The protoplanetary disc of Beta Pictoris

[SkyViking]

Hi Everyone,

I remember as a young boy being particularly fascinated by one picture in an astronomy book I had. It was the 1984 image of the dust disc around Beta Pictoris.
This protoplanetary disc of debris and dust is orbiting the star Beta Pictoris 63.4 light years away. This is a very young system thought to be only around 12 million years old and is essentially similar to how our own Solar System must have formed some 4.5 billion years ago. The disc is seen edge-on from our perspective and appears in professional images as thin wedges or lines protruding radially from the central star in opposite directions.

For the last couple of years I have been wondering if it was possible for amateurs to capture this special target but have never come across any such images :question:
The main difficulty is the overwhelming glare from Beta Pictoris itself which completely drowns out the dust disc that is circling very close to the star. Images of the disc taken by the Hubble Space Telescope, and from big observatories, are usually made by physically blocking out the glare of Beta Pictoris itself within the optical path. But recently I then found this 1993 paper 'Observation of the central part of the beta Pictoris disk with an anti-blooming CCD' (Lecavelier des etangs, A., Perrin, G., Ferlet, R., Vidal-Madjar, A., Colas, F., et al., 1993, A&A, 274, 877)
Full article available here: http://adsabs.harvard.edu/abs/1993A%26A...274..877L

I then realised that it might not be entirely impossible to also record this object with my own equipment. So now that Beta Pictoris has risen to a favorable position in this year's evening sky I decided to have a go at it the other day :D
I followed the technique described in the paper above, which basically consists of imaging Beta and then taking another image of a similar reference star under the same conditions. The two images are subtracted from each other to eliminate the stellar glare, and the dust disc should then hopefully reveal itself.

First I collected 55 images of Beta Pictoris at 30 seconds each. The dust disc is most prominent in IR so ideally a better result would be expected with the use of an IR pass filter. Since I only have a traditional IR/UV block filter I just imaged without any filter, to at least get as much IR light through as possible.

Next step was to capture a similar image of a reference star under the same conditions. For this purpose I used Alpha Pictoris as the paper suggested. This star is of nearly the same spectral type (A7IV compared to Beta's A6V) and is also close enough to Beta in the sky so that the change in telescope orientation should not affect the diffaction pattern. However, since the two stars have different magnitudes I needed to calculate how long to expose Alpha for in order to get a similar image which I could subtract from the Beta image. Some quick math:

The magnitude difference between the stars is 3.86(Beta) - 3.30(Alpha) = 0.56
Due to the logarithmic nature of the magnitude scale we know that a difference of 1 magnitude equals a brightness ratio of 2.512. Therefore 2.512 to the power of the numerical magnitude difference then equals the variation in brightness.
2.512^0.56 = 1.67, so it appears Alpha is 1.67 times brighter than Beta. This means that exposure for Alpha should be 1/1.67 = 0.597x that of Beta. I took the liberty of using 0.6x for simplicity's sake...
So I collected 55 images of 18 seconds (30 x 0.6) for Alpha.

Both sets of images were stacked separately in Registax and I then imported these into Photoshop, layered Alpha in 'Difference' mode on top of Beta and flattened the result. This produces a very dark image (which it should!) apart from the different background stars. But after some curves adjustment I was able to see clear signs of the actual dust disc protruding on both sides from the glare of the star. I was very happy to conclude that the position angle with regards to the background stars matched the official images exactly.
This raw Difference image looked rather horrible though, so to produce a more natural looking result I took the original stacked Beta image and then blended in the central parts from the 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 seems better this way.

And the result is, I believe, the first amateur image of another solar system: The protoplanetary disc around Beta Pictoris. I must say it feels really special to have actually captured this.

The actual image is here: http://www.pbase.com/rolfolsen/image/139722640/original
(In the image the dashed line indicates the true disc plane)

Image details:
55 x 30s
10" Serrurier truss Newtonian
ToUCam Pro SC1
Prime focus, no filters


I'm sure this can be done much better with a higher quality camera, but at least here it is. And I'm personally extremely happy and proud of having achieved this :D

Hope you enjoy the view as much as I did! All comments and critique is of course welcome.

Regards,
Rolf

[DavidU]

Amazing Rolf ! Love your dedication.

[Octane]

Superb imaging.

Love your work, Rolf.

H

[Miaplacidus]

And that, Rolf, deserves to go straight to the pool room at JPL!

Sincere congratulations. Brilliant effort, brilliant execution. (And very nicely presented.)

You deserve ten of these...

:bowdown:

and a couple of these...

:party2:

Well done.

Regards,

Brian.

I eagerly await its appearance on APOD!

[ballaratdragons]

and all that with just a trusty old ToUcam :bowdown:

Congratulations Rolf from an old ToUcam DSO imager :thumbsup:
Your results always stun me.

[bartman]

Well done Rolf !!!!
Truly amazing!
Bartman

[RickS]

Wow! Very cool, Rolf.

[atalas]

Congrats and great work.

[gregbradley]

Brilliant Rolf!

Greg.

[astroron]

Shows great dedication to your craft Rolf:eyepop:
Cheers:thumbsup:

[Ric]

Wonderful work Rolf.

An amazing image and I'm sure a first on IIS.

Your an inspiration to all astrophotographers looking for something different to image.

[Dennis]

Hi Rolf

Well, well, well, you certainly do take the path less trodden; another gem so well executed and presented.:thumbsup:

Thanks for bringing these esoteric subjects to these pages; I can’t wait for the next instalment!:)

Cheers

Dennis

[alexch]

Excellent work and a truly amazing result! APOD candidate for sure.

Alex

[multiweb]

Vey cool - extreme imaging. :thumbsup::thumbsup::thumbsup:

[John Hothersall]

Did not think this was possible so congrats on an inspiring hires pp disc.

John.

[strongmanmike]

Great result and write up Rolf, very entertaining reading and viewing :thumbsup:

Mike

[marc4darkskies]

Very cool and very impressive Rolf - love your dedication!

Cheers, Marcus

[kinetic]

Hi Rolf,

I did some imaging over the last two nights in very good seeing
and wanted to show you how I went.

Firstly, I did a few rough calcs of what I was up against and
some comparisons of your imaging setup to mine.

Beta Pic is 63.4 LY away or 4,009,484 AU.
WFPC results on Hubble state the disk is roughly 1500AU edge to edge.

From that I worked out how much of the sky the protoplanetary disk would take up.
Trig gives me approx 1.286 arc mins or 77.16 arc sec.
On your f/5 rig and webcam the disk should take up approx 83 pixels.
Thats quite a substantial chunk of your FOV. All good.

On my f/5 rig and DSI II the disk should take up 66 pixels.
Sounds promising so far...with a sensitive enough chip, a big enough
mirror and a mountaintop we might have a chance.

Here is the BUT......

My camera is 16 bit approx, it has a bigger well depth and is mono
as well, meaning it doesn't have a Bayer matrix of RGB filters.
It is peltier cooled also.

Here are my results:

I stacked 150 frames of Beta and did a difference layer mask blend
over a 150 stack of Alpha.
My exposures were adjusted to compensate for the mag difference
method that you mention.
This method, btw, worked incredibly well as the two stellar disks in
the blend were an exact size match.

A curve adjustment of my image result shows no noticeable disk
that I could confidently say might be the PP disk.:sadeyes:
Notice that I can, (I think due to the sensitivity of my 16 bit setup)
resolve much more fainter detail very close to the star.

I've noted on your image how much 83 pixels extends and
on mine (a 2x upsample), shown how much 66 pixels is (132 pixels on
a 2x upsize)

I hope this doesn't sound like a dig at you Rolf, but I can honestly say
I really think trying to image what is essentially faint zodiacal IR
glow with a 12 bit webcam, albeit SC1.5 modded is a bit optomistic.
I sincerely hope I am wrong, I have admired your extreme imaging for years.

regards,

Steve

[SkyViking]

Hi Steve, I must say it does feel like a bit of a dig even though you say it isn't. Particularly because it's not the first time you doubt my credibility and I'm really not sure what you're implying by your statements.
But since you've had a go yourself and tried to replicate my results then I'll comment on it:

The literature gives the brightness for the dust disc as 15 magnitudes per square arcsecond. I don't know if that's an average, or only for the brightest part (I suspect the latter), but in any case that is well within the capabilities of amateur equipment. I have captured galaxies of magnitude 21.00 in the past. The challenge here is the overwhelming glare from Beta Pictoris.

Have you read the paper that I linked to? This dust disc was imaged with a Thomson THX 7852 CCD, which is now over 20 years old (Imaging area of 208x144 pixels...) Although I don't know the specs of that particular CCD I wouldn't think a modern webcam is particularly inferior in any way, except when it comes to sensitivity.
I also image with the RAW modification so I'm using the full resolution and am therefore not limited by the Bayer matrix other than when it comes to sensitivity.

Remember that what you see in my processed image is not what it looked like in my raw diff image. As I said, I blended in the parts from the diff image that showed the dust disc onto the normal image of Beta. This was after very careful processing, stretching, noise reduction etc. As a result my dust disc is nothing but a diffuse blur, it was indeed very faint in the raw data. I'm not sure what processing has been done to your diff image, but there seems to be a lot more glare and spikes than I had in mine.
Most importantly your diffraction spikes seem to lie very close to the plane of the dust disc. The position angle you have indicated is actually a little off, I have drawn the correct angle in the attached image which is even closer to the spikes. These spikes would probably put a severe limitation to what can be squeezed out of your data.

Also be aware that I have deliberately removed mirror holding clips and anything else that can produce excess diffraction patterns in my system. I'm using a wire spider with 0.08mm wires, which drastically reduces the amount of diffraction glare (see image of the spider here: http://www.pbase.com/rolfolsen/image/134140252). In your image I notice quite a bit of spikes and glare also around some of the other bright stars - I have also marked these in the attachment. There must have been quite a lot around Beta itself and this would again limit the possibilities of detecting the dust disc I think.
Your diff image also doesn't quite seem to line up, I can see quite large signals from the diffraction spikes that seem to have been different for Alpha and Beta and there is also a difference apparent in the stellar discs.

In addition there could be other reasons for the lack of detection in your images. I don't know what exposure time you used. You CCD is more sensitive than mine, so you'd need shorter exposures than I used, probably a lot shorter. Another complication could be if your skies are light polluted, but I don't know if that's the case.

I hope that answers your questions.

Edit: Can't seem to upload images at the moment, will add it later.

[Stevec35]

Very fine work Rolf! Much more impressive than accidentally discovering a globular cluster.

Cheers

Steve

[strongmanmike]

Ooooh cool, some astro contoversy :P....interesting discussion guys, you both make some valid points, lets get to the bottom of it, adds even more interest and intrigue :)

Mike

[sjastro]

That's very cool Rolf.

A discussion on the what is being observed doesn't detract from your efforts, I agree with Mike it adds interest to the thread.

Regards

Steven

[von Tom]

Ummmm...shouldn't this be in the Solar System Forum? ;) Well done with your efforts Rolf!

Cheers,
Tom

[richardo]

Cool stuff Rolf!!
Great write up on a very interesting topic...

Keep up the good work!

All the best
Rich

[kinetic]

Rolf,

firstly, I did read the article, in full.
I did doubt you in the past. I did make that admission to you, in full,
in a pm to that effect, even pasting the content of what my doubts were to a very
experienced imager in the pm to you.
You seemed to be gracious about it back then.:shrug:

Secondly, you seem to discount about 5 aspects of how I obtained my
result. You may be totally correct in that assessment.
I do , however, have a bit of faith in my ability to image at hi res and
down to a reasonable sensitivity to be within the ballpark of a
similar setup like yours.
If you feel like my scrutiny or discussion is not welcome I'll remove it in full.
If you would like to have a go at aligning/processing my raw FITS to see
how you go with them, you are welcome to do so.

On the subject of the initial alignment being slightly off and the disks of
the stars being not equal, I can tell you that perfect align with a 2x upsample
had them exact, before post processing the 'dark' result.
Slightly mis-aligning the difference image made almost no noticeable
difference to the flares that you see.
There are several flares, none any more prominent than the other.
I have stars resolved very close to Beta and Alpha too.
My exposures were 10s for Beta and 6s for Alpha.
Do you think that was too much? I'd like to know how you can estimate
what would be a good exposure for this PP imaging?
The article mentions way different exposures. It was also done with a
very big scope.

Finally, my sentiment at that end of my post stands.
'I sincerely hope I am wrong, I have admired your extreme imaging for years.'
Rolf if I am totally wrong in doubting your result I would be the first
to apologise in this thread.

regards,

Steve

[SkyViking]

Hi Steve,

I provided my opinion on what I could see in your image, based on the information you posted. I don't think it amounts to discounting anything.

The main problem, as I see it, is still that your diffraction spikes lie very close to the dust disc plane. I have attached an image which shows my image overlaid on yours. Notice how the diffraction spikes in your image nearly covers the area where the dust disc appears in mine. Surely that will not help with detecting it.
Reducing the glare is paramount, and I also believe the wire spider I'm using makes a big difference. I don't know what kind of spider you are using but there just seem to be more glare in the images you posted than what I saw in mine.

The second image attached (Kalas & Jewitt, 2000) is a good reference, it's upside down though.

[zipdrive]

Very impressive. Nice Work!

[Dennis]

Nice work Rolf. I am very impressed by your dedication to squeezing the maximum performance out of your set up; the clip-less mirror along with a skinny spider are the hallmark of an obsessive striving for perfection. I just love reading about this stuff.:)

Cheers

Dennis

[Ross G]

An amazing image Rolf.

Ross.

[marco]

Brilliant Rob, this is an outstanding effort and you actually blown out my mind, I would never -ever- imagined it was possible to take such an image with an amateur equipment (and a webcam!) !!

Heat off

:prey2:

Marco

[Ken Crawford]

Very nice work indeed - congrats! I am working on a project trying to detect a bow shock very near a bight star.

One thing you can do is remove the PSF of the star itself using an AstroFractool. This is heavy reading but the results are pretty cool. there is a link towards the bottom to download the tool.

http://staff.polito.it/amelia.sparavigna/Astronomical-astrofractool-web.htm

Regards,

[Ken Crawford]

The larger the secondary the heaver the spiders but some of that is light scatter. I have some on my excellent 20" RC optics. You can get extra scatter from an unmasked edge on the primary, a field flattener or even dirt on the optics. Also poor seeing can cause the star halo area to expand.

If you can use thinner spiders that is excellent but my secondary is almost 8" across (larger than my first 6" reflector) so one cannot use wire to be stable. I fght bright stars with longer exposures so sometimes I will cut my subs down to just overwhelming the read noise.

Even with an expensive excellent system bright stars can be an issue to get a clean star profile. It seems no matter what you pay you have to tweak and modify to get things right.

This is good discussion as it helps us understand how to better utilize our imaging systems.

[SkyViking]

Thank you very much for your comments everyone, Dave, H, Brian, Ken, Bart, Rick, Louie, Greg, Ron, Ric, Dennis, Alex, Marc, John, Mike, Marcus, Steve, Steven, Tom, Rich, Dave, Ross, Marco and KenC. This certainly created a bit of buzz, much more than I expected! :eyepop:


Thanks for that link Ken, it looks very promising I'll have to look into that.

By the way Universe Today ran the story yesterday (http://www.universetoday.com/91283/first-amateur-image-of-another-solar-system/), and today Phil Plait has written a very comprehensive article over on Bad Astronomy:
http://blogs.discovermagazine.com/badastronomy/2011/11/26/amateur-astronomer-glimpses-an-alien-solar-system

Again, thanks for all your comments, I'm glad you liked it. :)

[LightningNZ]

Congratulations Rolf! This is an amazing achievement. I'd just like to point out that this story has made it on to Slashdot.org too:
http://science.slashdot.org/story/11/11/26/1844223/amateur-astronomer-snaps-pic-of-planet-forming-disk

Best wishes,
Cam

[naskies]

Congrats - amazing work!

[iceman]

Congrats on all the publicity this is getting, Rolf. Just need you to mention "IceInSpace" in all your upcoming media interviews ;)

The fact that you've captured it is going to inspire many others to try the same thing, and it's only going to enhance and enrich our hobby.

[alexch]

It made it to the news.com.au frontpage:
http://www.news.com.au/technology/sci-tech/first-amateur-image-of-another-solar-system-captured-by-new-zealand-man/story-fn5fsgyc-1226208187176

Congrats for a truly well deserved recognition of your efforts!

Alex

[SkyViking]

Hi Everyone, thanks again for your comments and greetings. This story has certainly gone around the world, I had no idea it would create such a buzz!
I've lost count of the places it has been published now, and it's been a crazy day today! Just this evening I've had crews from 3News, Dominion Post and Western Leader at the house. Probably spent a good 1 1/2 hour giving interviews and explaning how my telescope works :) Also managed to mention IceInSpace, so hopefully they'll include that somewhere.
It's supposed to run tonight on TV3 Nightline 11:10pm NZST. And be repeated tomorrow morning on Firstline from 6am. Don't know how it'll turn out yet :)

I was also interviewed by Jim Mora live on RadioNZ, the interview is here: http://www.radionz.co.nz/national/programmes/afternoons/audio/2503606/unique-solar-system-photo

And many others have contacted me, including Dr Grant Christie of the Stardome Observatory in Auckland with whom I had a very enjoyable chat this afternoon.

And here I thought astronomy was a peaceful quiet passtime :)

[glenc]

Congratulations Rolf. I read about it here:
http://au.news.yahoo.com/tech-news/a/-/technology/12130523/amateur-captures-new-solar-system-in-stunning-pictures

[SkyViking]

Thanks Glen :)

It was also on 3News Nightline:
http://www.3news.co.nz/Auckland-amateur-astronomer-makes-waves-around-world/tabid/1160/articleID/234500/Default.aspx

They've cut out 90% of it though... I gave an explanation of how the telescope works etc, but what can you do :shrug::lol:

[NorthernLight]

Hi Rolf,

I´ve seen it right after X2 on 3 last night and was stunned by your result.

Your dedication is truly inspiring and I wonder what else you are going to unlock from the domains of the MOA and the like.

Are you a member of the Auckland Astro Society?

[alistairsam]

Rolf,

Very inspiring work. You must be much sought after by the media.
I'm just a beginner, but do work with digital imaging. could you explain the subtraction concept a bit more?

when you overlay images of alpha and beta pictoris, does the visible area around alpha pictoris extend over the dust disc of beta pictoris or is it just the black area in the middle of your image?

what I'm curious to understand is whether the dust disc became visible as lobes only after subtraction and if so how there are no subtracted or black areas as a result of the subtraction outside your central subtracted area?
would you be posting both images before subtraction?
can the same be done with a dslr?

is the black area in your image roughly the same as in the centre of this ESO image? http://en.wikipedia.org/wiki/File:Beta_Pictoris_system_annotated .jpg

congrats again.

[John Hothersall]

Just taken a look at your telescope truss design with ultra thin spiders and no mirror clips which is inspired thoughtful improvement as I am getting sick of the clip shadows around bright stars. Beta Pict gives a clear clean image as a result of this.

John.

[renormalised]

Brilliant bit of work, Rolf. You deserve all the accolades and them some :)

I was thinking...you know that the GStar mono camera has a very good IR response. I wonder how it would go at attempting such an image?. You might want to have a little look into trying one out and see if it works. A mono Flea would also be good. Speaking of IR pass filters, you could try Astrodon's IR pass filters. They seem to do the trick.

[Paul Haese]

Cracking job there Rolf. You always seem to image the way out of left field stuff and it is always of special interest. When people ask me about imaging I always say there are people out there that image things that most people would not think of; and you always come to mind. te point being that pretty pictures is not always the goal of the astro imager. Fantastic achievement and it deserves the accolades you have obtained so far. :thumbsup:

[SkyViking]

Hi All, thanks again for your comments. I have completed a new image with new data and created another thread for it here: http://www.iceinspace.com.au/forum/showthread.php?p=793590#post793590
It's much better than this one so please have a look if you like. I have also written up a lot more details so some of the questions I have been asked should be covered over there I think.


Thanks very much Max, I'm not a member but I would like to be, need to look into that :)
I might get involved in microlensing research, it's very interesting and it would be great to contribute to science in that way.


Thank you Alistair :) The black area in the centre corresponds to the saturated are where the signal reaches the well depth of the chip. Even after subtraction there will be no information hidden there. I'm not sure of the scale of the ESO image since there are no reference stars visible, but my guess is it's about the same size as the light blue circle.

Yes the dust disc is only visible after subtraction. In the new thread I'm showing the difference images etc so you can get a better idea about what I did.


Thanks John, yes the wire spider made a huge improvement to my star profiles. I don't know if a wire spider is absolutely necessary to see the dust disc, I wouldn't think so, but it certainly helps. It all depends on the combination of scope and camera I suppose. The ToUCam is fairly good at picking up IR light too.


Thank you Carl, glad you enjoyed it. Yes I believe other cameras can do this as well, it's probably just that nobody thought to try before. I'll definitely get an IR pass filter at some stage, probably together with a new CCD camera.


Thank you very much Paul :) I have had to make it my mission to image the more obscure stuff because my little chip cannot compete with the modern ones. But I have learned a lot from it and enjoyed it immensely. When I buy a better camera then I'm sure I'll continue in this direction, there are lots of strange things to image :)

[kinetic]

Rolf,

I've done a few more sets on a few more nights, pretty much with no change in my imaging train.

Seeing has been better on two occasions to my initial sets. Still no result for me.
The moon is in the way now for a few weeks so I hope to use the down time to try a few things with the secondary/ spider.

You may be right about the spider vanes.
It's certainly not the primary obscured by clips, and I feel it's also not due to collimation, or collimation
change rather, due to OTA flex when slewing from Alpha to Beta.
See the attached Airy disks of out of focus stars near Sirius (low declination) and stars near the SCP (high
declination).
Almost no change.
I really want to get to the bottom of this and hopefully get a positive result from my rig.
I'm reluctant to turn the entire OTA 10 or so degrees to take the diffraction spikes further away from the PP Disk PA.
And I probably won't if the tests with an alternative spider show no
improvement.
I might even give one of the SC1.5 webcams a go too! :)

Also, it has been remiss of me not to apologise.
I did raise doubts, I followed them up with my own observations, and
until I get to the bottom of it, I really need to apologise for firstly
hijacking the thread, and secondly doubting your results.
I never doubted your abilities BTW Rolf, only your results.

It's also interesting the list Dennis has attached to your better result thread.
I noted the PA, inclination and angular size of a few other PP disks.
It looks like we could have some far easier targets for amateurs, based
on your result with beta Pict.

regards,

Steve

[Dennis]

Hi Steve

I might select one from that list and give it a go with the Mewlon 180 if the weather ever clears in Brisbane. I haven’t had much success with Miranda, one of the fainter moons of Uranus, because of the distinct diffraction spikes from my 3-vane spider (6 spikes) and the plane of Miranda’s orbit always seems to place it on one of the vanes!

Cheers

Dennis

[SkyViking]

Hi Steve and Dennis, I received the following advise from Karl Stapelfeldt, chief of NASA's Exoplanets and Stellar Astrophysics Laboratory:

Beta Pictoris is by far the brightest one. I don't think any of the other discs are going to be easy but they are certainly worth a try.
I got a significantly better image when using shorter exposures of only 7 and 4 seconds for Beta and Alpha respectively. I chose 7 seconds because with less exposure I didn't see any noticeable decrease in the area of saturation unless I went all the way down to something like 0.5s where I'd imagine the disk is definitely not visible. But that depends on the camera's well depth, it may be different for you. It might be worth trying 5 and 3 seconds when you have a more sensitive camera than mine.
Just remember it still has to fit with the factor of 0.59 for Alpha, so depending on how fine you can adjust the exposure times you may choose another number. I can only adjust exposure in 0.5s increments, so I had to choose something that was compatible with that :)

[kinetic]

Thanks for the heads up Rolf re: other disks to try.
I too thought Au Mic was the standout disk to attempt maybe next.

I have made a new spider over the weekend and all I need is
some clear weather:rolleyes:

Steve

[SkyViking]

Here is comparison of Beta Pictoris and AU Microscopii: http://astro.berkeley.edu/~kalas/disksite/pages/aumicvis.html
The image has the same scale for both stars, so it seems AU Mic might be quite a lot more difficult than Beta Pictoris. It will most likely require a lot of experimentation to catch it since the sweet spot between oversaturating the star and picking out the disc will likely be different again in this case.

[kinetic]

Rolf, all,

here is a report on yet another attempt to get this very difficult object,
if only to show what still has not worked for me and maybe help others
with their attempts.:sadeyes:.

A bit of background info first:

I have changed out the spider vanes to thinner vanes yet again.
I have rotated the OTA so that the diffraction spikes are now East/West.
I have captured many sets over four good nights now, last night being
the best recently for seeing. FWHM was reading 1.76 at one point on the
live readout!
Collimation is as good as I can get it.

Now, I have also refined a way to exactly match my darks to lights
as far as CCD temp goes with a better temperature control than I
previously had.
I can keep the CCD at an accuracy of 0.1C whereas previously it was
swinging around a delta of 2C. This much change shows up in results.

Results are below,

I don't think I can say I got anything.

Note the similar diffration patterns in the pre-layered Alpha and Beta raws. This I think, shows that
swinging from Beta over to Alpha has not significantly changed any collimation.

Layer alignment was sub pixel, I was working with the actual 4x resized raws, not these 1x jpgs.

The next thing I'm going to try Rolf is an obcuring disk on the CCD itself
and I will let you know the results. A difficult bugger to be sure!

Steve

[SkyViking]

Cheers Steve,

Yeah it doesn't look like you got it there.
My thoughts are as follows: I can see you used ~70 frames, I think that's too few. I tried a couple of weeks ago using a NIR filter but like you I came up empty handed (more on that below). I did use 500 frames on each though and it really makes a difference for the background noise. My conclusion so far is that the disc is not very bright in IR at all, contrary to what I've always thought. At least it's not bright in the NIR range, but maybe at longer wavelengths.
I did some further reading on it and as far as I can gather the disc is optically neutral, meaning that it simply reflects the same colour of light that hits it. So there wouldn't be any wavelength that offers a particular advantage in contrast between the star and the disc.

I think the best option is to just use no filter at all, so for me I'll need to have another go witout the NIR filter.

Apart from number of subframes you do seem to have some star trailing (the bright double star in the 2 o'clock position looks close to an 8), but I'm not sure if or how that amount of blurring will impact the detectability of the disk.
Also, the disk gets exponentially brighter closer to the star, and the saturated area is quire large. Maybe try shorter subframes and many more of them.
The diffraction pattern is also visibly different between the two stars, though only slightly. But maybe still enough to overpower the faint signal from the disk in the difference image? I think more subframes will help here too. I don't think it's due to collimation changes but it's my experience that all the small diffraction spikes slightly change shape and size under atmospheric influence so it does need to be averaged out over a large number of frames to get a true image of the PSF of your system.
That's what I can think of at this stage. I'll probably try myself again once I get a break in the clouds that coincides with a new Moon.

[kinetic]

Thanks for the comments Rolf,
Here is a result from 27 Nov.

details: exposures for Beta: 5 sec, exposures for Alpha 3 sec.
(that is still a a ratio of 0.6, same as 10sec vs 6 sec for previous attempts)
You state that 0.591 is ideal and your successful attempt was 0.571 with
the critical Beta exposures at 7 secs.
So I'm happy that I'm close to the ideal. Maybe closer to the ideal than you were :)

Difference align was done with 4x resize raws
I've also shown an inset with a deliberate misalign using the same raws.
You can see the same resultant flare pattern after a curve manipulation shows up with both alignments.

Conclusions:
I might have something resembling the PP disk in the correct P.A of the disk.
However, curve adjustment of the difference layer should show anything
'different' in a 'brighter' layer as a brighter feature.
My artifact is darker.

Shorter exposures than 10s/6s and other ratios have shown
a different flare pattern.
Now what has also changed?
I remade the spider with 0.25mm vanes, and made a secondary vane holder and screw adjustment assembly on the lathe.
Laser collimation was spot on. Collimator was also collimated in a vee block as previous.
Also, 27 Nov was a brilliant night, way superior to many recent nights.
You can see how good it was by the 'star' curve I have applied to
the close double star, inset.
Another plus was that all subs were obtained with the CCD sitting at 10.3C for over two hours, both lights and darks.
That is very stable imaging.
I'm confident that this is a fairly tight set of data to use as a benchmark
for future nights.

Confident though :)

regards,

Steve

[kinetic]

Edit:

a bit of an oops moment Rolf !:rolleyes:
I realised I had been stacking crops!! of the main result raws instead of full frames for the latest attachment (27 Nov)
This only clicked when I puzzled over why the 'eclipse' Alpha/Beta dot was so stark and different in size in this set!
(http://www.iceinspace.com.au/forum/attachment_browse.php?a=127541)
Attached is a layer difference with usual curve with the intended 1:1 ratio
of beta Pict raw and alpha Pict raw.
The dark stars are from the Beta frame, white stars from the Alpha frame.
So, by definition, I'm guessing the bright(dark) artifact in the almost correct P.A.
of the P.P. disk is a bright feature (once curves made it stand out) on
the Beta raw.

Hmmmm....

promising :)

Steve

[Regulus]

That is astonishing. Very well conceived and executed.

[kinetic]

Hi all,

I post the following further results in his thread with kind permission from Rolf,

27 Nov results were redone right from scratch.
This is a very good data set. I had let a bad sub slip through
which shows as an elongated blob almost N-S on the central star(s).
I resized all dark calibrated/ BPM subs to 6x and restacked.
Difference layer was performed on the full dynamic range FITs of
Alpha and Beta this time, not a TIF or PNG crop.
Curves were performed on a TIF result.

A second 12th December set was also done.
This was , again , an exceptional night of data.

Same processing sequence was used.

Conclusions:

There again seems to be a promising bright artifact at the approximate P.A. of the protoplanetary disk.
While I am not even close to assuming I have nailed it, it really does
look promising.
I think a lot of follow up imaging needs to be done.
Rolf agrees that it would be great if others could try this technique.

It really is not such an onerous task.
1500mm F.L. imaging with 5-10 sec subs is not that hard.
Cooling a CCD doesnt seem to be a big deal either (the 10C result shows
the same artifact as 19C results).
What does matter is what Rolf has been saying all along:
The spider vanes do need to be thin and well aligned.
The night has to be exceptional seeing, otherwise the PP disk will smear
over more pixels.
IR filters don't seem to matter.
The use of a Baader IR filter has still picked up this artifact.
The timing of Alpha to Beta subs is critical, also as Rolf has been saying.
You can see by brutal manipulation of the difference layer that stars
have rings around them, most notably the central dot of the main stars.
If the timing had been exact, the central star would be black and not reappear after a severe stretch.
That means resolving the PP disk could get better if timing was tweaked
more.
On a personal note, nothing would give me more pleasure after many decades of imaging and observing under the stars, than knowing I
might have captured a protoplanetary disk around a star from a backyard
scope setup. For that possibility I have Rolf to thank for the inspiration.

Steve

[SkyViking]

Hi Steve,

Congratulations to you and thanks for your kind words. I have no doubt that you've captured the disk this time. Particularly the 5th image is very convincing - is it a 3D plot? The contours of the anomaly in your image has a strong resemblance to the 1984 discovery image (image is upside down): http://astro.berkeley.edu/~kalas/disksite/images/bpic84full.jpg

So, now that imaging the circumstellar disk around Beta Pictoris is apparently common routine among (two) amateurs, I wonder what's next... :D

Actually I strongly suggest you create a new thread with your latest post because you've got a significant result, and it's also a scientific confirmation that this can indeed be done routinely by amateurs.
You'd probably also get more response from other forumites than when it's buried in here in the old thread :)

Cheers,
Rolf

[kinetic]

Rolf,

A result from very , very steady skies last night attached.
The plan was to place two finepoint texta dots on the CCD and
try to obscure the central part of Beta.

This was always going to be a bit hit and miss because the dots
weren't exactly opaque, not hard edged, and the optimum place for any obscuring
plate or dot is on the CCD wafer itself, not on the cover glass.

Because of this they were just fuzzy semi opaque dust bunnies.
I did a quick preview on Beta, saw that it was hopeless and because
I didn't want to strip down the camera and clean them off, I proceeded
to just do the normal subtract/ difference method with the dust bunnies
off to the side, out of harms way.
So these full frame results show the smear of the two obscuring texta dots as tracking PE made them oval.

Conditions were brilliant, and I did a few other objects the same night.

As far as the anomaly , I think the diffraction type artifact spiking off at about 4:30 on the clockface is pure diffraction but the two lobes arrowed
are definitely part of the consistent anomaly being picked up, matching the 1984 discovery image you referred to.:thumbsup:

Steve