Sirius A+B

[johnh]

SPX350 F33.1  11,585mm,  PGRFlea3, Baader LRGB filters.

This is a great visual challenge as the white dwarf companion B has widened to 9.8" and needs a blue filter to see visually.  I live here in Australia and Sirius gets right overhead.  I decided to give it a quick go with my planetary ccd and could see it on screen in the luminance filter.  FL of at least 6-8 meters with a fast frame ccd needed - I used 16fps for all four filters.

Many in the UK have had success during twilight with Sirius separation visually, but it will get easier in the next 10-15 years widening to 10.4" - it has a 50 year period.

Thanks for looking, John.

[xtreemchaos]

great shot of one of my favs,heres one i took with my ed80, not sure which is companion B  in mine. thanks for sharing charl.

[jsmoraes]

John, What was the resolution (image scale) in arcseconds per pixel of your image ?
There is a star very near Sirius that many people think it is Sirius B.

My equipment (GSO 305 mm - Canon 1100D plus 1.14x barlow from my Coma Corrector) give me 0.65 arcsec per pixel.
You said the separation is around  9.8". To separate Sirus A and B I will need around 15 pixels. And normally my image of Sirius A has more than these 15 pixels in diameter.

Your Sirius A is very bright and shows spikes. Maybe that litle star isn't  Sirius B.

[jsmoraes]

I never got separate Sirius, because of difference of magnitude between them.

Apparent magnitude:
Sirius A  -1.46
Sirius B  +8.44

Alpha Centaurus A  +0.01
Alpha Centaurus B  +1.33

I did Alfa Centaurus with 5 arcsec of separation but with less difference of magnitude. Look how it appears for me with resolution around 0.8 arcsec per pixel (GSO 305 mm Canon Rebel XT Coma Corrector.

And with GSO 305mm - ASI120MC - resolution around 0.5 arcsec per pixel.

[jsmoraes]

It seems don't be Sirius B. The image scale is around 0.086 arcsec per pixel. Am I wrong ?

[johnh]

Hello RJ, my imaging scale is 0.1-0.09"/pixel at 11.6 meter fl (from ccd calc).   I got 9.8" from internet, but wikipedia orbit image puts it at a little over 10" as does another image of the orbits.

You need less than .2"/pixel to get it and blue gives the brightest image while red is very faint indeed.

 

I imaged Sirius B in 2011 with my Mintron 10.4m fl and 0.16"/pixel and my image was used in Sky&Telescope - image below.  I also got Alpha Centauri at 6" separation about the same time beginning of 2011 with the same planetary ccd - the Flea3 is very sensitive.

Regards, John.

[jsmoraes]

Wow ! "... my imaging scale is 0.1-0.09"/pixel at 11.6 meter fl..."  I never thought that this imaging scale was possible with the qualilty of image you did.
I have difficulty with my resolution and refraction. I would like a 400 mm but I gave up because this. You should have a good site to shot, with very stable atmosphere.

With your information I must congratulate you for share the image you did. It is impressive by its quallity.

[xtreemchaos]

hey guys, i know ive only a 80mm frac, but a qwick yes or no or even "your outa your mind " would do charl.

[jsmoraes]

Perhaps, xtreme, since John told that "...You need less than .2"/pixel to get it and blue gives the brightest image while red is very faint indeed. "

If I take the nearest star, your image scale is around 0.12 arcsec per pixel.

We need know what was the real image scale to be sure.

 

Only me don't (or didn't) get it, yet !

John, I read about the camera Flea3 ... wow ! Very nice camera and not expensive ! I must wait for a better exchange rate (now is 4 x 1) to think import one.

[johnh]

Hello xtreemchaos, I think an 80mm refractor will not work it does not have the oomph.  I used a 14" newtonian and blue filter at 320x in 2011 from Australia when Sirius was at 60 deg altitude and it peeked out of the diffraction spike quite strongly but a 8-10" newt may work.  Visually glare is the biggest problem that's why I used a blue filter as Sirius B is a bit bluer than the bright A.

The thread in 2011 was a popular one with many trying it and some succeeding from the UK where Sirius is quite low.

https://stargazerslounge.com/topic/87191-sirius-b/

Thanks JS,  but check the link above for my 2011 thread.  My Flea3 planetary ccd is meant for bright objects similar to the ASI you have.  Finding even the brightest star at this long fl takes patience but I do it with planets so not too difficult and focusing at this focal length takes quite a while and even with no wind the scintillation moves the bright star around quite a bit.

Regards, John.

 

[xtreemchaos]

thanks John, yer i though asmuch,but i didnt know before i asked ,i have a AR127l frac do you think id stand a chance with that and say 3x barlow or is deff a job for a big newt? thanks charl.

[xtreemchaos]

thanks JS, i see the problem now mate A is so bright and that at the small distance that B is from A i wouldnt be able to see it over A,s brightness. thanks charl.

[jsmoraes]

Sory, Charl. I sent your full image to Astrometry.net and they say : Pixel scale: 1.64 arcsec/pixel.

http://nova.astrometry.net/user_images/1013978#annotated

[johnh]

Yes charl some have had success with 5" refractors some have failed with 8" sct, remember it was discovered with an 18" refractor in 1862.  It is very difficult a challenge in fact but your best chance is at twilight most success seems to be at this time as Sirius is not so glarey as with dark sky the glare eats up the pup B.  Even at twilight it will poke in and out of the glare unless seeing is perfect.  Magnification 200-250x or near.

One person saw it in a 4" refractor but this is not realistic.

John.

[xtreemchaos]

thanks John, ill givie it a go with the 5inch frac, yer never know might get lucky. thanks for your advice.clear skys charl.

[xtreemchaos]

thanks JS,  the plan its to try with my 5inch frac.thanks for your advice,charl.

[chiltonstar]

Nice image John!

I've imaged it a few times with my 5" Mak and a webcam (the sep and PA are correct), and can see it visually even with my ED80 on exceptional nights (others quote the same experience on CN). easier with my 180 Mak, of course.

Chris

[FranckiM06]

Wow, it is great shot John. Congratulations for this image. I would like to get the same result with my refractor and the Powermate x4 but I don't know if I can get something.

Franck

[laudropb]

This has been a very interesting discussion and thanks to all for contributing.