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HKATER
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Supernova?

22 Jul 2019 03:05

I think I just saw a supernova (exploding star) in Bootes near the star Izar, 10 minutes ago, 7:45 pm Sydney time Australia, GMT+10. It only lasted about 1 minute. I watched it with the naked eye for about 30 seconds, then went in to get my binoculars and by the time I returned (another 30 seconds) it was gone. It was a bright white smudge, half as bright as the moon but hazy and of no distinct shape. My first thought was it looked like a comet. The moon is not at that position (low to the horizon) and in any case will not rise till later tonight. Strangest thing I have ever see at night. My location is pitch-black (its winter here, the sun set over 2 hours ago) near Nyngan in outback Australia. Don't know what a supernova is supposed to look like? This was a hazy thumbprint type of bright white haze about the size of te tip of your finger held up (about the same size as the moon behind a cloud). No clouds tonight - crystal clear skies. Strange part was it was not a bright point like a star - but a hazy patch the size of the moon looking like a comet tail, but more round, not a line.
 
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Supernova?

22 Jul 2019 05:30

If it appeared large and fuzzy (not pointlike) on the sky, and faded quickly, then it cannot be a supernova.  It would have to be very large in physical size (hundreds of light hours across at least) to appear that big in the sky from many light years away, but something that big cannot change brightness that quickly.  

A typical supernova will increase in brightness over a period of hours to days, and then slowly fade over weeks to months.  It will appear point-like during this whole time, as it takes years to centuries for the remnant to expand enough to resolve.

It's hard to know what you saw, but one possibility is something much closer to Earth: a satellite rocket body venting fuel.  If this is illuminated by sunlight it can appear in the night sky as a bright fuzzy cloud that expands and dissipates over a few minutes.  Example:

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Supernova?

22 Jul 2019 05:57

Today July 22, at 2:43 local Indian time (9:13 GMT), India launched Chandrayaan-2 mission with a Geosynchronous Satellite Launch Vehicle Mark III, directed to the moon surface. The launch was expected last week but it was postponed today. Given your local time, it could be that you've seen the rocket, or the probe release.
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FastFourierTransform
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Supernova?

22 Jul 2019 08:23

SHORT ANWER:
You have probably witnessed the launch of Chandrayaan-2 spacecraft (the last stages of the launch litted by the Sun). The Indian spacecraft is headed towards the Moon and carries a Lander and a Rover for the Lunar South Pole!

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LONG ANSWER:

Supernova?
Supernovas are not so easy to spot in principle. The last time we saw a supernova with the naked eye was 415 years ago and the last one that happened in our galaxy was  151 years ago (we didn't register it when it occurred sadly but we have backpropagated the motion of its remanent shell of gas and dust now that we have discovered it). To be seen with the naked eye it is in principle necessary for them to be located in our galaxy. As you can see they are fairly unfrequent. The current estimated rate is of 4.6 supernovas per century but this is considered to be optimistic and the even then the majority of them wouldn't be visible to the naked eye (due to them happening in dust-obscured regions of the galaxy).

The chances are lowered if you observed it close to Izar. Bootes is very close to the North Galactic Pole, which is located in Coma Berenices. This means that you are watching almost perpendicularly with respect to the galactic plane. Since the vast majority of stars in our galaxy concentrate on the plane, having a high latitude supernova makes it even more improbable. The chances for that are extremely small. I've labeled this chart to show you the location of the galactic plane.

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Could it be an extragalactic supernova? A supernova in some other nearby galaxy? As I said, those would be very dim. There is an updated list of all the recent detections and today there haven't been any detections by any instrument. Yesterday 21 there were 2 detections made by the Asteroid Terrestrial-impact Last Alert System but 1) it was yesterday, not today 2) both are no way near Bootes and 3) Their brightness was of 17.3 mag and 18.7 mag, which is so dim you wouldn't expect to see them even with a semi-professional observatory.

Also, supernovas are point-like sources with no details nor extension as seen from Earth (unless you are just a few light years away in which case we would be dead) and not "hazy with non-distinct shape". We therefore should seek other possible explanations.


A flash associated with a GRB?
Gamma-ray bursts are complex phenomena that still largely need explanation. Associated with the gamma-rays there can be a visible counterpart. In some cases the GRBs have even be visible with the naked eye. A good example is GRB 080319B, which was detected by the Swift satellite in 2008. At its peak brightness GRB 080319B reached 5.8 mag (just barely visible but visible in dark sky areas). It was visible for 30 seconds (in the same order of magnitude as your source). The object was located on the other size of the universe, 7.5 billion light years away! (this is in fact the farthest object ever seen with the naked eye).

A closer GRB could be brighter and the afterglow could be visible for more than a minute so this matches some of your parameters. Let's see if there is some detection for today or yesterday; The last time the automated system of the Swift satellite triggered was 3 days ago and it didn't happened in Bootes. The Fermi telescope automated system triggered 8 times two days ago but since then there haven't be any. INTEGRAL was triggered yesterday (not today) but in a completely different region of the sky. The last trigger of MAXI, installed on of the ISS, was 4 days ago. Since these lists are updated in real-time and due to the differences in the date with respect to your observation I would say that if yours was a GRB it wasn't detected by any instrument. If you saw it with the naked eye it means that it probably should have been detected by some of those telescopes at the moment.

Even if you had luck and no instrument detected the highly luminous flash that you saw with your naked eye a GRB still doesn't match the "hazy thumbprint type of bright white haze about the same size as the moon" description. GRBs like supernovae are point-like sources as seen from Earth.

A meteor/bolide moving in your direction?
I know very little on this topic so it might be nice to have midtskogen's opinion on this (since he has an observatory dedicated to meteor detection and is part of a larger network of observers).

A meteor is a bright event but it moves across the sky. I don't think it can endure for as much as a minute in any case and for it to be still you would need to have it moving in your direction (which is excedenly improbable). The only match I see is the brightness and the possible non-point-like shape since it could look like a small trail or, if it fragmented in the upper atmosphere, like a small cloud. But again, it looks like we need to tune the parameters too much to match your expectations and even then I doubt I'm correctly predicting what it would look like.


A satellite flare?
Flares are quite spectacular phenomena. I reccomend you to plan some observation to look for them. Satellites are rotating in space and also their relative configurations with respect to the Sun and Earth change as they move in their orbits. Iridium satellites (some communication satellites that are located in LEO) have large panels that in certain occasions reflect sun-light directly into some spot on the surface of Earth, as they angle correctly by chance for that. You see them as a star appearing out of nothing and increasing to brightnesses that match that of the brightest star or even more in a matter of seconds. They can last for even a minute if you are lucky. iridium satellites display the most notable flares (they are reflective and nearby), butthere is no Iridium flare prediction for that location at that time apparently.

There are two problems here. They are point-like again and they move (not significantly but noticiably for sure). We live under an atmosphere so a "hazy" appearence should give you a hint; A small isolated cloud aligned in that direction could explain the hazy appearence of the light (even if it was a clear night there's always some small isolated clouds that one can't spot in many cases due to the darkness of the night). If you find a cloud to be something improbable think about the fact this observation was certainly unfrequent (at least for you) so it might be explained by common factors but in unfrequent dispositions. It looks like it was indeed clear at the moment but still small clouds can form

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Also the movement of the light could be reduced if the flare was yielded by a Geostationary satellite instead of an Iridium satellite. Let's search our candidates. Using a free software called Heavensat updated with the satellites orbital parameters of today we can see which objects where near Izar (a more specific separation from it would help) at 7:45 pm (a more specific date would help) as seen from Nyngan (a more specific location could help refine this). Here I've selected only high-altitude satellites (since LEO satellites would move to fast in the sky for them to be seen as still).

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As you can see the geostationary satellites are located in a belt close to Bootes but to far away to be our candidate sources (also flares from geostationary satellites are very dim). Izar is marked with the green circle. But moving the slider for 2 minutes before and 2 minutes after 7:45 pm there are two candidates close to Izar that barely move (one of them moves in the same direction as the rotation of the sky so the relative distance to Izar is mantained). Both would look almost still for a naked eye observer for a span of 1 minute.

The first candidate is BREEZE-M R/B 2017-057B which is the upper stage of a Russian rocket that launched ASIASAT 9 (a geostationary satellite). This upper stage of the rocket is orbiting Earth uncontrolled at an altitude of 32.600 km.

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And the second candidate is FREGAT R/B 2011-060C which is also the upper stage of a Russian rocket. This rocket launched ESA's satellite GAL E11 (part of the Galileo constellation). It's orbiting Earth uncontrolled at an altitude of 23.600 km. Since it is a big object and it is closer than BREEZE-M R/B 2017-057B we should expect him to yield the largest flares of them both.

But again satellite flares at that altitude shouldn't be very bright except for some special cases and satellite flares are still point-like in general (as you can see astrophysical phenomena that can be seen with the naked eye are usually point-like in shape).



An airplane with the headlights directed to you?
It might sound stupid but we are not as familiar with airplane lights as we might think. When airplanes are headed towards us the directional navigation lights increase a lot in brightness. This surprises the first few times you see it (which is not as common as we think). Many times it has been so unfamiliar that it has been announced as a UFO. Also, in this situation the source of light might appear to not move at all. When we are not directly lighted (because of the plane making a turn for example) it vanishes quickly.

Let's check if there was an airplane coming at 7:45 pm from the North to Nyngan. As you can see there were two airplanes: A huge Airbus A330-343 with ID PAL213 from Manila to Sydney and a large Boeing 737-838 with ID QF705 from Cairns to Melbourne.

Image

The problem is that both airplanes are very far away or do not point directly into Nyangan's surroundigns when they are closer some minutes later. At that distance with those elevations both should have appeared at 2º - 3º above the horizon (which could explain the haze) and Izar is way higher in the sky (at 30º). Overall the area is an airplane dessert, there is little air traffic there so I think this is not a plausible explanation either.


A rocket launch?
As Watsisname has said a plausible explanation is a rocket launch. The different stages of the rocket can be litted by the Sun way after sunset and the exhaust looks just like a very interesting haze in the sky for some minutes.

There has been a launch today! A Geosynchronous Satellite Launch Vehicle Mark III (a rocket with 3 stages) has launched the Chandrayaan-2 mission to the Moon. It has been launched from Satish Dhawan Space Centre in India. It was launched at 7:13 Sydney Time (half an hour before your observation).

You can watch the entire launch here




From the video I took a screenshot of the ground trace of the object some minutes after launch. I can recognize Sri Lanka's shore in there. With that we can estimate the flight path.

Image

This is a very rought propagation (done by eye) of the trajectory shown in the monitors of the control room. But as you can see it extends roughtly to Australia. Half an hour seems a totally right time for that to arrive there.

Image

This I think is the most probable situation. You saw the launch of Chandrayaan-2 on its way to the Moon. Maybe tomorrow we have some video records on YouTube of witnesses like you.
 
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Supernova?

22 Jul 2019 12:26

FastFourierTransform wrote:
Source of the post I know very little on this topic so it might be nice to have midtskogen's opinion on this (since he has an observatory dedicated to meteor detection and is part of a larger network of observers).

Yes, a meteor can leave a smoke trail which can take all kind of shapes and its duration is usually counted in minutes, but I don't think that's likely here.  The meteor itself would have been hard to miss, probably bright enough to briefly illuminate the entire sky.  Also, the smoke trail usually have some kind of shape, not just like a fuzzy, comet-like expanding ball, though I suppose that can't be ruled out.  It depends on the wind in the upper atmosphere and entry angle relative to the observer.  I think the rocket explanation is much more likely.  There are numerous examples of launches causing phenomena looking just like what's described.  It could be a stage separation, and if it matches the Indian launch headed for the moon, it's really neat to have observed that by total accident.
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Supernova?

22 Jul 2019 18:08

It looks pretty much confirmed now. HKATER, if this is what you saw then it is indeed the Chandrayaan-2 mission according to Prof. Jonti Horner. It was an engine burn to start the climb to the Moon. I envy you HKATER, that is an awesome sight. Maximum neatness.

The light you are seeing is a combination of the rocket burning, but you've also got the gas being ejected from the rocket, the gas is spreading out in space and reflecting spotlight as well, so it's like it creates a cloud in space that gradually disperses with the rocket at the end of it.



Image


Image
 
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HKATER
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Supernova?

23 Jul 2019 01:24

Thanks guys - amazing response. To be honest I came back tonight doubting what I saw. A low level cloud seemed the most likely as I agree that small clouds can form in clear skies and in pitch black conditions they are almost invisible, not like in a city where you can see clouds at night. BUT I agree about the chandra rocket. It makes sense. I am on a remote sheep station 20km West of Nevertire (100 km South of Nyngan NSW). I can describe what I saw as follows. I went out on the porch to pee (call of nature) and my eye was drawn to the tree line almost directly North. I saw a bright spot (was difficult because it was right on the top of the tree line and likely partially obscured by leaves, but our trees have sparse leaves, so you can see through them a bit). My first reaction was surprise as it was pitch black (no sunset remains, no moon) and that part of the sky, low to the horizon should be pretty dark. Then as I moved around a bit trying to see what it was it seemed to dissappear altogether (this happened over about ten seconds from my first noticing it. Then as I am watching I see it not only return but grow in brightness. Sorry I was slightly incorrect in my earlier description. It did have a shape. It was fan-shaped like an upside down Ice cream cone with the pointy end straight down roughly near Izar. The point was in the trees but I could see the wide top of the fan clearly. Then being a bit incredulous about what I was seeing I did what I sometimes do in astronomy. I looked away slightly (not looking at it directly) so I could see it off my centre of view and that was when it grew quite bright about the size of the moon. It was hazy and not moving at all, only increasing in brightness. This lasted another twenty seconds (30 seconds approx in total). I then went inside to get my binoculars.

I can confirm it was definitely not an aircraft. We are under several flightpaths and I see aircraft at altitude all the time, day and night. Low flying GA aircraft are rare at night and they always can be heard. I can hear the high altitude jets as well and am familiar with their contrails and nav lights which appear as pin points of light. Aircraft landing lights above 10k feet is unlikely.

Definitely not a satellite (not sure about flares though?). I see satellites all the time as very fast moving pin points of light, especially near dawn and dusk when they reflect the sunlight (that is a fantastic sight I have seen a few times), but I always need binoculars or telescopes to see satellites.

The only installation to the North of my position by about 20km which is unusual (other than the very tiny town of Nevertire, its literally a one horse town with one pub, basically a truck stop - most truckies only stop there to sleep), is the newly constructed Nevertire solar farm, but this farm though brightly lit at night can not be seen from my location.

Thanks guys - it was an odd sight. I have to say though that as an amateur astronomer my most amazing experience was looking at the star sirius in a 14" dobsonian Meade telescope I have. Its the only star I have views in a telescope that really looked like a star. Looking at it you were worried you might damage your eyesight. Its impressively bright. Alpha Centauri is bright, but Sirius In a telescope looks dangerous.
 
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HKATER
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Supernova?

23 Jul 2019 01:51

Was just discussing this with my Father and he tells me there were reports on the radio this morning of people living on the Australian East Coast reporting strange lights in the sky last night. Seems to confirm it.
 
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HKATER
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Supernova?

23 Jul 2019 02:00

My error. 20km to the North of us is not Nevertire - that is roughly 20km East North East, and that is where the solar farm is, so due North is just country properties between us and Nyngan.
 
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HKATER
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Supernova?

23 Jul 2019 02:05

Thanks guys - its confirmed. It was Indian rocket going to the moon.

https://www.abc.net.au/news/2019-07-23/ ... y/11336446
 
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HKATER
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Supernova?

23 Jul 2019 02:14

Just for the record the Centaur venting fuel image given above is what it looked like but without the bright points. It was a uniform white haze. If you have seen the small magellanic cloud at night with the naked eye at a dark site, it was like that at about the same intensity (about half as bright as the moon).
 
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Supernova?

23 Jul 2019 04:38

It definitely sounds like Chandrayaan-2's heading to the Moon is the best explanation for what you saw, and it's awesome that you got to witness it!  I'm jealous! :)  You also did an excellent job describing the details of your observation, which is something many struggle with when they see something unusual in the sky.  Those details were extremely helpful for ruling out other possible explanations.

And wow that was an amazing post, FFT.  Great job exploring the numerous possibilities in detail.
 
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HKATER
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Supernova?

23 Jul 2019 18:11

Pleased to describe, no problem. Now I know that India launches its space rockets over Australia, I will be watching for Chandra-3 you can be sure. One disturbing point I noticed about the ABC report was that the professor from Queensland explained that after watching the video footage he could tell that it was not a rocket in the atmosphere, that it was a rocket burn outside of the Karman line. How do they know this? There must have been something about it that showed him this. As you know I was convinced it was a distant phenomenon, far from earth. Something in the heavens. It seems that even a civilian scientist can tell the difference between an atmospheric rocket burn and one in space. I expect the USA is constantly on the look out for rocket burns and know the difference between an atmospheric burn and a space burn. This professor's knowledge of space objects is impressive. This is obviously a very relevant and well funded research field for any scientist, civilian or military.
 
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Watsisname
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Supernova?

24 Jul 2019 02:54

HKATER wrote:
Source of the post One disturbing point I noticed about the ABC report was that the professor from Queensland explained that after watching the video footage he could tell that it was not a rocket in the atmosphere, that it was a rocket burn outside of the Karman line. How do they know this?

This is actually very easy to tell if you know what to look for.  In the atmosphere, the rocket's exhaust gases quickly slam against the surrounding air, which confines the gas into a narrow plume.  The higher the altitude, the lower the density and pressure of the air, and the farther the exhaust gases can freely expand against it.  So the plume widens out and becomes more streamlined and comet-tail like, rather than the roiling column we usually imagine.

The effect is beautifully demonstrated in this SpaceX Falcon 9 launch, with the exhaust plume illuminated by the Sun while it is night on the ground.
 
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Supernova?

24 Jul 2019 03:21

EDIT: Dammit! I've been flashed by Watsisname once again :lol: :lol:
_________________________________________________________________

I am definitely not an expert in the field but I think it might have to do with how the exhaust expands in the exit of the engine nozzle. Under sea level pressure the stream is well confined and thus rockets leave a tubular thin trail of smoke. In a low-pressure environment (like in high altitude or even in space), the exhaust is free to expand more and more outside.

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You can see the change in regime from low pressure to high pressure in the Falcon 9 launch of the 7th of October 2018

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I suppose that the professor from Queensland reasoned that a cone-shaped cloud is more easily explained by the engine burn happening in space. Also the timing is coherent with the scheduled Chandrayaan-2's ignition from Earth's orbit. By the way if you haven't seen it take a look at the spectacle of Falcon 9's launch:




Also take a look to this gorgeous exhaust cloud fron the SolarSail 2 launch a few days ago:

Image

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