When you want to see the stars, find someplace dark
Yes, DarkerView has been a solar eclipse blog over the last couple weeks. No worries, it will soon be over and regular programming will resume… After the obligatory photos from the eclipse expedition!
Total Solar Eclipse 2017
Eclipse Observing Checklist
The Eclipse Plan
Safe Eclipse Viewing
Two Solar Film Filters
Countdown to the Eclipse
The Sun on Eclipse Day
The Solar Corona on Eclipse Day
Correcting a Baader Solar Film Solar Image
The Eclipse Petroglyph
Hodgepodge
Miss any?
Ahead of our aircraft a crescent Moon is rising. Outside the window it is completely dark, a blackness broken only by the strobing anticollision lights across the wing and the rising Moon. Seattle is still hours away as we cross the Pacific, there are no city lights below to break the darkness.
Somewhere below me in the cargo hold is the telescope mount, assembled from restored and hand made parts. In the luggage bin overhead is the telescope, the little refractor that is a prized posession. Through it I have watched and photographed eagles and whales, volcanic eruptions, and distant galaxies. At my feet is a pack with a few cameras in it, only five.
For over a decade I have awaited the coming of this event. A day that once seemed so remote draws swiftly near as a rising crescent Moon portends.
With a little short of two minutes of totality I need to go into this with a plan. I do want a few photos, but I also want to experience the eclipse. How do I balance that?
The plan calls for three cameras… A single camera on a solar telescope, this will be primarily run on automatic with an intervalometer. I just need to check focus and centering of the solar image periodically during the long partial phases. I will use part of totality to attend to this camera and take a deep corona photo.
In the end it is a Celestron C8 telescope drive and forks containing custom electronics, a Meade heavy duty wedge from an LX-90, a hand-made tripod, holding a Televue 76mm APO telescope, using a Vixen style dovetail base, with a Baader film solar filter.
It is tempting to call it Frankenscope after the similarities with the classic monster.
To further add the the Mary Shelley plot similarities, much of this was revived from the junk pile. I very nearly decided to toss the drive and fork, they were that bad, peeling paint and rusty bolts. A great deal of work was necessary to re-animate these components.
The wedge came from a telescope that was killed in an unfortunate incident with an aquarium heater. The heater was used to de-humidify the OTA and prevent fungus on the optics. Note: Aquarium heaters are not made to operate out of water.
Several new aluminum parts were machined from scraps, some of which were scavenged when the observatory shop was being cleaned out and a lot of metal stock was tossed.
Many of the electronic components used to build the drive corrector were also scavenged parts from dead electronics, this includes the 1.8432MHz crystal that forms it’s beating heart. This heartbeat keeps the mount turning at exactly sidereal rate.
Yeah, you could call it Frankenscope.
But I will call it Hodgepodge.
A few days ago I looked at the solar imagery from the spacecraft and ground observatories and feared that our Sun would be completely spotless for next week’s solar eclipse. The one sunspot visible had just rotated out of view, not to return until well after the eclipse. There were no other sunspots apparent.
Sunspot group AR2671 formed on the eastern limb of the Sun over the last couple days. It has even produced a few c-class solar flares to show it has some vigor.
Better yet… This sunspot group will be a boon to eclipse photographers across the US. The pattern of dark spots will make the difficult task of focusing a telescope on the Sun far easier. These spots will provide a focus target to untold telescopes.
The only question now is will the group last for five more days? Will is grow or shrink.
Among the petroglyphs at Horsethief Lake is one that has always caused me to wonder. Of course the site is home to the famous Tsagaglalal or She-Who-Watches image. This is not the one I refer to, rather a somewhat smaller and usually overlooked image.
To my eye the image is clearly that of the solar corona surrounding the black shadow of the Moon against the Sun. The image is all the more striking to me personally… In 1979 I witnessed a total solar eclipse, my first, just a short distance from here, from the bluffs above Maryhill.
Take a photo with a thin film solar filter and you get a blue-white image of the Sun. Correcting this to a yellow gold image is fairly simple in most any photo processing package.
Color is a fluid subject, simply our interpretation of frequency across a very small slice of the electromagnetic spectrum. As such there is no absolute right and wrong, just a set of conventions we normally use.
The issue is that people expect the Sun to be yellow-gold. Present an image of the Sun in any other hue and it is rejected as fake, or false color. We are accustomed to certain visual cues to identify and interpret our world, color is a major part of that. Unless you want to argue with a million people or two, you are better off making your Sun photos yellow-gold.
Continue reading “Correcting a Baader Solar Film Solar Image”
With a quiet Sun, no active sunspot regions on the face or limb of the visible disk, one wonders what the solar corona will look like. What will we see when the Moon blots out the Sun and the corona is revealed.
Just up the hill from me is the Mauna Loa Solar Observatory. I know a couple folks that work there and have toured the facility. MLSO is a fairly modest telescope equipped with some very specialized instruments. This telescope stares at the Sun all day, every day, monitoring our star as part of a worldwide network of solar observatories.
What will the Sun look like when eclipse day arrives on August 21st?
Very quiet!
I observed this spot several times while training some folks at the observatory to use a solar setup and while testing my eclipse telescope.
AR2670 is now disappearing from sight as it rotates over the limb, maybe it will be back in another couple weeks for a third appearance.
Checking the SOHO image archive and the GONG farside maps shows there is nothing else, no significant solar activity that will appear before the total eclipse in eight days. Nothing hiding on the farside to rotate into sight.
There is a slim chance of something new developing over the next week. However, we are approaching solar minimum, a quiet Sun is to be expected. Indeed, I expect we will have an almost featureless solar disk on eclipse day.
Update 14 Aug 2017: With one week to go a new spot has appeared! I do not see that is has an AR designation yet, but this new spot should be in the middle of the Sun on eclipse day if it lasts for the week. It may not be big or pretty, but it will at least give everyone something to focus cameras on in preparation for the main event.
Update 15 Aug 2017: The new sunspot has been designated AR2671 and has already produced some C class flares. Looks like has the energy to develop a bit more. At least one small sunspot for the eclipse?
When travelling to an eclipse, one solar filter is not enough. I need a backup!
Having the two filters available for use mean I must choose between them when the moment is critical. Which is better? Some testing is in order to find out.
The two filters appear very different, the thin silver film of the Baader quite different than the thicker black polymer film of the Orion filter. Both filters are safe to use and provide decent solar viewing. Both provided pleasing solar images using my Televue 76mm APO telescope at low and medium power.
Stepping beyond basic use I do find that they perform quite differently. So differently I felt some notes are in order.