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Has anyone seen the "pup" ?

John

By John
in Observing - Discussion

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John

John

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I've been reading about Sirius and it's 9th magnitude companion, Sirius B, also known as the pup. The separation between the 2 stars is around 7 seconds of an arc I believe but the real challenge is that Sirius is 10,000 times as bright as the pup. I've read reports of quality 5" apochromats being able to detect the pup in exceptional conditions and of specially designed aperture masks being used to reduce the glare from Sirius A.

I wonder if any SGL members have managed to see the pup ?. Another challenge for us in the UK is that Sirius does not get that high above the horizon :)

I've looked for it on quite a few occasions myself through different scopes but with no success yet. I've not tried any special tricks yet though so there is hope yet I guess.

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Demonperformer

Demonperformer

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I have never actually seen it myself, but I have heard that one of the easiest ways is to get one of those cheap filters that produces spiky effects [starburst filters?]. The trick is then to rotate the filter until the pup is between two of the spikes of the main star. As most of the light from the primary is diverted away from the secondary, it becomes easier to see. imho the effect produced is a horrible one, so have never attempted it myself, but I pass it on for what it's worth.

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James

James

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I've been too immersed in imaging this year (well, immersed

in cloud more like) to give it a go but I tried last year to no avail. I'm kicking myself a bit as I had a night of fantastic seeing a week or so back and got great views of Mars but didn't think of looking for the Pup. Next clear night I get I'll try again :)

James

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brianb

brianb

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I'm kicking myself a bit as I had a night of fantastic seeing a week or so back and got great views of Mars but didn't think of looking for the Pup. Next clear night I get I'll try again

It's a real beast, you need excellent transparency as well as good seeing, the slightest trace of haze will spread the light from the primary around & prevent any chance of seeing the Pup. A triangular aperture stop is said to help, by spreading much of the light from the primary into a hexagonal diffraction pattern - if rotated correctly, the Pup will be between the spikes. But I haven't seen the Pup, except with an occulting bar in the eyepiece on an exceptionally transparent night with reasonable seeing - I was using a 6" reflector. The Pup is reasonably bright & the seperation is reasonable, it's the glare from the primary that's the issue.

Whatever eyepiece you're using should be well exorcised, too (see your local priest :) ) - "ghost" images play havoc with this sort of observation. A monocentric is ideal but a Baader Genuine Ortho works pretty well.

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Andrew*

Andrew*

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Good challenge! I'd love to try this. Is not the most sensible thing to put Sirius just out of the FOV?

The field stop on my Zeiss orthos is razor sharp, and there are no ghosts of course. The ED120 should be a good tool for the job as well.

Should you just go for the highest magnification the seeing will allow, or is there an optimum mag.?

I'll have to remember to have a go next time.

Andrew

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Doc

Doc

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I've tried numerous times John and had no luck. I did place Sirius just outside the fov as well but still couldn't split them. The problem is the glare from Sirius, it just washes everything out.

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Moonshane

Moonshane

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I've tried a few times myself to no avail. no special techniques (just squinting to avoid the glare of Sirus!).

I cannot even see the companion of Procyon properly yet (well I tried and thought I saw it once but not for sure).

will try again though - the triangular mask sounds interesting.

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Towa

Towa

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Here is an observation I made of the pup with an APO refractor using powers from 100 to 200x. You will only see it on nights of the very best seeing, and giving the altitude of Sirius, these tend to be few and far apart, but it is possible.

post-17619-133877425086_thumb.jpg

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John

John

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Interesting responses and congrats to Towa for the only reported sighting ...... so far !.

I'm going to keep trying when conditions allow and perhaps try out some "dodges" if I can devise some. I was wondering about building an occulting bar into an eyepiece at the focal plane - something with variable thickness if I can come up with that.

I like a good challenge :)

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afm038

afm038

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I haven't actually tried visually or photographically but saw an interesting image recently in Astronomy magazine (October 2009) from Damien Peach that shows Sirius and the pup. It was from a stack of 1800 frames done with his SKYnyx camera, not sure if it was done in the UK though.

Andy

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John

John

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Well, I've just been trying to no avail... there's nothing wrong with the seeing, stars A to F are visible in the Trapezium. Sirius is just too bright... ;)

James

Thanks for trying anyway James. I'll give it a go when I next get a chance but I'm not too optomistic.

I'm going to read up on "occulting bars" though - that might just be the key to it ;)

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brianb

brianb

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I'm going to read up on "occulting bars" though

Straightforward, with most eyepieces. There is a field stop at the "objective" end of the eyepiece, this usually unscrews for the purpose of getting the field edge sharply focused. Remove it & tack something opaque across the field stop - anything flat will do, a strip of black craft card is ideal. Replace the field stop & adjust its focus.

If using a Nagler or other exotic eyepiece where the field stop is not readily accessible, forget it.

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Andrew*

Andrew*

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I tried last night. Seeing was pretty horrendous - the airy disk was wobbling all over the place - not a chance ;). Then the clouds rolled over.

I quickly went over to the Trap to see if I could tease out E or F - nope - clouds were too fast ;)

Andrew

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