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Kullat Nunu
2008-Mar-19, 08:30 PM
AAVSO Alert Notice 372: Possible naked-eye gamma ray burst detected (GRB 080319B) (http://www.aavso.org/publications/alerts/alert372.shtml)


The intense gamma-ray burst GRB 080319B was detected in gamma ray, x-ray,
optical light, and early indications by two automated cameras suggest that
the optical afterglow of the burst may have briefly reached naked-eye
visibility (mag ~ 5.76, GCN 7445, Cwiok et al) within 60 seconds of the
onset. It is highly unlikely the burst was caught visually, but it is
possible the burst may have been detected if any observers were monitoring
this area of the sky (e.g. for minor planet searching).

:eek:

If you have seen or photographed it, let them know!

Don Alexander
2008-Mar-19, 11:24 PM
Yep.

This is it.

The monster event everyone has been waiting for.

Swift detected a GRB this morning, GRB 080319A. It slewed to the GRB (which was discovered to have a very faint optical afterglow), and several robotic telescope systems observed it too - mostly without results. Several of these systems have wide-field sky imagers that reach 8th - 12 magnitude in single shots, usually a domain where afterglows don't get to.

But not long after, just roughly 10 degrees away, another GRB exploded, and this one was a blast. It's one of the brightest GRBs ever detected!! Since quite a few robots were already pointing in this direction, at least three wide-field systems recorded images before and during the explosion which lastet about a minute. One of these is a video system that seems to yield a time resolution of maybe a second per image or so.

Of course, multiple larger robots then slewed to the GRB, some of them also catching the peak magnitudes.

The peak magnitudes reported still diverge a bit, but the consensus is ~ 5.5!!!

Therefore, as mentioned before, under dark skies it was visible to the naked eye!!!!

Now, the real clou is that the redshift is 0.937!! This means the GRB exploded roughly when the universe was half it's current age, and the distance to the event is very roughly 10 BILLION light years!!!!!!!!!!!!!!!!!

Furthermore, I've just figured out that this event was nothing less than the brightest optical flash ever detected. The luminosoty at peak exceeds 10^17 solar luminosities, so this basically outshines the entire universe for a few seconds. :O

peteshimmon
2008-Mar-20, 12:01 AM
If current theories are correct:)

01101001
2008-Mar-20, 12:55 AM
Sonoma GRB Real-time map (http://grb.sonoma.edu/index.php)

GRB 080319E 2008/03/19 17:05:09 Swift 06:37:55 23:56:00
GRB 080319D 2008/03/19 12:25:56 Swift 17:15:53 55:24:35
GRB 080319C 2008/03/19 06:12:49 Swift 14:31:42 36:18:10
GRB 080319B 2008/03/19 05:45:42 Swift 13:45:24 44:04:44
GRB 080319A 2008/03/19 01:57:09 Swift 16:18:32 -15:16:30

Of course, GodlikeProductions (http://www.godlikeproductions.com/forum1/message522883/pg1) (warning: adult -- juvenile, actually -- language, and lack of critical thinking) has an I'm-freaking-out topic.

Do I see the most on a day, in the last 4 years, was 3 (5 times previous)?

fotobits
2008-Mar-20, 01:46 AM
This is fascinating, and will keep astrophysicists busy for months, no doubt. I look forward to follow-up analyses.

FriedPhoton
2008-Mar-20, 02:44 AM
I imagine this dark room (the universe) in which a flash bulb goes off.

"exceeds 10^17 solar luminosities" <- I can't even comprehend that.

Kullat Nunu
2008-Mar-20, 10:23 AM
Now, the real clou is that the redshift is 0.937!! This means the GRB exploded roughly when the universe was half it's current age, and the distance to the event is very roughly 10 BILLION light years!!!!!!!!!!!!!!!!!

Jeez, you must be kidding!

I was expecting a close one, like a few hundreds of millions of light years.

John Kierein
2008-Mar-20, 11:47 AM
I have my own theory. A GRB must cause a huge ionization. This in turn causes the light from it to be redshifted by the Compton effect. Thus, the GRB redshift is intrinsic and not a measure of distance or velocity of the source. This is the same as the large (nearly 1%) red shift on the sun seen in the gamma spectrum by HESSI during a solar flare. The sun doesn't suddenly temporarily appear at the red shift distance nor does it move away from us. http://sprg.ssl.berkeley.edu/adminstuff/webpubs/2003_ajl_L81.pdf

dr_lha
2008-Mar-20, 07:41 PM
I have my own theory. A GRB must cause a huge ionization. This in turn causes the light from it to be redshifted by the Compton effect. Thus, the GRB redshift is intrinsic and not a measure of distance or velocity of the source. This is the same as the large (nearly 1%) red shift on the sun seen in the gamma spectrum by HESSI during a solar flare. The sun doesn't suddenly temporarily appear at the red shift distance nor does it move away from us. http://sprg.ssl.berkeley.edu/adminstuff/webpubs/2003_ajl_L81.pdf
GRB redshifts are measured using absorption features from their surrounding host galaxy, not from emission lines from the GRB itself. Redshifts seen in GRBs are purely cosmological, not intrinsic, so their estimated distances are sound. GRB 080319B is very bright, and very distant. A truly exciting event.

Kaptain K
2008-Mar-20, 10:05 PM
dr_lha,

This is one of John's "pet ponies", like "pushing gravity" and "intelligent molecular clouds in interstellar space" that he trots out every once in a while!

Oh yeah. Welcome to BAUT!

Squink
2008-Mar-21, 03:00 AM
NASA Satellite Detects Naked-Eye Explosion Halfway Across Universe (http://www.nasa.gov/centers/goddard/news/topstory/2008/brightest_grb.html) -with photos from Swift X-ray and Optical/Ultraviolet Telescope.
Someone caught it with a CCD on their 400mm reflector here. (http://ccder.blogspot.com/2008/03/20080319.html)

John Kierein
2008-Mar-22, 11:10 AM
Wonderful data from "Pi of the sky":
http://grb.fuw.edu.pl/pi/index.html

The coincidence of the optical and gamma radiation within 10 seconds has implications that there is no wavelength dependence on the index of refraction of the interstellar and intergalactic medium.

Doodler
2008-Mar-24, 12:46 AM
I imagine this dark room (the universe) in which a flash bulb goes off.

"exceeds 10^17 solar luminosities" <- I can't even comprehend that.

After a certain point, your ability to see is just completely overwhelmed, so for an individual's understanding, that measure is less one of how really bright the event was, than it is of how REALLY REALLY REALLY REALLY far away anything with some form of vision similar to ours would want to be if they wanted to ensure that wasn't the last thing they ever saw from behind their utterly fried optic nerves.

That kind of bright makes burning magnesium look like moonlight through mirrored sunglasses.

eburacum45
2008-Mar-24, 12:55 AM
Isn't it more likely to have been a highly directional ray from a distant GRB, rather than a flashbulb burst which shone in all directions at once?

winensky
2008-Mar-24, 02:45 AM
Thanks John for that wonderful link. :clap: for the Pi in the sky team and their contribution to the wavelength dependence question. In terms of the overall energy release, This thing was VERY far away. Even if we happened to be in the limited 'cone' of projection, The energy required to create a 5.8 magnitude burst is staggering.

Kind regards
Matt

ryanmercer
2008-Mar-24, 11:05 AM
Nice

broken_arrow
2008-Mar-25, 06:23 AM
More like a laser than a flashbulb, makes you wonder how many of these miss us on a constant basis.

m1omg
2008-Mar-25, 06:11 PM
Just out of curiosity,at which distances it would have to be to completely obliterate the Earth (fully), melt all of Earth, just melt the crust, melt 1 km of the crust, melt crust 1 meter deep,evaporate all the atmosphere, boil the seas, exterminate life,cause mass extintion and cause a cool aurora display visible from the entire Earth while disrupting electronics assuming, that it's luminosity is 1017 Suns?
How it can be calculated?

Kullat Nunu
2008-Mar-26, 09:07 PM
Well, luminosity drops as inverse squared, i.e. if the at the original distance d the luminosity is L (which you need to know), then at twice as far (2*d) luminosity is 1/(L*L) = 1/L2, at 4*d luminosity is only 1/L4 and so on (in other words, the amount of energy drops rather rapidly).

You also must know how much energy is needed to for example to melt the crust of of the Earth; then find a distance at which the energy of the burst is same and so on...

In order to cause a mass extinction, the burst has to within a couple of thousand light years. But to really fry up the Earth it must be located really close.

m1omg
2008-Mar-26, 10:12 PM
http://www.stardestroyer.net/Empire/Essays/Planet-Killers.html

Well, according to this website, the energz needed to completelz destroy Earth would be roughly 5E16 megatons..

Would someone do the maths for me pls?I am no good at maths.

Kullat Nunu
2008-Mar-27, 01:34 PM
Would someone do the maths for me pls?I am no good at maths.

There's a cure for that: study it.

5 1016 megatons? If the BA is right, the Sun produces 100 billion = 1011 megatons worth of energy every second. The GRB released million million million times (= 1018) more energy in the few seconds it lasted (= 1011 1018 = 1011 + 18 = 1029 Mt). In other words, you could blow up the Earth 1029 / (5 1016) = 2 1028 - 16 = 2 1012 times. That's 2 trillion times. Even if the number is a few orders of magnitude off, it is still a mindbogglingly insane number.

antoniseb
2008-Mar-27, 01:36 PM
http://grb.fuw.edu.pl/pi/ot/grb080319b/grb080319b.gif

From the Pi in the Sky camera in Poland.

m1omg
2008-Mar-27, 04:02 PM
There's a cure for that: study it.

5 1016 megatons? If the BA is right, the Sun produces 100 billion = 1011 megatons worth of energy every second. The GRB released million million million times (= 1018) more energy in the few seconds it lasted (= 1011 1018 = 1011 + 18 = 1029 Mt). In other words, you could blow up the Earth 1029 / (5 1016) = 2 1028 - 16 = 2 1012 times. That's 2 trillion times. Even if the number is a few orders of magnitude off, it is still a mindbogglingly insane number.

Ok, but what is the maximum distance where Earth would be still obliterated?Sorry, I don't know how to calculate it.