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RA Setting Circle - Advice Please!


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Hello,

The setting circles on my TAL-1 seem big enough to have a go at using, so I had a go....but here is my question.

The RA circle increases in 'time' in a clockwise fashion eg 1,2,3 hrs.

But my books and star charts show RA to decrease in a clockwise fashion. As you look at the chart, the numbers decrease going left to right, eg 12, 11, 10 hrs.

The result is that when I aim at Castor in Gemini and set the circles to the exact co-ordinates, then I go for something in Orion which is to the right, the RA circle tells me to go the wrong way i.e to the left.

The TAL is of northern hemisphere manufacture and does not have

a dual scale with numbers going either way. What am I doing wrong? I could turn the dial upside down (which would work) but that makes it harder to read and I don't envisage the manufacturer expecting the user to do this.

Thanks Steve

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  • 2 weeks later...

Well, did the re-label and the circles do actually work!

I was having difficulty with M81...

I centred on Dubhe in the Plough, calibrated the circles for that star and turned to the coordinates for M81. It (and partner M82) were near the edge of the FOV.

Rather pleased, the TAL circles are better than some but to still get the object in the FOV with such small scale on the dials is rather cool in my opion :)

Thanks all - Steve

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Hi.

Yeah, doing a recallibration on a nearby star etc, lessens any potential error, especially when moving large distances across the sky.

Pleased it's worked out and jealous you've had clear skies !!!

Cheers,

Andy.

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Hello,

I am a novice astronomer (in the Tal user group) and have a Tal 1 Scope. I have been trying out setting circles myself. After polar aligning and setting RA off Rigel (in Orion) I tried to point it at the RA / Dec settings for the Andromeda Galaxy (RA 02H 22.6M AND +42 DEG 21 M), but whichever way I rotate the scope it hits the pedestal at this setting.

Is it me ?, or is this a Tal shortcoming?

Andy

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If you're hitting, or are close to hitting the scope on the pedestal, then you need to rotate the RA arm 180 degrees to the other side of the pedestal which will give you room to work with.

Hope that makes sense.

Andy.

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Thanks for reply Andy,

I tried Scope every it "which-way" in near darkness and could not get it aligned for Andromeda galaxy.

After your advice, I tried a dry run in daylight and positioned scope to correct RA -Dec.

One of life's little mysteries!

Andy

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  • 8 months later...
For unknown reasons Tal have always had their RA circles set for southern hemisphere usage.

The general concensus amongst users, seems to be to re-label the numbers the correct way.

Cheers,

Andy.

Just ran up against this problem tonight when decided to move beyond 'point and hope' navigation; is there an easy way to re-label the circle? Do the divisions coincide with cm/mm or is there a template?

Sorry if the answer is obvious, it's just not obvious to me right now :)

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My Tal-1 *is* a 'scope past' :)

...and if it can be made to work then it can't help as an aid to finding less clear objects

Blimey. The English language suffered greatly in the making of that post. I meant anything that helps to locate things is a help. But clearly was incapable of saying that!

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Just ran up against this problem tonight when decided to move beyond 'point and hope' navigation; is there an easy way to re-label the circle? Do the divisions coincide with cm/mm or is there a template?

Sorry if the answer is obvious, it's just not obvious to me right now :)

I just used long sticky strips to cover the numbers, then reversed the numbers by hand writing them on. Looks rubbish, but it works and so far no one has commented.

So going one way around the dial - 0, 1 , 2, 3, 4, hrs becomes 4, 3, 2, 1, hrs etc. I'll stick a picture up of my talentless artwork (I think that's why I'm an engineer and not an artist). :)

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Are all Tal's made for the Southern Hemisphere?

I have a tatty 1998 TAL 2 and the RA dial, when rotated clockwise, (looking from Polaris) increases 23, 00, 1, 2 etc

Isnt that right for the Northern Hem?

(another) Andy :)

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It's not done intentionally for the purpose of southern hemisphere users. Why is it done that way? No idea, but they'll have their quirky reason !

Bill Brady said the following 'The RA circle is labeled backwards, according to sun time rather than celestial coordinates.'

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Are all Tal's made for the Southern Hemisphere?

I have a tatty 1998 TAL 2 and the RA dial, when rotated clockwise, (looking from Polaris) increases 23, 00, 1, 2 etc

Isnt that right for the Northern Hem?

(another) Andy :)

Needs to go the other way, decreasing when rotated clockwise. I will get a picture on here tonight.

I'm not sure why this was done, I imagine that the Russians had their celestial co-ordinates in reverse to Western society, and after the collapse of the Soviet Union this little issue was never addressed. I bet if you looked at a Russian star chart from the 80's the RA co-ordinates would be in reverse order and would work with the TAL mount. That's my little theory anyway :)

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Right!

All, I have stripped down me Mount and have discoverd that the ring (RA) is reversable, only thing is, on reassembely the pointer then appears to underneath the scale, so I have now done this. to make matters worse I have photographed the process, if there is sufficient interest, I'll knock together a "Haynes" style howtoo, stick it on the TAL group pages.

Andy (world spinning backwards) McK :)

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Right!

All, I have stripped down me Mount and have discoverd that the ring (RA) is reversable, only thing is, on reassembely the pointer then appears to underneath the scale, so I have now done this. to make matters worse I have photographed the process, if there is sufficient interest, I'll knock together a "Haynes" style howtoo, stick it on the TAL group pages.

Andy (world spinning backwards) McK :)

Hiya Andy, I tried exactly the same thing, yes it does make everything the right way round. But because the pointer is now on the opposite side to the numbers, far away from them and not 'over' them I regret I found it quite hard to get an accurate 'set'. The pointer needle really needs to be directly over the digits to get anywhee near reasonable accuracy for finding things. Very annoying!

Cheers Steve

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