Go Back   IceInSpace > Images > Deep Space

Reply
 
Thread Tools Rate Thread
  #1  
Old 05-12-2011, 06:32 AM
SkyViking's Avatar
SkyViking (Rolf)
Registered User

SkyViking is offline
 
Join Date: Aug 2009
Location: Waitakere Ranges, New Zealand
Posts: 2,260
New improved image: The Circumstellar Disc around Beta Pictoris

Hi All,

As you may have noticed I managed to capture the first amateur image of the debris disc around Beta Pictoris on 16th November 2011 (see this thread: http://www.iceinspace.com.au/forum/s...ad.php?t=83185).
This image generated a lot of attention from both professional and amateur astronomers and was reported in the media all over the world. I had some fairly hectic days last week and I managed to get IceInSpace.com mentioned a couple of places too, for example in the Space.com article

I have now completed a new and much improved image based on new data. The full details and a couple of different versions of the image are available here: http://www.pbase.com/rolfolsen/beta_pictoris

After the initial success of capturing the disc I was contacted by several people in the astronomy community, among which were Dr Grant Christie of Auckland's Stardome Observatory. Following his suggestions I had a go at imaging it again using shorter exposures. This was to minimise the area saturated by Beta Pictoris itself and potentially reveal more of the debris disc closer to the star. The ICX098BQ chip in the ToUCam saturates fairly quickly for bright stars, even at very short exposures. Since long exposures with my ToUCam can only be controlled in 0.5s increments I decided to use 7.0s and 4.0s for Beta and Alpha respectively, which translates to a factor of 0.571. This was very close to the calculated brightness factor of 0.597 and still significantly shorter than the 30.0s I used for the first image on 16/11/2011.

So for this second image I collected 344 images of Beta Pictoris at 7.0 seconds each and 299 images of Alpha Pictoris at 4.0s each. Both sets of images were dark subtracted and stacked separately in Registax. I then subtracted the Alpha image from the Beta image in PixInsight LE, and also created the absolute difference between the two. It is clear that there is a fairly strong signal corresponding to the exact location of the debris disc and that it is coming from the Beta image.

I created a more natural looking final image by taking the original stacked Beta image and then blending in the central parts from a stretched version of the absolute difference image that showed the dust disc. I decided to also keep the black spot of the central glare from the difference image since the contrast with the protruding disc just seems better this way. So there is no occulting disc involved, it is simply for the sake of presentation. I created a couple of versions which can be seen in the gallery below. This is a vastly better image than the first one taken on 16/11/2011. I believe the higher number of subframes (344 versus 55) coupled with the shorter exposure times are responsible for the improvement.

I used MaximDL to produce some more in-depth illustrations of what is going on in the difference image. First a area plot of the intensity immediately around Beta Pictoris. The circular plateau in the centre corresponds to the saturated area caused by Beta Pictoris itself (The narrow trough immediately surrounding it is an artifact of the image processing). The debris disc is visible as the elevated red areas on each side of the star.
Also attached are profile plots taken both through the debris disc plane and perpendicular to it. The horizontal scale is Astronomical Units and the area saturated by Beta itself is highlighted on the plots.

The visible part of the debris disc seems to extend to roughly 250-300AU before it falls below the background noise levels.
I have found that the limiting magnitude with the ToUCam from my location is around 20.0. So how far out should the debris disc theoretically be visible in my image? Attached is a plot of the magnitude pr. square arcsecond for the debris disc (Smith, B. A. & Terrile, R. J. 1984, Science, 226, 1421 A Circumstellar Disk around Beta Pictoris)
It seems that if a limiting magnitude of approximately 20.0 is assumed, then the debris disc should be visible out to somewhere around 250-300AU. This corresponds with what is seen in the profile plots.

Finally, an annotated crop of the final image shows the extent of the debris disc on both sides of Beta itself.

Some notes on ToUCam and IR sensitivity
The disc is most prominent in IR and fortunately the ICX098BQ CCD chip is very good at picking up signals in IR, probably on par with or even better than some modern CCD's in this aspect.
Another property of the ICX098BQ that helps here is actually the Bayer colour matrix. This is because each pixel either receives only red, green or blue light due to the overlaid Bayer matrix. But since the matrix dyes are practically transparent to IR light, every pixel therefore receives signal from the IR band. So the IR S/N ratio in the final image can be assumed to be correspondingly higher than the RGB S/N. This could easily explain why the ToUCam seems to pick up IR light so well; the Bayer matrix effectively acts like a IR pass filter and allows a proportionally higher number of pixels to be IR illuminated than RGB illuminated.
While I have not tested this in practice it could mean that the limiting magnitude of the ToUCam is higher in IR than in RGB.

Hope you enjoy, I have certainly had a lot of fun with this lately.

Regards,
Rolf
Attached Thumbnails
Click for full-size image (140084589.lE26VRBR.BetaPictoris30112011finalADD.jpg)
102.0 KB211 views
Click for full-size image (140084587.vD06BgJy.BetaPictoris30112011finalXOR.jpg)
105.1 KB203 views
Click for full-size image (140084590.KrRbTIs6.Annotatedzoom.jpg)
44.0 KB231 views
Click for full-size image (140084596.bRcLaW6o.BetaminusAlpha.jpg)
81.2 KB179 views
Click for full-size image (140084597.nfYHMmFY.Absdifference.jpg)
112.6 KB191 views
Click for full-size image (140084594.LSKUJkJw.Profilepresentation.jpg)
177.1 KB170 views
Click for full-size image (140084713.fagany6z.Discprofile1984.jpg)
68.1 KB138 views

Last edited by SkyViking; 12-12-2011 at 09:25 AM.
Reply With Quote
  #2  
Old 05-12-2011, 06:45 AM
iceman's Avatar
iceman (Mike)
Sir Post a Lot!

iceman is offline
 
Join Date: Sep 2004
Location: Gosford, NSW, Australia
Posts: 36,760
Fantastic presentation Rolf. The extra images are great.

You might want to fix up the link to the gallery - it's trying to go the 'edit' view.

Well done again for this groundbreaking image and all the success that has and will follow. I love seeing people push the boundaries of what we thought was possible.
Reply With Quote
  #3  
Old 05-12-2011, 07:19 AM
SkyViking's Avatar
SkyViking (Rolf)
Registered User

SkyViking is offline
 
Join Date: Aug 2009
Location: Waitakere Ranges, New Zealand
Posts: 2,260
Thanks very much Mike. I've updated the link
Reply With Quote
  #4  
Old 05-12-2011, 10:35 AM
Miaplacidus's Avatar
Miaplacidus (Brian)
He used to cut the grass.

Miaplacidus is offline
 
Join Date: Jul 2005
Location: Hobart
Posts: 1,235
Yep, Rolf, you've got my vote for Astronomer of the Year.
Reply With Quote
  #5  
Old 05-12-2011, 11:08 AM
astroron's Avatar
astroron (Ron)
Supernova Searcher

astroron is offline
 
Join Date: Mar 2005
Location: Cambroon Queensland Australia
Posts: 9,313
Wow Ralf, brilliant
What will you come up with next?
The mind boggles
Cheers
Reply With Quote
  #6  
Old 05-12-2011, 11:24 AM
strongmanmike's Avatar
strongmanmike (Michael)
Highest Observatory in Oz

strongmanmike is offline
 
Join Date: May 2006
Location: Canberra
Posts: 17,152
I think the I's have it

Great project and nicely followed up Rolf

Mike
Reply With Quote
  #7  
Old 09-12-2011, 02:44 AM
square_peg114GT's Avatar
square_peg114GT
Registered User

square_peg114GT is offline
 
Join Date: Aug 2005
Location: Maple Valley, WA, USA
Posts: 98
Superb work, Rolf! You've really raised the bar.
Reply With Quote
  #8  
Old 09-12-2011, 07:27 AM
Dennis
Dazzled by the Cosmos.

Dennis is offline
 
Join Date: May 2005
Location: Brisbane
Posts: 11,704
Hi Rolf

Thanks for the follow up work and explanations, it has been quite an adventure just reading about your exploits.

I cannot imagine what you must have felt like in exploring the concept and possibilities of attempting this, and then achieving it so well.

Just in case you are wondering what to do next, here is a list of other resolved circumstellar disks that await your attention!

Cheers

Dennis
Reply With Quote
  #9  
Old 10-12-2011, 09:46 AM
PeterM
Registered User

PeterM is offline
 
Join Date: Jun 2006
Posts: 1,997
Been watching both threads with interest.
What can I say that hasn't already been said Rolf. Mind blowing, Gobsmacked or just plain old WOW. Setting the path for other amateurs to follow. It never ceases to amaze me what amateurs, amateurs? did I say amateurs? can and do accomplish - you will never never know if you never never go - simply inspiring.
Reply With Quote
  #10  
Old 11-12-2011, 08:24 AM
Ross G
Registered User

Ross G is offline
 
Join Date: Apr 2007
Location: Cherrybrook, NSW
Posts: 5,006
Amazing work Rolf.


Ross.
Reply With Quote
  #11  
Old 11-12-2011, 08:35 AM
multiweb's Avatar
multiweb (Marc)
ze frogginator

multiweb is offline
 
Join Date: Oct 2007
Location: Sydney
Posts: 22,060
That's a milestone in amateur astronomy and you've got your name on it. That's what pioneers do. Kudos to you.
Reply With Quote
  #12  
Old 12-12-2011, 05:39 AM
SkyViking's Avatar
SkyViking (Rolf)
Registered User

SkyViking is offline
 
Join Date: Aug 2009
Location: Waitakere Ranges, New Zealand
Posts: 2,260
Quote:
Originally Posted by Miaplacidus View Post
Yep, Rolf, you've got my vote for Astronomer of the Year.
Thank you Brian, glad you liked it

Quote:
Originally Posted by astroron View Post
Wow Ralf, brilliant
What will you come up with next?
The mind boggles
Cheers
Thanks Ron, I'm not sure what's next but I have borrowed an ST-7 from Auckland's Stardome Observatory so I'll play around with that if it clears up here. Now the clouds have rolled in for the next while it seems...

Quote:
Originally Posted by strongmanmike View Post
I think the I's have it

Great project and nicely followed up Rolf

Mike
Thank you Mike I was surprised that my second image turned out so much better, but I think this target is quite sensitive to exposure time versus well saturation etc. There seems to be a sweet spot which is probably different depending on which camera/scope is being used.

Quote:
Originally Posted by square_peg114GT View Post
Superb work, Rolf! You've really raised the bar.
Thank you very much Pegster

Quote:
Originally Posted by Dennis View Post
Hi Rolf

Thanks for the follow up work and explanations, it has been quite an adventure just reading about your exploits.

I cannot imagine what you must have felt like in exploring the concept and possibilities of attempting this, and then achieving it so well.

Just in case you are wondering what to do next, here is a list of other resolved circumstellar disks that await your attention!

Cheers

Dennis
Thank you Dennis, it has been an adventure for sure! Very exciting project, and I never thought so much would come out of it.

I received some advice regarding the list of circumstellar discs from Karl Stapelfeldt, chief of NASA's Exoplanets and Stellar Astrophysics Laboratory which I posted to you and Steve over in the other thread. I'll repeat it here since it may interest others:
Quote:
Originally Posted by Karl Stapelfeldt
Let me advise you a bit on which disks to try in the catalog. Many of them are only detected at radio or infrared wavelengths, have been tried with Hubble in visible light and not seen. You'd only be frustrated with those, so let me steer you away from them. For your equipment you need disks that are bright and large. I see that you are in New Zealand. The best targets to try for these criteria are AU Mic and HD 15115. Both are a good bit fainter than beta Pic though.



Quote:
Originally Posted by PeterM View Post
Been watching both threads with interest.
What can I say that hasn't already been said Rolf. Mind blowing, Gobsmacked or just plain old WOW. Setting the path for other amateurs to follow. It never ceases to amaze me what amateurs, amateurs? did I say amateurs? can and do accomplish - you will never never know if you never never go - simply inspiring.
Thank you very much Peter I always enjoy a stroll off the beaten path, you never know what might turn up. The best thing is that I've gotten quite a few messages from beginners having read the story and saying that this is what has prompted them to now go out and buy their first scope or camera

Quote:
Originally Posted by Ross G View Post
Amazing work Rolf.


Ross.
Thank you Ross, glad you enjoyed it

Quote:
Originally Posted by multiweb View Post
That's a milestone in amateur astronomy and you've got your name on it. That's what pioneers do. Kudos to you.
Thanks very much Marc It feels great to have achieved this. Who knows, in time it might be a regular occurrence for amateurs. Maybe someone can even discover a new disc one day.
Reply With Quote
  #13  
Old 12-12-2011, 08:42 AM
gregbradley's Avatar
gregbradley
Registered User

gregbradley is offline
 
Join Date: Feb 2006
Location: Sydney
Posts: 17,877
That link to the image does not work for me. It takes me to your log in to edit page instead of the image.

Greg.
Reply With Quote
  #14  
Old 12-12-2011, 09:26 AM
SkyViking's Avatar
SkyViking (Rolf)
Registered User

SkyViking is offline
 
Join Date: Aug 2009
Location: Waitakere Ranges, New Zealand
Posts: 2,260
Thanks Greg, I though I'd fixed it already but apparently not. It should work now
Reply With Quote
  #15  
Old 12-12-2011, 09:55 AM
gregbradley's Avatar
gregbradley
Registered User

gregbradley is offline
 
Join Date: Feb 2006
Location: Sydney
Posts: 17,877
Thanks, that worked. I like the coloured one. It makes the disc show up really well.

Fabulous work.

Its a wild concept that you can image a disc from such a distance.

Greg.
Reply With Quote
  #16  
Old 13-12-2011, 02:04 AM
Enrique
Registered User

Enrique is offline
 
Join Date: Dec 2005
Location: Singleton
Posts: 138
Rolf:

I have been following both threads with interest and admiration,

Regards,

Enrique
Reply With Quote
  #17  
Old 20-12-2011, 05:17 PM
SkyViking's Avatar
SkyViking (Rolf)
Registered User

SkyViking is offline
 
Join Date: Aug 2009
Location: Waitakere Ranges, New Zealand
Posts: 2,260
Thanks guys, glad you liked it. It was a very interesting project with a great outcome indeed. I plan to try some other circumstellar discs once the clouds clear here. I haven't checked though if any of the promising candidates currently are in a favorable position from my obs (I can't see the western sky very well from where I am).
Reply With Quote
  #18  
Old 17-12-2012, 10:46 AM
Poita (Peter)
Registered User

Poita is offline
 
Join Date: Jun 2011
Location: NSW Country
Posts: 3,586
Would results be better/easier with a different camera?
Reply With Quote
Reply

Bookmarks

Tags
beta pictoris, newtonian, rolf olsen, toucam

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 07:51 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Advertisement
Testar
Advertisement
Bintel
Advertisement