having to do this.

The scale marked A to F on the DioptRx doesn't mean anything; it rotates freely relative to the lens until it's tightened down on the eyepiece.

So what can you do? Here's my solution.

(1) By reading through the DioptRx lens with my glasses off, I found the best orientation for the DioptRx. Some people might have to look at distant obejcts instead. It's best to look at something with a fine grid in it, so you can make sure you have equal sharpness vertically and horizontally; I used my computer screen, close up.

(2) I used a silver Sharpie to make a mark on the rubber eyecup showing the point that was directly down (toward my chin) when the lens was oriented for best vision.

(3) I attached the DioptRx to the eyepiece and tightened it down so that it was just loose enough to rotate.

(4) I affixed a piece of white tape (which I can feel in the dark) to the ring with the A-F scale, directly below the dot. Now I can rotate the DioptRx "by feel" until the white tape is in the right position as I'm at the telescope.

The position of the tape is lost if I ever take the DioptRx off the eyepiece; after putting it back, I'll have to reposition the tape under the dot.

And the position of the dot is lost if I ever remove the rubber eyecup. In that case I could either put a dot on the metal, underneath the eyecup, or repeat the setup process.

Finally, note that if the dot or the tape comes out in an inconvenient position, you can put it 180 degrees from where it originally was; positions 180 degrees apart are equivalent.


Aaron and Emily

Today we celebrated the wedding of my nephew Aaron Paul and his bride, Emily Nash. It was held in a remote meadow... I mean, on the large back lawn of the First Baptist Church of Winder, and there were some playful touches: there was a chandelier hanging in a tree, and after the couple's first dance, guests were invited to play croquet and cornhole. (Isn't Emily a P.E. teacher? Hmmm...) But it was a serious, solemn, Christian wedding and a good testimony to the kind of commitment that marriage requires. As I told Aaron and Emily, "Your job now is to live happily ever after."


How I fight mosquitoes


No, I haven't been away, just busy and lazy about blogging. But today I waged chemical warfare against mosquitoes and want to share some notes.

The way I see it, mosquitoes are enemies. They are only slightly more welcome here than rattlesnakes. They're not just annoying; they carry West Nile virus and equine encephalitis.

To keep them off the human body, DEET is the long-standing most-recommended repellent, but I've seen them land on my hand, and bite, right where it had been sprayed with (supposedly) 7% DEET. 20% DEET spray works better, but picaridin and oil of lemon eucalpytus now reportedly work even better.

What I think is that mosquito populations differ. Every repellent has been proven not to work by some study or other, yet they do work, often surprisingly well.

I also think that anything that changes the scent of human skin will repel mosquitoes to some extent. People report better results after taking thiamine (B6, the smelly vitamin) or eating garlic. I have had very good results with talcum powder that contains menthol (Gold Bond Extra-Strength), and the great thing about this is that it's safe to apply to the body at any time, without fears of toxicity. Reportedly, talcum powder interferes with insects mechanically, not just chemically; they find it hard to land on, and it probably keeps them from recognizing you as a live animal.

A few weeks ago I realized that the mosquito bites around my ankles were actually chiggers (redbugs). To get rid of them, I spray the outside of my shoes and lower trouser legs with permethrin, available from an outdoor-sports store. Permethrin both kills and repels. Although it is used on human skin by prescription to kill lice and some microorganisms, it is not normally recommended for direct contact with skin. It also kills any mosquitoes that are foolish enough to go for my ankles.

Talcum powder mixed with finely powdered sulfur is reportedly very effective against chiggers. Sulfur is a very safe, low-toxicity insecticide; you could eat a spoonful of it without getting sick. Many years ago we used it effectively to get rid of fleas in our carport. We sprinkled it around, and some sulfur continued to be a component in the ambient dust for months or years afterward, and the fleas stayed away. In appropriate amounts, sulfur does not have much of a smell. It may be more of a repellent than a toxin — a very effective repellent.

Speaking of insecticides — I don't just repel the mosquitoes, I kill them. A third of a can of Yard Guard, sprayed around my telescope site before I start getting the equipment out, does a lot of good. But I can do a lot better.

Before sundown on the evening of an observing session, I spray the grass and shrubbery with a fine mist of insecticide. A very fine mist is important, and some of it should get on the undersides of leaves, so it will last longer and because that's where the mosquitoes reportedly hide. Such a spraying won't need to be repeated for several days unless there is heavy rain.

My preferred insecticide for the purpose used to be permethrin, which, as I said, both repels and kills. For those very reasons, though, it is no longer widely marketed to do-it-yourselfers. The newer alternative, bifenthrin, kills without repelling, so the bugs stay around and actually die. That means that a good bifenthrin spraying may take two days to achieve its full effect. I haven't tried the other alternatives, cyfluthrin and cyhalothrin, but permethrin is still available from some suppliers, so that's what I'll probably go back to using.

One insecticide is not enough; if the dose is kept low enough to be safe (and I'm a stickler for safety), some sub-populations will be resistant. Every so often, maybe twice in a summer, I spray with a fine mist of malathion. That is a stronger insecticide, although still safe in the recommended strengths, and has a distinctive smell. Although recommended mainly for fruit trees, it is very effective against mosquitoes and is used in public spraying programs.

What about the bites that can't be prevented?

Taking a non-sedating antihistamine such as Claritin or Allegra in advance will reduce the body's response to a mosquito bite. Immediately after the bite occurs, I've had good results with After Bite, which is a solution of sodium bicarbonate and ammonia; a baking soda paste would probably do the same thing. Gold Bond cream (menthol and pramoxine) is good at relieving the itching once it starts, and I've had better results with it than with steroids, which are slow-acting; it also repels mosquitoes, so you won't get more bites near the same place.

And a bath with a couple of ounces of baking soda powder in the water really helps relieve the itching later on.


Independence Day

I want to wish my fellow Americans a happy and thankful Independence Day.

I also want to emphasize that the flag you see here is the flag of our whole nation — not of one side in any recent controversy, despite what the chit-chat may be saying on Facebook.

People who are in the political mainstream (liberal, middle-of-the-road, and conservative) should claim their national flag and not let it be appropriated or reinterpreted by any special-interest group.


Rainbow continued in mist kicked up by car

Here's proof that rainbows come from sunlight shining on water droplets, and the position of the rainbow depends on the direction of the sunlight — if there are droplets in the right direction, you'll see a rainbow. Here the rainbow in the sky continues in the mist kicked up by a car. Melody snapped this picture with my iPhone as we drove across Athens this evening (June 30).

Venus and Jupiter together

Venus and Jupiter will be close together in the sky for some time, but this evening (June 30) was their closest pass. They were within 1/3 degree, which means that your thumbnail at arm's length would easily cover both of them, and they could be seen together in a telescope.

They are not close together in space, of course. Venus is much closer to us than Jupiter.

We had intermittent thunderstorms all afternoon, and I didn't expect to have a clear sky to see Venus and Jupiter, but in fact there was a brief period when the clouds turned to high haze. I grabbed my 12×50 binoculars and walked across the street to view the conjunction.

Then I hurried back to the house and got my tripod, Canon 60Da, and Sigma 105/2.8 lens. The picture you see above was taken at f/4, 1/10 second, ISO 1000, with diffraction caused by crosshairs that I added in front of the lens to make stars stand out when I photograph star fields.

Next trick would be to view them with a telescope. I ran back up the driveway, put down the tripod with the camera on it, grabbed a light tripod that came with a NexStar 5 that I no longer own, along with the Celestron 5.

But when I got to the street, the tripod failed catastrophically — the spreader came detached from the legs. Further mechanical investigation will ensue, but I was glad the telescope wasn't on it at the time. And clouds came in before I could arrange any other way of viewing the conjunction telescopically.

The ideal would have been to photograph the planets together, through the telescope, at a high enough magnification that they can both be recognized as planets. I didn't get to attempt this. It's not easy because Venus is something like 10 times as bright as Jupiter. I'm sure someone somewhere was successful, and we'll see the published pictures soon.

If what you are looking for is not here, please look at previous months.