See a Supernova From Your Backyard 182
hasanabbas1987 writes "Want to catch a glimpse of the closest supernova astronomers have discovered in the last 25 years? All you need to do is get yourself a small telescope or a pair of binoculars (some DSLRs would do just fine as well). Astronomers think that they may have found the supernova within hours of its initial explosion on August 24. Generally, supernovas are around 1 billion light years away but this one is only 21 million light years away. The supernova is in the Pinwheel Galaxy and you can see it within the Big Dipper."
Discovered within hours of its explosion? (Score:4, Informative)
If a supernova were close enough to be seen within hours of its explosion, we probably wouldn't be here.
Supernova fun! (Score:5, Informative)
Just as a warning to those trying star-hunting for the first time: finding this guy can be tricky. Best thing is to get some charts from AAVSO.org. Use 2011fe as the search. Print a 15 degree chart for finding the general area from the big dipper, then 1 degree and 2 degree charts for finding the supernova.
For now, the supernova is getting easier to find by the day - I tried last week and couldn't find it, but now it's pretty bright. However, finding the correct area can be tough because there's no obvious landmarks in the area unless your sky is dark enough to make out the face of the galaxy. And, unless you live in an exurban or rural area, it won't be. Otherwise, you'll need to rely on patterns of stars at the 1 degree scale. Otherwise, you can easily be looking at the supernova but not know which star it is.
There are good threads over at cloudynights.com that provide helpful images and advice. Good luck all! It's really fun to know that you're looking at something that didn't exist last month (correcting for travel time of the light, of course).
Re:Discovered within hours of its explosion? (Score:4, Informative)
Huge Optics Needed (Score:5, Informative)
Another warning from another astronomy enthusiast: note that the guy in the video talks about "decent-sized" binoculars and then specifies 20x80 or 20x100.
That 100 at the end means the lenses at the front have a diameter of ten centimetres (four inches) each! So under any normal circumstances those are considered HUGE rather than decent binoculars.
My advice on how to see this supernova: ask someone into astronomy who has a telescope or huge binoculars. Doing the observing "from scratch" is probably a too tall order.
Re:Money (Score:3, Informative)
Re:Discovered within hours of its explosion? (Score:5, Informative)
Yet, no time has passed for the traveling light. Or more precisely: if an observer had followed the light emitted from the supernova at almost the speed of light, very little time would have passed in his frame of reference. So what we take as 21 million years would have been nearly instantaneous for our traveling observer. Simultaneity is a weird thing when time is relative.
Re:Huge Optics Needed (Score:5, Informative)
1.6x crop probably means you have a Canon DSLR. All I can say is that you should really explore the manual modes - with digital you can just try different shutter speeds until you get it right. The moon is illuminated by the sun so the settings that work in sunny daylight should work for photographing the moon too.
Photographing stars often isn't a matter of magnification, but rather of light gathering. Only few stars are close/large enough to be imaged as disks, and that's with professional equipment - you'll never resolve a star into a disk yourself.
Rather, stars are point sources. Everything comes from a single point, only the intensity and colour of that point varies. If you want to see fainter stars with a camera, you just need to expose longer. An 18-55 kit lens might very well be able to image this given the right other circumstances. The resolution of 500 mm would be more than enough in any case.
In fact, the hardest problem would probably be to get low enough magnification - the sky moves all the time and therefore everything is blurred when you make the shutter speeds longer. This means you need large apertures more than you need long focal lengths, and pretty fast you need a tripod/mount that's capable of tracking the sky.
Re:Discovered within hours of its explosion? (Score:4, Informative)
It IS different. With a firecracker we have a flash which reaches us 'instantaneously' and then a sound which takes a few moments to reach us. Moreover, different observers with clocks synchronized to a same source would see the flash at the same time (we're ignoring relativity) so they can agree on a universal frame of reference (Earth + UTC time).
With light it's different. We have NO other faster channel. Imagine that you have no way of knowing that firecracker has exploded except by listening to a sonic boom. And you have no faster way to communicate except by shouting.
Re:How Long Do They Last? (Score:5, Informative)
I don't know how long it lasts, but its daily intensity is being plotted here [aavso.org]. From what little I've read, it can be expected to increase like this for ~14 days from the initial explosion
Re:How Long Do They Last? (Score:5, Informative)
A Type 1 supernova reaches it's peak light output around 10-15 days of the initial explosion and then exponentially decays over a period of years. As the curve is exponential, a good chunk of the luminosity is lost within a couple of months and then the loss rate tapers off somewhat.
A type 2 supernova reaches its peak output in a few days decays, plateaus for a few months and then begins decaying again over a span of years.
The mechanism behind a type 1 is fairly well understood but the variation in modeled and observed luminosity is greater than 2%. A paper a few years back suggested that the variation might be evidence of dark matter but subsequent modeling has shown that the 2% variation can be accounted for by where the observer happens to be relative to the explosion as the explosions aren't symmetric.
Re:Discovered within hours of its explosion? (Score:4, Informative)
It did not happen "hours ago" from any reference frame.
Is that really true? Somebody mentioned elsewhere [slashdot.org] in this thread that:
"Yet, no time has passed for the traveling light. Or more precisely: if an observer had followed the light emitted from the supernova at almost the speed of light, very little time would have passed in his frame of reference. So what we take as 21 million years would have been nearly instantaneous for our traveling observer."
It seems that you can define a reference frame arbitrarily close to the speed of light at an arbitrary starting position and get the desired duration.