Sirius A & B – the Pup revealed.

[Dennis]

Hello,

Although the seeing wasn’t too cooperative earlier this morning (11th Nov 2008), nor were the clouds, I managed to grab some images of Sirius that also revealed the position of the Pup, Sirius B.

Due to the poor 5/10 seeing, the image was generally quite unstable, so to remove any potential seeing or system artefacts, I rotated the CCD camera CCW ( approx 0, 90, 180 & 270 degrees) between successive shots, in an attempt to place the Pup in-between the diffraction spikes.

Images taken with a Mewlon 180 F12, TeleVue x4 PowerMate and DMK31AF04 CCD camera. The apparent difference in size of the stellar disc of Sirius A between frames is mainly due to my experimenting with exposures of 1/5 sec and 1/15 second and Gain of 600 and 850. Gamma was set at 18.

Cheers

Dennis

Sirius, aka Alpha CMa, Magnitude: -1.46.
AB: -1.44+8.5 mag
PA 95° Sep 8.38" (2008.9)
Sirius is 9 times more brilliant than a standard first magnitude star.
B is first white dwarf ever discovered; predicted by Bessel (1844) on basis of orbital motion of Sirius, it was first seen by Alvan Clark in 1862, and its peculiar high temperature, small size and great density established by W. Adams in 1925.

[h0ughy]

you my friend are a legend! the presentation and details behind this are brilliant

[Dennis]

Thanks Dave; the gear I use is perhaps more of a legend than the operator – all I need do is set it up and point it in the right direction! :lol:

Here are a couple that I have really “pumped”, to reveal the Pup a little better. They are full size to illustrate what appears on the screen at the time of capture.

Cheers

Dennis

[avandonk]

We used to have a saying that one mans noise is another mans signal! You are that man!

Bert

[leon]

An exceptional image, very well taken indeed, well done Dennis

Leon

[Matty P]

Wow amazing work Dennis. Well done :)

[multiweb]

Wow. That's pretty tight. What's the angular distance between the two at the maximum?

[Dennis]

:lol::lol: Thanks Bert!

There are some amazing tools out there, such as Registax that can literally pluck the Pup from out of nowhere, with a high confidence level that it is indeed the Pup, not some artefact.

In the initial start position there are a couple of concentrations or clumps of light that arguably, could be mistaken for the Pup but when I rotated the CCD, it soon became apparent that the software had indeed found the true Pup.

Cheers

Dennis



Thanks Leon!


Thanks Matt!


Thanks Marc - SkyTools puts it at around 8".

Cheers

Dennis

[multiweb]

Well that's it for me... I can't even guide that good :rofl:

[Octane]

Dennis,

Wow, brilliant. :)

Regards,
Humayun

[seeker372011]

that's a fantastic effort..never fully realised till now how faint the pup is...just knowing magnitudes doesnt tell the tale fully does it

[sheeny]

That's impressive Dennis! Well done.

Al.

[AlexN]

I dont think I've ever seen another image of this Dennis... Well done..

You always manage to bring the unseen wonders into the forums!

[Screwdriverone]

AAAAAAGGGGGGGHHHHH! My EYES :eyepop:

Its too bright! I could see and now I am blind!

Very well done Dennis! Never thought it possible.

We are "Dazzled" by your brilliance.

Interesting diffraction spikes too, I thought it looked like you might have left the hartmann mask in? :lol: Then I re-read your post.

Cheers

Chris

[Screwdriverone]

Oh, and it definitely gets my vote for IIS Image of the week, or even APOD!

Damn straight!

Chris

[alan meehan]

well done dennis a beautifull shot of this amazing couple

[RobF]

Dennis, just wondering, can you actually visualise the pup yourself looking down the scope?
i.e. are the images representative or much more sensitive than what the eye would perceive?

[glenc]

Dennis u r the master of high power imaging.

[Dennis]

Hi Rob

Sadly, although I have been sorely tempted, I tend not to mix visual observing and imaging during a session.

To remove the camera can be quite onerous in terms of having to physically remove it, insert an eyepiece, re-focus for the eyes, re-fit the camera and then re-focus the camera.

The camera cables (power & signal) are usually routed along the mount/OTA and tied up with little slack, so it’s not easy to just unplug the camera to insert an eyepiece. Once you have the target acquired, nicely framed, with perhaps good seeing and precise focus achieved, it would probably take an act of God to cause you to unplug that camera!

Cheers

Dennis

[RB]

I agree with Narayan, knowing the magnitudes alone doesn't give you the full story.
Your brilliant imaging has really shown just how much of a difference there is between the two.

Beautiful work Dennis !!!

[Rick Petrie]

Brilliant capture of this somewhat deceptive visual object.
Well done.:thumbsup:

[jase]

My hat goes off to you Dennis. Miraculous! If you want to get serious with this type of work, get yourself one of Custom Scientific's ND spot filters. It has a neutral density spot in the center of the filter that cuts the light transmission by a defined percentage. Actually, it operates similar to a moon filter, but selective. You can then place the dot over a bright star allowing the binary/companion to be easily measured. It will take the guess work out of the equation and provide an accurate reading. Look forward to seeing more of your gargantuan efforts - they don't seise to amaze. Thanks for sharing.

[atalas]

Great work Dennis !

[Dennis]

Hello,

Thank you all for your posts of appreciation – their contribution certainly extends the enjoyment of my imaging activities.:)

Splitting Sirius A & B is no doubt challenging, something I haven’t yet done visually. Although the images in the previous posts reveal the separation between A & B, they may also be misleading for anyone attempting this visually, as they show the Pup quite well in a couple of the panes.

CCD sensors are very efficient. They only require a few grains of light to clump together at the same x-y position on a few frames, just above the level of any background noise. Then, sophisticated image processing applications can latch on to these dim grains of light to reveal the presence of an object too dim to be easily seen by our eyes.

In my case, seated comfortably whilst looking at a computer screen with the exposure, Gain and Gamma optimised to suppress the blinding glare of Sirius A, is quite different to looking through an eyepiece. After acquiring Sirius on the screen, a good candidate for the Pup revealed itself after a few minutes of comfortably watching the display, despite other “clumps” of light occasionally appearing in differing positions, which were probably seeing artefacts.

Having established the likely position of the Pup, rotating the CCD camera 90 degrees gave me the advantage of knowing precisely where to look next. Sure enough, in those fleeting moments of steadier seeing, the Pup revealed its presence once more. Similarly for the 180 and 270 degree positions.

In review, some of the key success factors were:

Target “movement” is a great aid in finding an object. Now you see it (when the seeing steadies), now you don’t (when the image turns to mush). The unsteady atmosphere acts like a blink comparator!
Sitting comfortably, with eyes relaxed looking at a static screen proved very effective in latching onto the fleeting appearances.
Being able to configure the various image capture settings to tease B out of the overwhelming glare of A is a big plus – something the eye cannot really do at the eyepiece.
Rotating the CCD camera helped confirm I was actually seeing the Pup as it re-appeared in each new location.

So, here is a 4 pane collage showing 4 frames from the same AVI, revealing how fleeting the Pup can be, even to the tireless, efficient and unbiased CCD chip. This is as close I can get to representing how this may look visually, at the eyepiece.

Cheers

Dennis

[strongmanmike]

Great work Dennis, very interesting.

Amazing how in our hobby a magnificent colourful vista or a non descript clumping of pixels can both be so cool - that's astronomy :thumbsup:

Mike

[theodog]

Bugger! Up another notch.:(

Well done Dennis.:D

[Kevnool]

Great work Dennis ( i love it ) .....cheers Kev.

[Dennis]

Thanks guys - these shots give me some hope, as well as much need practice, whilst I perservere with the ongoing challenge of tuning my rig for longer, auto-guided shots of DSO's, weather permitting!

Cheers

Dennis