U.S. Solar Eclipse of Aug. 21, 2017

[Andy Resnick]

<snip>

Good grief. The total eclipse only lasts two minutes.
I think I'll skip the coronal spectrometry.
But then again...
@Andy Resnick , what do you think?

I say go for it: Fortune favors the bold!

 

[mfb]

I would check their math, as that doesn't sound right. But being that it's Nature, I can probably trust them.

The moon has an orbital velocity of 1.02 km/s, or roughly Mach 3. The Earth at the equator has a rotation speed of a bit more than Mach 1, leaving a difference of a bit less than Mach 2 if the eclipse is directly at zenith. It works with a Concorde - but only close to the equator around noon.

 

[Borg]

I think that I will be skipping the telescope upgrades but I'm drawing a blank on my searches for camera equipment. I have a Nikon D5100 camera that I would like to use. If anyone can help, I am trying to determine what telephoto lens would be needed to have the sun take up around 50% of the picture at max zoom. I currently have a lens with a 300 mm zoom. Do I need something with a greater zoom?

 

[tony873004]

I think that I will be skipping the telescope upgrades but I'm drawing a blank on my searches for camera equipment. I have a Nikon D5100 camera that I would like to use. If anyone can help, I am trying to determine what telephoto lens would be needed to have the sun take up around 50% of the picture at max zoom. I currently have a lens with a 300 mm zoom. Do I need something with a greater zoom?

I'm guessing that 300-400 mm is exactly what you want.

With the Sun taking up 50% of the picture, you will be losing the outer edges of the corona.

Google for Eclipse picture. Choose the one closest to the one you would like to take and note the size of the corona.
Since the Moon has the same angular size as the Sun, take a picture of the Moon with your 300mm lens.
Compare it to the Eclipse pictures you Googled and ask if it would properly frame the corona.

The challenge in taking pictures of the Corona is that it has a large dynamic range.
If you properly expose for the red flares, your corona will be too faint to show up in your picture.
If you properly expose the inner corona, the flares will be overexposed and the outer corona will be too faint to show up in your picture.
If you properly expose the outer corona, the inner corona and the flares will be washed out.
With a long enough exposure, you can see features on the Moon due to Earthshine.

So you need to bracket your shots.
Your Nikon can do this automatically.
Take multiple pictures in rapid succession, each with a different exposure, covering a wide range of exposures.
After the eclipse, photoshop them together to get a final image that properly exposes the Earthshine, flares and all parts of the corona.

 

[Borg]

I've always had difficulty taking photos of the moon because the auto-focus can't lock in on it. I will have to practice using the manual settings. Given the exposure references, I'll need a good tripod also. My list continues to grow...

 

[OmCheeto]

The moon has an orbital velocity of 1.02 km/s, or roughly Mach 3. The Earth at the equator has a rotation speed of a bit more than Mach 1, leaving a difference of a bit less than Mach 2 if the eclipse is directly at zenith. It works with a Concorde - but only close to the equator around noon.

But doesn't the Earth rotate in opposite the direction that the moon travels? edit: No! So wouldn't you add the speeds? edit: again, No! And should we take into account the orbital speed of the Earth around the sun? edit: You can't even figure out which way things are turning, Om. You are hopelessly, rotationally, dyslexic. Just give it up.
This is probably why I just extrapolated the information from the map, as I don't even know which direction things are turning.

Wait!

From following Ceres, I know that the Earth travels counterclockwise around the sun. (30,000 m/s)
And the moon travels counterclockwise, because it shifts to the left every day. (1020 m/s)
And the Earth spins counterclockwise, because the sun appears to move counterclockwise. (460 m/s)
<scratches head for awhile>

Never mind. This is an OFF TOPIC, impossibly hard, homework problem...
<scratches head some more... Maybe if I converted everything to radians/sec...>

Nope! I can feel an aneurysm in my brain throbbing...

My list continues to grow...

As does mine. Thanks for the reminder. I've actually been researching this since at least March 10th, and am realizing that I'm not even close to being prepared.

I noticed yesterday in another thread, regarding photographing the sun,

using only an ND4 metallic filter,

that I'll need a special filter. And given that my camera doesn't list what size adapter I need, I had to measure and cut out one of my diffraction grating slide thingys. I think it's 42 mm.

ps. Just don't forget to put fresh batteries in you camera. When I went to the museum to take pictures of the SR-71, I turned my camera on, and it immediately went dead. Fortunately, I had a spare set with me. Always carry spare batteries!

 

[Andy Resnick]

<snip> As does mine. Thanks for the reminder. I've actually been researching this since at least March 10th, and am realizing that I'm not even close to being prepared.

I noticed yesterday in another thread, regarding photographing the sun,

that I'll need a special filter. And given that my camera doesn't list what size adapter I need, I had to measure and cut out one of my diffraction grating slide thingys. I think it's 42 mm.

For solar ND filters, it's (IMO) important to use a reflective filter rather than an absorptive one- all that energy has to go somewhere, and an absorptive filter won't be able to withstand the thermal stresses. Look around to find an inexpensive one like these:

http://search.newport.com/i/1/x1/pageType/q1/Products/q2/Optical%20Filters/q3/Neutral%20Density%20Filters/q4/Optical%20Crown%20Glass%20Metallic%20Neutral%20Density%20Filters/x2/section/x3/chapter/x4/family/nav/1/

I haven't used mylar film, but it's an alternative:

http://www.astro-physics.com/index.htm?products/accessories/solar_acc/astrosolar

Then there's this:

http://www.instructables.com/id/3-Camera-usable-Solar-Filter/

I would try this before 'show time', tho...

As far as sizing, you can always just tape it to the front of the lens (or to the UV filter, if you have one). Kapton tape is best, since it doesn't leave an adhesive residue.

For the eclipse... I'm not sure what ND would be best- 4 may be too much. Maybe someone here with more experience can chime in...

 

[davenn]

For solar ND filters, it's (IMO) important to use a reflective filter rather than an absorptive one- all that energy has to go somewhere, and an absorptive filter won't be able to withstand the thermal stresses. Look around to find an inexpensive one like these:

I would seriously recommend a real solar filter like these ones

http://www.bintel.com.au/Accessories/Solar-Filters/128/catmenu.aspx

I have a smaller diameter one that fits my 150 - 500mm telephoto/zoom lens and a much larger one for the 9.25" telescope
Am sure there will be astronomy shops in UK/Europe and the USA that sell these ones
(Am NOT connected to the seller or manufacturer ... just a VERY happy user of the filters)

I haven't used mylar film, but it's an alternative:

I have often used it in years gone by before I got the above filters ... It's a respectable alternative - around 3 layers will be the minimum
visit a camping store and buy a mylar survival blanket

For the eclipse... I'm not sure what ND would be best- 4 may be too much. Maybe someone here with more experience can chime in...

Everything before totality you need full filtering
in the moments before totality ( to capture the "Bailey's Beads) and through totality you won't need any filtering
Then as totality ends put the filter back on and continue shooting the partial stage

Annular Solar Eclipse I shot from Blenheim, NZ in 1991 using mylar film ... has a distinguishable blue tint

Cairns, Australia 2012 almost totality with Diamond Ring then Baileys beads ... no filter

Totality, no filter, showing some of the Corona ... I could have easily slowed the exposure a bit and got a bit more corona
experiment with exposures of 50th - 100th of a sec and don't be afraid to push the ISO a little to around 200 - 400 to get enough light

hopefully that helps with a few ideas cheers
Dave

 

[Borg]

Thanks to @davenn and @Andy Resnick for the links. I will look through them this weekend.

 

[Borg]

I found out that there is a small store nearby that is a supplier for three major brands of telescopes. There were scopes up to 10 inch on display and they even had a few solar filters that I was able to look at.

The person that I spoke with, admitted that he wasn't very knowledgible about telescopes and the owner wasn't in because of a science fair in DC over the weekend. I definitely plan on going back in the near future to discuss my options.

 

[jtbell]

Another forum that I read has been discussing this eclipse. One person claims that all major hotel/motel chains are now booked solid, out to 200+ miles from Casper, Wyoming.

 

[1oldman2]

I can't decide on being in Lincoln city, Oregon or the middle of Wyoming for this, guess I'll have to see how the weather forecast is looking on 8/21.

https://www.nasa.gov/feature/goddard/2016/preparing-for-the-august-2017-total-solar-eclipse

On Monday, Aug. 21, 2017, a total eclipse will cross the entire country, coast-to-coast, for the first time since 1918. Weather permitting, the entire continent will have the opportunity to view an eclipse as the moon passes in front of the sun, casting a shadow on Earth’s surface. And plans for this once-in-a-lifetime eclipse are underway - scientists are submitting research proposals, NASA is sharing information on safe eclipse viewing with community centers, and citizen science projects are developing.

 

[Vanadium 50]

On Monday, Aug. 21, 2017, a total eclipse will cross the entire country, coast-to-coast, for the first time since 1918.

It was the entire country in 1918, but Alaska and Hawaii have since been admitted.

 

[1oldman2]

It was the entire country in 1918, but Alaska and Hawaii have since been admitted.

Very good point !

 

[tony873004]

It was the entire country in 1918, but Alaska and Hawaii have since been admitted.

Hawaii and Alaska are both 100% consumed by 2017's penumbra.
https://eclipse.gsfc.nasa.gov/SEanimate/SEanimate2001/SE2017Aug21T.GIF

 

[nsaspook]

I can't decide on being in Lincoln city, Oregon or the middle of Wyoming for this, guess I'll have to see how the weather forecast is looking on 8/21.

Most of the Oregon people I know that are planning an event will be in the high desert (camping) in central Oregon. From Lincoln city, Oregon to the coast range is very hit and miss that time of year. I plan to near the high desert at the local Indian casino.
http://oregonstarparty.org/

 

[1oldman2]

The new improved Eclipse map is out

https://www.nasa.gov/feature/goddard/2017/nasa-moon-data-provides-more-accurate-2017-eclipse-path

 

[russ_watters]

Another forum that I read has been discussing this eclipse. One person claims that all major hotel/motel chains are now booked solid, out to 200+ miles from Casper, Wyoming.

I've booked a house in Wild Dunes, SC:
https://www.google.com/maps/place/W...e3ea98f625af46!8m2!3d32.8108102!4d-79.7315747

I saw a story recently saying Columbia, SC is pretty well booked.

 

[tony873004]

I couldn't find any place in Madres Oregon. The campgrounds are probably full too. No big deal, totality is a 9 hour drive from San Francisco. I'll just sleep in the car if need be, and get a hotel room after the eclipse so I can drive home the next day.

 

[hsdrop]

I'm going to be taking my boy to southern Ill. since we live in southern wisconsin :) Hoping we can find a state camp ground down there to crash at

 

[Chronos]

I live right in the center of the eclipse path, just SE of St Louis. it should be spectacular. This region normally has crystal clear weather in late august. Plenty of campgrounds and motels around here too, and few expectations they will be heavily booked.

 

[OmCheeto]

I couldn't find any place in Madres Oregon. The campgrounds are probably full too. No big deal, totality is a 9 hour drive from San Francisco. I'll just sleep in the car if need be, and get a hotel room after the eclipse so I can drive home the next day.

Madras is probably where I'll be heading.
According to this graph, it's historically one of the best places in the nation to view the eclipse. (least chance of clouds)

The graph is from an interesting website, with WAY too much information: http://eclipsophile.com/oregon/
They have individual pages dedicated to the following regions: Oregon, Idaho, Wyoming, Nebraska & Kansas, Missouri & Illinois, Kentucky & Tennessee, Georgia & the Carolinas.

 

[Chronos]

I also happen to live in the path of the 2024 total eclipse, so double lucky. I will be able to observe both from my own backyard! Unfortunately, the totality in 2024 will only last about 2 minutes, but, I will be older then so it will seem longer.

 

[jtbell]

I've booked a house in Wild Dunes, SC:
https://www.google.com/maps/place/W...e3ea98f625af46!8m2!3d32.8108102!4d-79.7315747

That looks like a nice spot to spend a few days even if you get clouded out. I've visited Fort Moultrie at the other end of Isle of Palms.

 

[1oldman2]

From https://www.nasa.gov/feature/goddar...-unique-opportunity-for-science-in-the-shadow
"The first total solar eclipse in the continental United States in nearly 40 years takes place on Aug. 21, 2017. Beyond providing a brilliant sight in the daytime sky, total solar eclipses provide a rare chance for scientists to collect data only available during eclipses. NASA is funding 11 scientific studies that will take advantage of this opportunity."

 

[jim hardy]

According to this graph, it's historically one of the best places in the nation to view the eclipse. (least chance of clouds)

Hmm i think we'll arrange to be at our place in Idaho Falls for August , if Fair Anne feels up for it.

 

[1oldman2]

Hmm i think we'll arrange to be at our place in Idaho Falls for August , if Fair Anne feels up for it.

Speaking of cloud cover, here's a useful graphic.

https://apod.nasa.gov/apod/ap170131.html

 

[mfb]

"Sunshine state" Florida...

 

[Helios]

Hello Eclipse People,
Here's the best eclipse photo I've ever seen. It was taken from an island in the Pacific called Enewetak. Yes, where the first H-bomb was detonated.
http://www.zam.fme.vutbr.cz/~druck/eclipse/ecl2009e/tse2009_500_mid/Hr/Tse2009e_500mm_mid.png
I live in Charlotte, NC. My strategy is plan A: drive to mid-South Carolina, or plan B: drive to Tennesse. This I will decide the day before after previewing weather reports. The Carolinas do have loads of cumulus clouds in the summer, more than clear blue skies. Afternoon thunderstorms, day after day, are common. Also, the east and west of the Appalachian mountains always seem to have exactly the opposite weather. Rain here means a drought there, or vica versa.

 

[davenn]

"Sunshine state" Florida...

but it is well outside the totality path