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Crab nebulas's pulsar is blinking (not a joke)

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#1 J-Luc Dauvergne

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Posted 21 August 2010 - 01:01 PM

For my job at Ciel et Espace (the french astronomy magazine), I've tired an EMCCD camera. The electron multiplyng register inside, allow to have a read out noise under 1 electron. So you can realy see every photon recorded by the CCD, even if the time of exposure is very short.
So I've try a quite extrem test : detect the blinking of the Crab's pulsar. The time of exposure is 0,01 s because pulsar turns 30 times per second
Here is the result :
Posted Image
Date were processed by Bernard Tregon http://brizhell.org/pulsar_crabe.htm. The animation is the result of 3 images : an add max, median and an add min process. Raw data are more noisy.
The test have been made at the Pic du Midi observatory with an 1 meter telescope. You need a minimum of diameter because the magnitude is aroud 16.
If you speak french, you can find more informations here :
http://www.cieletespace.fr/node/5750
and in the september issue of Ciel et Espace.
Another test : M3 see throught à 150mm telescope f/9 :
Posted Image
The raw image on the left is à 0,15 s exposure. On the right of have the result of the addition of 950 images.
With a bigger telescope like a 600mm a time of exposure around 0,02s to 0,04 s is enought to see it.

JLuc Dauvergne
http://astrophotography.fr/

#2 Rick J

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Posted 21 August 2010 - 01:29 PM

Very well done.

I remember when Don Taylor cobbled together some very elementary gear in 1969 using a 36" reflector at Kitt Peak and after a failed attempt his grad students finally picked up the visual pulsation but it was seen as a peak on an oscilloscope wave form. Technology moves on!

Don is a very active amateur as well as professional (retired) astronomer and a super teacher.

Rick

#3 tricia

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Posted 21 August 2010 - 01:29 PM

wow, thank you!

#4 bill w

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Posted 21 August 2010 - 01:32 PM

cool

we're going to be able to get some very detailed small scale images soon with the help of these cameras

how much does the camera cost?

#5 J-Luc Dauvergne

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Posted 21 August 2010 - 03:50 PM

It's something like 6500 euros. Quite expensive but not worse than the price of some CCD here.

#6 dickbill

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Posted 21 August 2010 - 03:52 PM

Check Junior-ccd posts, he's using an EMCCD with great results.

#7 J-Luc Dauvergne

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Posted 21 August 2010 - 03:53 PM

Ok, very interesting. Since then the pulsar ahve been directly observed as a blinking objecti with the VLT ( http://lempel.pagesp...ns_le_crabe.htm ) and others télescopes.

#8 jgraham

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Posted 21 August 2010 - 03:58 PM

Wow! That's fantastic!

#9 quantumac

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Posted 21 August 2010 - 04:33 PM

I've often wondered if it would be possible to capture the crab nebula's pulsar actually pulsing with amateur equipment. I guess the answer is yes, although you have to have some pretty sensitive equipment. :)

#10 J-Luc Dauvergne

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Posted 21 August 2010 - 04:59 PM

Ok, interesting, I've found some of his post
http://www.cloudynig...wflat.php/Cat/1,2,3,4,5,6,7,8,9,10/Number/3908880/Main/3907153

In fact he use the Andor Luca, it's the equivalent of the Raptor Merlin, but it seems to me that it's more expensive.

#11 J-Luc Dauvergne

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Posted 21 August 2010 - 05:02 PM

Yes, here the telescope was a professional one, but you can find some amateur telescope that have the same diamter. You juste have to have à good seeing and a dark sky.

#12 Chris Rowland

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Posted 22 August 2010 - 04:03 AM

Robin Leadbeater managed to detect it using a mechanical strobe with a 200mm scope and a modified video camera.

http://www.threehill...ro_image_33.htm

Chris

#13 PatHolland

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Posted 22 August 2010 - 04:22 AM

A fascinating image. Thanks for posting.

#14 J-Luc Dauvergne

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Posted 22 August 2010 - 07:10 AM

Very interesting, and also funy, because this experimentation have also been done in france by amateurs, just fews days before Robin, with the 24" telescope from the Pic du Midi Observatory.
http://www.astrosurf.../cr_mission.htm
http://www.astrosurf...2003/pulsar.htm
What is impressive is that Robin used only a 8" telescope.

#15 Junior-CCD

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Posted 22 August 2010 - 11:27 AM

Hi!

Coolness factor 10 out of 10!

At least I'm not the only one using an EMCCD.

How did you do the timing?

CS, Carsten

#16 J-Luc Dauvergne

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Posted 22 August 2010 - 01:39 PM

Bernard Tregon have made a fourier transformation of the lightcurse of the star, you can see it here : http://brizhell.org/pulsar_crabe.htm
With this curve he has been able to find the frequency of the pulsar. This is not perfect beaucause the frame rate of the caméra is not a very precise data, he has been obliged to make a correction of 2% of the frame rate given with the avi. The main goal was realy to see the star blinking, not to find his frequency.

For a realy scientifical study a GPS datation would be requiered.

Do you know other EMCCD users that observes the deep sky with hight resolution using an EMCCD ? Do they have a web site that we could see ?

#17 Junior-CCD

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Posted 22 August 2010 - 02:22 PM

Do you know other EMCCD users that observes the deep sky with hight resolution using an EMCCD ? Do they have a web site that we could see ?


No, we are a rare species...

CS, Carsten

#18 J-Luc Dauvergne

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Posted 22 August 2010 - 02:58 PM

ok, probably because of the prise, and the small size of the senzore. May be it will evolve, it's still quite new.

#19 robin_astro

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Posted 22 August 2010 - 03:03 PM

Very nice. What is particularly impressive is that with an EMCCD you can do this do this without prior knowledge of the pulsar frequency. When I did it, I had to know the frequency to run the strobe at the right rate. Are the frames in the video individual 0.01sec frames or averaged over several cycles?

I am hoping that someone finds a use for EMCCD technology in consumer products so the price comes down

Cheers
Robin

#20 robin_astro

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Posted 22 August 2010 - 03:07 PM

Very interesting, and also funy, because this experimentation have also been done in france by amateurs, just fews days before Robin, with the 24" telescope from the Pic du Midi Observatory.
http://www.astrosurf.../cr_mission.htm
http://www.astrosurf...2003/pulsar.htm
What is impressive is that Robin used only a 8" telescope.



Yes, I remember it was quite a surprise when I presented my results at the 2004 QCUIAG conference and I found out that we had both been working on the same project at the same time :lol:


Robin

#21 J-Luc Dauvergne

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Posted 22 August 2010 - 04:01 PM

Hello
your stroboscopy experimentation is also very interesting.
Sub frame are 0,01 s but the final result shown here is made from 3 images : an add max, add min and median processing.
Raws datas are more noisy, and the seeing was not perfect, so they clearly show the pulse of the star but it's not so obvious than is this final processing.

#22 amateur

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Posted 23 August 2010 - 02:52 PM

Why was this not done with a gen IV image intensifier before?

#23 UniversalMaster

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Posted 23 August 2010 - 03:15 PM

That is amazing!!

When will all cameras start to use this technology?

#24 J-Luc Dauvergne

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Posted 23 August 2010 - 06:02 PM

I guess it's also possible with a classique CCD and an intensifier. That's not the same principe, but the result should be the same. May be it have ever been done by professionals, I don't know.

#25 J-Luc Dauvergne

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Posted 23 August 2010 - 06:11 PM

I would say that, it's realy not interesting for all kind of applications. With a long exposure time a classical CCD little bit better than an EMCCD, because in this case the read out noise is very low compared to the signal of the object. And with the emccd, the electron multiplying regiter have for result a small dynamic, and that is quite a probleme for a long exposure time.
EMCCD is only interesting for shorts exposures times. Typicaly under few seconds.

May be that the best of the tow worlds are cameras like some Andor for exemple, that have a classical CCD, but with a very low read out noise like 2 electrons if you read the sensor slowly. But it's defenitivly too exepnsive :)


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