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jetstream

Splitting Polaris

14 posts in this topic

Boy the moon is bright... it looks very clear but there must be ice crystals up there or something because I can hardly make out any stars. I'm playing with the 200mm dob and found Polaris to look at and found that I can split it down to 30x with the 25mm TV plossl. Just for a point of reference, what is the lowest mag that anyone has split this star?

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6 hours ago, jetstream said:

Boy the moon is bright... it looks very clear but there must be ice crystals up there or something because I can hardly make out any stars. I'm playing with the 200mm dob and found Polaris to look at and found that I can split it down to 30x with the 25mm TV plossl. Just for a point of reference, what is the lowest mag that anyone has split this star?

It's quite a wide double (18 arcsec) so using the normal rule, any magnification above x10 or so would theoretically be sufficient, but obviously the real issue here is the faintness of the secondary. For me, if I can't see it because of the conditions, then the magnification I'm using is probably irrelevant?? Certainly at x60 with my 180 Mak (the lowest practical mag for me with this scope), it's easily visible under good conditions.

Chris

Edited by chiltonstar
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I find aperture really helps with Polaris. Never really tried at very low powers as I don't have them available in the dobs and the fracs are good but obviously less aperture. I'll have a look next time out.

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Like Shane I've not tried this at very low power. Pretty sure it splits in the Tak with a 24mm Panoptic i.e. x30 but not sure below that.

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95x is my lowest power for the dob gerry, which is the 21e. its a easy split with that

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A bit of Googling on this suggests bins from about 20 x 80 should do the trick. Seem to remember doing it in my Heritage 130P with a 25mm e.p. (which would be x26) though much easier around x40. As others have said it's not the distance (which is pretty wide) but the relative faintness of te companion that can make Polaris a bit tricky.

Billy.

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5 hours ago, billyharris72 said:

A bit of Googling on this suggests bins from about 20 x 80 should do the trick. Seem to remember doing it in my Heritage 130P with a 25mm e.p. (which would be x26) though much easier around x40. As others have said it's not the distance (which is pretty wide) but the relative faintness of te companion that can make Polaris a bit tricky.

Billy.

...although some of these may have confused the nearby star SAO 305 with Polaris's partner - it's only 1/2 degree or so from Polaris. I have even seen the same thing on this forum...

 

Chris

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Thanks everyone, I'm seeing how well the mirror works and its f3.8. A Paracorr will used coming up I think. I tried the 32mm TV plossl and got a fleeting glimpse of it I think- I won't confirm it though. One interesting thing is that when very low power views are used eye placement becomes critical on stars with any eyepiece and I'm curious to see if the CC changes this.

A zoom really helps "watch" the double as you zoom out-to 25mm in this case- no trying to get the companion as its easily seen zoomed in. I found locking on the target this way and then zooming out worked very well.

It was -28c last night and the scope was close to equalized, but not perfect, the mirror was still "crawling" a bit. Collimation was close but I need the "radiation symbol" to increase it further,at least without the AC. I have AC'd the scope a while ago but not since setting up the mirror cell.

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9 minutes ago, chiltonstar said:

...although some of these may have confused the nearby star SAO 305 with Polaris's partner - it's only 1/2 degree or so from Polaris. I have even seen the same thing on this forum...

 

Chris

Yes, this star became more obvious visually the "tighter" SAO 305 got and actually became a distraction. VG point Chris.

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The only specific written note I've got is of an "easy split" with the VX14 and a 22mm eyepiece so about 73x, but I'm fairly certain I have split it at 52x with the VX14 and at even lower powers with the ST120.

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Once split its worth while to try a image of Polaris and its companion because its virtually motionless its dead easy with basic equipment.

Polaris 5.02.07.jpg

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Well with the moon observed and a few minutes left to observe I went back to Polaris using my lowest scatter set up- a 90mm SV APO triplet/Baader Zeiss prism diag and some low scatter EP's- 12.5mm Docter, 7mm KK ortho, 18mm BCO and the 25mm TV plossl. I was pretty excited to sneak in a 25x view of the double with this class of aperture, which bested (so far) the 200mm f3.8, mind you a paracorr will help on this. I didn't try the 32mm TV plossl yet- next time.

They all showed the Polaris companion well, but that 25mm TV plossl showing it easy was just icing on the cake. :grin:

On 2017-01-12 at 02:33, Moonshane said:

I find aperture really helps with Polaris. Never really tried at very low powers as I don't have them available in the dobs and the fracs are good but obviously less aperture. I'll have a look next time out.

Totally agree Shane, aperture does help. My little un coma corrected 200mm is chugging along nicely on this object and it was fun to see the little 90 do so well. It is a very good scope though.

Edited by jetstream

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Here is my image from a few months back, you need to zoom in quite a bit to see separation but I deliberately imaged it this way. 

Polaris

 

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It is an easy split at 59x (6mm setting of my Nagler zoom) with my baby Takahashi FS-60 so only 2.4" aperture. Not tried it lower but given the ease I suspect it wouldn't be hard. Must try it. It is considered a challenge for 3" because the secondary is so faint.

 

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