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Conditions tonight were excellent and gave me a chance to test the 9mm Kasai Tani eyepiece out against the 12.5mm Tak ortho and the 10BCO using the 15" dob. While all eyepieces easily showed the Pup, the edge distortion of the 10BCO was bothersome for how I like to view this star- at the edge of the field. the 9mm Tani out did the 12.5mm Tak but this could be because of the narrower FOV and possibly less scatter.

Anyway, I'm wondering what the other star is "underneath" (dob view) the Pup that shows a bit fainter? I never noticed this star before and the 9mm Tani ortho popped it right into view along with Sirius B when keeping Sirius out of the FOV. The 12.5mm Tak shows it too but not as well or noticeable. The 10 BCO struggled with it using my preferred method of observing.

Is this star common to see? Maybe I paid a little more attention tonight lol!

Edited by jetstream

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Gerry,

I am always drawn to look at Sirius with whatever scope I am using, even tried with the 70mm piggyback ED but so far drawn a blank. I can\t say I have noticed a star in the nearby FOV but I fel that would onlt be due to not really looking. At the moment weather is not being kind so no observing at the present.

Alan

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A third star doesn't show in the Hubble image, but there are some websites of the slightly eccentric variety showing other companion stars.

This is the Hubble image (from Wiki).

Chris

220px-Sirius_A_and_B_Hubble_photo.jpg

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Interesting report Gerry. I can't help on the "other" star because I seem to concentrate on Sirius and it's "Pup" when observing and I need high power to split the two so it's probably out of my FoV anyway.

That Hubble image always fascinates me because the view of Sirius A & B with my 12" dob at 265x is really not that far off that, except that the B star is a touch fainter, I don't get diffraction spikes and the position angle is different. Probably the only circumstances where my 12" dob can approach the HST :grin:

Edited by John
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35 minutes ago, John said:

Interesting report Gerry. I can't help on the "other" star because I seem to concentrate on Sirius and it's "Pup" when observing and I need high power to split the two so it's probably out of my FoV anyway.

That Hubble image always fascinates me because the view of Sirius A & B with my 12" dob at 265x is really not that far off that, except that the B star is a touch fainter, I don't get diffraction spikes and the position angle is different. Probably the only circumstances where my 12" dob can approach the HST :grin:

I'm never quite sure why Hubble should give diffraction spikes as it is an RC design, I believe?

Chris

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17 minutes ago, chiltonstar said:

I'm never quite sure why Hubble should give diffraction spikes as it is an RC design, I believe?

Chris

RC's do usually have a spider mounted secondary.  :icon_biggrin:

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1 minute ago, Peter Drew said:

RC's do usually have a spider mounted secondary.  :icon_biggrin:

Ah, mea culpa - I've only seen inside some large ones.

Chris

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Well maybe I wasn't looking at the Pup? :embarassed: This is the view through the dob and my 9mm gives about .2 deg TFOV, 203x  and please excuse the extremely poor sketch. If it is the Pup it is fairly wide at the moment?. Thoughts appreciated. And yes I don't believe in the hocus pocus Sirius "C".

 

sirius 006.JPG

Edited by jetstream

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Aside from the B component of Sirius, as seen from earth the Star TYC 5953-03295-1 is the next one out from the system, roughly where your in FOV sketch is showing. However the extra feature below it on your 'at edge of FOV' sketch seems stranger.  I imagine this could be an artefact feature of the optical system?  Just my thoughts. 

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Hi Gerry

Although it's difficult to gauge scale from your sketch, the separation is about 11 arc seconds so assuming you had a field of 0.2 degrees, the field would be 720 arc seconds. The gap would be smaller I think than your sketch shows? 

 

Created by the author.

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10 hours ago, jabeoo1 said:

Aside from the B component of Sirius, as seen from earth the Star TYC 5953-03295-1 is the next one out from the system, roughly where your in FOV sketch is showing. However the extra feature below it on your 'at edge of FOV' sketch seems stranger.  I imagine this could be an artefact feature of the optical system?  Just my thoughts. 

 

9 hours ago, Moonshane said:

e.g. compare your view with this

5473178-sirius-pup-sketch.jpg

 

 

I observed these again last night-up to 400x using the 9mm/2x barlow. I'm not sure exactly what stars these are... if it is an artifact it shows in all my orthos/Docter 12.5 UWA. My degree estimation is very poor and made worse by switching eyepieces frequently with their differing FOV's.

Shane, in the sketch is it possible with newt orientation I see "B" and the star in the upper left from it? or I could be way off base here lol!

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Could be Gerry.  could you sketch with a circle for the whole field and then what you see roughly through the eyepiece?  This would confirm I reckon

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Ps in newts and fracs the pup follows the primary out of field in an undriven scope in case you didn't know

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Ok, here is another poor sketch- the outer circle is the field stop and the dashed line is a line I tried to imagine that shows the gap but follows the eyepieces edge view. Looking at this now as I write the 2 stars ("B") might be shifted down a hair and the bottom star just a hair further again.

Another issue I have is viewing so low with the 15" and I have to place the scope view between pine trees to view Sirius atm, I see the first star with Sirius in the FOV, faint but there and both stars once Sirius's scatter is outside the FOV (very close).

Thanks for the help everyone...

 

sirius sketch 002.JPG

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hi Gerry

It's hard to say really but I am not convinced that's the pup. I have only ever seen it once that said so am no expert 

Looking at the gap at 200x in the newt sketch above and your sketch at 400x (and assuming that what you sketched is what you saw in field), I still think the gap is too large. I'd be delighted for you though if someone disagrees with me and proves me wrong! :happy7:

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What I'm hoping for now is that some one see the same stars -Alan?- so that we can eliminate them from the "picture", and I'll keep on my new doubles pursuit :bino2::icon_profileleft:

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Looks like you were seeing these three Gerry to me

sirius.jpg.278838d1dadfd912df9bc84552fb25ee.jpg

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I forgot to say that I obviously see more stars in the field of view than on my sketch. 

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53 minutes ago, Helix said:

This is my sketch, Gerry, last year.

IMG_3097.JPG

Tatyana, is your sketch the the "view through the eyepiece" as seen in your dob? Great sketch BTW...

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4 minutes ago, jetstream said:

I shall continue, undaunted :grin:

Agreed Gerry - never give in :headbang:

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3 minutes ago, jetstream said:

Tatyana, is your sketch the the "view through the eyepiece" as seen in your dob? Great sketch BTW...

Yes, it is, as far as I remember. Problem is that I change eyepieces ever so often that sometimes I forget what eyepiece i am observing with. I think this one is with 5mm Pentax as mentioned on the image.

 

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