A silver dollar and some change

Here's the best of my pictures from December 14. You're looking at the "Silver Dollar Galaxy," NGC 253, in the constellation Sculptor, plus the globular cluster NGC 288, which is in the same field of view. Stack of twenty 1-minute exposures with a 300-mm f/4 lens and Canon 60Da, taken in town under 5th-magnitude skies. Below are enlarged sections of the same picture, to show you the galaxy and the cluster at higher magification.

And that's all, until we have some more clear weather!

Hints for film photographers

[Minor corrections made.]

I've loaded some film (expired 2008) into the Nikon F3 and hope to get my darkroom working in a few weeks after a four-year hiatus. Here are a few hints I've gathered for anyone else who may be doing film photography. Some of this sage advice was going to go into the never-written third edition of Astrophotography for the Amateur, planned for about 2004 but made obsolete by the DSLR revolution. These notes, however, are fully up to date as of 2015.

(1) Instead of the common #76 (PX76, MS76, 76A) button-cell camera battery, use a #357. It is the same size and voltage, lasts distinctly longer, and is more widely available nowadays.

(2) Although Ektachrome is no longer made, Fuji Provia 100F is a rather good substitute.

(3) Film and darkroom supplies are still available from Freestyle and other major suppliers. Processing is available from Dwayne's Photo.

(4) Black-and-white film, paper, and chemicals often last much longer than the expiration dates, but test them. Outdated film will have lower contrast and higher fog. Outdated paper may mottle. Outdated chemicals may not work, and if they do work, you should use them on a one-shot basis (make enough for one roll, use it, and don't save it for reuse).

(5) Old liquid-concentrate fixer may need to be filtered to remove particles of sulfur. What remains is good fixer but has somewhat less capacity than it originally did.

(6) To test fixer, put a piece of unexposed film in it, in a dish with the room lights on. Agitate it regularly and time how long it takes to clear. The correct fixing time for that type of film will be twice that length of time.

(7) Stop bath is not a problem; the concentrate (liquid or powder) keeps forever. If you don't have any, go to the canning section of a grocery store and get some citric acid; then use 1 teaspoon of citric acid per liter of water as an odorless stop bath. Alternatively, if you like strong smells, use one part white vinegar to two parts water.

(8) You can use water instead of stop bath when developing film, unless the developing time is very short and needs to be "stopped" suddenly. Make sure the water is at the same temperature as the developer.

(9) To test film developer, first make sure you have some tested fixer available. Then take a piece of film and, under full room light, develop it in a dish, agitating regularly, for what you think is the correct developing time. Rinse it, fix it, and wash it. Then inspect carefully. It should be black but not pitch-black; you should be able to see bright lights through it. If it's not very dark, your developer is weaker than you thought. If it's pitch-black, then assuming the fixer was OK, the developer is stronger than you thought.

(10) Fixer that is good for film is also good for paper.

(11) To test paper developer, expose a piece of paper to full room light and then, with the lights on, put the paper in the developer. It should be dark within 30 seconds and very dark within 60 seconds.

(12) Safelight filters can fade, making them less safe. To test your safelight, expose a piece of paper so that it will develop to mid-gray. (It may take some experimenting to find the right exposure.) Then, with the safelights on, lay it down on the table and put a coin down on it. After two minutes, develop it. If you can see the outline of the coin, the safelights are not safe for two minutes' exposure. If the coin is only barely visible, you're probably OK as long as you keep the paper out of the direct light of the safelights most of the time.

(13) A safelight filter that has faded can be "beefed up" with a sheet or two of Amberlith, a plastic material used in the graphic arts. In fact, about eight sheets of Amberlith will substitute for a safelight filter (test it, of course).

(14) Red LED light bulbs — new on the scene — are very safe for black-and-white paper. They are incapable of emitting light at wavelengths that will fog it. However, they are not very good for judging print quality; that's why we still use orange safelights.

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IC 405, the Flaming Star Nebula

Here is the nebula surrounding the star AE Aurigae, together with another nebula to which I need to pay more attention. (I should plan my pictures with a really good atlas, such as the Interstellarum Atlas, so that I'll know when I'm going to get photobombed.) Stack of ten 1-minute exposures with a Canon 60Da and 300-mm f/4 lens, taken on December 14.

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The last slide-filing session

For forty years I've been putting astronomical color slides in plastic pages after writing the date and serial number on the slide mount. Tonight (Dec. 28) I did this for the last time, with the Ektachrome astrophotos that had been out on my desk since 2013.

I've been keeping astronomy notebooks since 1969. The latest volume is a 3-ring binder just an inch thick; it is labeled Astronomy and Astrophotography 2005-2015 and begins with a note that since 2008, notes are only printed on paper if slides or negatives are filed with them; normally, I keep records digitally.

End of an era. There may be just a bit more film astrophotography; meteor showers are one thing that shows up better on film than on a digital sensor because reciprocity failure gives the transient light of the meteor an advantage. And there will surely be more film fine-art photography — when I get around to it.

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Calendars, combinations, and the "money bags" hoax

In elementary school, they don't teach us quite enough about the calendar. They teach us the basics, but otherwise well-educated people still believe hoaxes like this one, which circulates on Facebook:

"This year July has five Tuesdays, five Wednesdays, and five Thursdays. This happens once every 823 years. This is called money bags. So: copy this to your status and money will arrive within 4 days... based on Chinese Feng Shui."

Now, the obvious question is how copying this to your status is supposed to bring money, and from where.

But the other question is, how often does July have five Tuesdays, five Wednesdays, and five Thursdays? Do you really have to wait 823 years for that to happen again?

(No, of course. The first thing you should be wondering is what the other 822 combinations are, since we have only seven days of the week. But let's be thorough...)

In what follows I want to point out some simple facts about the calendar that ought to be better known — in fact ought to be taught in elementary school.

I'm going to ignore the phases of the moon, and also the date of Easter, which depends on the phases of the moon.

Considering just dates and weekdays, it ought to be obvious that:

• The calendar for the whole year depends only on what day of the week January 1 falls on, and whether or not it is a leap year. (Apart from leap year day, the number of days between January 1 and any other date cannot vary.)
• That means there are only 14 possible calendars. There are seven days of the week on which January 1 can fall, and every year either is or is not a leap year, so, 14 combinations.
• A year of 365 days = 52 weeks plus one day. Because of this, when leap year is not involved, the day of the week of January 1 (or any other date) shifts one day per year. Christmas 2014 was a Thursday; Christmas 2015 was a Friday.
• Leap year "jogs" this shift by adding one day to it. Christmas 2016 will be not a Saturday but a Sunday.

What most people don't realize is that the calendar repeats every 28 years as long as you don't run into an "odd" century year such as 1900 or 2100 in which the rule for leap year is different. This 28-year repetition is called the Julian Cycle.

Here's a full Julian Cycle, plus two more years to show that the cycle has started over. During the Julian Cycle, you get each of the 7 possible leap year calendars once, and each of the 7 possible regular-year calendars 3 times.

2000  Saturday   (Leap year)
2001  Monday
2002  Tuesday
2003  Wednesday
2004  Thursday   (Leap year)
2005  Saturday
2006  Sunday
2007  Monday
2008  Tuesday    (Leap year)
2009  Thursday
2010  Friday
2011  Saturday
2012  Sunday     (Leap year)
2013  Tuesday
2014  Wednesday
2015  Thursday
2016  Friday     (Leap year)
2017  Sunday
2018  Monday
2019  Tuesday
2020  Wednesday  (Leap year)
2021  Friday
2022  Saturday
2023  Sunday
2024  Monday     (Leap year)
2025  Wednesday
2026  Thursday
2027  Friday
2028  Saturday   (Leap year)    (Cycle starting over;
2029  Monday                     compare 2000 and 2001.)

What about the century years that are not divisible by 400, such as 1900 and 2100? Thanks to Pope Gregory, those are not leap years; the extra "jog" fails to happen. But then the 28-year cycle repeats almost four complete times before the next one. So the relative frequency of the 14 possible calendars is hardly affected.

Now back to the "money bags" problem. July has 31 days, which is 4 weeks plus 3 days. That means some 3 consecutive days of the week will occur five times in any July. If the first of the three is a Tuesday, the others will be Wednesday and Thursday.

And that will happen 1/7 of the time as July cycles through 7 different positions relative to the days of the week.

Because of leap years, it won't be a precise cycle of once every seven years, but it will still be an average of one year out of every seven. Specifically, it happens when January 1 is a Wednesday in a regular year, or when January 1 is a Tuesday in a leap year; that is, in 2003, 2008, 2014, and 2025 in the cycle shown above.

Remaining elementary-school-level question: Why did "they" make a year 365 days, not 364?

It would be more convenient if a year were exactly 52 weeks; why isn't it?

The answer: To keep the calendar in step with the seasons.

It takes the earth 365.2422 days to go around the sun (reckoned by the position of the earth's axis, which is what determines the seasons).

If we want the shortest day of the year always to be December 21, as it is now, then we have to make the year 365 days long, not 364.

In fact, 365 still isn't close enough. If we observe a strict 365-day year, the shortest day will shift to December 22 after about four years, and then to December 23 after another four, and so on, so that after some centuries, we'd be having short chilly days in June and long sweltering days in December.

To keep that from happening, we have a leap year every 4 years.

But even that isn't quite right. It would lead to an error of almost a day per century.

Thanks to Pope Gregory's reform, the actual calendar year, complete with the exceptions in 1900, 2100, etc., averages 365.2425 days. We need 365.2422, so in a few thousand years, we're going to have to make another adjustment.

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C#: When to use ref on a reference-type parameter

We know that in C#, the ref keyword can be used to pass a value-type parameter (such as an integer variable) by reference, so that the called method can alter its value and the alteration will stick. Otherwise, the called method makes a local copy of the variable and works on that.

We also know that in C#, reference-type objects, such as arrays, lists, and user-defined classes, are always passed by reference. Right?

But that's not quite the whole truth. Sometimes you need to use ref on a parameter that is a reference type.

The reason? If you leave out ref, the called method gets its own local copy of the pointer to the array, list, or whatever. It has no trouble finding the object and making permanent alterations inside it. What it cannot do is replace the whole object. It can try, but the calling program is not affected because what was replaced was a copy of the pointer, not the original.

Bottom line: If you're going to create or replace an object, you need to pass it in with the ref keyword. Here's a short program that demonstrates all this:

using System;

namespace RefDemo
{
    class Position
    {
        // A simple user-defined class.
        // Just two numbers (which default to 0)
        // and a method to print them out.

        public int x;
        public int y;

        public override string ToString()
        {
            return String.Format("({0},{1})", x, y);
        }
    }

    class Program
    {

        static void Example1(Position p)
        {
            // No "ref" is needed to change fields
            p.x = 3;
            p.y = 4;
        }

        static void Example2(Position p)
        {
            // No "ref", so the new p is only local
            p = new Position();
            p.x = 5;
            p.y = 6; 
            // These changes don't affect the real p
        }

        static void Example3(ref Position p)
        {
            // Successfully replaces p entire
            p = new Position();
            p.x = 7;
            p.y = 8;
        }

        static void Main(string[] args)
        {
            // Make a Position
            var p = new Position();
            p.x = 1;
            p.y = 2;
            Console.WriteLine(p);

            Example1(p);
            Console.WriteLine(p);

            Example2(p);
            Console.WriteLine(p);

            Example3(ref p);
            Console.WriteLine(p);
        }
    }
}

The output from the program is

(1,2)
(3,4)
(3,4)
(7,8)

(never "(5,6)") because method Example2 does not affect the object p as seen by the outer program.

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The truth about await in C#

Why await does not actually wait for the process to finish

We all know that we use the await keyword in C# to run a time-consuming computation in the background. It is a newer alternative to the older BackgroundWorker object class.

But some key facts about await are not sufficiently understood by C# programmers, including, until recently, me. They are:

• await does not create a background process. That is done by Task.Run or whatever else is the argument of await.
• await does not exactly mean "await." It means "launch the background process and keep going, but don't run any subsequent statements in this method until that process has finished."
• async marks a method as able to be interrupted by await in that way.
• async void is wrong, except in event handlers. Normally, you should declare async Task or async Task<Type>. You do not have to return a Task; the compiler takes care of that for you.
• The argument of await must be something that returns Task or Task<Type>.

Crucially, await suspends the method in which it occurs until the awaited task is finished, but it does not suspend the calling method. And that can give strange results.

Consider for example this program:

using System;
using System.Threading.Tasks;

namespace AwaitDemo
{
    class Program
    {
        static void Calculate()
        {
            // A time-consuming computation.
            Console.WriteLine("Calculating...");
            int n = 0;
            for (int i = 0; i < 2000000000; i++) { n++; }
            Console.WriteLine("Done.");
        }

        static async Task Method1()
        {
            await Task.Run(() => { Calculate(); });
            Console.WriteLine("End Method1.");
        }

        static void Main(string[] args)
        {
            Method1();
            Console.WriteLine("End main program.");
        }
    }
}

You might think the output would be

Calculating...
Done.
End Method1.
End main program.

but it isn't. All you get is

Calculating...
End main program.

and the program ends, unceremoniously killing the "Calculating" task before it's finished calculating.

What's going on?

The answer, of course, is that the await in Method1 only makes Method1 wait until the task is finished.

The main program, which calls Method1 conventionally, is not affected. It calls Method1 and then keeps right on going to the end of the program.

To be precise, the effect of calling Method1 is to perform the actions before the await, if any; launch the awaited task; and schedule the rest of Method1 for execution after that task completes.

When that has been done, Method1 returns control to Main, which called it, and Main happily finishes and terminates.

Sure enough, Visual Studio gives us a pop-up warning:

but we can't do exactly what it suggests because Main cannot be async and thus cannot contain await. Instead, we have to say "call Method1 and wait," as follows:

        static void Main(string[] args)
        {
            Method1().Wait();
            Console.WriteLine("End main program.");
        }

Because Method1 returns Task, it can use the Task.Wait() method.

Using Wait makes the whole program stop until the task finishes. In this case, that's what we want. But in a program with a GUI, we don't want to do this because it would make the program unresponsive. So read on...

What about await in the event handler of a GUI button?
Keeping the GUI from freezing while doing a computation

Consider a WPF program that has one button, whose purpose is to do a time-consuming calculation. You might be tempted to write it like this:

namespace AsyncDemoWPF
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private void button_Click(object sender, RoutedEventArgs e)
        {
	    // Wrong - not using async and await
            button.IsEnabled = false;
            button.Content = "Calculating";
            Calculate();
            button.Content = "OK";
            button.IsEnabled = true;
        }

        private void Calculate()
        {
            // A time-consuming computation.
            Console.WriteLine("Calculating...");
            int n = 0;
            for (int i = 0; i < 2000000000; i++) { n++; }
            Console.WriteLine("Done.");
        }

    }
}

Straightforward enough. (Unlike in the previous example, now the methods aren't static because they belong to the window object. And I've left out the usings.)

When the button is clicked, the program should disable the button, change its label to "Calculating...", do the calculation, and then change the button back to "OK" and re-enable it.

But it doesn't work as intended. When you click on the button, the program simply freezes — you never see "Calculating..." appear on the button, and you can't even move the window — until the calculation is done. Then all is well again.

To make it work properly, we have to change it as follows:

        private async void button_Click(object sender, RoutedEventArgs e)
        {
            button.IsEnabled = false;
            button.Content = "Calculating";
            await Task.Run(() => { Calculate(); });
            button.Content = "OK";
            button.IsEnabled = true;
        }

Now all is well. This is the one and only proper use of async void. Event handlers have to be void.

But the question you must be wondering about is, why don't we have problems with the program ending prematurely?

The answer is: This is a GUI program, and it doesn't end when it runs out of things to do. It ends when the user closes it. And if the user closes it while the calculation is going on, that's probably what the user wanted to do!

Note by the way that you could make a very subtle mistake if you broke the event handler up into two or more methods. As coded, the event handler itself is async, and thus, everything in it after the await statement gets delayed until the task ends. If I had written this:

        private void button_Click(object sender, RoutedEventArgs e)
        {
            // Wrong - Tries to off-load the async to another method
            button.IsEnabled = false;
            button.Content = "Calculating";
            DoCalculationAsynchronously();
            button.Content = "OK";
            button.IsEnabled = true;
        }

        private async Task DoCalculationAsynchronously()
        {
            await Task.Run(() => { Calculate(); });
        }

the program wouldn't wait for the calculation to finish. The GUI would remain responsive, but you would never see "Calculating..." on the button, nor would you see the button disabled, because everything in button_Click would run as fast as it could. It would launch the calculation and then immediately put the button back to its original state. The calculation would be done, all right, but you wouldn't be able to see when, and you might well start more than one of them at the same time.

A note on the syntax of Task.Run

Purists will note that where I wrote

await Task.Run(() => { Calculate(); });

I could equally well have written

await Task.Run(new Action(Calculate));

or even

await Task.Run(delegate { Calculate(); } );

or several other things. But now that C# has lambda expressions, we no longer need these other syntaxes, and I prefer to stick with the most versatile one.

I could also have used Task.Factory.StartNew, which is equivalent but has more options. For an interesting example of how to start a task that way and hang an exception handler onto it, see Answer 4 in this StackOverflow discussion.

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A low-energy but happy Christmas

Christmas came, and we enjoyed just being at home together. All three of us (Melody, Sharon, and I) are still a bit weak from our continuing bouts with bronchitis and its kin. But we had a good Christmas. At my request, my presents were practical (pajamas, slippers, and a Pelican case for my telescope accessories) because I have too many new toys and not enough time to play with them. We gave Sharon amusing things, even down to a Star Wars illuminated light-saber lollipop.

On Christmas Day, Melody and Sharon went to see the new Star Wars movie, and I settled into a hobby project — making a presentation about the missing Messier Objects (more about this later). I fell into browsing around the Bibliothèque Nationale de France's online rare book collection, which has lots of historical astronomy material.

On December 26, back to consulting work. Now that I'm not in academia, I don't get a lot of time off for Christmas. There's a lot to be done, and soon I'll be back to doing it.

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M103

For December 24, a Christmas tree, or rather the star cluster M103 in Cassiopeia, which looks like a Christmas tree. Stack of ten 1-minute exposures with a 300-mm lens; this is yet another in the series taken on December 14. Still more pictures will be posted here after Christmas.

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M78, a reflection nebula in Orion

This is the reflection nebula M78, a dust cloud illuminated by stars in Orion. The first picture shows nearly the whole field of the 300-mm lens and also picks up the Flame Nebula (Zeta Orionis Nebula) at the bottom right. The second picture is the center of the same image, enlarged.

Stack of twenty 30-second exposures, Canon 60Da, 300-mm f/4 lens, Celestron AVX mount without guiding corrections, in my driveway under magnitude 5 skies.

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Not a white Christmas...

I don't think we're getting a white Christmas this year. This warm weather is very abnormal, and past experience suggests it will be followed by ice storms later in the winter.

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Orion Nebula (M42)

It's that time of year again, and I can't resist photographing the Orion Nebula. This picture is basically an equipment test, one of many taken on December 14 to verify correct operation of the repaired AVX mount, and doesn't offer anything new; in particular, I didn't try to handle the enormous brightness range very well, and the middle of the nebula is overexposed. But it's a nice picture anyhow.

Stack of twenty 30-second exposures, Canon 60Da, Canon 300-mm f/4 lens, Celestron AVX mount, PEC playback enabled, no guiding corrections.

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M35 and NGC 2158

Another familiar sight from the winter sky: the star cluster M35 and the more distant star cluster NGC 2158. Same equipment and technique as the picture of M42 above.

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Comet Catalina C/2013 US10 (with two tails)

This is not a great view of Comet Catalina, but it's comparable to what you might see in binoculars. Comet Catalina is going to remain visible in the pre-dawn sky for some time. In this picture you can see, at least dimly, that its dust tail and its ion tail point in quite different directions, about 1 o'clock and 5 o'clock if you imagine a clock face centered on the comet. People at dark country sites are getting much better pictures.

This isn't the only Comet Catalina out there. Comets are discovered regularly by the Catalina Sky Survey in Arizona.

Stack of twelve 5-second exposures, Canon 60Da with 105-mm lens at f/4 on iOptron SkyTracker.

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Star cluster M37

This picture of M37 and the picture of M1 below are from an equipment-testing session on December 15. Unsteady air was causing me to have a lot of trouble with the autoguider, and the star images were visibly elongated; I corrected them with deconvolution. This is a stack of four 1-minute exposures through the 8-inch EdgeHD at f/7, Canon 60Da, ISO 3200. This is the full frame; notice how the EdgeHD optics gave me sharp star images all the way to the corners.

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The Crab Nebula (M1)

This is the Crab Nebula, one of the most interesting celestial objects. It is the remnant of a supernova that was seen on earth in 1054 A.D. and contains, among other things, a pulsar. Stack of eleven 1-minute exposures, same equipment as for the picture of M37 above. Consider this picture a test; I need to re-do it under better conditions.

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Tricked by a polar alignment scope

Like many good telescope mounts, my Celestron AVX has a little telescope built into its polar axis for sighting Polaris and getting the mount lined up with the axis of the earth. Because Polaris is not exactly on the north celestial pole, the polar scope has more than just crosshairs. It has a reticle, shown above, that tells you how to line it up with constellations in the sky to get Polaris into the right position.

To learn how it tricked me, click here.

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Moon with earthshine

Here is the first picture from my extraordinary December 14 observing session. This is, of course, the crescent moon, but the picture was exposed and processed to bring out "earthshine" — the dim light reflecting from the earth to illuminate the part of the moon that is not sunlit. Look at how much lunar detail you can see. If you were standing on the moon in the dark gray region, you would see a nearly full Earth high above you in the sky.

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When did scientists stop using Latin?
The role of Antonín Bečvář, 1956, 1964

Anyone interested in astronomy quickly realizes that Latin was, for a very long time, the international language of science. Indeed, in astronomy (as also in biology), names are still in Latin, at least in form; the geographical features of Pluto that are just now being named get designations like Tombaugh Regio.

When did scientists stop using Latin to exchange real information, not just names?

Latin certainly hung on longer in astronomy than in other fields. For example, D'Arrest's descriptions of deep-sky objects, published in 1867, were in Latin (and are still worth reading).

But 1867 was not the terminus ad quem. I contend that the last real exchange of astronomical information in Latin consisted of the keys to several star atlases by Antonín Bečvář published from 1956 to 1964.

Antonín Bečvář (click for pronunciation) was the astronomer who gave us the colorful style that has been used by most star atlases since, especially those by Wil Tirion. Here is a sample:

This is from his Atlas Coeli 1950.0, first published in color by the Czechoslovak Academy of Sciences in 1956 and immediately re-published jointly with Sky Publishing Corporation in 1958. Notice the green nebulae, red galaxies, yellow star clusters, gray dust clouds, and bluish Milky Way. This was the first atlas to plot faint nebulae such as the wisps in Taurus that you see here; it made observers aware of them. (1950 is the date of the star positions, not of publication.)

The 1956 and 1958 editions has a gray cloth cover. By the time I bought my own copy of the atlas, I got the 1962 edition, which had been retitled Atlas of the Heavens and had a blue plastic cover. Here you're looking at the 1958 edition; I seem to recall that the 1956 one was titled simply Atlas Coeli with no English on its cover, but I could be wrong.

There was an accompanying catalogue (list of objects with positions and physical data), which originally was titled in a mix of Latin and Slovak (?), with brief texts in a handful of languages (Slovak, Russian, and English; not Latin) followed by numerical tables.

Again, by the time I bought my own copy of this, the printing on the cover was all in English.

Bečvář went on to produce another set of atlases covering the whole sky in three volumes, Atlas Borealis, Atlas Eclipticalis, and Atlas Australis. These were much less used because they plotted only stars, not nebulae or galaxies, and had a different brightness limit in different areas of the sky because of uneven data sources. Their main use, probably, was interpretation of astronomical photographs. They used a color code for the spectral type of stars, which would affect how well a star would show up on a red-sensitive or blue-sensitive plate. The last of these, Atlas Australis, was published in 1964.

Now then. I contend that the last significant use of Latin to convey information to astronomers was the key card accompanying each of these atlases. Here you see, first, the key to the 1958 Atlas Coeli, scanned from the University of Georgia's copy, and then the key to Atlas Eclipticalis, scanned and sent to me by Rick Woods.

Have you seen this moon globe before?

Photo by Christine Packwood

I'm told that this globe of the moon — not one like it, but this very one — was a prop in the movie Apollo 13. It is now in the University of Georgia's map library, which I visited today for a reason that will soon be disclosed here...

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An excellent night under the stars

On the evening of December 14, I had an astronomy session I will not soon forget, even though it took place at home, under magnitude 4.8 skies, rather than at a dark country site.

For the past couple of days, we've had unseasonably warm yet clear weather, with 70-degree (and higher) daily highs on the 14th and 15th, and I've done a lot of astronomy. This was the first opportunity to use my Celestron AVX mount at length since it came back from repair.

On Monday evening (Dec. 14), I set up the mount and 300-mm lens in the driveway and took a series of pictures, which I'll be processing and posting here. Meanwhile, I sat in a deck chair (actually Melody's very comfortable camp lounge chair) and just looked at the sky. It was 50 F or warmer and I was wearing a coverall, so for once I wasn't bothered by either chill or mosquitoes (here we almost always have one or the other).

What I watched was the Geminid meteor shower, already past its peak but still definitely going on. As I sat there for about three hours, facing Auriga, Taurus, and Orion, I must have seen over 35 meteors, 30 of which were first magnitude or brighter. Two were bright enough to cast shadows; they, plus about three more, gave off a trail of sparks.

Apart from the Leonids of 2001 and 2002, this is easily the finest meteor shower I have ever seen. And the Geminids make up in splendor what they lack in numerousness compared to the Leonids.

The meteor shower dwindled after 10 p.m. (= 03:00 UT Dec. 15); there were still a few meteors, but most of them looked like fast sporadic meteors rather than slow, bright Geminids.

Then at 5:15 a.m. I was up again, to photograph Comet Catalina (pictures coming). There was a first-magnitude meteor below Polaris...

And on the evening of the 15th, I set up the AVX mount with the 8-inch telescope and autoguider and took more pictures, mostly as tests of tracking. Again I sat in the deck chair, but there were absolutely no meteors. The show was over.

Now to spend the rest of the month processing pictures...

December 15 was the 50th anniversary of the Project Gemini rendezvous and docking, which I watched on TV at the time. The high points of the U.S. space program are now half a century in the past.

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A shortage of real Christmas music?

I want to wish everyone a blessed Third Sunday in Advent and remark on something...

Maybe it's because this bad cold has kept me from getting out as much, but I have heard virtually no real Christmas music in public places or even on the radio this year. No "O Come All Ye Faithful." No "O Holy Night." Not even "Deck the Halls."

Public places still play "Jingle Bell Rock" and "I'll Be Home for Christmas" and various attempts at comedy such as "Grandma Got Run Over by a Reindeer." And there are all too many sappy love songs that mention Christmas or the holidays or the snow. Those become tiring fast.

So lots of people are not getting to hear some of the best music our civilization has ever produced.

Is this the work of the "Holiday Tree" crowd, afraid to use a word that has "Christ" in it, for unclear reasons?

Surely non-Christians can admit that Christianity is part of the world, and maybe they can even admit they like some of our music, even if they don't agree with our religion. Much of it is genuinely great music.

Or are we doomed to an apocalypse of "Jingle Bell Rock"?

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If an ancient Roman...

Thought for the moment: If an ancient Roman were transported to the modern world, he would not be able to read the Latin books on my shelf.

The reason? He would have never seen lowercase letters. Nor the distinction between I and J or between U and V.

To the ancient Roman, IVLIVS CAESAR looks normal; JULIUS CAESAR is readable but has a few letters oddly formed; and Julius Caesar is mostly gibberish, with only the C definitely right.

A Roman looking at signs and inscriptions would see lots of words that look partly familiar but mean unexpected things — the same experience you have when you look at signs in France if you know English but not French. Or the experience an Italian has in Starbucks, where latte means not milk but coffee, and venti is a cup rather than a numeral.

[Update:] In later classical times the Romans did have "cursive," which was not connected handwriting like our cursive, but did prefigure lowercase to a considerable extent. With that knowledge, they would at least understand what our lowercase was intended to be, even if it did not look the same. More here.

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A short note on Luke 2:2

I have heard it argued that the Biblical account of the birth of Jesus must be fictional because present-day historians can't identify the census under governor Quirinius that it refers to.

My friend and fellow blogger Doug Downing points out something obvious: The people in the ancient world knew more about the censuses than we do. If the reference to the census had not made sense to knowledgeable people at the time, it would have been changed.

That is actually true whether it's factual or fictional. So the argument about the census carries absolutely no weight toward discrediting or verifying the text. The only thing it tells us is that we don't know quite enough about when Quirinius conducted his censuses.

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Short notes

The coughing continues. I am mostly on the mend but still have a noticeable upper respiratory infection. Melody and Sharon are better, but far from recovered.

And we are having 70-degree weather in mid-December. Past experience suggests this means we will have a major ice storm before long. You heard it here first...

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Available for consulting work

A couple of my biggest projects are between steps and not requiring much of my time right now, so if my consulting practice were a taxicab, I'd be turning on the light on the roof. That is, I have some availability for consulting work in the next few weeks. I am far from completely idle, but my slate isn't completely full.

My specialties include natural language processing, data mining, and software for science (especially psychology), but I also enjoy creating user-friendly Windows software for any purpose. (Software for other platforms, when needed, too.) Read more here.

And remember that a less expensive software developer might charge less per hour, but also take a lot more hours.

If you know anyone who might need my services, I'd be glad to hear from them.

P.S. Depite what the news media think, "data mining" doesn't mean spying. It means finding patterns in data you legitimately own.

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Are you helping ISIS?

OK, trying again. I wrote something like this a few days ago, then took it down because I thought it was overstated. As the political situation has unfolded, I've become convinced that it was, if anything, understated. So let me repeat myself.

But first, some cautions.

First: Facts matter. International politics is not a fantasy game that you get to make up for yourself. The interpretation of events that most appeals to your emotions is not necessarily the correct one.

Second: This is no place for "football-game thinking." Americans are easily tricked into viewing any conflict as like a football game: they show you two teams, and you choose one and root for it unconditionally. ISIS would very much like to play this trick on you right now, to impose their view of the conflict on you and keep you ignorant of details.

Third: Manipulators will say you are soft on the enemy if you don't do exactly what they want. It's an old kind of manipulation; we've heard it from playground bullies when we were ten years old; and it seems to be working amazingly well right now.

Now then. ISIS' strategy and tactics are not secret. Fortunately for us, terrorist organizations are not good at keeping secrets — they have no place to keep them — and they operate out in the open. To try to recruit supporters, they publish a lot of information about what they want done.

And in this conflict, the strategy is to start a war between all Muslims and the whole West. No such war is going on right now. Instead, there is a war between ISIS and virtually everybody else, including Muslim states that ISIS is trying to take over. ISIS wants to change who's fighting whom.

The main tactic is to trick the West into fighting all Muslims rather than just a specific terrorist organization.

This benefits ISIS in several ways. First, it makes Muslims feel endangered and more likely to join ISIS (to radicalize). Second, it diverts the resources of the West into fighting the wrong people. And third, it pressures Muslim countries to join ISIS rather than appear to be surrendering to the imagined western enemy.

Let us not lower ourselves to ISIS' level. Let us not become the enemy they want to have. They want us to give up our American values and become a second ISIS, an armed religious movement that is just like them except that we're promoting the wrong religion. Then they would feel justified in exterminating us.

Some people on the American political scene are doing exactly what ISIS wants. I leave it to you to decide who they are.

And a final note: Be careful whom you support and whose propaganda you spread. Be smart enough to realize that this isn't a football game — you can't just join in with anybody who seems to be rooting for your side. Keep your wits about you. I've already seen some suspicious activity. As the conflict progresses I expect to see ISIS using the Facebook gossip mill (or fake news mill) more extensively.

Although I do research on terrorism for a defense contractor, I do not have any privileged information about the matters discussed here, and I am not speaking on behalf of any government agency. Basic information about ISIS and international terrorism is readily available from many sources.

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About "political correctness"...

There are two kinds of people objecting to "political correctness" in public discussion these days, and they mean opposite things.

Some (including me) mean, "People should be able to express any reasoned opinion and invite reasoned responses. 'Political correctness' shouldn't be an obstacle to this." I agree.

Others, however, mean, "I should be able to say obnoxious and foolish things and not get any criticism. Whenever anybody disagrees with me, I'll whine about how they are imposing 'political correctness' on me." Wrong, wrong, wrong.

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A nonexistent star cluster discovered over 360 years ago

I've had my first article published in a professional astronomy journal. If I keep this kind of thing up, will I lose my amateur status?

You can read a preprint of the article here. It's about a star cluster discovered by Giovanni Battista Odierna (Joannes Baptista Hodierna) and reported in a book published in 1654.

The delightful thing about doing this kind of research in 2015, as opposed to the research on early Latin grammarians that I did in the 1980s, is that I didn't have to travel to a distant library to look at a copy of Hodierna's 1654 book. I could easily view the whole thing on line.

Hodierna was a Catholic priest and pioneer telescopic astronomer. He lived on Sicily, and his book was published there, rather than at a major academic center such as Rome or Bologna. The local printer seems to have had a little trouble with Father Hodierna's handwriting, or with the Latin language, or with the printing equipment, or maybe all three, and the surviving copies of the book are hard to read in a variety of ways.

Hodierna may have been the first person to publish a catalogue of deep-sky objects (see this overview).

I was investigating the 8th object in his list of "luminosae" (star clusters at least partly resolvable with the naked eye). In the article, I argue (convincingly, I hope) that it is the compact trio of stars shown in the picture above. They look like a star cluster to the naked eye; it looks as if there may well be more than three stars. But in fact there are only three, and they do not constitute a cluster. Nonetheless, this compact trio is one of the most conspicuous features of the dim, rambling constellation Aquarius.

Map from Wikipedia, credited to the International Astronomical Union and Sky and Telescope

In fact, the upper right star in the trio, Psi-1 or 91 Aquarii, is interesting in its own right. It is a double star (visible as such in my original picture, though not in the version reproduced here) and also has been found to have an extrasolar planet.

The picture is from a hasty astrophoto session that went awry. I put my 105-mm lens on my Canon 40D and set it up on my iOptron SkyTracker, then made six 15-second exposures. Unfortunately, I didn't tell the camera to save raw files. By a fortunate mistake I did tell the camera to subtract dark frames automatically, so the JPEGs that I got were already dark-frame-corrected, and I was able to stack them with Deep Sky Stacker. All's well that ends well!

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Lizardry

This exotic tropical creature is actually one of the green anoles that live in my back yard. Closely related to the iguana but smaller, this lizard changes color from green (warm) to dark brown (chilly), and here you see it in the middle of a color change. Photographed on a warm day in mid-November.

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Cough, cough...

[Revised.]

I should explain a bit more of what's going on. When I was in New York, my cough from last month came back. And when I got home, I found Sharon very sick, with a bad cough. She went to an urgent care clinic and was diagnosed with bacterial pneumonia. I then hurried along to the same place to get my own cough checked out; it was only a sinus infection. Then Melody came down with bronchitis.

So we're all too sick to do much right now. Fortunately, I'm not behind with work.

Too sick to do anything else, I'm seeing more than the usual amount of social media these days, and I'm dismayed at how easily people are induced to pass along messages that they wouldn't agree with if they thought about it.

In particular, when you pass along a message without knowing who wrote it, you really don't know where it came from. Not everything that people want you to spread is true and accurate.

I see way too much "friend-or-foe thinking." Some people react to everything by giving it either their total trust or their total opposition, instantly, without thinking, and without looking for mixtures of truth and falsehood. A wildly unreasonable statement that starts out by saying something pious or patriotic can get that kind of person's instant loyalty.

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They scrape the sky in New York, too

Here you see a skyscraper doing its job, scraping the sky, like the one I photographed in Atlanta recently. I've just completed a hurried business trip to work with research colleagues on this project at Lenox Hill Hospital. This was actually my first trip to Manhattan since (I think) 1998, although I used to go there quite regularly.

Here are a few quick notes on a lot of things.

Schizophrenia: That is the subject of the research; I'm using computers to measure characteristics of the speech of mentally ill people. We have already had one good spinoff result, showing that some impaired muscle movements can be tracked by their effect on speech. Much more is coming as we focus on sentence structure and word choice.

We won't announce results until they're published, of course, but the goal is to define mental illness in terms of measurable impairment rather than strange behavior. I think this protects the dignity of the mentally ill. It also provides objective measurements of whether patients are getting better or worse — which is the key to all imaginable improvements in treatment — and should facilitate early detection, so people can get help before their lives have been ruined. Schizophrenia is common, affecting 1% of the population, and even a small percentage decrease in its prevalence would relieve a lot of suffering.

Another key direction we are taking is not to assume that all cases of schizophrenia are the same disease. Instead, we are looking at specific symptoms and trying to figure out how they work — exactly what kind of brain impairment is behind them.

Speaking of percentages, there is increasing evidence that use of marijuana (cannabis) increases a person's risk of developing schizophrenia, even years later. People who are in love with marijuana have argued with me about this, to the point of claiming that "medical studies" are politically motivated bunk, but I can tell you that the marijuana-schizophrenia connection was discovered by Van Os and Henquet in a country where marijuana is legal (the Netherlands) and in a study that was not at all looking for dangers of drugs — it was a study of the onset of schizophrenia, which is also my colleague Michael Compton's specialty. (And yes, they've considered the "self-medication hypothesis," that people in early schizophrenia turn to drugs to get some relief from their distress; it doesn't hold up.)

Recent terrorist attacks: Of course I lament the tragedies in Colorado Springs and San Bernardino. Last one first: it sounds like the attackers were "wannabe jihadists" who became jihadists on their own without close contact with a terrorist organization. They were probably complying with an appeal published by ISIS and/or Al-Qaeda, who try actively to recruit people to do such things so they can commit attacks without leaving a trail to the people who put them up to it. The case, however, does have some peculiar features, and unlike most people, I'm not going to try to tell you what was going on before we really know.

As for Colorado, what do we make of Mr. Dear's claim that he was a Christian? My take is that if he was a Christian, he was a bad one. There are sinners of all kinds within Christendom — indeed, the reason we follow Christ is to be freed from our sins — and anything is possible. But I submit that by reasonable criteria, he was not a Christian even if he called himself one. We have no indication that he belonged to any church or Christian fellowship; other elements of the practice of Christianity were conspicuously absent from his life. Does calling yourself a Christian make you one? I'm aware of the No True Scotsman fallacy, but that is a fallacy because we have an agreed-upon way to tell whether people are Scotsmen, so we reject casual attempts to change it for the sake an argument. In this case we have different people honestly using the word "Christian" in very different ways.

Finally, here's some data strongly suggesting that our national problem is not abundance of guns but something else. (Key point: The increase in gun ownership has been accompanied by a decline in overall gun violence, despite the increase in spectacular mass shootings.) I call upon responsible gun owners to distance themselves from kooks and make it harder for dangerous people to get guns.

Note however that even though declining, our rate of gun violence is extraordinarily high by world standards. Let's not rest too easy.

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