What do you estimate is the field covered in your pictures?
There's another informative Sirius A and B Split thread, you may want to check that out. I haven't been able to accomplish the split yet. The details given regarding your accomplishment is appreciated.
Regards,
Thad
Quote:
Originally Posted by solissydney
Using my 8 inch Celestron Ultima at prime with Canon 300D ISO 100 at 8 sec exposure I captured Sirius A & B.
Separation between the two varies between 2 arc-seconds and 10 arc-second, as the 8th mag white dwarf orbit Sirius on its 50 year journey.
Minimum separation was in the mid 1990s, since then the pair has slowly drifted apart again. Over the next few years the pair will be at about 8 arc-second separation, giving us plenty of opportunities to enjoy the most challenging binary star, challenging, because of the huge difference in brightness between the two. I choose my 8 inch scope in order to avoid the spikes.
Hmm...
If we assume the current distance between A & B is 7", with 350D in prime focus (FL 2000mm) you should have 10 pixels distance between A and B. But on your image it is much, much more...
Did you use barlow?
Because 300D has larger pixels, the distance between A & B should be even less (~8, expressed in pixels).
I think this star close to Sirius is not a Pup...
Bojan, A thought has occurred to me. In the past , when taking images of stars I would get similar artifacts, like the tiny star on my image. Aaaarghh. not again. Back to using film??? It must then be an internal reflection!
Thanks for working this out Bojan.
Regards
Ken
That is easy to confirm.. Just take a pic of some other bright star, and see if there are artifacts. I am sure they will be visible in eyepiece too.
Celestron, being a cathadioptric system, certainly will suffer from internal reflections, especially visible near such bright objects.
My MTO1100 has them too (well, this is not a very good comparison, but still..)
I must admit that I was suspicious because I know that Alvan Clark needed 50cm scope to see it back in 19th century...
I appreciate the opportunity to participate in this forum.
Although you may not have imaged Sirius B, I think you did capture a real star. I believe you have imaged one of a few 9th to 11th magnitude stars that are 1-4 arc minutes or so separated from Sirius. I've snapped a couple of them with my Celestron C11 and have not noticed such an artifact. If you could identify North and East or West in your pictures we might identify it.
There is some nice work from a French professional astronomer, Bonnet-Bidaud (http://www.obspm.fr/actual/nouvelle/bobi.en.shtml) from the year 2000 which discusses the starfield near Sirius. Dennis and Vicent in the other IIS thread, Sirius A & B Split, have some nice pics.
Hi Thad,
This is an interesting website..
Re Sirius and surrounding starfields, I found this: http://www.obspm.fr/actual/nouvelle/bobi.en.shtml
With the help uf this webpage and knowing Ken's camera scale, the star he thought it was a Pup can be identified, I presume it is the brightest one on the right side of the image.
I also tried to download HST guide star cat for the area withing CdC, but of course, there is almost nothing around Sirius (because of it's glare).
Anyway, this is a very interesting and intriguing problem :-)
Looking forward to the new pictures. We're getting some much needed rain in North Carolina, so no chance for observing for the next week.
Sirius will soon be behind the trees in my observing site, but I hope to get a couple of more chances this spring. I'm going to try adjusting my webcam settings so as not to overexpose each frame and collect 3-4 minute .avi files in another attempt to capture the Pup. A separate exposure, during which I turn off the drive briefly defines West. If that doesn't produce results, next season I'll be looking into a better camera and maybe try a hexagonal mask.
