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

[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.

 

[DaveC426913]

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.

That makes perfect sense. As I mentioned, I did not actually calculate the height of of STEVE per se, I calculated the height of one of the blobs in the pic. I don't really know what part of the pics are STEVE. They could be tens of kms higher.

 

[DaveC426913]

Actually, this is a much clearer pic.

I believe that STEVE is the blue/purple arc above the green pickets, yes?

 

[astroscout]

Yes Dave, that is STEVE.

 

[Siv Heang Tav]

Hi guys I have some over the arch of Steve hope it help, but it was around 1:39AM.

 

[Bill Archer]

Hi all,

My name is Bill Archer and I am a space physics researcher currently working on Steve. One of the questions I am trying to answer is exactly what you folks are working on here, using more or less the same approach as in this thread.

I’m not sure how much I can really contribute, as the logic of what you are doing is sound and everyone is stating clearly the assumptions they are making. I will be excited to link my calculations on this forum once I have them written up properly.

I can’t fully express how great it to see people interested in the field that I work in, asking and answering the same questions that I am working on.

 

[DaveC426913]

Welcome Bill.

 

[astroscout]

Welcome Bill. Here is how Dave came up with the 157.4 Km. I Think it looks better if you go back to page 3 in this thread because the original post looks better than this "Quoted" post.

OK, here's what I get:
View attachment 236194

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

PIC S (Savoie)
View attachment 236195
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)

View attachment 236190
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:

View attachment 236193

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.

View attachment 236189

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

 

[astroscout]

Siv Heang Tav... That is a nice capture. Can you post your GPS location for the photos you took that evening?

 

[stefan r]

Is 1:09 in this video the same phenomena?

 

[astroscout]

Stefan r...I checked with Paul and he says it isn't. Would be Cool if the ISS were to capture STEVE. Maybe they have and no one has noticed.

 

[Siv Heang Tav]

51.239535,-113.795572

That was my location from Google map

 

[astroscout]

Thanks Siv. I'm going to check the starmap for 1:39am and the location you just posted. I'll post a pic later with the info.

 

[Siv Heang Tav]

https://www.instagram.com/p/BhbvlPLFezO/?utm_source=ig_share_sheet&igshid=rg6777o69nxn

Alan Dyer have Full fisheye len maybe ask him for his pics on that night easy for u guys.

 

[Siv Heang Tav]

https://www.instagram.com/p/BhaqwobBcXp/?utm_source=ig_share_sheet&igshid=1fzh3eeyvkyvi

That night I just got my fisheye 16mm so my shots wasn't that great

 

[astroscout]

@DaveC426913 and @Bill Archer...To get a precise calculation we will need the help of the AAC members on the next STEVE event. I think what we need is photos taken from different locations with the same timestamps and with common elements in them, like what Dave indicated in an earlier post. We will need the GPS location of each photographer to be able to calculate the distance between them, like what Dave did in an earlier post. We can then find the angles using a starmap and Dave can then do the necessary calculations. Also, if the distance between the photographers is great, then we have to factor in the curvature of the earth. I also wonder if it would be preferred to capture the top of the arc of STEVE, like in Paul's photo.

Please let me know if there is another way of going about this because we have to find a way to get the necessary data to do the calculations.

 

[astroscout]

Siv Heang Tav...Here is the astrometry results I found. We will have to go through the images we have so far to see if this could help in making the necessary calculations. Thanks.

 

[gneill]

Dave and Bill...To get a precise calculation we will need the help of the AAC members on the next STEVE event.

A smidgen of advice: Use "@" + "member name" (for example: @gneill) to signal the participants. It will generate an alert in their ALERTS dropdown that will garner their attention. We often use it to "call" mentors or science advisers or homework helpers with the requisite skillset or knowledge base to help with a given problem. It's more efficient than waiting for them to read the thread. Hope this helps. Cheers.

 

[DaveC426913]

Also, if the distance between the photographers is great, then we have to factor in the curvature of the earth.

:slaps forehead:
Didn't even take that into account. Those photos are taken (39-22=) 17 degrees apart! Yet my diagram treats the Earth as flat!

Don't rely on me to do this stuff with any accuracy. There are zillions of members better at this than me.

 

[Siv Heang Tav]

@astroscout You can post a threat on Alberta aurora chaser group, many of our chasers willing to help and provide our images for sure. We just need to know what kind of position u need so we won't focus too much on our foreground lol...
May 06 2018 was a strong Steve over head too

 

[astroscout]

@Siv Heang Tav Yes, That is what I am thinking. We should focus on the center of the arc so we can find a reference star within the band, like I did with Paul's photo and yours. And yes, that would probably mean sacrificing the foreground, and I know that hurts, Lol. I'll let Paul relay the info to your group. It was his idea to do this and he has more knowledge of aurora chasing than I do.

 

[astroscout]

@DaveC426913 Thanks to your efforts we were able to wind up in the ballpark of 170 Km, so we are getting close. A few months ago I took on the task of finding the height of a Gigantic Jet Lightning discharge that I captured over the Caribbean. These Jets travel from the top of a storm cloud and reach very near the Ionosphere at about 90 Km. Here is the data I gathered to attempt to find its height.

1. I contacted Michael J Peterson to find the Goes16 imagery of the cloud that hosted this GJ.
2. From that data I was able to find the exact GPS location of the storm cloud.
3. In Google Earth I was able to find the distance between me and the storm cloud.
4. I then used starry night to find the altitude of a star that was at the same height of the GJ.
5. I found Epsilon Columbae to be a good reference star so I used it's altitude as the angle.

I then used an online calculator and it was way off so I posted my results in my facebook group and Jozsef Bor sent me a code that I could use that will take into consideration the curvature of the earth. The final result came out to be approx 87 Km, so I was well within the ballpark of 90 Km.

Unfortunately, this code can't be used for STEVE because we would need the exact GPS location of STEVE on the ground and we all know that STEVE doesn't shoot up from the ground. The attached image shows the data I gathered.

 

[Siv Heang Tav]

@astroscout which len u prefer
sigma 8mm circular fisheye or the one on April 10 - Nikon 16mm fisheyes? The 8mm circular can get the whole sky... Since I bought it, never get Steve on it yet.

 

[astroscout]

I would stick with a standard lens, not fisheye, because it distorts the star field. Astrometry.net failed to get star info from some of the photos I uploaded because of that. I guess anywhere between 18mm and 85mm is OK.

STEVE is usually dimmer at the center of the arc so use a wide aperture lens like Paul did. F/1.8 is good but F/1.4 is better.

 

[Siv Heang Tav]

Ya I think my Nikon 14-24 F2.8 should be good enough for aurora if u don't like fish eye lens. I also have Sigma art 20mm F1. 4 rokinon 24mm F1.4 but when Steve is over head those lens won't be wide enough... I don't have Sigma Art 14mm F1.4 haha

 

[astroscout]

If steve is bright enough, I guess F/2.8 should be OK.

 

[DaveC426913]

I would stick with a standard lens, not fisheye, because it distorts the star field. Astrometry.net failed to get star info from some of the photos I uploaded because of that. I guess anywhere between 18mm and 85mm is OK.

Perfect. I was going to suggest that.

You know what would be even more awesome? A reference point in the pic.

A simple yardstick should work fine. We could calculate inclination from it, as long as it is
- parallel with the focal plane and
- at a known distance form the focal plane and
- is calibrated (somehow) with the horizon.

 

[Siv Heang Tav]

Is it good to use Polaris in the middle of the frames? That's the only star I know lol

 

[astroscout]

@Siv Heang Tav Not necessary, the top of the arc of STEVE is what we want and in the center if possible. I will take care of finding a reference star.

@DaveC426913 That would help but only the hardcore citizen scientists will do that, but then again you never know.

I have a Christmas party to go to so I will have to get back to you guys tomorrow.

Merry Christmas Everyone !

 

[DaveC426913]

@DaveC426913 That would help but only the hardcore citizen scientists will do that

Yes. I got the impression he was offering pics made-to-order.

 

[astroscout]

@Siv Heang Tav Can you post a photo of the night sky, or an aurora, that was taken by your Nikon 14-24 F2.8. I want to see if I can get the astrometry from it before you use it to capture STEVE. Thanks.

 

[Siv Heang Tav]

@astroscout this was Nikon 14-24mm @14mm

 

[Siv Heang Tav]

Looking north

 

[astroscout]

@Siv Heang Tav Both photos failed.I upload Paul's image to test the server and his works fine. Do you watermark your photos?

 

[Siv Heang Tav]

Pics was saved from my Facebook... Let's try again if u can see it.

 

[astroscout]

@Siv Heang Tav It failed again. Was the lens set to 14mm or 24mm?

 

[astroscout]

@Bill Archer @DaveC426913 I have a friend from Hungary named Jozsef Bor (http://www.ggki.hu/en/staff/researchers/bor-jozsef-mta-ggki/) that is in the process of trying to find a code that will take into account both photographers location and the curvature of the Earth and he will try to help us find a way to figure this out.

In the mean time, I used his code and assumed that STEVE was in between both photographers, in Latitude only, and got 157.363952 Km. This is a very big assumption so the results are not valid at all. I guess it is just a coincidence, but strange, that it is very near what Dave had calculated.

You can see the code and the Octave at this website:
https://rextester.com/YAXQ35757
https://rextester.com/l/octave_onli...eBfHoGePd5szW4Y5QFHHfQcmW7kiR2g6c4cPFjBaT4Pa4

Let me know if the links work.

 

[DaveC426913]

@Siv Heang Tav Both photos failed.I upload Paul's image to test the server and his works fine. Do you watermark your photos?

I am seeing Siv's photos just fine.

 

[DaveC426913]

You can see the code and the Octave at this website:
https://rextester.com/YAXQ35757
https://rextester.com/l/octave_onli...eBfHoGePd5szW4Y5QFHHfQcmW7kiR2g6c4cPFjBaT4Pa4

Let me know if the links work.

Alas, these pages are borked.

 

[Siv Heang Tav]

@Siv Heang Tav It failed again. Was the lens set to 14mm or 24mm?

It was 14mm and did u see the last Pic? If not maybe send it via something else... This forum kinda not convenient

 

[astroscout]

@DaveC426913 It's just when I upload them to get the astrometry that it fails to get the results but yes, I can view them in this thread.

I don't know why the links are broken. Could be congestion at the server. I'll run the program again tomorrow and see what happens.