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The Dog Stars – A tale of Two Pups


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 Right now Sirius B is East-North-East of Sirius A, so it looks that you got it, @IB20, congratulations! Under good conditions it can be done with small scopes. Personally I've seen it with 180mm Mak, 127mm Mak and lately with a 100mm refractor, including last night  when I saw just occasional glimpses of the Pup in moments of stability. Your observation of it with a  76mm scope is very impressive, especially from the UK where it's only 20 degrees in altitude at best.

 

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I've seen it a few times now with the Starfield 102mm. I'll try again the next clear night.

I often wonder if there's an optimum scope size with perhaps larger scopes having too much glare from the dubious seeing conditions we have here?

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38 minutes ago, Nik271 said:

 Right now Sirius B is East-North-East of Sirius A, so it looks that you got it, @IB20, congratulations! Under good conditions it can be done with small scopes. Personally I've seen it with 180mm Mak, 127mm Mak and lately with a 100mm refractor, including last night  when I saw just occasional glimpses of the Pup in moments of stability. Your observation of it with a  76mm scope is very impressive, especially from the UK where it's only 20 degrees in altitude at best.

 

I will chalk it in the possible/probable detection category - very much like my observations of Antares. I like a split to stay stable and split rather than a repeated microevent😅.

I’ve never seen Sirius appear so perfectly white and disc like apart from through the 76Q though. Through an 8” dob it looks like an underwater mirrorball and is horrendous.

Interestingly I couldn’t detect it when I cranked up the mag as much, and it was undetectable when it started to descend in altitude.

I see a lot of Rigel comparisons where observers say if Rigel is easy to view on the night then Sirius should be splittable, but I have split Rigel with every scope I have ever pointed at it. To me it’s a very easy split even in bad seeing. 

With March approaching we’re approaching twilight Sirius in its transit so hopefully I get a lot more opportunity to have a crack at it. By all accounts twilight can remove some of the glare issues from such uneven magnitudes between the pair.

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37 minutes ago, Mr Spock said:

I've seen it a few times now with the Starfield 102mm. I'll try again the next clear night.

I often wonder if there's an optimum scope size with perhaps larger scopes having too much glare from the dubious seeing conditions we have here?

Definitely think this is a thing. My 8” dob makes it look like a dog’s dinner at low altitude through normal UK seeing.

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1 hour ago, IB20 said:

I see a lot of Rigel comparisons where observers say if Rigel is easy to view on the night then Sirius should be splittable, but I have split Rigel with every scope I have ever pointed at it. To me it’s a very easy split even in bad seeing. 

I had read this too and was very surprised to split Rigel in my FS60CB.

I can't help feeling there is a big difference in splitting Rigel and splitting Sirius.

I had a possible/probable on the Pup last year with my 100DC, very similar to your observation. Spotted something often enough in the same position to make me feel I wasn't just seeing things. After putting a description up on SGL it seemed to be in the right place to be the Pup. So I call it more probable than possible 🙂Well done on 'probably' getting it in the 76 @IB20, I think that must class as a very impressive observation.

Your's, and @Mr Spock's Starfield observations give me confidence I should be able to get a more definite split with the 100mm. If only the clouds would let me try 🙂

Malcolm 

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Something I wondered the other day, and this thread seems as good a place to ask as anywhere.  

If you are observing something very bright, like Sirius, The moon, maybe Jupiter etc.  are you actually better off observing it with less of a light bucket scope.  For example, I have a reducer that I fit on the end of the 8" reflector that narrows the opening to just a scant few inches.  I imagine that this then means less light it received.  Does this then help the eye when brighter objects are viewed?  Would a narrower scope actually be more likely to be able to see Sirius B as it wouldn't be flooded by as much light?  NB.  Sorry if this is a daft question, but for some reason it occurred to me the other night.

Edited by JOC
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The problem with planets is reducing the aperture reduces resolution. If you find planets too bright with a large aperture you are better off reducing the light with a filter, like a variable polariser. That way you can keep the fine detail.

With something like Sirius the filter may reduce the brightness but it won't fix the scatter, so reducing the aperture may be a solution. I know due to scatter the 102mm is much more capable of seeing the pup than the 12"; the 12 would be fine if seeing was perfect and Sirius was a bit higher in the sky. Not likely in the UK.

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Great thread….

I managed to split Rigel this evening. I was observing from London and using the FC100DZ with both 12mm Morph & 5mm Nag EPs. I think current separation is circa 9.5” but still quite chuffed to have seen it. Very feint secondary in glare of much brighter primary. I preferred the view with the 12mm, more crisp. 

Edited by PatG
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Spotted Sirius B for the second time in my life yesterday evening, again with the 18" f/4.5 Obsession. The seeing was quite promising - Sirius twinkling just slowly; and in M 42, the E and F stars could be made out easily (E) and with a bit of effort (F). But the Pup was a tough target. Trying a variety of magnifications, up to 400x (10 mmf Ortho+2x Barlow), for more than 45 minutes, I was unable to split the double. Relaxing in between with M 42, M 35/2158 didn't help.Finally, almost desperate, I put Sirius A just outside the western edge of the field of view, tracking continuously very carefully (you can do this, at 400x mag, with a well-kept Obsession!), and got the Pup into view, repeatedly for just a second, and with a clear dark gap to Sirius A. The colour I noticed was slightly green/blue. Helpful with finding the correct direction was the 11.2 star GAIA 29470.... (19-digit number), 1.9 arc min to the E. Very pleased, I finished with the galaxy NGC 2903 in Leo's head, always a nice spring harbinger.

Thanks for reading

Stephan

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  • 4 weeks later...

Had another go at Sirius in lighter skies this evening. As before, there’s definitely something there, just off the shoulder of Sirius. Detected a separate dim dot multiple times very close to Sirius’ disc. Seemed to show “easier” in the lighter sky as wasn’t fighting so much glare. Maybe my brain is now tricking me in to seeing it because I know it should be there, it’s pretty convincing though. 
 

 

5FEC35C4-DBDE-4FE8-8F56-074CBCD90A2F.jpeg

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39 minutes ago, IB20 said:

Had another go at Sirius in lighter skies this evening. As before, there’s definitely something there, just off the shoulder of Sirius. Detected a separate dim dot multiple times very close to Sirius’ disc. Seemed to show “easier” in the lighter sky as wasn’t fighting so much glare. Maybe my brain is now tricking me in to seeing it because I know it should be there, it’s pretty convincing though. 
 

 

5FEC35C4-DBDE-4FE8-8F56-074CBCD90A2F.jpeg

Is that a photo or digital sketch? I just checked in SkySafari and it seems a little too far round to the North in comparison? Hard to be sure of course, I would just keep at it until you convince yourself 👍

D7CE3102-3C91-43FB-B59C-F3D1547B3BDE.png

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12 minutes ago, Stu said:

Is that a photo or digital sketch? I just checked in SkySafari and it seems a little too far round to the North in comparison? Hard to be sure of course, I would just keep at it until you convince yourself 👍

D7CE3102-3C91-43FB-B59C-F3D1547B3BDE.png

It’s a digital sketch. Sirius is in favourable position for me for the next couple of weeks earlier on so I’ll be sure to keep trying for “a split”. I’m certain of detection, however.

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Just now, IB20 said:

It’s a digital sketch. Sirius is in favourable position for me for the next couple of weeks earlier on so I’ll be sure to keep trying for “a split”. I’m certain of detection, however.

Good stuff, very effective way of showing it. I would try to get an accurate judgement of p.a. Then you can be more certain. As said, your sketch shows it around 45 degrees I guess, but SkySafari says 62.5. That may just be an error in recording it but that’s the way to prove it in my view.

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42 minutes ago, Stu said:

Good stuff, very effective way of showing it. I would try to get an accurate judgement of p.a. Then you can be more certain. As said, your sketch shows it around 45 degrees I guess, but SkySafari says 62.5. That may just be an error in recording it but that’s the way to prove it in my view.

I was observing in twilight so around 6:30-7pmish, if that helps?

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25 minutes ago, IB20 said:

I was observing in twilight so around 6:30-7pmish, if that helps?

It doesn’t change with time, the angle stays the same relative to N, changing very slowly over the years.

I’ve clumsily marked up the angle relative to your marked East so you can see what I mean. They are quite different, so it depends on whether your sketch was accurate or not.

DF8B7D23-3D95-4E0D-A8AC-2DC0E676C496.jpeg

2AE93101-DF81-46D9-8EF8-BB4407F2A256.jpeg

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Cool. I get what you’re saying. Well I am drawing on an iPhone with my finger. It’s just a recalled representation of minute glimpses not an at eyepiece sketch. I’m going to try some lucky imaging next time, perhaps with the hexagonal mask trick.

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Interesting catch from a Japanese observer of a “ghost” pup through a 120L Kenko achromat; D=120, L=1000. Very large blue flare in appearance but coincidentally in the correct position but not actually Sirius B.

 

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  • 3 weeks later...

I cant see Procyon's 'dog'  with my Bresser 127L or 12 inch dob, tried last night, the Bresser refused to reveal and the Dob wasnt cooled enough as I de-focused and it looked like the mirror was barbequeing something.

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  • 3 weeks later...

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