Calculating STEVE's Height from Two Photos 370km Apart

[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.

 

[astroscout]

@Siv Heang Tav I am now a member of the AAC so send it to me via personal message.

 

[Tom.G]

The link to 'rextester' resolves to 'no name found', the URL resolves to 5.35.224.2 which is an un-assigned address at the ISP 'hosteurope.de' in Germany.

 

[Siv Heang Tav]

@Siv Heang Tav I am now a member of the AAC so send it to me via personal message.

Cool, PM me on my Facebook Siv Heang Tav

 

[Bill Archer]

@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.

I expect your answer of ~160 km is about right. From what I have seen so far anything between 130 and 230 km seems reasonable. Some of the differences in answers that people are getting probably from the different techniques used, but it is just as likely from genuine geophysical differences between events. It might be fun for multiple techniques to be used on a single event to see just how much it affects the altitude you get. I would not be surprised if the straightforward approach that does not account for the curvature of the Earth gets you 90% of the way there.

I also wanted to note that the "170 km" altitude stated earlier in the thread from my colleague Dr. Gallado-Lacourt is (I believe) based on red-line data. Although it is not apparent in the pictures Steve radiates in red wavelengths as well, very likely at different altitudes than at other frequencies.

-Bill

 

[astroscout]

It might be fun for multiple techniques to be used on a single event to see just how much it affects the altitude you get. I would not be surprised if the straightforward approach that does not account for the curvature of the Earth gets you 90% of the way there.

@Bill Archer Sounds interesting. My other approach to this is to find a longitude and latitude where steve can be seen looking straight up at about 90 deg and then use that location as a reference or a constant in the code. I will still need the location of other photographers, with the same timestamp, and who are located at a higher or lower latitude, but preferably not too far off in longitude. I could then use the same code that I used to calculate the height of my Gigantic Jet.