Sirius A & B, the Dog Star and the Pup

I had set up the 4-inch TV102 refractor with the intent of sketching M33 in Triangulum last night. As I waited for the galaxy to rise over the trees, I tried to find some really bright galaxies. The light pollution at home in town is a real killer for faint fuzzies. I should have known that M33 would be washed out based on what I was seeing and it was. All I was able to see was a very faint smudge or hazy spot, no detail at all so I did not try to sketch this.

Next I decided to stay up and look at M42 in Orion. This nebula is so bright that with a Orion Sky Glow filter, you could still see the bat like shape. As I was looking at the Trapezium, theta 1, I noticed that both the E & F stars were comming in and out of view as the seeing changed.

As I looked at these stars I remembered a challenge that a friend had given a group of visual observers this past fall. He had challenged us to see if we could see the double star alpha CMa, Sirius the Dog Star and its faint companion the Pup. So since I could see the E & F stars of the Trapezium, I decided to go for seeing the Pup. First I looked at Rigel in Orion to get a feel for the separation, since both this double star and Sirius are both separated by approximately 9 arc seconds. With Sirius being the brightest star in our sky, I needed to know how far away from Sirius to look so I could find this faint star in the glow of Sirius. Knowing that I would have my best chance of seeing this faint companion with a magnification of around 200x, I started with my 4mm eyepiece for a magnification of 220x. Man did that star scintillate. It was just boiling at that high a magnification. There was no chance of seeing the Pup with that high a magnification so I backed off the magnification a good bit. I used my 20mm eyepiece and a Orion 2x shorty plus barlow for a magnification of 88x. The view at this magnification was very nice and steady too. After spending a few minutes looking all around Sirius with averted vision, suddenly there it was. I looked at the Pup for maybe 5 or 6 minutes while I made a sketch of the field-of-view. Then just as suddenly as it appeared it was gone. It was gone for several minutes only to reappear for a shorter period of time. It is funny how the seeing can make a faint star blink in and out of view but it does.  With good seeing it probably would have been easier to see with more magnification but not tonight. The good news is that I can now say that I have seen the Pup with my 4-inch TV102 refractor. Here is my sketch of this double star from last night.


4 thoughts on “Sirius A & B, the Dog Star and the Pup

  1. Buddy,

    I have put off attempting this for too long, and hopefully this will be my year to see the illusive companion.

    Good job!


    • Buddy

      I think that my problem with my Vixen 102 ….attempting too much magnification. I read that you had used less than 100x

      Can’t wait for the next clear night with good seeing.

      Roger Ivester

  2. It will only get easier untill the year 2025. It is a good test for a 4″ refractor now in my opinion. The seperation is an easy distance now but seeing a star ten magnitudes fainter than Sirius is the problem. But hey, I know that you can do it. I look forward to your report once you find the Pup.

  3. Buddy,

    Re: Sirius A and the Pup

    I attempted the other night with my 102 refractor, but Sirius was bubbling from the poor seeing. It is my desire to continue every available night before Orion gets more than an hour beyond the meridian…hopefully this year. I have about 600, 3 x 5 note cards covering all of the objects in James Mullaney’s classic little book (my first reference book) “The Finest Deep-Sky Objects,” however this is the only one that I have not seen.

    Roger Ivester

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