9:46 - In counterpoint to what I wrote yesterday about CD-R archival stability, Andrew Duffin writes:

You're not unobservant. I don't post an email address as a way to encourage people to post to the messageboards rather than sending mail. I still get lots of mail, of course, and when I get interesting messages like yours I post them to my journal page.

Your problem may be caused by the discs you're using. Although a reasonable person might assume that "Sony-branded" discs are made by Sony, that's not necessarily the case. I have seen Sony-branded CD-R discs that were made by Sony, Mitsubishi, Mitsui-Toatsu, Taiyo Yuden, and probably others that I've forgotten. Although all of the companies I just mentioned are good ones, it's quite possible that Sony has also second-sourced CD-R discs from other not-so-good companies. The world of CD-R discs is quite confusing. Some companies that actually manufacture discs don't sell them under their own names, but simply relabel them for other companies. Some companies that sell discs under their own name don't actually manufacture discs, but relabel discs from numerous sources. Still others, including Sony, sell discs they manufacture under their own name, relabel discs made by other companies, and sell the discs they've manufactured to other companies, which relabel them with their own names.

There are CD-R disc manufacturers--Princo, ProDisc, and Ritek, to name a few--whose products I wouldn't consider using. Their discs are inexpensive, which is about the most that can be said for them. Unfortunately, many of these companies OEM discs to major names, so it's possible to buy some mediocre blanks with big names on them. I used to recommend using the CD-R Identifier program to determine the actual manufacturer of a given disc, and it's still somewhat useful. The problem is, CD-R Identifier uses the ATIP information to identify the actual manufacturer, and the ATIP data is no longer reliable. Some disc makers use masters produced by another company, which means that the discs they produce misidentify themselves.

Until Kodak discontinued their writable optical discs in early 2002, we used either Kodak or Taiyo Yuden CD-R discs exclusively. Now we use only Taiyo Yuden discs. If I were very concerned about archival stability, I might use Verbatim DataLifePlus CD-R blanks. Those use Azo dyes, which are probably more stable than the stabilized cyanine and phthalocyanine dyes used for other blanks.

Speaking of optical writers, Plextor tells me that I should receive one of their new PX-708A DVD±R/RW writers within the next couple of weeks. This is a true do-it-all drive. It writes DVD+R at 8X, DVD+RW at 4X, DVD-R at 4X, DVD-RW at 2X, CD-R at 40X, and CD-RW at 24X. It reads CDs at 40X and DVDs at 12X. It's not so much the hybrid capacity that excites me, although many people are still more comfortable buying a DVD±R/RW drive than a single-standard DVD+R/RW drive or DVD-R/RW drive drive. Oh, I'll test the drive with DVD-R/RW media, but as I've said elsewhere as far as I'm concerned DVD+R/RW has won the war.

What is significant about this drive is its DVD+R recording speed. Although 4X DVD writing is fast in terms of the amount of data written per minute, it still takes quite a while to fill a disc. Those used to writing CDs at 48X or 52X typically think that 4X DVD writing is "slow". And they have a point. Although 4X DVD writing is fast in a relative sense--you're filling the equivalent of six or seven CD-R discs, after all--it still takes a lot longer to fill a DVD disc than a CD disc. Plextor says the PX-708A can fill a DVD disc in about eight minutes. That's not as fast as a fast CD burner, certainly, but it's getting there.

The major question mark is whether 8X DVD media will be available. Rumor has it that the PX-708A will reliably write 4X-certified discs at 8X. If that's true, it's wonderful, as 8X discs, when they finally appear, are likely to be quite expensive. We'll see what happens. I'll post a preliminary report after I've had a chance to play with the drive for a while. I'll probably build a new test-bed system to test the PX-708A drive in, because it comes with a bunch of Roxio software.

10:34 - I see that Vivendi's Universal Music Group has cut the MSRP of most of their CDs from $18.98 to $12.98, in response to plummeting sales volume. "Too little, too late" is my first impression. I think they're still overpriced by a factor of two. A CD should sell for about the price of a paperback book. Production and distribution costs for CDs should be a bit lower than for paperback books, with returns costs a bit higher. Sales volumes should be similar. So why should CDs sell for twice the price, even after the price cut? Five or six bucks is a reasonable price for a new CD. Ten or twelve bucks isn't. I'm afraid UMG is going to learn that the hard way.

I saw something disgusting on the news the other night, but as it turned out the object of my disgust changed once I learned more. A young couple had been charged with failing to report a birth, which is a felony in North Carolina. From the TV report, it sounded as though the woman had given birth to a full-term baby, strangled it or something, and stuffed it in the trash. The newspaper report yesterday morning gave a few more facts. The "baby" was in fact a 19-week fetus, and there was no evidence that the couple had done anything to induce the birth or taken any action to harm the fetus.

Now, I am not a physician, but I believe that a 19-week fetus is not viable. That's only a bit over four months. Nor am I a lawyer, but it seems to me that the "birth" part of "failing to report a birth" implies that the fetus in question must be viable for a crime to have occurred. Apparently not.

The upshot is that the couple are both in the Davidson County jail, under $100,000 bond each. Is it just me, or is there something seriously wrong here? I've seen reports of violent criminals released on $20,000 to $50,000 bonds. As far as I can see, this young couple did nothing particularly wrong. Stupid, yes. But what it boils down to is that the woman suffered a miscarriage and is now in jail under $100,000 bond for failing to report that fact. Does this mean that any woman in North Carolina who suffers a miscarriage, no matter how early, must report it or risk being jailed?

Being a man, I can't imagine what it must be like to suffer a miscarriage. But I have known several women who have, and in each case it was emotionally devastating. Surely the authorities could have left it at that?

11:55 - Many of my readers have been observing Mars, and I've gotten repeated questions about Mars and Mars' moons. Here's a representative one:

I'll never say never, but I think it's very unlikely that you saw the Martian moons in your scope. Even ignoring the Mars glare factor, Deimos and Phobos are right at the edge of visibility in your scope. The generally-recognized limit for naked-eye visibility at zenith on a clear, dark night is magnitude 6. That also assumes young eyes, which can dilate to 7mm, and the use of averted vision.

Your 70mm scope has ten times the aperture of the human eye, and therefore 100 times the light gathering ability. As it happens, a change of 100X in brightness is defined as five magnitudes. In theory, then, your 70mm scope should allow you to see with averted vision 11th magnitude stars at zenith on a dark, clear night. That's only true, though, if your entrance pupil is 7mm. The ability of the eye to dilate decreases as we age. After age 40 or so, you're probably limited to 5mm dilation, which cuts the amount of light entering by a factor of two relative to a 7mm entrance pupil. One magnitude is roughly a 2.5X difference in brightness, so assuming you're over 40, you'd be limited to seeing about 10th magnitude stars (again, on a very dark, very clear night at zenith, and using averted vision). Deimos is about magnitude 11.5 and Phobos 10.5, which probably makes them dimmer than your scope can resolve, particularly since Mars is nowhere near zenith where you're observing.

At 0300 UTC last night, relative to Mars, Phobos was at about 3:15 on the clock face (natural view, not inverted or reversed), with a separation of about 32 arcseconds (just over one Mars diameter). Deimos was at about 2:45 on the clock face, at about 67 arcseconds separation (less than three Mars diameters). My guess is that the objects you saw were the stars SD-17 6537/HD213251/SAO165129 (mag 7.26) and SD-17 6536/HD213199/SAO165122 (mag 8.17).

As far as your two questions, calculate magnification by dividing the focal length of the telescope in mm by the focal length of the eyepiece in mm. The Meade ETX-70AT has a focal length of 350mm. With your 9mm eyepiece, it yields 350/9 = 38.9X. With your 25mm eyepiece, it yields 350/25 = 14X.. If Meade lists 240X as the maximum practical magnification, they're being extremely optimistic. Most experienced observers consider an exit pupil of 1.0mm as the smallest generally useful, although some would argue for 0.7mm or thereabouts. The exit pupil is calculated by dividing the eyepiece focal length by the focal ratio (not focal length) of the scope. Your ETX-70AT has a focal ratio of f/5, which means that it yields a 1.0mm exit pupil with a 5mm eyepiece. That translates to 350/5 = 70X. A 0.7mm exit pupil translates to a 3.5mm eyepiece, which yields 100X. Attempting to use any smaller an exit pupil results in very dim images, and also starts to reveal floaters in your eye and other anomalies. Some double-star observers find exit pupils in the 0.5mm range useful for splitting stars (although not for anything else). At a 0.5mm exit pupil, you'd be using a 2.5mm eyepiece, which would yield 140X. You're very likely to find even that power useless, though.

As far as inverting and reversing images, things get a bit complex. It has to do with the number of reflections. If there are an even number of reflections, as in a standard Newtonian/Dob scope (primary and secondary mirrors), the image is not reversed. Many will tell you that a standard reflector inverts images, but that's not precisely true. The orientation of the image in the eyepiece depends on the observer's orientation to the eyepiece. In other words, it is possible to view a correct image with a Newtonian reflector. It's therefore more accurate to say that the image in a standard Newtonian (or any other scope with an even number of mirrors) that the image is arbitrary rotated, depending on the eyepiece position relative to the ground.

A refractor inherently inverts the image. Most refractors, including yours, use a diagonal mirror to make it easier to look through the eyepiece. To complicate matters, it is possible to use a refractor (or catadioptric, which uses lenses and mirrors) without a diagonal, or with a diagonal which is designed to correct inversion and/or reversal of the image. For example, refractors intended for terrestrial use (or combined astronomical/terrestrial use) are often supplied with diagonals that use an Amici prism or other arrangement to present correct-image views. The only way to know for sure is to try the scope on a terrestrial target to determine whether the image is inverted, reversed, both, or neither.

10:53 - George is shedding his skin again. Let me tell you, there're few things worse than a grumpy 7-foot rattlesnake. He tried to bite me this morning when I was giving him his Purina Snake Chow (he likes the mouse-flavored variety). I yelled, "Bad snake!" (even though he has no ears--it's a hard habit to break) and exiled him to his terrarium until he cheers up. I'll let him out to patrol the house while we're up at Pilot Mountain for the Mars Public Observation, but other than that he's confined to his terrarium until he calms down a bit. Barbara keeps telling me to have him de-fanged, but I don't believe in that any more than I do in neutering dogs.

Here's something I'd never thought about:

That's interesting. I'd never thought about it. When I'm writing something that requires the Greek alphabet (like an astronomy document), I always just keep the Character Map applet up and insert symbols as needed.

As long as you're giving your great-niece interesting numbers to play with, why not give her the most interesting of all? The number 142,857 (the repeating decimal of one-seventh) is purely magical.

As I mentioned, we plan to head up to Pilot Mountain for the Mars Public Observation. The weather is supposed to be reasonably clear, and we're expecting big crowds, possibly in the range of 3,000 or 4,000. Forsyth Astronomical Society is co-sponsoring the event with SciWorks and Pilot Mountain State Park, and we hope to have enough FAS members up there to run 20 or more scopes. Running thousands of people past 20 scopes in perhaps three hours means we'll all be busier than the proverbial one-armed paper hanger with a rash, but we'll do the best we can.

Just getting there may be atrocious for a lot of the people who attend. There's a small parking lot where we set up. It's at the highest point of the access road, which winds up the mountain for a mile or more from the entrance. I'm afraid we're going to end up with a line of cars all the way back to the park entrance, if not farther.

Several years ago FAS had an all-time record for attendance at a public observation. I think it was Comet Hale-Bopp. They later estimated that more than 6,000 people had shown up. The line of cars went all the back to the park entrance, down the state road from the entrance to the exit ramp off US 52, and at one point they actually had traffic backed up on US 52, trying to get onto the exit ramp. Needless to say, we plan to show up very early and then stay until the crowds have disappeared. We'll also use the bathroom before the crowds start to arrive. The men's section has two urinals and three toilets, and I assume the women's section has five toilets. That's not many for thousands of people. Come to think of it, we'd better take our own toilet paper and paper towels, just in case.

Many of those who attend will be disappointed. They're primed to see Mars based on Hubble Space Telescope shots. What we're going to show them is the real Mars, which unfortunately in ground-based scopes won't appear very large. At 75X or so, Mars has the same apparent size as the Full Moon naked eye. That sounds large, but it really isn't. We'll probably be running magnifications in the 150X to 300X range, depending on seeing. If the atmosphere is stable, we'll use higher powers. Otherwise, we'll use lower ones because with unsteady air high magnifications simply produce a larger but much blurrier image.

Also, much as I like our Dobsonian telescope, it doesn't track. That means that at high powers Mars crosses the field of view very quickly. At 270X in our scope, for example, it takes Mars only one minute to transit the field of view from one side to the other. That's not a problem for us. We can track manually. But for the public it is a problem, because we have to keep re-centering the image before it exits the field of view. Fortunately, there'll be quite a few equatorially-mounted scopes with drives. With those, you can center Mars, turn on the motor, and it'll keep Mars centered in the field of view all evening.

There may also be some clouds, which may be a problem. Haze is no problem at all. Mars, at magnitude -2.8, is bright enough to burn through haze, and in fact the atmosphere is often more stable when there's haze. But if Mars ends up behind clouds for any significant percentage of the time, it's going to be a problem. Fortunately, Luna is well up. As a DSO observer, I regard Luna as light pollution, but there's no doubt that it's the most impressive object in the skies as far as the public is concerned. Many of them have never seen Luna other than naked eye, and they're always amazed when they see it under medium to high magnification. So, we can hope that if Mars is behind a cloud, Luna will be visible, and vice versa.

Barbara and I will set up two scopes, and each of us will run one. If the turnout is anything like we're expecting, we're not likely to get many breaks throughout the evening. Still, it's worthwhile. We all think of it as a numbers game. If we can get even 1/10 of one percent of the people who come to develop an interest in astronomy in particular or even science in general, we'll consider it a successful evening. It's always in the back of our minds that when we offer a child his first glimpse of Mars or Luna, we may be helping to develop an interest in science that may blossom. Some day, one of those kids might find the cure for cancer or win a Nobel Prize.

14:47 - Bo Leuf posted an interesting item on his journal page today, to which I just had to respond:

"In the local news, newsmedia are voicing some concerns about the new police sidearms with expand-on-impact bullets being phased in. On the one hand, the police are citing incidents where up to 8 direct body hits using current ammunition have been needed to stop an armed and dangerous perp. On the other, "mild" concern from surgeons who say that the new bullets will result in more massive internal injuries and more serious operations."

I have never understood the European fascination for the 9mm and other .36 caliber pistols. It's been proven time and again that they are simply inadequate as man-stoppers. Expanding bullets don't do much to help.

A very close estimate of stopping power can be made using the WAVE method--simply multiplying the Weight, Area, Velocity, and a semi-arbitrary Efficiency factor for the bullet. On that basis, comparing a .45 ACP 230-grain roundnose bullet (assuming 0.9 E) at 900 feet/second with a 9mm 115 grain hollowpoint or semi-wadcutter bullet (assume 1.1 E) at 1,200 fps, you get:

.45: 230 X 0.160+ X 900 X 0.9 = 29.9
9mm: 115 X 0.099+ X 1,200 X 1.1 = 15.0

which pretty much corresponds to reality. A single .45 ACP hardball round, or anything else in the ~30 range, stops a bad guy about 19 times in 20. A single 9mm round, or anything else in the ~15 range, stops a bad guy about half the time. Unfortunately, the second and subsequent hits with minor calibers like the 9mm typically don't have much effect.

The proponents of fast-moving light bullets make the mistake of assuming the muzzle energy has anything to do with stopping power. They greatly exaggerate the weight of velocity by squaring it (mv^2), when in fact it's really momentum (mv) that counts. Give me a big, heavy, slow-moving bullet any time--the so called "flying ashtray" school of ballistics.

John Wesley Hardin, when asked why he carried a Colt .45, is alleged to have replied, "Because they don't make a Colt .46." John Wesley Hardin knew what he was talking about.

9:31 - Stolen shamelessly from C. J. Songer, mystery author and pistolero (pistolera? No, I think that's a holster. At any rate, she's not someone you want angry at you...)

This woman walks into a pharmacy, and tells the pharmacist that she wants some arsenic. Not unnaturally, he asks her what it's for. She says, forthrightly enough, "I want to kill my husband." He says, "Oh, good heavens, no -- I'm sorry, but I just can't do that!" She then reaches into her handbag and pulls out a photograph of her husband in bed with the pharmacist's wife and hands it to him.

"Ah," he says, "you didn't tell me you had a PRESCRIPTION...."