Transit of a mystery satellite on 5 June 2022 at 23:44 UT

[Averton]

While capturing some white light images this morning an object started to transit the Sun.
It was traveling so quickly that by the time we had pressed record it had already travelled a significant distance across the disk.
It looks to be smaller than the ISS but larger than the many small Space X satellites.
We checked Stellarium that shows quite a few satellites but couldn't find anything there.
Tried transit finder and there was nothing there.
We are unsure what to check so its a mystery to us.
Any suggestions????


https://www.cloudynights.com/topic/826791-transit-of-a-mystery-satellite-on-5-june-2022-at-2344-ut/

[Dennis]

Nice recording.:thumbsup:

Not knowing the exact orientation, one possible candidate could be a weather balloon.:shrug:

Cheers

Dennis

EDIT:
I have just attached a photo of a weather balloon I grabbed back in 2007, with a Canon 400mm F5.6 lens.

[Averton]

Thanks Dennis. Great shot of the balloon.

A couple of other people on CN have also suggested the same thing. So we are going with that theory :)

[AdamJL]

+1 to the balloon theory
you can almost see it oscillating.

[mura_gadi]

Ah, but which balloon?

If it's Sunrise III, then it's a great shot to have!

Might be able to get the sub-orbital path of the balloon from the web and back date it... at a guess.

[AdamJL]

this one (https://tenor.com/view/it-it-movie-red-balloon-library-ben-hanscom-gif-8133465)

[Averton]

Yes Adam, when we originally captured the video we thought that some sort of motion of the shape itself was visible but couldn't work out what it was. The balloon theory fits perfectly.

[Averton]

:lol::lol:

[Averton]

Unfortunately that seems unlikely. From what we can see it's yet to launch and it is taking off in Sweden and landing in Canada having transited the Arctic. We are afraid that it is more likely just a regular mundane weather balloon.

[alw50]

Out of curiosity, I had to go at figuring out the balloon path.

Took a while, but it was fun.

Is this (see pic) about where it would have been when you observed it?

Regards, Andrew

[mura_gadi]

Did think about the artic bit after posting, but was too late.

You might also have some extra high altitude balloons due to SA rocket testing as well. But the Melbourne weather balloon should be a safe bet.

[Averton]

:thumbsup:

[Averton]

Out of even more curiosity, how the heck did you find out the information about balloon launches and narrow down to this one? Presumably its been launched from Melbourne Airport. Who is the owner of the balloon? BOM? The amateur call signs in the list pertain to what? Are they amateurs who were tracking the balloon or did you get met data on wind strength and directions to predict a path?

Judging by the marked position and the altitude given it is quite possibly the balloon in question. Great work Andrew!:eyepop:
PS. Thanks for doing this followup, its very cool!!

[alw50]

Great, looks like I was on the right track.

Yes, BoM data was the starting point.

I'll explain in more detail tomorrow.

Andrew

[Averton]

Definitely looks like the right track. Look forward to more explanation. :thumbsup:

[Dennis]

Nice investigative work!:)

Cheers

Dennis

[Averton]

:thumbsup:

[alw50]

Ok, more explanation.

Back in the recesses of the infinite dark past I worked at the BOM in Adelaide for four years going through university. I remembered that balloon launches were typically mid-morning. And also, a few years ago we did a little drive from Adelaide up the Birdsville Track and across to Longreach. Naturally, I visited the BOM outpost there, arriving just before they launched the morning balloon. So we watched that go up, and went inside the hut to see the radiosonde traces coming in in real-time.

So I checked the standard launch times for weather balloons: 2315Z and 1115Z. I figured it was pretty likely that this observation was a weather balloon.

It then occurred to me that, given that satellites, planes etc are all trackable online these days, why not weather balloons?

So I dug around, and found enough sources of data to put the information together.

I found an interesting write up of a rather well-developed balloon tracking project in the radio astronomy group of our SA astronomical society (which I joined a few months ago).
https://www.assa.org.au/resources/radio-astronomy/projects/balloon-tracking/
This explains very clearly how you can build an antenna and a receiver to track balloons and collect data.
It seems that a lot of people do it, hence there is always tracking of weather balloons.
And also software, which I will come back to shortly.

I also found a website for glider pilots that harvests BOM data for weather balloon flights all around Australia.
https://slash.dotat.org/atmos/info.html
Graphical traces for the relevant time here:
http://slash.dotat.org/cgi-bin/atmos?loc=94866&time=20220606000000
And raw data here:
http://slash.dotat.org/cgi-bin/atmos?raw=1&loc=94866&time=20220606000000
These show WSW-ish winds of about 30 knots. A comparatively pleasant day, for last week.

So that alone could give a pretty good idea of where a balloon was heading. One could use the data to calculate a path, but fortunately I discovered that I didn't need to do that.

The above-mentioned ASSA write up includes a link to this site:
tracker.sondehub.org
This tracks hundreds of balloons around the world.
This URL will show the Melbourne Airport site (the leftmost open circle):
https://tracker.sondehub.org/#!mt=Mapnik&mz=8&qm=12h&mc=-37.32649,145.72266
This will immediately show any current or recent flights.
But because I was looking for one in the past I had to do a bit more work.
This involved clicking on that circle, and fetching historical data for June, which generates 30 odd dots on the map, representing the finishing points of all flights made so far in June.
So I had to figure out which was the relevant one.
From the glider data above, it wasn't hard to figure out that the finishing point would be somewhere to the east of the airport.
So I tried three or four, and came up with the right one. (There might be an easier way which I haven't found yet, being a beginner with the software.)
A link to the information for that flight is:
https://tracker.sondehub.org/T2250440
With some difficulty, it's possible to click on points on the path shown, to look at time and data at that point.
That's what I did for the picture that I posted yesterday.

Anyway, that was interesting, but the dot by dot search at the end is a minor PITA.
However, the PITA factor arises because I was searching for flights in the past.

The good news is that it is easy to find current flights.
You only have to use the site URL, or the Melbourne URL above, and it will show them immediately.

So that's a good way to check for balloon flights next time something like this happens!

[Averton]

Hi Andrew,


Thanks for the excellent and detailed explanation of your investigation. We have followed through all of your links and found the information very interesting. In the end we just used your second last link to open up SondeHub Tracker and used the historical data button, found the correct balloon and traced its flight path.
As you pointed out, for some reason it is quite finicky to click on the flight path to get the data from each location but once you get the hang of it, its all good.

So we got the data with a little bit more accuracy on the time and plotted the location on google maps. This gave a distance from our observation location of 19.60km and a bearing of 36 degrees 13' 8" East of North.

Then Stellarium gave the azimuth and alt of the sun at the time of the observation as 37 degrees 38' 17.9" / 19 degrees 35' 57.4".

With the height given from the balloon data and our calculated distance to the balloon, trig gives an angle of 19 degrees 45'.

A bearing within a bit over 1 degree and an elevation within 10' seems pretty conclusive although we can't really identify where the errors are as the time of our capture is synchronised with network time and presuming all of the balloon data is reasonably accurate, there is a bit more error than you'd like.

However, a last bit of evidence is if you go to Tilting Sun software and calculate the angle of the sun at the time of observation, the path from west to east transcribed in the video matches the orientation of the sun from the software.

We rotate our camera so the image is orientated as per convention with North at the top and East at the left. This means that the west to east path of the balloon viewed from the ground has transited the image correctly.



Conclusion, you definitely found the mystery satellite/balloon :thumbsup::thumbsup:


Thank you so much for taking the time and effort to work all this out and share the information!!

[Dennis]

Such an enjoyable read about what appeared to be a "problem" that did not have an easy or straightforward "solution".:)

The subsequent collaboration and investigation reads like a detective novel that led to solving the balloon puzzle.:thumbsup:

Cheers

Dennis

[multiweb]

Great catch and some brilliant investigative work. :thumbsup::thumbsup::thumbsup:

[alw50]

Thanks for the kind comments! It's good when interesting detective work actually turns out to find an answer and be useful.

Clare and Peter, thanks for adding your insights about reconciling this information with the sun position. I did have some passing thoughts about that while I was gathering the information, but didn't really know how it could be done. The Tilting Sun software looks quite interesting. This exercise has actually piqued my interest in solar observing.

Anyway, I'm pleased this turned out to be a useful exercise!

Best wishes, Andrew

[Averton]

Thank you Andrew. It was good fun and we learned a lot about weather balloons along the way. If you haven't actually found the Tilting Sun software, here is the link.
https://atoptics.co.uk/tiltsun.htm
We never anticipated being as interested in solar observing as we have become. It is quite fascinating as the Sun is such a dynamic and changing object. It has ended up surpassing all our other astronomy interests.