I Calculating STEVE's Height from Two Photos 370km Apart

[Paul m Smith]

Don't take offense from Davenn. We have no way of immediately knowing whether your claim is true, and personal experience is hard to trump without access to a reliable and verifiable source of information on the topic.

Thanks, I understand. But there is a lot of reliable and verifiable information out there. Most of my learning is from the experts like Eric Donavan and Elizabeth MacDonald (both with NASA) with whom I interact via the Alberta Aurora Chaser facebook group. I cannot link information directly from there. I don't take offense to Davenn 's comments , but it is frustrating to face resistance from people who don't care to research.. I will get to the point and post the diagram when I can. My question will be more apparent then.

 

[Drakkith]

Thanks, I understand. But there is a lot of reliable and verifiable information out there.

Such information is much more difficult to find than you would imagine. Especially for many PF users who don't consider anything short of a textbook or a peer-reviewed paper reliable. A quick browse of the first fifty or so google and arxiv hits turned up nothing for me regarding whether or not STEVE always accompanies a picket fence aurora or not. So what information there may be out there isn't particularly easy to find. One thing I noticed is that this appears to have been seriously investigated only recently (around March of this year), which means that there is unlikely to be very much reliable information at all.

If you want to change peoples' minds, I suggest finding and providing links to reliable sources instead of telling people to "do some research".

 

[Paul m Smith]

https://www.facebook.com/PhenomenalSTEVE/
All information can be found here. Links to papers are within threads. Yes, it is a relatively new topic of research...

 

[astroscout]

Please guys...Lets focus on what is needed to calculate the height of the purple arc. If he were to get the angle using stellarium, can we calculate the height or do we need the info from the second photographer?

 

[Tom.G]

Gonna need that second observation... and hopefully a third one to get at least a vague idea of the error band.

 

[astroscout]

Thanx Tom. Good to know. We'll see what we can do.

 

[DaveC426913]

My concern is how you will be able to determine the angle above the horizon. You won't be able to calculate altitude without that.

I suspect that you'll need
1] a shot with the horizon (or other object with known angle) in the pic with the phenomenon
2] EXIF data from your camera that will include such things as focal length setting for the shot

Although, I suppose you could always reference any visible star formations in the shot. Coupled with time and date, that would do the trick. Yeah.

 

[astroscout]

I was able to use starry night software and astrometry.net to find the star formations and the altitude of Beta Sextantis using the timestamp and location of Paul Smith at the time of the photo.
Timestamp = April 10, 2018 at 1am
Altitude of Beta Sextantis = 22 deg
Location of the camera = Latitude = 54.937806 N Longitude = -112.510886 W

 

[DaveC426913]

I was able to use starry night software and astrometry.net to find the star formations and the altitude of Beta Sextantis using the timestamp and location of Paul Smith at the time of the photo.
Timestamp = April 10, 2018 at 1am
Altitude of Beta Sextantis = 22 deg
Location of the camera = Latitude = 54.937806 N Longitude = -112.510886 W

OK, can you do the same with the other one?

 

[astroscout]

Paul has not been able to contact the other photographer yet. Hopefully he will. If he can't, can the info I found be enough to get an approximation?

 

[DaveC426913]

Paul has not been able to contact the other photographer yet. Hopefully he will. If he can't, can the info I found be enough to get an approximation?

No.

I mean, no better than simply checking the general understanding of STEVE altitude. If you want to add to the body of knowledge, you'll need that other photo.

You know, that photographer is surely not the only one who took pics of that particular event. Looking around the webernets, you could probably gather quite a few photos and correlate them all.

Wait. You mean you found another photo in addition to the photographer's? Then yes. If you can find the location and date/time of the other photo.

 

[astroscout]

We will continue to try to contact the other photographer and get the info needed. Thanks Dave.

 

[stefan r]

Please guys...Lets focus on what is needed to calculate the height of the purple arc. If he were to get the angle using stellarium, can we calculate the height or do we need the info from the second photographer?

Do we know the STEVE (or the aurora) is radiating the same in all directions. Rainbows make a counter example. Someone else sees violet in the section where you see red. The red photons you see are coming from water droplets over a deep range. Two photos of a rainbow would not accurately tell you where a squall line was located.

 

[Tom.G]

Here is a rather detailed semi-technical article on STEVE published in SCIENCE magazine.

http://advances.sciencemag.org/content/4/3/eaaq0030.full

Cheers,
Tom

 

[TEFLing]

Plasmasphere cools and contracts on Earth's night side, leading to radially inward current flows, if I understand correctly

https://wiki.oulu.fi/download/attachments/5243547/plasmasphere.gif

https://wiki.oulu.fi/display/SpaceWiki/Plasmasphere

Out beyond the Plasmasphere, where the plasma is tenuous and relatively warm, whistler-mode waves create primarily rising chirps, like a flock of noisy birds. This type of wave is called chorus and is created when electrons are pushed towards the night side of Earth... When these low energy electrons hit the plasma, they interact with particles in the plasma, imparting their energy and creating a unique rising tone.https://3c1703fe8d.site.internapcdn.net/newman/gfx/news/hires/2017/1-nasalistensi.jpg

https://phys.org/news/2017-07-nasa-electrons.html

 

[TEFLing]

"The ring current (e.g., Frank, 1967) consists of geomagnetically trapped 10 - 200 keV ions (mainly H+, He+, and O+) and electrons that drift azimuthally around the Earth at radial distances of about 2-7 Re (Earth radii), overlapping the radiation belt region. The drift is a combined curvature and gradient drift which is eastward for electrons and westward for ions, i.e., the direction of the current is westward ."

https://wiki.oulu.fi/display/SpaceWiki/Ring+current

 

[astroscout]

Here is the photo taken by the other photographer, Savoie. Looks like he didn't get the top of the arc like Paul did so I guess we are out of Luck in trying to figure out the height of it. Any Suggestions?

 

[DaveC426913]

Here is the photo taken by the other photographer, Savoie. Looks like he didn't get the top of the arc like Paul did so I guess we are out of Luck in trying to figure out the height of it. Any Suggestions?

If it were possible to identify common elements of each, you should be OK.

But - it's also possible that STEVE's change fast enough that, even if they were taken less than a minute apart, they would have no common elements.

Unfortunately, the implication that is that the boundary of the phenomenon - including its maximum height - is ever-changing.

And that means any attempt to triangulate its height would be little better than a vague estimation.

 

[astroscout]

Thanx Dave. The only common elements is the picket fence that comes and goes in their videos. I'll see if I can find anything in STEVE.

 

[DaveC426913]

Here is the photo taken by the other photographer, Savoie. Looks like he didn't get the top of the arc like Paul did so I guess we are out of Luck in trying to figure out the height of it. Any Suggestions?

Were you able to get any time/location alt/azimuth and direction info on this one?

 

[astroscout]

I just got the location which is: Lat = 49.709387 N Long = -112.866389 W in Lethbridge, Canada. I still do not know the timestamp of the video taken by Ryan Savoie. We are still waiting for him to give us the info.

 

[Tom.G]

Those location numbers give you about a 360+ mile (580+ km) baseline, which is several times the expected altitude of Steve. Looks like the accuracy will be limited by how accurately you can determine the camera elevation angle and the avoidance of any time scintillation of Steve.

 

[DaveC426913]

OK, here's what I get:

So, total distance 583.81km (looks like you meant 370 miles).

PIC S (Savoie)

Angle of Polestar = latitude of observer.
So angle of polestar in pic S is 47.71

I picked the top of that group of spikes as a reference point.
It is 82% of the height of the polestar, which would make it an angle of 39.12 degrees (82% of 47.71).

PIC P (Paul Smith)

Angle here is a given of 22 degrees.

I assume here that I have the same reference point as in PIC S - a whopping assumption.

This gives the following geometry:

I used this handy calculator: to arrive at a height of 157.37km

This gives an altitude of that bit of aurora of 157.4km.

As to what that means in relation to the altitude of STEVE, do with it what you will.

 

[astroscout]

Nice Work Dave. STEVE is known to be an Ionospheric phenomenon so the fact that the results came out to over 100Km is a good thing because the Ionosphere is above 100km. I know you had to make assumptions, but at least we are in the ballpark. If I get any more info from Ryan Savoie, I will let you know. Thanks.

 

[DaveC426913]

I am wondering if this could be refined a little more.
I'm comparing the two images for similar structures, but I think they're not pointed at the same place.

Looking North, the green spikes are off the the left (West).

Looking South, the spikes are also off to the left.
If they are the same spikes, then the South-looking pic is not looking due South, but more like Southwest (so that the spikes are on the left side of the pic).

I'm not good with Alt and Azimuth. Is it possible someone could identify due south in the top pic?

 

[DaveC426913]

I'm also realizing that my clumsy attempts at measuring angles is egregiously flawed.
Both pictures are very wide angle - you can see how the aurora is distorted into an arc in both pictures. If that arc were physical - as opposed to an optical distortion - they could not both be accurate. So my geometry will likely be way off.

 

[astroscout]

Your are right about Paul facing southwest instead of south. The azimuth for the reference star Beta Sextantis is 233 deg. South would be 180 deg azimuth and west would be 270 deg azimuth so the 233 deg azimuth would mean somewhere between south and west.

 

[astroscout]

I just found out from Paul that Bea Gallardo-Lacourt, the scientist who wrote the recent paper on STEVE, is in contact with Paul. Paul relayed your calculation of 157.4 Km to her and she says that using their instruments they were close to that result at about 170 Km. Paul is still looking for more photos and gathering as much data as he can to help you guys with the calculations.

 

[Paul m Smith]

Thanks for the fascinating discussion. I am trying to gather more images - which shouldn't be too hard to do. Someone by Airdrie ( almost half way between myself and Ryan) captured some nice images looking almost straight up on that night. Also waiting to see what her timestamp and precise locations were. I observed Steve for almost 1 hour that morning and the position didn't seem to change that much. I would be really interested to get a general size of those picket fence features . Must be many tens of kms

 

[astroscout]

I just got an email from Bea Gallardo-Lacourt indicating that William Archer will review what we have done here and contribute what he can.

Dave. Here is another photo thanks to Paul's efforts at the Alberta Aurora Chasers Facebook group. This one is from Siv Heang Tav. She stated the she was just east of Airdrie, Canada. The location I used for the altitude of polaris is just an approximation because I don't have her exact gps location.

PS : I made a mistake in the earlier photos I sent you with the dates. I used May 10th instead of April 10th so the 22 deg for Beta Sextantis should be 21.5 deg.