Monday, 8 November 2004
[Last
Week]
[Monday] [Tuesday] [Wednesday]
[Thursday]
[Friday] [Saturday] [Sunday]
[Next Week]
[Daynotes Journal
Forums] [HardwareGuys.com
Forums] [TechnoMayhem.com
Forums]
{Five
Years
Ago Today]
11:08
- This week is short-shrift time.
I have a deadline today to get some changes done in time for the
second printing of Building the
Perfect PC to go off to the printer tomorrow. O'Reilly sold out
the remaining copies in the first printing, and we desperately need to
get a second printing done so there will be books in stock to fill new
orders.
I have another deadline tomorrow, to get the final draft of the BPP
Pocket Guide book complete and ready to go to production Wednesday
morning. The remainder of this week, I'll be answering urgent queries
about the Pocket Guide, as well as trying to get back into working on
the 4th edition of PC Hardware in a
Nutshell and several other pending projects.
[Top]
Tuesday, 9 November 2004
[Last
Week]
[Monday] [Tuesday] [Wednesday]
[Thursday] [Friday] [Saturday]
[Sunday] [Next Week]
[Daynotes Journal
Forums] [HardwareGuys.com
Forums] [TechnoMayhem.com
Forums]
{Five
Years
Ago Today]
10:12
- The Pocket Guide book is finished and off to O'Reilly's
production folks, as are the changes for the second printing of
Building the Perfect PC.
Someone asked yesterday if it was common to make edits to a book before
a reprinting. The answer is that it's not, but in this case we decided
to do so. In the first printing, we'd recommended Hitachi flat-panel
displays. Literally a few days after the book went to the printer,
Hitachi announced they were departing the FPD market.
I'm taking a break today to set up the scope and watch Luna occult
Jupiter, assuming I can find a 10% illuminated Luna in broad daylight.
That's not as easy as it sounds. Luna is a tiny sliver in a bright blue
sky, about 40° to the right of and very slightly higher than a very
bright Sol. (If you try to observe this yourself with a scope or
binocular, be extremely
careful not to get Sol in your field of view. You can be blinded
literally instantly, before you have time to react.)
There's another Lunar occultation of Jupiter on Tuesday, 7 December,
from 0350 to 0501 local time. We'll probably get up early to watch that
one as well.
12:57
- I drove over to Paul Jones' and Mary Chervenak's house around
10:30 and got the 10" Dobsonian scope set up. Bonnie Richardson showed
up not long after, and set up her 127mm Maksutov-Cassegrain scope.
Bonnie was the first to locate Luna, which was a tiny sliver against
the deep blue sky. When you're looking right at Luna, it's obvious, but
when you try to scan the sky to locate Luna, it's not obvious at all.
I finally located Luna by seeing where Bonnie was pointed, and got Luna
in the 10". I was able to get Luna naked-eye, but I couldn't get
Jupiter naked eye. Mary, Bonnie, and I watched the ingress together.
The seeing was variable, pretty bad most of the time, but at times good
enough that Mary and I were both able to spot two equatorial bands on
Jupiter at about 90X. We tried, but were unable to spot any of the
Galilean moons of Jupiter. After Luna had entirely covered Jupiter,
Mary went back in the house to get some work done, Bonnie took off to
do her grocery shopping, and I sat in a lawn chair in the driveway and
tried to get some work done myself.
At a few minutes before noon, Mary and I heard a squeal of tires and
saw Paul's 4X4 come around the corner on two wheels (okay, I'm
exaggerating). Paul had been stuck in a meeting, and so had missed the
ingress, but was determined to see the egress (or, as we've all started
calling it, the "outgress'). The four of us sat around talking,
checking the scopes periodically.
Bonnie was the first to spot the outgress. By the time I had it,
Jupiter was nearly tangent to Luna, with just a small part remaining
occulted. After separation, we all tried to spot Jupiter naked-eye.
Paul, Mary, and I were able to do so, and Bonnie may have but wasn't
sure. Paul had seen Jupiter naked-eye just before ingress, which I
wasn't able to do. But ingress was against the illuminated portion of
Luna, whereas outgress was against the dark portion, which made it
easier to spot. We also spotted Venus naked-eye, only 5 degrees or so
from Luna, and well within a binocular field.
There's another Lunar occultation of Jupiter on Tuesday, 7 December,
with ingress at about 0350 local and outgress at 0501. Mary and I are
definitely going to observe it. Paul said he might be up for the
outgress, but probably not for the ingress. Mary is making hot cocoa.
[Top]
Wednesday, 10 November 2004
[Last
Week]
[Monday] [Tuesday]
[Wednesday] [Thursday] [Friday]
[Saturday]
[Sunday] [Next Week]
[Daynotes Journal
Forums] [HardwareGuys.com
Forums] [TechnoMayhem.com
Forums]
{Five
Years Ago Today]
08:15
- I see that John "Let's shoot ourselves in the other foot"
Ashcroft has resigned. Good riddance. John Ashcroft rode roughshod over
the Bill of Rights, doing more damage to our freedoms than Usama bin
Laden could ever have hoped to do. John Ashcroft is an evil man, and
we're well shut of him. My only concern is that his replacement may be
as bad or worse.
Barbara took the day off work to prepare for the trip to Savannah she's
making with her parents, sister, and brother-in-law. Right now, she's
playing White Tornado, getting the house cleaned up in preparation for
her departure. The dogs are sad, figuring they'll probably have to do
without food, water, walks, or ball playing until Barbara returns on
Sunday.
[Top]
Thursday,
11 November 2004
[Last
Week]
[Monday] [Tuesday]
[Wednesday] [Thursday] [Friday]
[Saturday]
[Sunday] [Next Week]
[Daynotes Journal
Forums] [HardwareGuys.com
Forums] [TechnoMayhem.com
Forums]
{Five
Years
Ago Today]
09:20
- Armistice Day and Veterans Day. My mom would have been 86
years old today. She was born almost at the instant the First World War
ended. I still miss her every day, just as I still miss my dad, who
died in December 1990.
Five years ago today, I
wrote up a story that my dad had told me about his experiences as a
navigator on a B-17 over Nazi Germany. I'm sure I got some of the
details wrong, because my dad had told me about it 30 years or so
before I wrote it up, but it's right in the essentials.
Forever after, my dad never liked to fly commercial airliners, although
he did from time to time. I remember once when I was young asking my
mom why dad was so nervous flying on commercial airliners. "He can't
help it, Bobby. He worries about Messerschmidts." I thought that was
funny at the time. I was just a kid, and even I knew there weren't any
more Messerschmidts. It wasn't funny at all, of course.
I remember my uncle Bob telling me a story about one of my dad's
missions. They'd just gotten a shiny new B-17, which the crew chief was
very proud of. When my dad and his crew returned from that first
mission in the new plane, the crew chief shouted, "Jesus Christ! What
the fuck did you do to my new airplane?" It had been pretty much
shredded. They counted, and came up with a total of more than 2,300
bullet, cannon, and flak holes in that new B-17. Amazingly, none of the
crew had been killed or even injured. They had to scrap the plane,
though, after only one mission.
I've often given silent thanks to the people who designed and built the
B-17 Fortress and the P-51 Mustang. Without them, I'd probably never
have been born, because my father would almost certainly have died in
battle. The B-17 was legendary for its ability to sustain battle damage
and keep flying. I've seen photographs of B-17s that made it back
missing major parts of their structure. Engines blown off, parts of
wings missing, the tail nearly gone. The B-17 could absorb incredible
amounts of damage and still fly.
And the P-51 Mustang was just as important. My dad flew his early
missions without fighter support. The P-47 Jugs simply didn't have the
range to escort the B-17s all the way to target. And the German fighter
defenses kept getting better and better. Although my dad was always
reluctant to talk about the war when I was young, in later years he was
willing to answer questions. I remember asking him one time about the
German Me-262, the first operational jet fighter.
The P-51 was one of the fastest piston-engine fighters ever made. It
had, as I recall, a top speed of about 440 MPH. Even at that, though,
the Me-262 was fast enough to literally fly circles around a P-51. My
dad told me about the first time he and his crew saw an Me-262. No one
could believe it. It had no propeller, and yet it flew like a bat out
of hell. The B-17s were literally defenseless against it, because their
gun mounts couldn't move fast enough to track it.
If that was the case, I asked my dad, how did the B-17s survive? He
replied that the Me-262s really weren't much of a problem because there
weren't very many of them and there were a lot of P-51s. A whole bunch
of P-51s would gang up on one Me-262. Whichever way the Me-262 turned,
it'd be in the sights of at least one P-51, which would begin hosing it
down with 50 caliber.
Also, he said, the trick was not to fight the Me-262 at altitude, but
down on the deck where the P-51 outperformed the Me-262. Our guys soon
knew the locations of all the Me-262 bases, and when they were flying a
bombing mission, the P-51s would get there first and loiter at low
altitude near the Me-262 bases. The Me-262s were helpless when they
were taking off. They were moving slowly, unable to accelerate quickly,
and unable to maneuver. A bunch of P-51s would jump them as they were
taking off or shortly thereafter. If an Me-262 did succeed in taking
off, it would soon have to return to base to refuel and rearm. Again,
the P-51s would be waiting for it. So the Me-262s were really never a
major factor.
It might have been different, though, had Hitler allowed the Me-262 to
be developed as a pure fighter and produced in large numbers, rather
than insisting it be developed as a fighter-bomber. Had it not been for
the P-51s, though, even a relatively small number of Me-262s could have
brought the daylight bombing campaign to a complete halt. It wouldn't
have taken many such foxes among the sheep to raise B-17 losses to an
unsustainable level. Unchallenged, one Me-262 could easily have ravaged
an entire combat box of B-17s all on its own.
But the Me-262 was a minor factor. What really scared the American air
crews were the large numbers of Folke-Wulfe 190s and even the older
Messerschmidt Bf-109s. The Bf-109 was an aging design, but in its
Bf-109G "Gustav" variant, it was still a serious threat to the B-17s.
And the Folke-Wulfe 190s terrified the bomber crews. They were fast,
maneuverable, well armored, very heavily armed, and competently
piloted.
When Boeing introduced a late variant of the B-17, they had a
propaganda poster printed, with a picture of the heavily-armed B-17 and
idealized images of the young, handsome crew members standing by it.
The headline was "Who's afraid of the Big Bad Wulfe?" Someone pinned up
a copy of that poster in the rec room of one B-17 group. The group
leader wrote "We are!" and signed it. Every man in the group also
signed the poster, and they returned it to Boeing.
It was against these Messerschmidts and Folke-Wulfes that the P-51 was
so important. Without the P-51, the B-17s would have been overwhelmed.
But the USAAF deployed P-51s in huge numbers, and those P-51s escorted
the B-17s all the way to target and back. When Hermann Goering saw the
first P-51s over Berlin, he turned to his companion and said, "The war
is over." And so it turned out to be. With P-51 escorts, the B-17s were
able to bomb, if not with impunity, at least with much, much lower
losses than they would otherwise have incurred.
The huge number of P-51s escorting the bomber streams mean the German
fighters could no longer concentrate on shooting down B-17s because
they were too busy avoiding or defending themselves against P-51s. Some
of the German fighters still got through to attack the bombers,
certainly, but they were distracted to say the least. Many, many bomber
crews owe their lives to the "little buddies", and my dad may well have
been among those who made it back who otherwise wouldn't have.
So that's why I probably owe my very existence to the folks who
designed and built the B-17 and P-51.
I just sent the following message to subscribers:
If you own a domain name, this is important. In the past, if anyone
attempted to transfer a domain name, the current registrar notified the
domain owner and waited for approval before transferring the domain to
the new registrar. If the domain owner did not respond, the domain
transfer was denied.
Under new (and inexplicable) ICANN rules that take effect tomorrow, if
the domain name owner does not respond, the transfer must be approved.
This raises the very real possibility that domain "slammers" will be
able to hijack your domain. Note that if you respond to the
notification email and explicitly deny the transfer, that still
prevents the domain from being transferred, but in this age of spam
filters it's quite possible that you'll never receive the notification
and will lose your domain.
Nor is the risk only that your domain will be transferred to another,
more expensive registrar, but remain under your control. If I'm reading
the rules correctly, a malefactor could transfer ownership of your
domain as well.
I have all of my domains at GoDaddy.com. GoDaddy offers free "domain
locking", which prevents any unauthorized transfer. If your domain is
registered at GoDaddy.com, I strongly recommend that you update your
account information to enable domain locking. If your domain is
registered at a registrar that does not offer such a feature, I
recommend that you transfer your domain immediately to GoDaddy.com or
another registrar that does offer domain locking.
Under this new and unjust ICANN policy, I foresee a flood of bogus
transfer attempts to hijack desirable domain names. Make sure yours
isn't one of them.
Best regards.
Bob
-------- Original Message --------
Subject: ICANN Changes Transfer Policy - Announcement for Customer
Number: <redacted>
Date: 10 Nov 2004 23:37:03 -0700
From: <support@godaddy.com>
To: <thompson@ttgnet.com>
******************************************
Important Notice Regarding your Domain(s)
******************************************
Dear Valued Go Daddy Customer,
Effective November 12, 2004, ICANN, the Internet Corporation for
Assigned Names and Numbers, will put in place its new transfer policy
for all accredited domain name service providers.
The previous ICANN policy allowed us to deny requests to transfer your
domain names to another registrar unless you explicitly confirmed to us
your intent to transfer. The new ICANN policy removes that protection.
When we receive a request to transfer your domain name to a new
registrar, we will still attempt to contact you to confirm that you
authorized the request. However, if you do not respond, or are not able
to respond within 5 days, your domain name WILL be transferred.
Rest assured, your domains have NOT been transferred, and IT IS
UNLIKELY that this will happen.
Nonetheless, with this change in mind, we are recommending that all Go
Daddy domain customers visit GoDaddy.com and "lock" their domain
name(s). Locking your domain(s) is free and prevents unauthorized
changes to contacts and name servers. Most importantly, it prevents the
domain name from being transferred to another registrar without your
knowledge. You may lock or unlock your domain at any time by revisiting
your account. It takes only a minute, and it WILL protect your domains.
To lock your domain names, simply:
Go to: https://www.godaddy.com
Click My Account and enter your username or customer
number and password.
Click on Manage Domains
Select the domain name(s) that you wish to lock.
Click Set Locking. In the right side pane, select
"Lock" and save your changes.
After your changes have been submitted, there will be a short duration
while your request is pending update. During this period, details of
the domain(s) will be temporarily unavailable.
If you have any questions please email us at support@supportwebsite.com
or call our customer support line at (480) 505-8899.
Again, this email is simply a notification of a change in ICANN policy.
Your domains have NOT been transferred, and IT IS UNLIKELY that they
will be. Locking your domains will assure that they won't.
To review the new ICANN transfer policy, please visit:
http://www.icann.org/transfers/policy-12jul04.htm
Thank you for your attention.
Sincerely,
GoDaddy.com Domain Support
14:53
- TV stations are canceling
their plans to run Saving Private Ryan. On the one hand,
Spielberg's contract with the network requires them to run it uncut. On
the other hand, stations fear the reaction of the FCC, because the
movie includes graphic violence and uses the fuck word. The network
asked the FCC to review and pre-approve the movie. Staggeringly, the
FCC refuses to give a binding opinion before the movie airs, claiming
that, if they review the movie and refuse to approve it, that would
constitute censorship. True enough, it would. But instead, the FCC is
telling the networks and stations to show it if they wish, but in doing
so risk complaints that might result in heavy fines and other sanctions.
Whatever happened to the First Amendment? Why should the FCC have
anything at all to say about content? Let it take care of licensing
spectrum (although even that is a dubious task for the government, and
would be better done by the free market), but when it comes to what is
transmitted on the public airwaves the FCC should have no control. And
I mean no control.
If a television station chooses to broadcast hard-core pornography,
that is its right under the First Amendment. If you don't like it,
don't watch. If you don't want your children to see it, forbid them to
watch. Duh. Personally, I find religious broadcasting very offensive,
much more so than good clean porn would be. And I mean that seriously.
Religion is the enemy of reason, and having Falwell and those like him
spewing their ignorant evil over the public airwaves deeply offends me.
But I haven't asked the FCC to ban Falwell because I defend his right
to speak his mind, tiny though it is.
My question to the FCC is this. If the standard of acceptability is to
be that broadcasts on the public airwaves not offend public
sensibilities, what about me and the millions of people like me? We are
deeply offended by religious broadcasts, as well as what passes for
news nowadays. Many of us are deeply offended by commercials. I simply
refuse to watch stations that broadcast them. So why shouldn't stations
be forbidden to broadcast religious services, their so-called news, and
commercials?
It's pretty clear that a standard based on people taking offense is
unsustainable. If your standard is that no broadcast can offend anyone,
well you've just said that there will be no broadcasts at all. Anyone
can take offense at anything, or nothing at all. To repeat something
that should be obvious but has been obscured by Political Correctness,
offense is not injury. So, if offensiveness is not a workable
yardstick, what should the yardstick be? How about not having a
yardstick at all? The Founding Fathers would thank you.
[Top]
Friday,
12 November 2004
[Last
Week]
[Monday] [Tuesday]
[Wednesday] [Thursday]
[Friday]
[Saturday] [Sunday] [Next
Week]
[Daynotes Journal
Forums] [HardwareGuys.com
Forums] [TechnoMayhem.com
Forums]
{Five
Years
Ago Today]
11:15
- I've been cleaning up my office, clearing the decks for the
current book project and a forthcoming one. As I cleaned off my
credenza yesterday, I noticed that there are half a dozen computers on
or under it that haven't even been powered up recently. One of them,
for example, is old theodore,
which used to be our NT4 file server.
I decided it made sense to spend a bit of time to strip these older
systems down to bare metal (to remove our data and installed software),
clean them up a bit, and donate them to a local non-profit. So I called
Senior Services and spoke to Peggy, their one-woman IT shop.
Non-profits have a lot of junk foisted on them, so Peggy was naturally
leery. Non-profits don't want to insult prospective donors, but they
don't want to receive a bunch of antique junk, either.
I told Peggy that theodore
was probably the oldest of half a dozen systems I could donate. It's an
old Slot 1 440BX Intel motherboard with a Pentium III/450, a couple of
Maxtor IDE hard drives, a SCSI host adapter, Plextor SCSI CD-ROM drive,
and Tecmar Travan tape drive, all in a PC Power & Cooling case with
a Turbo-Cool power supply. Not suitable as a desktop system, but built
with top-notch components, and perhaps suitable as a supplemental
server. I have several other systems I can give her, including
reasonably fast Pentium III, Athlon/Duron, and even an older Socket 478
P4 system or two.
They have very limited storage space, so I told her I'd donate the
systems in onesies and twosies. They're downtown, so I'll probably
periodically load a system or two in the back of Barbara's truck and
let her deliver them on her way home from work. I told her I'd not be
offended if she decided to discard something. It's totally up to her.
She said that if there was stuff they couldn't use there was an
alternative. There's a local group that refurbishes older systems and
donates them to disabled people who can't afford to buy their own
systems. I told Peggy that was fine with me, that I'd just deliver
stuff to her and let her sort out what she wanted to keep and what she
wanted to donate to that group.
Barbara I'm sure will be relieved. We have a dozen or more unused but
still useful systems sitting around here and we need to get rid of them
because there's always more new stuff on the way. It would be a waste
to discard these older systems, so by donating them to a non-profit
everyone wins.
I'm not sure what to put on them. I want to strip them down completely,
both to remove our data and to remove installed software. I installed
Xandros OCE yesterday on theodore,
but that's not a workable solution. Xandros OCE is free for personal
use, but it's not licensed for business use, including for non-profits.
I'll probably download Mepis or Ubuntu Linux and deliver the systems
with that installed on them. Any suggestions would be appreciated.
[Top]
Saturday,
13 November 2004
[Last
Week]
[Monday] [Tuesday]
[Wednesday] [Thursday]
[Friday]
[Saturday] [Sunday] [Next
Week]
[Daynotes Journal
Forums] [HardwareGuys.com
Forums] [TechnoMayhem.com
Forums]
{Five
Years
Ago Today]
08:18
- Friday the 13th falls on a Saturday this month...
Holy Cow! Barbara is due back from her trip tomorrow. That means I need
to clean up around here.
I should give the dogs food and water and walk them at least once
before Barbara gets home. That and clean up the bathrooms and kitchen,
although it might be easier just to rip them out and replace them. And
tomorrow morning I need to take four showers and change my socks and
underwear. (That way I can honestly tell Barbara that I changed clothes
and averaged one shower a day while she was gone.) She left me my daily
pills in one of those little pill holders labeled by day, so I'd better
go take all the ones from the Wednesday, Thursday, Friday, and Saturday
sections. And I need to remember to send back those young teenage
virgins I ordered from a spammer.
[Top]
Sunday,
14 November 2004
[Last
Week]
[Monday] [Tuesday]
[Wednesday] [Thursday]
[Friday]
[Saturday] [Sunday] [Next
Week]
[Daynotes Journal
Forums] [HardwareGuys.com
Forums] [TechnoMayhem.com
Forums]
{Five
Years
Ago Today]
11:25
- Barbara is due back this afternoon. The dogs will be happy. I
will be happy. We will all do our little circle-dance of greeting.
I went up to our club's site near Pilot Mountain to observe last night.
Perfect skies, no clouds, great transparency. No moon. One of the best
nights in a very long time. Steve Childers was the only other person
there. Steve had his 17.5" Dob set up. I didn't bother to set up our
10" Dob because I planned to work the Deep
Sky Binocular list.
By the end of the evening, Steve and I had each logged ten or so new
objects. That now leaves me with 50 of the 60 objects on the list. I
have 9 objects remaining in Monoceros and Puppis, and one in Coma
Berenices. If I'd wanted to stay out until oh-dark-thirty I could have
gotten all ten of those, but they'll wait for another night when those
constellations are well-placed at a more reasonable hour.
Steve was working dim objects in the dim northern constellations of
Ursa Minor, Draco, Cepheus, and Camelopardalus. Among those were
several objects on the so-called Caldwell
list. The Caldwell list has a strange history. Compiled by British
astronomer Sir Patrick Caldwell-Moore, this list is sometimes
represented as the "best objects Messier missed" or words to that
effect. In fact, most serious deep-sky observers, including me, think
it's a hideously bad list.
Moore made his name in astronomy many, many years ago as a Lunar
observer. He was never known as a DSO guy, and in fact when he was in
his prime very few amateur astronomers observed DSOs. They simply
didn't have large enough scopes back then to make DSO observing a
rewarding activity. Even as late as the 1960's and 1970's, most amateur
astronomers concentrated on Lunar and planetary observing, along with
double stars, variable stars, and similar objects. The faint fuzzy DSOs
were simply too dim to be realistic targets. It wasn't until Dobsonian
"light buckets" came along in the late 1970's that most amateurs had
access to the seriously large apertures needed for DSOs.
So, some years ago, Sky & Telescope magazine published and
copyrighted the Caldwell list. I remember at the time thinking it was a
very strange list. There are a few magnificent objects on the Caldwell
list, certainly, such as the Double Cluster in Perseus (NGC 869 and NGC
884), but overall the list appears to be the result of Caldwell going
through star atlases and picking objects almost at random. My opinion
is that Moore probably talked to S&T about coming up with a new
list and then sat down and spent five or eight minutes making the list.
I can't believe that anyone actually took the trouble to view the
objects on the list before it was published, or it would never have
been published. There are simply too many profoundly unimpressive
objects on that list.
In addition to the very poor object selections, the Caldwell list has
another serious problem. Barbara and I are located at about 36°
North latitude, very close to but south of the 40° North latitude
for which most lists are designed. But we can't observe all of the
objects on the Caldwell list from our latitude. We can't even come
close to all 109 objects on the list. I checked once, and I think we
can get at most 80 or so. The others are too southerly. Observing them
would require us making a trip far to the south, ideally south of the
equator. And, believe it or not, this is represented as a feature of
the list rather than the flaw that it is.
But even many of the objects that are visible at this latitude are
singularly unimpressive. The official description from AL says:
"While
Charles Messier made a catalogue of faint fuzzy objects to be avoided
when searching for comets, Sir Patrick Caldwell-Moore has made a
catalogue of beautiful and interesting objects you should, literally,
go out of your way to observe."
Yeah, right. If the Messier Objects are faint fuzzies, most of the
Caldwell Objects are much fainter fuzzies. And the claim that these
objects are all observable with ordinary amateur equipment is a cruel
joke.
Steve confirmed that last night. With his 17.5" scope, which is huge
compared to the average amateur scope, on a night with nearly perfect
transparency, observing at a reasonably high altitude in a relatively
dark northern sky, Steve tracked down several of the northerly
Caldwells. Some, like the Cat's Eye Nebula, a planetary nebula in
Draco, are in fact bright and impressive. But most were so dim, even
under excellent conditions with a very large scope, that most observers
wouldn't have a prayer of seeing them. A couple of them, we had trouble
seeing in the 17.5" scope, which goes more than a full magnitude deeper
than the largest scopes in common use among amateurs.
I think the problem is that Moore compiled this list looking only at
visual magnitudes. That's a common mistake among astronomers who don't
have much DSO experience. The problem is that DSOs are extended
objects, which is to say they are not point sources like stars.
Extended objects have a surface area. The magnitude given for DSOs is
an integrated magnitude, which means that if all of the light being
emitted by the extended object were condensed into a point source
(star), that star would be of the stated magnitude. That's why stellar
observers talk about magnitude and DSO observers talk about surface
brightness.
And the magnitude for an extended object is a matter of opinion,
because the integrated magnitude of an object depends on how large you
define the extent of the object. The sizes given for many extended
objects are photographic sizes, which is to say the size of the object
as it appears in long-exposure photographs. But the visual size of the
object is often much smaller, sometimes much, much smaller. If the
integrated magnitude is based on photographs, it will be lower
(brighter) than if it's based on visual extent.
Conversely, the surface brightness is a realistic representation of the
appearance of an object, because it takes into account not just the
total light emitted by the object, but how large an area that light is
distributed over. For example, a galaxy might have a visual magnitude
of 8.5, which is bright, but that galaxy may spread that light over a
large surface area, giving a resulting surface brightness of, say,
13.6, which is quite dim.
I think Caldwell, who was not an experienced DSO guy, looked only at
magnitudes when choosing his objects. For example, one of his objects
is the Bubble Nebula, which he lists as magnitude 7.0 (bright). Cartes
du Ciel lists that object, NGC 7635, as having a magnitude of 11.00
(very dim) and a surface brightness of 15.94 (extremely dim), both of
which are much closer to what Steve and I actually observed last night.
There was no question we'd found the object and had it in the eyepiece.
The Bubble Nebula is less than half a degree from the bright Messier
Object M52 in Cassiopeia. It's within the same eyepiece field, so
there's no question that we had located the object. And yet, it was
just barely visible in the 17.5" scope, and that using what club member
Bonnie Richardson calls "averted imagination". Someone with a more
typical 8" or 10" scope wouldn't have had a prayer of seeing that
object.
In my opinion, the Caldwell List is a disservice to amateur astronomers
everywhere. The challenges beginning amateurs face are, first, what
objects to look for; second, locating these objects; and third, having
located the objects, being able to see them. None of these challenges
are trivial, and the Caldwell List fails on all counts.
[Top]
Copyright
© 1998, 1999, 2000, 2001, 2002, 2003, 2004 by Robert Bruce
Thompson. All Rights Reserved.
