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midtskogen
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Re: Astrophotography

16 Dec 2022 04:48

Something else just occurred to me.  During an occultation of a star by a planet, asteroid or another planet's moon-- could that help determine how thick the atmosphere of the occulting body is and what it's composed of? 
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Re: Astrophotography

17 Dec 2022 05:05

That the timescale indeed seems to be in the millions of years does seem reasonable.  However, an eclipse happening during the middle of the occultation is no fun.  We need the planet to touch the rim of the Moon during the eclipse.  The Moon's shadow takes some time to travel across the Earth, but less that those 6 hours.

Absolutely. That makes it even less common, by about an order of magnitude. But grazes would also be pretty good. Venus or Jupiter being within even a whole degree of the eclipsed Sun would be awesome to the naked eye, too, and that would be a lot more common.

Wow I find this fascinating-- are there any historical records of such an event happening in the past?  It might be considered something that would "inspire" one of our world religions haha.

Not that I know of. But I also don't think that by naked eye, an occultation during a total solar eclipse would be that much more inspiring than the total solar eclipse itself. The occultation happening simultaneously would be more impressive as a telescopic or photographic target.

If you care to know my personal ranking of celestial events by how spectacular I think they are visually (out of 10 points, 10 being most spectacular), I rate transits of Venus in front of the Sun as just a 2 out of 10. They are rare, sure, but not spectacular... just "interesting". Partial solar eclipses up to about 80% obscuration? Also a 2/10. You barely notice any change. Total lunar eclipses? 6/10. Both your environment and the Moon changes and there's a slightly magical feeling to it. Occultations of bright planets by the Moon: 5/10. Better than Venus transits, but still more "interesting" than spectacular. 

Totality portion of a total solar eclipse: solid 10 out of 10. It's hard to add anything to it that would make it more awesome. Maybe if it happened while you're also watching a volcanic eruption, or if you were inside the eye of a hurricane. :P

I also find the calculation fascinating, is twice the inclination used for the occultation calculation because the planet could be that amount either "above" or "below" the sun? And I wonder if the odds of occultation are higher with a total lunar eclipse?  They should be since those last much longer and cover a much larger area?

Yes to both.

That's very interesting about determining an asteroid's orbital path that way-- I wonder if that's how the orbits of asteroids like Ceres and Vesta were determined? 

It's not for determining their orbit (which we have to already know to some degree in order to predict the occultation anyway), but for making the determination much more precise -- even down to a few 10s of meters. It's especially important for potentially hazardous asteroids that come close to Earth, where even a small uncertainty in the orbit may mean the difference between it eventually hitting Earth or not.
 
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Re: Astrophotography

17 Dec 2022 05:17

Wat I thought of something even more exciting!  This might rank infinity/10 on your list!  A supernova exploding, being visible in daylight AND getting occulted by a total solar eclipse?!

There was an asteroid whose path was recently altered-- I don't believe that asteroid ever presented a danger to Earth, but it was a test run to see if it could be done? I wonder if an occultation was used to determine its original orbit more precisely and if that could also be used to help determine its new path after the collision with the spacecraft?

On your list the rarest thing I have ever seen is a total lunar eclipse (which isn't very rare).  I've seen a few partial solar eclipses, the max was one in the 90s (1994 maybe?) where the sun was 90% covered in the NE.  It almost looked like an annular but there was a slight bit more sun visible on one side than on the other.  Back in my high school days and I was a little more gungho back then and since it was mostly cloudy and I could barely see the sun through the clouds I decided to use my 10x50 binoculars on it!  I still have those binos.....and luckily, I still have my eyes lol.  I only looked at it for a few seconds but got a great view of the mostly eclipsed sun through the mostly cloudy skies (it was midlevel clouds, the sun was barely visible through them even with the binos.)

I guess seeing the new moon on Day 1 doesn't get a spot on your list does it? I've only seen it once and just barely-- I was on top of a mountain in the Poconos and it was a very clear and brisk evening-- very rare for the middle of summer in July!  I barely got a hint of the very new moon but I could tell it was there because my eyes were drawn to that spot and it was more clearly seen with averted vision.

You mentioned a planet being in the vicinity of the totally eclipsed sun and I just remembered there was a planet that was in some pictures (you could even see it in NY through a 70% eclipsed sun) during the August 2017 total solar eclipse-- I wonder what planet that was?  Even with a 70% eclipsed sun we noticed some interesting weather effects-- the weather got cooler and a wind started to blow.  This planet also became clearly visible in the sky.

Where do meteor showers rank for you?  Fireballs and meteors changing colors as they streak across the sky?  What about a sporadic random shower that was not "scheduled"-- like what I saw a few years ago in late December when a group of meteors streaked right over Orion's belt at 9 PM!  I never saw anything like that before-- and a few minutes later another group of meteors followed the same path!
Last edited by A-L-E-X on 17 Dec 2022 05:27, edited 3 times in total.
 
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Re: Astrophotography

17 Dec 2022 05:20

Something else just occurred to me.  During an occultation of a star by a planet, asteroid or another planet's moon-- could that help determine how thick the atmosphere of the occulting body is and what it's composed of? 
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Thanks, I wonder if this is how they found out that Venus doesn't have that molecule which they thought it had (I forget which compound it was) that could only originate from life?
 
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Re: Astrophotography

17 Dec 2022 05:25

Wat I thought of something even more exciting!  This might rank infinity/10 on your list!  A supernova exploding, being visible in daylight AND getting occulted by a total solar eclipse?!

Seeing a bright supernova under any conditions would be pretty cool, but the visual impression of seeing one during a total solar eclipse would not be much different than seeing Venus during a total solar eclipse, which I have seen and is extremely common for solar eclipses. Having one be occulted by the Sun/Moon at the same time would be unfathomably rare, but similar in appearance to the diamond ring effect anyway (just appearing or disappearing nearly instantaneously instead of over a couple of seconds.)


Put another way, you will probably be blown away by your first time seeing the diamond ring effect. :)
 
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Re: Astrophotography

17 Dec 2022 05:30

Wat I thought of something even more exciting!  This might rank infinity/10 on your list!  A supernova exploding, being visible in daylight AND getting occulted by a total solar eclipse?!

Seeing a bright supernova under any conditions would be pretty cool, but the visual impression of seeing one during a total solar eclipse would not be much different than seeing Venus during a total solar eclipse, which I have seen and is extremely common for solar eclipses. Having one be occulted by the Sun/Moon at the same time would be unfathomably rare, but similar in appearance to the diamond ring effect anyway.


Put another way, you will probably be blown away by your first time seeing the diamond ring effect. :)
I can't wait!  The closest I've ever come to seeing anything like that was that 90% eclipse in May 1994 (is there a way to check if I got the month and year right?)-- the sky was mostly cloudy but they were high and midlevel clouds and what I saw did bear a resemblance to a ring, but it was thicker on one side than the other and there was a diamond like bulge visible on one side.  A poor man's diamond ring effect I guess?  Seeing one during a total solar eclipse should be MUCH more exciting though.
 
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Re: Astrophotography

17 Dec 2022 05:40


I can't wait!  The closest I've ever come to seeing anything like that was that 90% eclipse in May 1994 (is there a way to check if I got the month and year right?)-- the sky was mostly cloudy but they were high and midlevel clouds and what I saw did bear a resemblance to a ring, but it was thicker on one side than the other and there was a diamond like bulge visible on one side.  A poor man's diamond ring effect I guess?  Seeing one during a total solar eclipse should be MUCH more exciting though.
Yes, you'll be surprised how much changes between 90% and 99%, and from 99% to 100%. :)

The diamond ring effect doesn't really show up until the last few seconds before totality (and again at the end of it), when the Sun is more than 99.9% covered and the corona starts becoming visible. Cameras can capture the effect for a bit longer, but be careful that you don't burn them out.

If you watch the last minute or two before totality with eclipses glasses, you may also see some Bailey's Beads, where the thin sliver of Sun breaks into individual points which are shining through the lunar valleys. It is the final Bailey's Bead that gives the diamond effect to the naked eye, before vanishing into the black Sun.
 
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Re: Astrophotography

17 Dec 2022 06:18


I can't wait!  The closest I've ever come to seeing anything like that was that 90% eclipse in May 1994 (is there a way to check if I got the month and year right?)-- the sky was mostly cloudy but they were high and midlevel clouds and what I saw did bear a resemblance to a ring, but it was thicker on one side than the other and there was a diamond like bulge visible on one side.  A poor man's diamond ring effect I guess?  Seeing one during a total solar eclipse should be MUCH more exciting though.
Yes, you'll be surprised how much changes between 90% and 99%, and from 99% to 100%. :)

The diamond ring effect doesn't really show up until the last few seconds before totality (and again at the end of it), when the Sun is more than 99.9% covered and the corona starts becoming visible. Cameras can capture the effect for a bit longer, but be careful that you don't burn them out.

If you watch the last minute or two before totality with eclipses glasses, you may also see some Bailey's Beads, where the thin sliver of Sun breaks into individual points which are shining through the lunar valleys. It is the final Bailey's Bead that gives the diamond effect to the naked eye, before vanishing into the black Sun.
Can I see it and capture it without the filter? I saved what you wrote last time so I can remember it-- I have about 30 seconds at the end of totality where I can still take unfiltered pictures and view the eclipse without a filter I think.

I'll leave the eclipse glasses on right up until I start to see the corona but I'll wait an extra 30 seconds after totality ends to see that diamond ring effect.  I take it I should be near the midpoint of totality to see all these effects the best?  The way you described it, Wat, I feel like I could picture it with my mind's eye!
 
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Re: Astrophotography

18 Dec 2022 03:53


Can I see it and capture it without the filter? I saved what you wrote last time so I can remember it-- I have about 30 seconds at the end of totality where I can still take unfiltered pictures and view the eclipse without a filter I think.

You can only see and capture it without the filter. It only lasts a few seconds on either side of totality, and your eyes will tell you when it's too bright to keep looking at it. A camera can capture it a bit longer, but do not have the camera pointing at the Sun unfiltered more than about 30 seconds before or after totality or you risk damage.

During the partial phases, I don't bother with photography, or even looking at the Sun all that much. It's much more interesting to watch the changes in the environment, which are very slow and subtle at first, but then become faster and very intense in the final minutes. I recommend not missing out on all of those phenomena and especially totality itself by fixating too much on photography. Like midtskogen said, keep your first total eclipse experience as simple as possible. 
 
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Re: Astrophotography

18 Dec 2022 05:30


Can I see it and capture it without the filter? I saved what you wrote last time so I can remember it-- I have about 30 seconds at the end of totality where I can still take unfiltered pictures and view the eclipse without a filter I think.

You can only see and capture it without the filter. It only lasts a few seconds on either side of totality, and your eyes will tell you when it's too bright to keep looking at it. A camera can capture it a bit longer, but do not have the camera pointing at the Sun unfiltered more than about 30 seconds before or after totality or you risk damage.

During the partial phases, I don't bother with photography, or even looking at the Sun all that much. It's much more interesting to watch the changes in the environment, which are very slow and subtle at first, but then become faster and very intense in the final minutes. I recommend not missing out on all of those phenomena and especially totality itself by fixating too much on photography. Like midtskogen said, keep your first total eclipse experience as simple as possible. 
You're right, I actually plan on setting everything up in the early part of the partial phase and start looking around the environment around 3 PM or so (which is 20 minutes before totality in the northeast.)  I want to see what kind of temperature changes there will be and if it gets windy (I noticed this in the Aug 2017 eclipse even though I was only in the 70% zone) as well as the behavior of different animals and especially birds.   I actually have an idea that I should just set the cameras up in timelapse mode and set them to start taking pictures about 30 seconds before totality until 30 seconds after totality-- what do you think about that, Wat? I'll use the settings you recommended and just let the cameras do their thing while I concentrate on the observing aspect.
 
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Re: Astrophotography

19 Dec 2022 01:40

I actually plan on setting everything up in the early part of the partial phase and start looking around the environment around 3 PM or so (which is 20 minutes before totality in the northeast.)  I want to see what kind of temperature changes there will be and if it gets windy (I noticed this in the Aug 2017 eclipse even though I was only in the 70% zone)
A temperature drop is not surprising as you typically get the same if the sun is obscured by clouds on an otherwise sunny day.  Rapid temperature changes could affect wind.  I've read multiple places that the wind often calms down during totality.  Out of my three total eclipses, I've only noticed a change of wind in one, the 2015 eclipse.  However, then the wind went from calm (<2-3 m/s) to maybe 6-7 m/s during totality which was quite noticeable since the temperature was -21C.  It might have been a coincident, though.
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Re: Astrophotography

19 Dec 2022 02:19

Yes, eclipse wind is a real thing and has been verified by comparison of measurements to models. However, it's not a very easy thing for one observer on the ground to notice (I couldn't sense it unambiguously in 2017 at Madras). It is more of a small systematic change in wind speed and direction according to a cold temperature cyclone following immediately behind the center of the shadow. Its strength depends mostly on the Sun angle and the albedo of the surface. Lovely dissertation all about the meteorological effects of solar eclipses here. :)

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Re: Astrophotography

19 Dec 2022 02:30

I actually have an idea that I should just set the cameras up in timelapse mode and set them to start taking pictures about 30 seconds before totality until 30 seconds after totality-- what do you think about that, Wat? I'll use the settings you recommended and just let the cameras do their thing while I concentrate on the observing aspect.
Watching the effects in your environment, especially in animals and other people, is all a great part of the experience. I set up a GoPro to record the Sun, sky, and crowd reaction through totality in 2017, and I'm glad to have that video even more than the photographs of the eclipse itself.

For your plans I think that sounds just fine, just be sure that the Sun does not drift out of frame during the totality. Remember also that different aspects of the totality require very different exposure settings to capture. It may be about 1/1000th of a second to capture prominences, about 1/100th a second for the inner corona, 1/10th a second for middle corona, to several seconds for the outer corona and any details on the Moon. 
 
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Re: Astrophotography

19 Dec 2022 04:01

I actually have an idea that I should just set the cameras up in timelapse mode and set them to start taking pictures about 30 seconds before totality until 30 seconds after totality-- what do you think about that, Wat? I'll use the settings you recommended and just let the cameras do their thing while I concentrate on the observing aspect.
Watching the effects in your environment, especially in animals and other people, is all a great part of the experience. I set up a GoPro to record the Sun, sky, and crowd reaction through totality in 2017, and I'm glad to have that video even more than the photographs of the eclipse itself.

For your plans I think that sounds just fine, just be sure that the Sun does not drift out of frame during the totality. Remember also that different aspects of the totality require very different exposure settings to capture. It may be about 1/1000th of a second to capture prominences, about 1/100th a second for the inner corona, 1/10th a second for middle corona, to several seconds for the outer corona and any details on the Moon. 
Yes!  That's why I was also thinking I should set up one of the cameras in video mode.  Videos have a three dimensional immersive experience quality to them that pictures don't usually have.  I'll try to get the right settings for each but may have to manually take over one of the cameras-- especially since one of them will be set to a very high focal length-- I don't have a non telescope mount tracker so I'll leave the other in video mode and at a wider focal length.  During the August 2017 eclipse how much time did you spend taking pictures, Wat?  Was totality about the same length of time for that eclipse?
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Wow thanks Wat!  I think I noticed it because it was such a hot summer day here and there was no wind at all most of that day and then all of a sudden right when the sky got darker I felt this cooling breeze come in-- it almost felt like an entirely different airmass had moved in but there were no clouds like we get with frontal passages.  How long was totality there for you?  I'm thinking that being in a region with a 3 minute totality is a reasonable amount of time to have it to enjoy the experience and to take some nice pictures.
 
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Re: Astrophotography

19 Dec 2022 04:11

I actually plan on setting everything up in the early part of the partial phase and start looking around the environment around 3 PM or so (which is 20 minutes before totality in the northeast.)  I want to see what kind of temperature changes there will be and if it gets windy (I noticed this in the Aug 2017 eclipse even though I was only in the 70% zone)
A temperature drop is not surprising as you typically get the same if the sun is obscured by clouds on an otherwise sunny day.  Rapid temperature changes could affect wind.  I've read multiple places that the wind often calms down during totality.  Out of my three total eclipses, I've only noticed a change of wind in one, the 2015 eclipse.  However, then the wind went from calm (<2-3 m/s) to maybe 6-7 m/s during totality which was quite noticeable since the temperature was -21C.  It might have been a coincident, though.
Wow where were you located for that eclipse, Mid?  That sounds as cold as any temperature I've ever experienced....my coldest was  -3 F or about -20 C so about as cold as that and it was difficult for me to be outside for more than a few minutes.

I wonder if you get any "extra" effects from having an eclipse under such cold conditions, perhaps with ice particles in the air you could also see a solar halo during the partial phase of the eclipse?

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