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2024 October 29
On November 5, remember January 6
We have a bitterly controversial, divisive presidential election coming up.
Here is my exhortation to my fellow citizens:
For the rest of your life, people will be asking you what you thought about it. Will your answer be honorable?
Do you think Mike Pence did wrong by refusing to throw out the vote counts? Do you think the crowd calling for him to be hanged was in the right?
Do you think Donald Trump did right by watching the insurrection for hours while making no attempt to call it off?
Did you keep your head in the sand by watching only extreme right-wing newscasts and telling people that the truth was "fake"?
If you are a conservative, did you do your best to keep conservatism honest and respectable, or did you give up conservatism to pursue something else?
If you are a Christian, do you recall the early attempts to portray Trump as God's anointed, and have you taken into account the warning in
Matthew 24:24?
Your children and grandchildren will be asking you. Make sure you can give an answer that you won't be ashamed of
— and think about that answer now, when you vote.
I posted a shorter version of this challenge on Facebook and found that some people think a great many other issues
are more important than an armed attack on the seat of our nation's government.
I am dismayed.
I continue photographing the comet on every clear evening, refining my technique but
getting a worse view of the comet each time as it recedes from the sun and earth.
This picture was processed to have a light background so you can see as much of the
comet as possible. The star cluster IC 4665 is above the comet. The picture is rotated;
the comet was actually pointing down, toward the horizon and the sun.
Stack of 8 15-second exposures, 100-mm lens, f/2.8, Canon 60Da, ISO 800,
calibrated with flats and darks, followed by usual PixInsight processing, which now includes
gradient removal and deconvolution by BlurXTerminator.
Here is the North America Nebula again, photographed with my vintage 1976 or 1977 Zuiko 100-mm
f/2.8 lens at f/4. This is a stack of 60 30-second exposures with a Canon 60Da, ISO 800,
and iOptron SkyTracker, calibrated and processed the usual way.
This should look very much like the picture I posted two days ago,
taken with a much more complex lens. (I did not aim to make the pictures have exactly the
same brightness and contrast.) The Zuiko is serving me well, and its light weight is
an advantage when I'm using the SkyTracker. I like it so much that I've just ordered,
from Japan, its slightly bigger brother, the 135/2.8, from late in the production run, with
better multicoating. The two lenses have essentially the same design, inspired by the
Zeiss Sonnar.
I know this may be getting monotonous, but here are the last two of my series of
early-evening comet pictures (cloudy weather has now set in). To fit the screen,
the pictures are rotated from the usual orientation; in the actual sky,
the comet had its head down
(toward the sun) and tail up. See how much it moved in one day, and note that
it is moving tailward, as comets do when retreating from the sun.
The loose star cluster IC 4665 is prominent on the left in both pictures.
I've photographed the North America Nebula many times, and here is one more.
I was testing my ultra-portable setup (also used for the comet), consisting of an
iOptron SkyTracker, Canon 60Da, and Sigma 105/2.8 DG EX lens.
This is a stack
of 30 exposures (each 30 seconds at ISO 800, f/4),
but in fact I took 120 and had problems with the lens drifting
out of focus due to some kind of looseness in its mechanism. I'll get it serviced
if I can; it probably just needs lubrication.
Star clouds in Cygnus
A vintage lens continues to serve me well
Because of problems with the Sigma 105/2.8 lens (which I've had since 2005), I got out
another lens that might substitute for it, the Olympus Zuiko 100/2.8 that I bought in
1977 as the second lens for my film OM-1. It fits on Canon DSLRs with an adapter.
Intending to photograph the North America Nebula, I mis-identified stars while aiming
the SkyTracker and got a random star field in Cygnus, with M29 at the upper right corner.
Surprise! At f/4, this lens may actually be sharper than the Sigma. It has slight aberrations
in the corners (of the APS-C frame, smaller than it was originally designed to cover),
but they are of a very familiar type, and BlurXTerminator recognizes them and corrects them.
So I have a very lightweight lens to use as part of this portable setup.
For more about the classic Zuiko 100/2.8, click here
and here
and here.
Mine is from early production and is not multicoated; if it's to become a workhorse, I may look
for one with a serial number over 190,000, with a high-grade multicoating.
My last few comet pictures have been very much alike, and I haven't been
sharing all of them. But last night the comet had moved into a dark enough
region of the sky that I was able to use the tools of deep-sky photography
and get a much better image (of a fainter comet).
Stack of 7 15-second exposures, Canon 60Da, ISO 800, 105-mm f/2.8 lens at f/4,
iOptron SkyTracker; stacked with PixInsight, with some gradient removal.
I am not clear on whether the antitail has disappeared; it hasn't shown up
on my pictures in some time, but others may still be imaging it against dark
desert skies.
Here's the comet on the evening of the 21st — slowly receding, not changing much from
day to day, although to the visual observer it's obvious that it's getting dimmer.
(A dark country sky is now definitely required to see it without optical aid; I found it
surprisingly hard to see in binoculars from my home.)
Single 30-second exposure, Nikon D5300, ISO 400, 105-mm f/2.8 lens wide open,
on an iOptron SkyTracker.
Comet Tsuchinshan-ATLAS C/2023 A3 is now high enough in the evening sky that I can see
it from my driveway, which means I can use star trackers and telescopes.
Last night I went at it with an iOptron SkyTracker, which enabled me to get longer
exposures, and in one of them, a meteor graced us with its presence.
Comets and meteors are completely different kinds of objects, of course, and this shows
how different they look.
Nikon D5300, 10 seconds, ISO 400, 50-mm lens at f/2.8. Single exposure.
Perhaps the most important design goal for an alphabet is for all the letters to look different
from each other. Contemporary typeface design does not always achieve this
(e.g., lowercase L and uppercase I look the same in Arial, a flaw
that can be fatal to web addresses and the like).
I've written about this before and advocated Bahnschrift,
a German road-sign font now distributed by Microsoft,
where a sans-serif font is desired for labeling or charts.
Now my daughter Sharon calls my attention to the Atkinson Hyperlegible Font, produced by the
Braille Institute for ease of reading by people with poor vision.
It is a free download, both for use in print and for use on web pages.
Besides people with poor vision, it also benefits people sitting far from the screen when you give
a PowerPoint, people reading labels from a long way off, and the like.
I'm going to use it for labeling equipment.
Atkinson Hyperlegible is not as elegant as Bahnschrift, which is not as elegant as, say, Palatino.
I use the latter two a lot. Atkinson isn't for everything.
But if you want maximum elegance and don't care about readability at all,
you could join the chorus of atavists (not including me!) who still clamor
for cursive handwriting. Where nowadays can you get a job handwriting in cursive all day?
Or even doing arithmetic with pencil and paper? Some people always want the elementary schools
to train people for the jobs of a century earlier.
This evening the comet was high enough to see from my back yard; it will continue
to be until it recedes from view.
Also, I was able, for the first time, to photograph it against a dark sky,
after the end of twilight (or at least what passes for a dark sky in town, as
the moon is rising behind me).
Stack of 5 3-second fixed-tripod exposures (stacked manually in Affinity Photo),
Nikon D5300, vintage 50-mm f/2 lens wide open, ISO 400.
The brightest star in this (cropped) picture is σ Serpentis.
As far as I can tell, the comet's antitail has faded.
The time on the picture is in UTC, hence the October 19 date.
The attentive reader will note that this comet picture and the previous one
are quite similar. The comet is receding from the sun, getting dimmer, but only slowly.
For this one, I didn't go to a dark-sky site, but simply walked down the street last night
to get to a place with a low enough horizon. With a Nikon D5300 on a fixed tripod,
and a vintage 1971 50-mm f/2 Nikkor lens at f/2.8,
I took several 2-second exposures (dodging satellites and aircraft) and
stacked the best consecutive four.
Note that in this picture, you can faintly see the antitail, pointing forward (downward) from the
head of the comet.
And then I went home and came down with the worst cold I've had in months, so I won't
be going out every night for a while. But the comet won't be completely gone for a while,
and I hope to catch it farther down the road.
Here is what will probably be my best picture of the comet, as it is now
receding from the sun and getting dimmer. From a reasonably dark site outside
of Athens, Georgia, I could see it faintly with the unaided eye, and clearly
with binoculars.
This is a stack of four 2-second fixed-tripod exposures with a Nikon D5300 at ISO 400
and a 105-mm lens at f/2.8. I did the stacking manually in Photoshop. Although I rarely
retouch astrophotos, in this case I used Photoshop to take out an aircraft that was in
a different position in each of the four images, before stacking. An outlier-rejecting
automatic stacking algorithm would have done the same.
A couple of nights ago, continuing to try out new equipment, I did something unusual —
put the new ToupTek 678C planetary camera on my old Celestron 5 telescope and recorded a wide
area of the moon. This was largely to pin down techniques and software settings, as the moon
was too low in the sky to give a first-rate result. But I did get something...
Stack of the best 75% of 961 video frames. I should have taken more frames but
was troubleshooting software. I continue to have trouble using FireCapture with this
camera and have switched to SharpCap, in the hope that a future version of FireCapture will
sort everything out.
Q. Is this something that only happens every 50,000 years?
A. We get a bright comet every few years, just not the same comet. Many comets have very long orbits (estimated at 10,000 years or more) although quite a few are shorter (down to just 3 years or so). So... Seeing THIS comet is rare; seeing SOME comet is not. We had a bright one in 2020, if you remember.
Q. Will it "streak across the sky"?
A. Not like a shooting star. It will take weeks to move gradually across the night sky. See the map below.
Q. How bright is it?
A. [Updated.] Probably bright enough to see without binoculars, at least for the first few days;
definitely visible in binoculars.
The brightness of comets is hard to predict.
This one will get farther away from the sun, higher up in the evening sky, but dimmer, as time goes on.
Q. How did it get its name?
A. Comets are named after their discoverers. This comet was jointly discovered by professional teams
at the Purple Mountain Observatory (Zijinshan, sometimes spelled Tsuchinshan) in China and the
Asteroid Terrestrial-impact Last Alert System (ATLAS) in South Africa; the latter is an observing program
that normally looks for asteroids that might hit the earth, but also picks up other fast-moving objects
in the Solar System.
This map is for observers in the contiguous 48 states. My understanding is that
Sky and Telescope allows it to be
shared freely.
Christianity and the history of science, continued
I'm continuing my course on Christianity and the history of science
at Alps Road Presbyterian Church.
It has been very well received. I think it's important that Christians
must not be afraid of science or feel that they are somehow forbidden to
know about it.
Here are links to three more talks that are now on YouTube.
The entire set is on
the church's YouTube channel.
There will be 10 in all.
This evening (October 11) I managed to see and photograph the highly publicized comet
that has just entered the evening sky, after giving a good show (which I did not witness),
mainly in the Southern Hemisphere, while it was on the sunrise side of the sun.
The circumstances were a comedy of errors. The Athens Astronomy Club gathered at
Sandy Creek Park, but we had all almost completely concluded that the comet was
still too close to the sun and too low in the sky after sunset.
Adding to the fiasco, I had gotten there with no memory card in my camera.
But I decided to take one last, long look with binoculars — and found the comet,
very low down in the last glow of sunset.
Soon everybody was looking at it.
And someone lent me an SD card for my camera.
So, under very adverse conditions, I used my Nikon D5300 to take a single
1/30-second exposure with a 105-mm lens at f/2.8, at ISO 1600,
on a fixed tripod. (Memo: Next time, use ISO 400 or 200. This is only a
really low-noise camera at low speeds.) After some cropping and processing,
this yielded the blurry, grainy picture you see here.
But I did photograph the comet, at 7:48 p.m. EDT on October 11,
when it was still too close to the sun for most observers.
The earth had another auroral storm last night, predicted a day or so in advance,
and I've been seeing pictures of the aurora from such unlikely places as
Valdosta, Georgia; Cambridge, England; and Sydney, Australia.
I wasn't able to get out into the country for this one, but I was able to
photograph it, and barely see it, from my own driveway in Athens, Georgia.
I took a camera outside to check for it, since it shows up much better on even the simplest
photographs than to the unaided eye.
For the most part, what we saw in Georgia was a SAR arc (stable auroral red arc), which, I'm told,
is due to electric currents induced in the ionosphere, rather than the direct impact of particles
from the sun onto the north and south magnetic polar regions (those produce green curtains and
streamers).
As you can see above, the main display was a red stain on the sky — simply a large reddish patch fairly high up
in the northeast. Later it moved toward Cygnus in the northwest, and the camera picked up a red
background very high up, but almost featureless. With my eyes I could see that the sky was
slightly lighter than it ought to be, particularly to the left of Cassiopeia — something that a person not familiar
with the appearance of the sky from here would not have noticed.
I don't think I would have detected the aurora without a camera.
For a brief period, there were streamers in the north, which confirmed that this was really an
aurora and not some kind of reddish city lights. I was able to see the main streamer very
faintly with my eye — the eye of an experienced galaxy observer, sensitive to slight
variations in the dark gray background. Out in the country, people could probably have seen
it fairly easily.
That was the second auroral storm of 2024. I've slightly updated my
entry about how to know
whether there's about to be an aurora.
Thanks to NOAA, we get predictions and information that we never could have gotten in the past.
When I was starting out, in the 1970s, an auroral storm like this was something we would read about
two months later in magazines; there was no easy way to be alerted to it as it was happening,
although I think there was a ham radio net for aurora alerts, which I ignored because
aurorae are so rare in the South.
A feast of astrophotography
M33 partly resolved into stars
On the evening of October 2, we had reasonably clear weather, and I had a good, long
astrophoto session with my 8-inch telescope in my driveway.
Let's start with perhaps my best astronomical photograph ever,
the galaxy M33 partly resolved into stars.
Yes, as you can confirm by comparing to the maps in the November Sky and Telescope,
some individual stars in the galaxy are plainly visible (as well as unresolved star clouds,
and stars in our galaxy in front of it).
Copyright 2024 Michael A. Covington. Image file contains copyright notice.
Stack of 120 2-minute exposures, Celestron 8 EdgeHD with f/7 compressor, Altair 26C camera,
Losmandy GM811G mount, controlled with NINA and PHD2.
This is the Pelican Nebula, a cloud of ionized hydrogen gas
just to the right (west) of the North America Nebula in the sky,
seemingly out in the Atlantic. The pelican's big face and beak are on the left.
Copyright 2024 Michael A. Covington. Image file contains copyright notice.
Same equipment as above, stack of 118 exposures (2 of the 120 were rejected due to either
poor guiding, or airplanes, or satellite trails).
This nebula, in Cepheus, is supposed to look as if there's a man silhouetted on it
who is wearing a wizard's hat. I leave it to others to figure that out.
What is interesting is the patch of white reflection nebulosity around a star in the
middle of the nebula (just below the dark wizard's hat). The white color indicates that
it is made of dust rather than ionized gas.
Copyright 2024 Michael A. Covington. Image file contains copyright notice.
Same equipment as above, stack of 117 30-second exposures.
Quite similar to the Wizard Nebula, the Pac-Man Nebula is a cloud of ionized hydrogen in Cassiopeia.
(Or more correctly, "in the direction of the constellation Cassiopeia." A constellation
isn't a place; it's not somewhere you can go. It's a patch of the sky, comprising
everything in the patch no matter how near or far.)
Copyright 2024 Michael A. Covington. Image file contains copyright notice.
The previous evening (October 1) I got a somewhat better image of Saturn, again using
my new ToupTek 678C camera.
This is still not first-rate, as Saturn was quite low
in the sky.
This is a stack of the best 25% of nearly 6000 video frames. This camera delivers quite a high
frame rate (in this case, 50 per second), making it easy to acquire a large number of frames and select the best.
Theoretically, the best 75% or even best 100% would produce almost as good a finished image,
since they introduce random blur that is correctable, but if 25% are enough to make a smooth
picture, that's what I'll use.
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