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

Popular topics on this page:
Truth cannot be exaggerated
Lightness masking in Pixinsight
The decline of Facebook?
Old symbols for the planets
Economical lead-acid batteries
Did I discover a star cluster?

Sunspot group
Moon (Tycho to Clavius)
Moon (Bullialdus, Rima Hesiodus)
Moon (several scenes)
Jupiter Jupiter Jupiter
Jupiter Jupiter Jupiter
Tau Canis Majoris cluster (NGC 2362)
Horsehead and Flame Nebulae
M65, M66
M65, M66, NGC 3628
M65, M66, NGC 3628
M95, M96, M105
Comet 67P
NGC 2264 and unnamed nebula
NGC 2579
NGC 3184 with supernova
NGC 3189
HD 109141 cluster?
Cosmic rays
Many more...
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Jupiter: Third time's the charm

Here is yet another attempt at processing my unusually good Jupiter picture, plus an ordinary Jupiter picture to compare it to. Both were taken with an 8-inch telescope, one in unusually steady air and one under average conditions. When the air is unusually steady, the picture shows more detail than usual, and the settings for processing it (to extract maximum detail) become tricky.

Jupiter in Leo: I feel old!

Jupiter is now in the constellation Leo, the same as when I first started watching the sky in April 1968, 48 years ago. That is four Jupiter years. That is, Jupiter is now in Leo for the fifth time since I started observing. I feel old!

This is a stack of four 30-second exposures with a Canon 60Da and Canon 28-mm lens at f/4.5. It was hard to process because the bright stars didn't stand out. Light does not spread sideways on a digital sensor the way it does on film, and if the lens is very sharp, very bright stars don't look much different from moderately bright ones — once a star image is fully exposed (maximum white), it can't get any brighter.

I ended up doing two things to spread out the light. First, I put two of Sharon's hairs in front of the lens as crosshairs to introduce diffraction. Second, I combined this image with a blurred copy of itself before gamma correction, that is, before the step at which medium-brightness stars became maximum white.

I'm going to experiment further with such techniques.

I am very busy now and will close out April. See you in May!


More about that unnamed nebula in Monoceros

Last month I wrote about an unnamed and little-studied nebula in Monoceros. Here are some good pictures of it, taken on April 3 at Deerlick. It is centered in the upper picture, which is an enlarged section of the lower picture, showing NGC 2264 and other nebulae and clusters in the vicinity.

Stack of fifteen 1-minute exposures, Canon 60Da, ISO 3200, 300-mm Canon lens at f/4, AVX mount, no guiding corrections.

Horsehead and flame

Here's a famous piece of celestial scenery, the Flame and Horsehead Nebulae in Orion, photographed from Deerlick on April 3. The view is spectacular. Unfortunately, there is a bluish-green reflection next to the bright star to the lower right of center. Canon 60Da, Canon 300-mm lens at f/4, stack of twelve 1-minute exposures at ISO 3200, AVX mount, no guiding corrections.

Can I show you this view in my telescope? No! These objects are too dim for the human eye to see very well with any telescope. We rely on photography to accumulate light in long exposures and show us things the eye can never see.


Jupiter, with more pizazz

Here's last night's Jupiter image with a bit more "zip." What I posted yesterday is similar to how Jupiter would look from a spacecraft, but what you see here shows more detail. I did some low-frequency enhancement (unsharp masking) and noise reduction in Photoshop.


Here, from the evening of April 17, are several lunar scenes, all taken with the 8-inch telescope at f/10, no extra magnification, and a DMK camera with infrared-pass filter; that is, they are infrared images. Each is a stack of the best 2/3 of about 3600 video frames.

The mighty crater Copernicus:

To the upper right of it is the crater Eratosthenes, and between them, a plain littered with chains of small craters. Those small craters are probably from secondary impacts of matter thrown out of the large craters when they were formed by meteorites hitting the moon's surface.

Next, the harsh landscape (and smooth, gently undulating lava plain) of the Bay of Rainbows (Sinus Iridum):

And the familiar southern highlands from Tycho to Clavius, with the sun higher in the lunar sky than when I photographed the same area the other night:




Here's Jupiter, taken this evening (April 24 in our time zone, April 25 in UT) with my 8-inch telescope, 3× extender, and DFK camera. This is the best 2/3 of about 1600 video frames, processed with PIPP, AutoStakkert, RegiStax 6, and Photoshop.


Did I discover a star cluster?
A taste of real astronomical research with Aladin

Last night (April 23), while trying out an autoguiding setup, I photographed the field of the star HD 109141 (HR 4776, HIP 61212, SAE 157350), which is in Virgo near Corvus. I noticed that this 6th-magnitude star is surrounded by a sprinkling of 11th-magnitude stars, but no cluster is plotted there on any of my atlases. Did I discover a star cluster?

(Stack of three 2-minute exposures, C8 EdgeHD, f/7, Canon 60Da, ISO 1600.)

Well... At first I didn't even know that the star was HD 109141. I just chose it at random because I had been taking aim at M104 and wanted to try guiding on a brighter star.

If I'd thought about it, I could have asked the computer built into my telescope mount for the right ascension and declination. But I didn't. Instead, I uploaded my picture to Astrometry.net and had their computer identify the stars in the picture. Within a couple of minutes, it gave me star identifications, as well as field of view, image scale, and other data. A quick look at Stellarium (my usual star map these days) confirmed that the identification was right.

Next, is there a cluster around that star? A quick "query around" on Simbad, the professional astronomers' database, did not show a star cluster in the vicinity.

So had I discovered a cluster that nobody had previously recognized? If so, the stars in the cluster should all be about the same distance from the earth.

To get answers quickly, I downloaded and installed the free Aladin software package for Windows and turned on Tools, Simbad Pointer.

Aladin displays Digitized Sky survey images, and other images, of anything in the sky it can identify. (You can query by position or by identifier.) With Simbad Pointer turned on, if you hover the mouse pointer on an object for 3 seconds, you get a web link to Simbad's data page for that object.

I found out very quickly that the distances of these stars have not been determined. However, their proper motions (apparent motions against the sky) have been measured...

...and are all different. The stars in a cluster should have similar proper motions. These, I think, don't (although I will be glad to defer to the judgment of a professional astronomer).

So it looks like this is a chance sprinkling of stars after all.

"Aladin" and "Simbad" are the French spellings of two characters in the Arabian Nights. They also have a "Vizier."

Cosmic rays

Another of my pictures, astronomically inconsequential, caught some cosmic rays. Camera image sensors respond to cosmic rays as if they were light, except that a cosmic ray usually hits only one or two pixels; it certainly isn't spread out by any optical effects. So here, among slightly blurry stars, are some cosmic ray impacts:

Cosmic rays are high-energy subatomic particles originating far away in space. When a cosmic ray hits an atom in the earth's atmosphere, it produces a shower of secondary particles such as protons and muons, which, in turn, are recorded by the camera. In this picture there are at least four specks that are probably secondary particles from a single cosmic ray. The actual shower is likely to have been much larger, but not all of it hit my camera.


Rotation of Jupiter in 15 minutes

On the evening of April 17, I got some unusually good images (and views) of Jupiter, which was high in the sky. Above you see the rotation of Jupiter in 15 minutes — which is why I don't record video for more than 2 minutes to make a single picture, and usually not even that long. Each image is a stack of thousands of individual video frames.

You might try viewing the two images as a stereo pair for a 3-D effect. Shrink your screen display down to about half size, so the two Jupiters are about as far apart as your eyes; focus your eyes on something much farther away; then, keeping your eyes aimed as if for a distant object, look at the screen. You will see three Jupiters, the middle one stereoscopic.

Having compared the two cameras side by side under good conditions, I'm becoming convinced that the uncompressed video from my DFK camera is better than the compressed video from my Canon DSLR in video mode, although the difference is small.

I also got a black-and-white image, and thereby hangs a tale. If you read this blog page yesterday, you may have seen some "infrared" pictures of Jupiter on it. They weren't infrared. My monochrome camera used to have an infrared filter on it, but I changed it to a yellow filter when experimenting with using that camera for autoguiding back in October. Then I forgot to change it back. My logbooks and blog entries have been corrected.


Battery time

It's battery time! During a recent power failure, we had a mass die-off of the rechargeable batteries in our UPSes. As you know, when a rechargeable battery is reaching end-of-life, one good discharging will often finish it off. Mine were 4 to 7 years old, well past the 3-year replacement interval, and sure enough, the day after the power failure, one of the UPSes complained (with loud beeps) that it couldn't recharge its battery.

Some testing revealed that both UPSes, and also my two astronomy power boxes, needed new batteries, so I did some online shopping and am glad to recommend Apex Battery as a supplier of good batteries at low prices.

The most common lead-acid battery is the one you see in the picture, rated at 7 to 8 amp-hours depending on the manufacturer. Each of my UPSes contains two of these. You can buy them for about $39 at Batteries Plus. Curiously, Academy Sports sells them for about $20, as batteries for wildlife feeders, but I'm not sure they're fresh. At Apex, a battery of this type, OEMed by Werker (a very reliable brand), is only $11 plus about $5 shipping. Apex wins.

I have nothing against Batteries Plus, of course. They're handy to have around; all too often I need a battery right now, and they have it. But you pay for convenience.

Getting back to testing: The tricky thing about lead-acid batteries is that a failing one will often pass all electrical tests as if it were a perfectly good one with fewer amp-hours of capacity. The only sure way to test one of these batteries is to discharge it down to 12.0 volts with a known load (an automotive light bulb will do) and see how long it takes. (If it's a 1-amp bulb, then one hour of discharge time equals 1 AH, one amp-hour, of capacity.) Don't take it below 12 V, and if you're going to continue using it, charge it back up immediately.

(For two years I've been meaning to build a lead-acid battery tester that will do all this automatically. One day, one day... Maybe a reader will point me to somebody who sells them!)

For my astronomy gear, I carry a 12-volt 18-AH battery box that I made out of a "jump starter" by removing the heavy jumper cables and adding some connectors and a digital voltmeter. I also carry a smaller 12-volt 7-AH battery box as a backup or when using only the iOptron SkyTracker.

Should I switch to lithium? Well, right now, especially at Apex's prices, lead-acid is still a lot cheaper! But here is a lithium product that looks very good. It has 12- and 19-volt outputs, the latter for laptops. Most lithium battery packs don't have enough capacity for a long astronomy session, but that is changing. In three years, I may make the switch.



Jupiter is now high in the night sky well before midnight. Here are two images of Jupiter taken around 10:30 p.m. EDT on April 16. 8-inch f/10 EdgeHD telescope, 3× telecentric converter, DFK and DMK cameras respectively. The monochrome picture was taken with an yellow filter, not an infrared filter as mistakenly reported earlier. Each is a stack of the best 50% to 75% of thousands of video images, processed with PIPP, AutoStakkert, RegiStax 6, and Photoshop.

Moon (Tycho to Clavius)

Using the same equipment and technique as for the black-and-white Jupiter image, but without the 3× converter in order to work at lower magnification, I got this image of the southern highlands of the moon, including the craters Tycho and Clavius. The air was actually rather unsteady, but video astronomy, stacking, and digital postprocessing managed to pull out a reasonably good picture.

Some interesting lunar topography

Using the same equipment and technique as the picture above, I also photographed an area of more varied terrain on the moon. The crater at the upper left is Bullialdus. Running across the plain from lower left to upper right is a long streak, or rather a long, shallow depression called Rima Hesiodus.

Telescope notes

I've bought the CGEM mount that I was testing, and now I have two ways to set up the 8-inch telescope. Here you see them (CGEM first, then AVX). For lunar and planetary work, both work equally well. For autoguided deep-sky work I prefer the CGEM.

In the second picture you also see part of the cart that I use to transport the heavy mount head to where I've set up the tripod.


Old-style symbols for the planets

One of the things I and others like about astronomy is the sense of being linked with the past; astronomy is a science that goes back more than 3000 years.

One of these links is a set of symbols, actually extracted from a much larger set of symbols most of which have fallen into disuse. These symbols are used as abbreviations, labels in diagrams, and subscripts in mathematical formulae (to indicate which object a letter describes). In astronomical calculations, it is common to need a lot of symbols, and after running through all the Latin and Greek letters with mnemonic value, astronomers often feel the need for yet more labels!

During the second half of the Twentieth Century, under the reign of typewriters and ASCII-based word processors, there was a movement against using special symbols, and the IAU still recommends not using them. But now that we have Unicode, we can type a lot of things that we formerly couldn't, and I think judicious use of these symbols is appropriate.

Some astronomers shy away from them because of the connection to astrology (fortunetelling), a pseudoscience in which these symbols are used avidly and the set is still being added to. But I think astronomers have just as much right to use these symbols as anyone. Most of them date from the Byzantine Empire and were refined in Renaissance Europe before astronomy and astrology became distinct.

A few of the planet symbols deserve comment. Starting from the bottom, Percival Lowell was not actually the discoverer of Pluto, but he launched the project that led to its discovery, though he did not live to see Clyde Tombaugh actually find the planet. Now that Pluto is no longer classified as a full-fledged planet, some people want it to lose its symbol, as the asteroids did once people realized there were more than a handful of them.

Wikipedia does not support one theory I've heard about the symbols for Jupiter and Saturn, which is that they are stylized digits 4 and 5 (the fourth and fifth planets if you don't count the earth).

In biology, the symbols for Mars and Venus stand for male and female. The latter is popular with feminists, who may not realize they are using a picture of a symbol of vanity (a hand mirror).

In recent publications I have actually seen the following symbols for positions in orbits used more than the symbols for objects:

The first one is actually part of a set of symbols for 30-degree segments ("signs") of the plane of the solar system (the zodiac). The last one is not a symbol; it is a relic of Byzantine cursive handwriting, and it definitely needs to be ω with ~ above it, not ^, which is equivalent in Greek, and preferably, the ~ needs to be as wide as the ω. This one does not seem to have made it into Unicode as a distinctive symbol, although some fonts render it appropriately.

I have given Unicode numbers for the symbols, but most fonts lack most of them. The Arial Unicode MS font supplied in Windows contains all of them except for the symbol for perihelion, which I rendered as an accented lowercase omega in Times New Roman.


One sunspot group

There's only one sunspot group visible on the sun right now, but it's a big one. I was able to see it by just holding up my sun filter and looking through it, without a telescope. If you have an eclipse-viewing filter, or if you happen to see the sun through very thick haze, take a look yourself; the sunspot will remain visible several days.

This morning (April 15), I did some blitzkrieg astronomy. It took me only 15 minutes to set up my vintage Celestron 5 on its pier, take this picture, and bring everything indoors again.

Stack of the best six of nine 1/2000-second exposures, Canon 60Da, Celestron 5 (f/10), Thousand Oaks sun filter. The images were opened and downsampled in PixInsight, then stacked with AutoStakkert, and finally processed with Photoshop.


Here's a fairly decent picture of Jupiter taken on April 12. Celestron 8 EdgeHD telescope, 2× teleconverter, Canon 60Da in movie crop mode; as usual, this is a stack of thousands of video frames, processed with PIPP, AutoStakkert, and RegiStax 6.

Tau Canis Majoris star cluster (NGC 2362)

The star Tau Canis Majoris is surrounded by a star cluster that is easily overlooked because Tau is so much brighter than any of the other stars. Tau is definitely a member of the cluster, and it's somewhat mysterious why, when the cluster formed, one star ended up so much larger than any of the rest.

I took this picture with a somewhat unusual technique. The telescope was set up for planetary work, with no autoguider. So I took five short (2-second) exposures, with the camera to take its own dark frame automatically after each of them, and then I stacked them. Celestron 8 EdgeHD, f/10.



I am now the proud third owner of a Celestron CGEM computerized telescope equatorial mount. (CGEM stands for Celestron German Equatorial Mount; the "German" type of mount was pioneered in Estonia by Joseph Fraunhofer (a German) in 1820.

An equatorial mount allows the telescope to turn around an axis parallel to the earth's, making it easy to track stars as the earth rotates (one carefully regulated motor does the job) and to measure positions in the sky.

Many equatorial mounts are forks or yokes, built around the telescope. The German type, however, has its two axis bearings in the middle, with a counterweight on a shaft and the telescope opposite it.

That means it makes no strong assumptions about the size of the telescope; the same mount can be used with any telescope that is not too long or too heavy. What this means for me is that my 8-inch telescope, or a camera with a telephoto lens, or (potentially) a different telescope could all be used on the same mount.

I've had a Celestron AVX equatorial mount for some time. That is the CGEM's baby brother. The CGEM is much better at precise tracking with a heavy telescope and guidescope.

I've actually had this CGEM for several months and have been checking it out, so I know it's a good one. There is significant unit-to-unit variation in mass-produced telescope mounts, so I jumped at the chance to give this one an extended checkout for the friend who owned it.


Today I added an AT&T microcell to my computer network. The microcell acts like a miniature cell tower, enabling our cell phones to work well throughout the house. Without it, reception here was weak.

The microcell uses our Internet connection (which is not through AT&T) to relay our calls to and from the telephone system. If I walk outside while a call is in progress, my cell phone is automatically handed off to a cell tower.

(Why is it called a cellular telephone? Because the city is divided up into cells served by particular towers, and a computerized system automatically connects you to the nearest one. This works far more smoothly than earlier mobile telephones that typically could only connect to one tower and required an operator's assistance. Yes, you could have a telephone in your car in 1960, but it was clumsy, expensive, and disappointing!)

The sales staff at AT&T were a little confused about how the microcell works; they sounded like they were mixing it up with a cellular signal booster (repeater), which would simply amplify signals and retransmit them to and from cell towers. The microcell does nothing of the sort. It sends my calls to and from AT&T through the Internet.

To my surprise, the microcell has to be placed near a window (well, maybe; at least, that's what they recommend). Why? Because it has to listen to GPS satellites to determine its exact location. I can think of two reasons why: in order to know what cell towers I'm near so that it can hand off my call if I walk out of the house, and in order to refuse to operate outside AT&T's service area. (You can't buy an AT&T microcell, hook it up to the Internet in England or China, and have AT&T service there!)

To my pleasant surprise, it does not seem to require TCP port 443 (HTTPS) open inbound, although the documentation seems to say so. That is fortunate because I am using that port for something else. (If you successfully crack into my server through it, you get to see, at present, a blank web page.) It uses HTTPS and several other protocols to contact AT&T on the Internet. Bottom line: It worked with my Asus router without changing any firewall settings.

Can any AT&T customer use it? No, thank goodness, only the ones I've registered (up to 10). I'm not using my Internet connection (which isn't even through AT&T) to provide free cell service to strangers!


Truth cannot be exaggerated

Truth cannot be exaggerated. When you are defending what you believe in, you must be scrupulously accurate in all the claims of fact that you cite in support of it, and you must deal honestly with relevant facts that seem to weigh against you. When exaggerated or overstated, truth becomes falsehood.

(This is from a Facebook conversation. What brought it to mind was an essay I saw about the special importance of music in Christianity. The author started out on solid ground, but for some reason he wanted to say there is no music at all in Islam, Buddhism, or Hinduism, at least no music that is not recent Western influence. And that is false, and by saying it, he threw away his credibility. Either you're a reliable source of information or you're not.)


M95, M96, M105

This is what was high in the sky when I went to Deerlick last week — a group of galaxies in Leo. And here are the identifications, courtesy of astrometry.net, which identified the objects automatically by computer:

Stack of twenty 1-minute exposures, Canon 60Da at ISO 3200, Canon 300-mm f/4 lens, Celestron AVX mount with no guiding corrections.

Arguably, I need to expose longer than one minute (and perhaps dial back the ISO setting to 1600 to reduce noise), so the next time I use this setup, it will include an autoguider.


The decline of Facebook?

The web site of Inc. Magazine tells me I'm not the only person who is feeling less and less happy with Facebook. In fact, Facebook may be starting a serious decline.

In its early days, I was skeptical of Facebook. Then, as more people near my own age and educational level started joining it, I joined it too and was delighted to reconnect with hundreds of old friends.

Facebook gave us what other Internet forums did not — a forum where people were accountable, identified, and well-behaved. It was for fellowship of friends rather than clashes between strangers. And it was accessible to people on all educational levels. I was glad to be able to keep up with some extended family members who are not computer enthusiasts and would never have used other forums.

Of course, it was never perfect. Some people spend all their time spreading false gossip, the weirder the better. ("Three moons in the sky next month!" Or "Secret proof Obama is from Mars.") Some fall for every fake ad. ("Bill Gates will save this starving child if you click 'like' on this." Actually, when you click 'like' you're giving your contact information to a complete charlatan.) And all too many spend all their time passing along messages from others, as if there were no World Wide Web. Fortunately, by the judicious use of the "unfollow" button I am not much bothered by these any more.

A few post things like, "I want to see who my real friends are. Copy and repost this or you aren't really my friend." I take that unfriendly gesture as the signal to remove them from the friends list entirely.

Even with this weeding-out done, Facebook seems to be becoming something of a drag these days. What happened?

As the Inc. article notes, a big change is that people aren't sharing personal news. They're carrying on discussions that require a lot of energy. Of course, that's entirely proper when you have a set of friends like mine — writers, scientists, philosophers — but it can get tiring.

No matter how interesting the discussions are, I am starting to feel that I can't follow them all. It's like trying to read the newspapers of ten cities every morning. So many things asking for my attention, and having some right to it — but I just can't pay attention to them all.

And that segués into another change — everybody's list of Facebook friends has grown until it's too big! I now have nearly 700 Facebook friends, many of whom are fans of my books.

That means that if they did post personal news, I wouldn't be able to follow it and wouldn't even know who the people in it were.

It also means any conversation is going to be of no interest to 90% of them.

And it means that controversial subjects have to be handled delicately. That's not as big a problem as it might be because I always want to hear both sides of a controversy. I want to hear the best that can be said for several different possibilities, then choose the best one. That's how my mind works.

It's not how other people's minds work. Many people only want to argue one side, as forcefully as possible. Some are frankly seized by fear when they see a sympathetic presentation of the side they're against.

Managing all this takes energy that I am starting to want to put into other things. I'd rather write in the Daily Notebook, where there is no comment section.

When I write here, I'm not challenging you to a debate. I'm saying, Take this and think about it. It's OK if your thoughts aren't the same as mine.

If I wanted to do a lot of work, I could divide my Facebook friends into subgroups. I'd have to classify 700 people and then remember to select groups every time I write anything. But that's too much work.

Apart from that, I have only three choices: I can "unfollow" a friend (which means not see their postings at all), or see their postings in the normal manner, or "see first" (give them top priority, as I do for a few people who have important things going on).

And that's the problem. I don't want to lose track of friends, but I don't have time to read everything they write, either. Nor do I want to write hundreds of words a day on Facebook and respond to challenges and discussion. The world would probably rather see the next edition of Digital SLR Astrophotography than a few hundred Facebook postings.

What is NGC 2579?

Finally we get to the pictures I took at Deerlick on April 3. This one was something of a surprise. I saw a thick cloud of stars in the constellation Puppis, low in the southern sky, and decided to photograph it. (It more than fills the field here.) My atlas showed a nebula there, NGC 2579, about which I knew nothing at all. So I figured the picture would reveal what it is — and it did. It's the compact reddish cloud around a close pair of bright stars above the center of the picture. It is an emission nebula, not very well studied.

I very much like it when I get to turn my attention to exploring the sky rather than debugging the equipment, and this was a good instance of that.

Stack of ten 1-minute exposures, Canon 60Da, Canon 300-mm f/4 lens, Celestron AVX mount, no guiding corrections.


Once more, with color
Lightness masking in Pixinsight

This is the same picture from two entries back, but with higher color saturation — but only in the bright areas. This is a useful thing to do with pictures of galaxies because it distinguishes dusty areas (yellowish) from regions full of young stars (bluish).

(The picture two entries back was in color, though you can hardly tell it; galaxies are rather colorless objects.)

The challenge was how to increase the color saturation only in the bright areas, not in the sky background, which deviates from dark gray in random ways due to digital noise.

It's done with lightness masking.

I'll probably write this up somewhere else later, but here are brief instructions. The key concept is to make a second image, black-and-white, that tells the first image where subsequent operations should be applied. The second image is called a mask, and when it is applied normally, white allows and black prevents changes to the first image. When it is applied inverted, it works the other way around.

So the first step was to make a black-and-white copy of the original: Process, ChannelManagement, ChannelExtraction, L*a*b, and extract only the L (luminance) channel. That gave me a second image to use as a mask.

The next step was to do some histogram adjustment on the mask so that the black areas would be quite black. That step is optional, but I found it useful. You can also blur the mask if you want to.

The third step was to attach the second image as a mask to the first image. That's done by selecting the first image and then choosing Mask, Select Mask.

When that is achieved, the areas of the first image where the mask is dark will (probably) be displayed as bright red. To stop that, choose Mask and uncheck Show Mask. The mask is still in effect; you just aren't being shown where it applies. That is fortunate, because now you can see what you're doing to the image.

The fourth step was to raise the color saturation as described here (scroll down a bit). Because the mask is in effect, it applies only to the bright areas, where the mask is far from black.

To complete the process, I inverted the mask and reduced the color saturation in the dark areas of the picture.

Then I chose Mask, Remove Mask, and did some histogram equalization on the final result.



"Faint fuzzies" and a comet

This is the upper left portion of that same picture of galaxies in Leo, processed differently to bring out faint objects (although it looks worse).

When he saw the original on Facebook, Rich Dailey pointed out that there appeared to be a faint smudge corresponding to Comet 67P/Churyumov-Gerasimenko. I used Stellarium to check the position, and indeed, there it is — 16th magnitude or so! This is the comet that the Rosetta spacecraft and Philae lander visited in 2014.

I also identified a number of faint galaxies in the picture.

All this was done with a telephoto lens, in my back yard, under bright Athens skies. The camera sensitivity was deliberately turned down so I could test guiding in a long exposure. It will be interesting to try this setup at Deerlick.


M65, M66, NGC 3628

No, this picture isn't from my trip to Deerlick. I took it from my back yard last night (April 5) while testing equipment. The question was how well I could autoguide the AVX mount and 300-mm lens (like this but with some zip-ties added for cable management), and the answer was, very well indeed.

At Deerlick, I took 1-minute exposures, which don't require autoguiding, and realized I needed to be able to expose longer. So, in the back yard, I tried 5-minute exposures with the autoguider and did well. What you see above is a stack of five 5-minute exposures with a Canon 60Da at ISO 800 and a 300-mm lens at f/5.6. Of course, at Deerlick, under a dark sky, it would have been ISO 1600 and f/4.

NGC 3628 at the top, M66 at lower left, M65 at lower right. This group of galaxies, in the direction of the constellation Leo, is called the "Leo triplets" or "Leo triplet" — the word triplet is used two ways, to mean a group of three or a member of such a group.

Note the diffraction spikes on a bright star, equally sharp in all directions, which shows that the tracking was good.


Financial sharpshooting

Thanks to careful calculations by my accountant, Dennis Haynes of Williams and Guined, I will only be paying about $340 in income taxes next week. That's a very tiny fraction of my income. The estimated payments were that close.

But wait a minute. Don't I want to get a multi-thousand-dollar refund?

No. Getting a refund now would mean I had paid in too much earlier. That's not the goal. I am not using the IRS as a zero-interest savings bank.

Of course, there could be good reasons to get a refund: you got some kind of tax credit that couldn't be established early in the year, or you were employed only part of the year but withholding was done at the full-year rate. Those situations don't apply to me.

As for the precision of my own estimated payments, I must take a little of the credit myself. My accountant gives me a table of the size of the estimated payments for various levels of income. I then keep a running tally of my actual income (especially Covington Innovations, which is variable) and fit a piecewise linear model to the table.

Financial follies

I often listen to financial-advice radio shows, not for the answers, but for the questions. It's a way to look inside other people's minds.

And I heard something surprising yesterday. A man had bought something big — a car, I think — and said, "My wife wouldn't let me negotiate the price."


But that's an attitude I've heard elsewhere. Some people think if you try to get a bargain, you're showing that you're not "rich," and making people think you're "rich" is much more important than actually saving money.

To such people, overpaying is something to be proud of.

Falsch. Really rich people shop wisely all the time and avoid overpaying. They didn't get rich by wasting money.

(However, I do not annoy people by trying to haggle about prices that aren't normally negotiated. I like the Wal-Mart principle of "everyday low prices" — tell me your best price immediately and let me take or leave it. But if it's high, I'll take someone else's instead.)

Back from Deerlick

Last night (April 3-4) I had an excellent expedition to Deerlick Astronomy Village. I don't usually get out there at this time of year, so it was an opportunity to get a really good look at a portion of the sky that I seldom see so well.

I used the 300-mm lens and AVX mount to photograph a number of deep-sky objects while exploring the sky visually with 12×50 binoculars.

The air was exceptionally clear; it was cool (falling from 60 to 50 F) but not humid; and the AVX mount led a charmed life, tracking perfectly in every exposure, never hitting a rough spot on the gears. (I think the new gears have "worn in" since it was repaired a few months ago.)

Meanwhile, with the unaided eye I got a fine view of the zodiacal light, as bright as the winter Milky Way, though I didn't photograph it. With binoculars, I saw a number of galaxies, including M51, M81 and M82 (positively bright), M51, M65, M66, and M104, and also the Rosette Nebula (not too surprising) and, more surprisingly, NGC 2174. A star cloud northeast of Zeta Puppis, far in the south, caught my eye, and I photographed it.

Pictures soon.


Rescuing a "Princess"

Back in our newlywed days in California, as I was revving up my electronics hobby, Melody and I stretched our newlywed budget so I could buy a high-quality Ungar soldering iron, and I built this dual-heat soldering station for it. (Dennis Hayes had just invented the Hayes modem on his kitchen table, and I suspect Melody was hoping I would do something similar.)

The soldering station has two 2-pound lead fishing weights in it to keep it from moving around the workbench. To keep the iron from overheating, it is set to low heat when it's idle (which still keeps it hot enough to melt solder), high heat when it's in use.

This type of iron — lightweight but grounded with a 3-wire cord — was considered small and dainty by the standards of the time, so Ungar dubbed it the "Princess."

Unfortunately, the "Princess" only served me a couple of years; the heating element burned out, and a succession of cheaper irons took its place in the same dual-heat station. Eventually I graduated to Weller digitally controlled soldering irons. Meanwhile Weller acquired Ungar, ending an old rivalry.

Fast-forward to 2016. Having lent most of my old soldering irons to the AI Lab for students to use, I found myself without a working spare. (The one that had been in this soldering station had burned out.) So I went to eBay and got new parts for the Princess, far cheaper than they had been in 1983. And I got the whole thing working again.

Incidentally, the reason for the awkward routing of the power cord on the homemade soldering station is that the box didn't originally have the Ungar iron and sponge holder on top. It was used in a different configuration with a British ultra-lightweight iron. I may correct the routing of the cord — or not...

In the same work session I also found that my hefty 50-watt tube-era Ungar soldering iron, from about 1971, works fine. Jobs suitable for it are infrequent these days because it has such a big, blunt tip. But it works. Nowadays, when I need a lot of power I either use a temperature-controlled iron that will put out 40 or 50 watts on demand (and only at the moments it's needed) or a Weller soldering gun.



Here's a series of Jupiter images taken with my 8-inch telescope from my driveway. Note that something apparently impacted Jupiter on March 17 but none of my pictures shows any effects of the impact; one happens to have been taken a few hours after the impact, but the rotation of Jupiter had carried the impact site out of view.

These are stacks of video images captured with a Celestron 8-inch EdgeHD, 2× telecentric extender, and Canon 60Da DSLR, except that the black-and-white one was captured with a DMK monochrome camera and yellow filter (not infrared as mistakenly reported earlier) with a Meade 3× extender.

Because of the interest in the impact, I am giving the date and time of each picture (UT).

Jupiter and Io, 2016 March 13, 02:38 UT

Jupiter, 2016 March 17, 03:40 UT

Jupiter and a double satellite transit, 2016 March 22, 04:59 UT

Europa (top arrow) and Io (bottom arrow) are barely visible as they pass in front of Jupiter; their shadows are clearly visible. Io looks like an oval blob because it is a sphere with a bright equatorial region and dark polar regions.

Jupiter, 2016 March 23, 03:17 UT

Jupiter, 2016 March 30, 04:14 UT

Only the last of these was taken in reasonably steady air.

M65 and M66

On the evening of March 29, I photographed galaxies from my driveway using the 8-inch, an f/7 reducer, a Canon 60Da, and (most importantly) a CGEM mount that I'm checking out for a friend, together with my 80-mm f/5 guidescope and STV autoguider.

Here are M65 and M66 (two of the Leo Triplets — the third one was outside the field), a stack of the best 15 out of 20 one-minute exposures at ISO 3200.

NGC 3184 with supernova SN 2016 bkv

Using the same technique as above, but presenting the picture at higher magnification (without downsampling), here's the galaxy NGC 3184 with a 15th-magnitude supernova. Look at the two stars close together. The supernova is the one closer to the center of the galaxy.

It occurs to me that these two stars must set some kind of record for the physical separation of an optical double. That is, they look like a binary star system, but actually, they are two stars that just happen to be close to the same line of sight; that's what "optical double" means.

Ordinary optical doubles, of course, are pairs of stars within our own galaxy. In this case, however, the supernova is in NGC 3184, 30 million light-years away. Not much is known about the 15th-magnitude foreground star, except that it's in our own galaxy, so it can't be more than 100,000 light-years away.

NGC 3189 by mistake

On the way to NGC 3184 I accidentally punched in NGC 3189 and was led to a striking group of galaxies:

NGC 3189 in the middle, NGC 3193 to the upper left, NGC 3187 (faint) to the upper right, and NGC 3185 to the lower right.

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