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Eclipse darkness measured at 13.73 SQM-L, what was your's like.

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#1 astrohamp

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Posted 12 April 2024 - 06:40 PM

Did anyone else measure their dark sky conditions with a Sky Quality Meter during totality? 

 

At 13.73 SQM-L just seconds prior to the solar maximum (at my location) I was not able to put in context what that meant.  I've waited for darkness many times at star parties and during solo viewing sessions and could not gain perspective on what was happening.

 

Where I was near Plattsburgh, Vt we had an ominous dark western sky moving toward us during the lead in to the beginning of totality.  High veiling clouds made imaging the corona streamers and sighting Comet 12P/Pons-Brooks useless although I tried with 7x binoculars for a brief time and had two sequenced cameras imaging the sun.

 

The horizon view where we were over 25 miles of water flat horizons in some directions produced a memorable sunset/sunrise like view not previously witnessed at a familiar location. 

 

Hope some of you were able to see the horizon effect and enjoy the long waited for event.

Attached Thumbnails

  • EclipseDarknessIMG_3610.jpg

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#2 astrohamp

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Posted 13 April 2024 - 06:08 PM

I actually have little recollection of how dark it was, could read a news paper, barely see the ground, can't see my hand in front of my face...like that.  I do however have a running GoPro video of the event where in the near field folks and equipment go black, unseen in the video, only my laptop monitor flashing two Sharpcap sequences with looped and varied exposures flashing at the camera. 

 

Anyone take note of ambient 'darkness'?


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#3 Seachange79

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Posted 13 April 2024 - 06:39 PM

I didn't do any measures with any tools other than my eyes. In the Shawnee National Forest, my eyes noted that it was a lot brighter than I anticipated. I remember having the fleeting thought of "oo, my long exposures will be blown out" before I put ALL of my attention on the show. Don't get me wrong, it did get dark, but I could still see clearly.
Visually, I'd say that it was bright like civil twilight...maybe late civil twilight to early nautical twilight?
The 360° sunset was really cool to see through the surrounding trees and the ridge to the east.
I saw no stars, neither did my cameras from what I can tell. Jupiter and Venus were visible, but no other planets that I could see.
And absolutely lovely shot, astrohamp!
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#4 astrohamp

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Posted 14 April 2024 - 12:15 PM

Now that you mention it we didn't see any stars unlike 2017 which was clear without any clouds where I was. 

 

The image brightens what we saw the day and it could have been taken late in the event as I haven't looked at the time stamp.



#5 Sebastian_Sajaroff

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Posted 14 April 2024 - 12:21 PM

I had a short totality (50 sec) being only 3 miles away from the "border".
I could see Venus and Jupiter (took a 5 seconds glance at them), but the sky was too bright for anything else. I spent the remaining 45 seconds in awe contemplating the corona and Baily beads naked eye.

#6 AJK 547

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Posted 14 April 2024 - 01:28 PM

Didn’t think to take a quick SQM reading but was blown away by the ‘magic’ of the event st Beall Woods Stare Park in Mt. Carmel Illinois.  Just very high cirrus clouds and totality lasted 4 min. 3 sec. at this location.   The C2 and C3 ‘diamond ring’, carina and the neon pink/orange triangular shaped solar flare at 6 o’clock to see visually will be a lifetime memory!

 

Dimple iPhone 14 image attached.

 

Clear skies. 😊

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  • IMG_4006-compressed.jpeg

Edited by AJK 547, 14 April 2024 - 01:35 PM.

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#7 timelapser

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Posted 14 April 2024 - 01:52 PM

From close to the centreline at Georgeville, QC, Jupiter and Venus were obvious through thin high cloud, but the eastern half of the sky was totally clear and Sirius, Betelgeuse, and Capella were pretty easy by naked eye (to an experienced observer, at least).


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#8 kfiscus

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Posted 14 April 2024 - 01:56 PM

My impression is that this was the brightest totality that I've seen ('91,'98,'17,'24).  I was surrounded by shiny surfaces (buildings, glass, marble deck, Pacific Ocean).  I saw only Venus and 1 star.  A building blocked everything to the east of the corona.



#9 astrohamp

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Posted 15 April 2024 - 07:26 PM

Changes in the sky during the event are only represented in these images which fall short of what my group and so many others experienced. 

 

In order shown: Pre-Event 1:30s to Go,

                       Totality in 30s,

                       Totality Start,

                       Totality Maximum,

                       Totality ends in 30s,

                       Totality ends Filters On.

 

 

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  • Pre1-30ToGo.jpg
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  • Tstart.jpg
  • Tmax.jpg
  • Tends30s.jpg
  • TendFiltersOn.jpg

Edited by astrohamp, 15 April 2024 - 07:31 PM.

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#10 astrohamp

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Posted 17 April 2024 - 08:39 PM

So for some days I have been thinking about the darkness level, or not, during the eclipse at my location.  Given the cloud cover during the event, as seen in the posted images, I suspected some ground reflection from the perimeter 'opening' was leaking though.  Since it is clearly visible off in the distance like twilight I should think it would affect things quite a bit.

 

I have been observing from this location for decades and recently obtained an SQM-L sky meter which I used during the event.  At a measured level of 13.73 during event maximum, my best night's value was 21.1 SQM-L during night time observing.  A good average is 20.7.  It did seem quite dark to those in attendance yet the cloud cover was there.  Perhaps our inadequate dark adaption was making it appear darker then it was, although the GoPro video I made during, depicted in the image sequence gives a good representation of what we experienced.



#11 dissent

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Posted 18 April 2024 - 12:24 AM

I don't have any measurements, but it certainly seemed darker than 2017 to my eye.



#12 zjc26138

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Posted 18 April 2024 - 09:17 AM

I think it was darker than the 2017 eclipse, perhaps the high thin clouds had something to do with it?

 

I captured the approaching shadow and totality with a buddies drone. I would say what the drone is showing is close to how I perceived the darkness.

 

https://www.youtube....pc1k2wvyMw&t=3s



#13 timelapser

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Posted 18 April 2024 - 09:40 AM

I captured the approaching shadow and totality with a buddies drone. I would say what the drone is showing is close to how I perceived the darkness.

 

https://www.youtube....pc1k2wvyMw&t=3s

Nice.

 

Yikes, I'm glad we didn't have fireworks where we were to distract us from experiencing and photographing the show!


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#14 zjc26138

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Posted 18 April 2024 - 09:57 AM

Nice.

 

Yikes, I'm glad we didn't have fireworks where we were to distract us from experiencing and photographing the show!

Yeah there were a bunch of folks lighting off fireworks. Thankfully it really didn't hamper our view on the ground.



#15 timelapser

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Posted 12 May 2024 - 04:29 PM

I don't have any measurements, but it certainly seemed darker than 2017 to my eye.

I have pics of the sky during totality from 2017 and 2024 with the same camera.  Looking at the darkest part of totality (around mid-eclipse) and 5-10 deg above the sun (but well outside the corona) I find the sky in '24 about 70% the brightness of the '17 sky.  '17 was totally clear but '24 had some thin high cloud which may have brightened the sky a bit.

 

I was expecting a darker sky for '24 due to the wider umbra (so light scattering in from outside the umbra had farther to go) but I wasn't sure how much darker to expect.

 

In both cases I measured from linear raw pixels, and compensated for differences in exposure.  The sun was 40-45 deg high for both eclipses.



#16 astrohamp

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Posted 12 May 2024 - 06:14 PM

Any images to compare of the surroundings to share 'timelapser'? 

 

We were about 49 miles or so from the southern edge of the umbra.  I did use the same GoPro camera to capture the eclipse both 2017 and 2024 but hadn't found the 'exposure lock' hack until weeks before 2024.  Also the camera was severely overheating in the 90 to 95 F heat and direct sun during 2017 that the image blurred a bit during totality.  I think I had left the internal battery inside, while running on an external one same time.  This time battery and back cover were removed and used the 'open' housing container for mounting.  I had DIYed a cooling fan for it as well.  With temperatures for the day starting below freezing barely reaching 60 degrees F, the 30 plus temperature reduction posed no issue for the ageing vid maker.



#17 timelapser

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Posted 12 May 2024 - 11:35 PM

The surroundings were really different - Idaho desert in '17 and Quebec lake in '24 - but I'll try work on a comparison.



#18 RonH47

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Posted 13 May 2024 - 10:12 AM

I have GoPro videos of the 2017 eclipse in South Carolina, and the 2024 eclipse in Arkansas. The 2024 was much darker, both on the videos and what I remember. During the 2017 eclipse we could easily walk around during totality, and in the 2024 version I had to use a flashlight to get around without knocking equipment over. Both eclipses were during clear skies. My daughter who was with me on both eclipses also noticed the big difference in totality darkness on the ground.



#19 timokarhula

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Posted 15 May 2024 - 01:40 PM

Did anyone else measure their dark sky conditions with a Sky Quality Meter during totality? 

 

At 13.73 SQM-L just seconds prior to the solar maximum (at my location) I was not able to put in context what that meant.  I've waited for darkness many times at star parties and during solo viewing sessions and could not gain perspective on what was happening.

 

Interesting.  I forgot to use my SQM-L meter while observing the eclipse from outside, Waco, Texas.  I have done many SQM-L measurements during clear summer nights here up in Sweden (60° north).  SQM-L 13.73 corresponds to the solar altitude of -6°.5 (end of civil twilight and beginning of nautical twilight).  I have been able to see the combined light of Epsilon Lyrae when the Sun has been so low below the horizon.  From Texas, I could only find Venus and Jupiter naked eye.  I suspect Mars and Saturn were behind some clouds.

 

/Timo Karhula





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