Sirius, Rigel and CastorPosted By Roland Christen |
Last night was clear and quite steady in the hour after sunset. I had never seen the companion of Sirius before at my observatory, so I swung the 8" EDF refractor into action, with 6mm and 4mm Zeiss Abbe Ortho oculars.
Just after sunset in the deepening twilight I saw the Pup sitting quite nicely removed from the primary, visible about 80% of the time as the skiy steadiness ebbed and flowed. Even though the star is only about 30 degrees above the horizon here, myself and Howard both saw it almost immediately, off to the right side. A quick look at the star chart confirmed that it was indeed the Pup.
What made it possible to see it visually was a little known accessory that Valery Deryushin (Aries Optics) sent me some years back. This is a special mirror diagonal with a variable prism that can be tuned to exactly cancel out the atmospheric refraction, which is quite noticeable at that low altitude.
In any case, I figured that if I could see it, I should be able to image it. I put up my trusty STL11K camera and the very first shot at 0.3 second exposure with a narrowband OIII filter showed the secondary quite clearly. The attached image was taken with an H-a, OII and normal Blue filter to achieve the RGB image. I also decided to image Rigel, which has similar separation, and Castor, which is a closer double.
All images were processed in MaximDL, 100 seperate sub-second exposures of each color stacked. The images were then scaled up by a factor of 4.17.
Rolando
Just after sunset in the deepening twilight I saw the Pup sitting quite nicely removed from the primary, visible about 80% of the time as the skiy steadiness ebbed and flowed. Even though the star is only about 30 degrees above the horizon here, myself and Howard both saw it almost immediately, off to the right side. A quick look at the star chart confirmed that it was indeed the Pup.
What made it possible to see it visually was a little known accessory that Valery Deryushin (Aries Optics) sent me some years back. This is a special mirror diagonal with a variable prism that can be tuned to exactly cancel out the atmospheric refraction, which is quite noticeable at that low altitude.
In any case, I figured that if I could see it, I should be able to image it. I put up my trusty STL11K camera and the very first shot at 0.3 second exposure with a narrowband OIII filter showed the secondary quite clearly. The attached image was taken with an H-a, OII and normal Blue filter to achieve the RGB image. I also decided to image Rigel, which has similar separation, and Castor, which is a closer double.
All images were processed in MaximDL, 100 seperate sub-second exposures of each color stacked. The images were then scaled up by a factor of 4.17.
Rolando
