9 replies to this topic

[stars1111]

It has been raining for a couple weeks, no stars.  Sigh.  Then yesterday afternoon I see a note that Io will be transiting around 9pm.

 

I have been learning how to set up the tripod & mount setup in the daytime with a level & compass, then later N.I.N.A. walks me through a polar align.  But with the rain nothing was set up yesterday.

 

Around 8pm notice some breaks in the clouds, walk out and I can see Jupiter.

 

Run back, grab tripod, mount, do quick cell phone level & north.  Attach scope & lowest power eyepiece.  Ask mount to please go to Jupiter.

 

Mount gets close, and I suddenly realize that instead of using hand controller buttons to center it, can I just use the mount fine adjustment screws?

 

So I try that, pretty intuitive, just make tiny adjustments to az & alt and presto, Jupiter is centered.  Switch to higher mag eyepiece, do it again.

 

The mount automagically starts tracking when you use GoTo, and over the next couple hours, Jupiter stayed in the field (!).

 

With all the clouds I doubt that a normal Polaris or multiple plate solve would have worked.

 

Feeling good, this was my first Io transit (yay!).  

 

But is this actually a way to get aligned?  And if not, why not?  Is it somehow less good than all the normal methods?

 

Clear skies,

 

-Bob

[PKDfan]

EXCELLENT Bob !

You just very quickly drift aligned your scope ! Your a natural !

and oh boy your journey to come...man is your wallet fat ?

Eyepieces become addictive now that you've corraled the field of view.


Cheers from frigid Edmonton.


CSS
Lance

[vtornado]

Since I view from the same spot a lot, and that spot is level, I simply point the mount north which is also know to me by land marks.

I can go inside for a bio-break, grab a cup of hot cocoa and all I have to do is turn the RA slow motion control to re-aquire a target.  Maybe every 30 mintues I have to adjust the dec a bit because my alignment is not perfect. 

 

This isn't good enough for pics, but for visual it is fine.

[rblackadar]

Lately I've done a lot of outreach events, and I almost never do a precise PA. People want to look through the telescope way before it's dark enough to see Polaris, and after the line forms and they start looking there's little time to go back and redo.

 

My trick is to scope out the site beforehand if possible, with something like Google maps, and use street view to pick out a likely landmark (like a big tree in the distance) that I can sight on, usually more accurately than I seem able to do with a compass. (My 7kg cast iron counterweight does not play well with compasses, funny thing.) This has worked splendidly.

[rblackadar]

Thinking some more about it, i guess I didn't really answer your question.

 

Assuming your mount is working correctly, which it apparently is, there are two possible sources of error in that initial slew to Jupiter. First is inaccurate pointing of the RA axis to celestial N -- the part you fixed with the alt/az screws, assuming the rest was good -- and second is whatever inaccuracy you had in setting the zero point, i.e. initializing at exactly 90* Dec and meridian RA before doing the slew command. The latter error is not accounted for in your method, but it's probably quite small if you were careful setting up. There are probably some subtleties I'm missing, but I think that's why it worked so well.

[stars1111]

Mercury-Atlas, thanks!  I phoned TeleView and they suggested a few eyepieces suitable for a 612mm FL refractor and will work OK while wearing glasses.  24mm like a finder, 10mm and 3.5mm if good seeing.  I figured better three keepers to start with.

 

Voyager-1, yup plan is to make three little divots in the patio for tripod points, I figured out one leg should point north .

 

Viking-1, Ah, yes now I think I get it - just leveling the tripod isn't enough.  The *OTA* has to be exactly level.  I'd spent some quality time futzing with the socket head bolts holding the Losmandy clamp to the mount, and again to get the Losmandy plate parallel to the OTA.  Some machinists 1-2-3 blocks and a machinist's level helped.  The mount has encoders so once things are squared up it should "just work".

 

Viking-1, thanks now you explained that if I spend (daylight) time with squaring things up really well, and leveling the tripod/mount, then all that's left is some tiny residual to tweak.  I guess that with practice this will become pretty fast (at least at home).

 

Compared to decades ago, SkySafari to name what you see, and a goto mount to get them in field is terrific.

 

Thanks all!

 

-Bob

[Paul Sweeney]

All this about perfectly polar aligning the mount is only important if you are imaging. Of course, the better the alignment, the more accurate the GoTo. But for visual, pretty close is usually good enough.

[PalomarJack]

All this about perfectly polar aligning the mount is only important if you are imaging. Of course, the better the alignment, the more accurate the GoTo. But for visual, pretty close is usually good enough.

Just as important as with setting circles. I have found it's best to be within 1/2 the field of your widest FOV eyepiece. For most, Polaris is not enough, that puts the error outside the field of anything less than 1.5*.

[trurl]

Mercury-Atlas,

 

Voyager-1, 

 

Viking-1

You've picked the wrong labels. 

 

This is like calling you Lift Off

[DeepSky Di]

Mercury-Atlas, thanks!  I phoned TeleView and they suggested a few eyepieces suitable for a 612mm FL refractor and will work OK while wearing glasses.  24mm like a finder, 10mm and 3.5mm if good seeing.  I figured better three keepers to start with.

 

Voyager-1, yup plan is to make three little divots in the patio for tripod points, I figured out one leg should point north .

 

Viking-1, Ah, yes now I think I get it - just leveling the tripod isn't enough.  The *OTA* has to be exactly level.  I'd spent some quality time futzing with the socket head bolts holding the Losmandy clamp to the mount, and again to get the Losmandy plate parallel to the OTA.  Some machinists 1-2-3 blocks and a machinist's level helped.  The mount has encoders so once things are squared up it should "just work".

 

Viking-1, thanks now you explained that if I spend (daylight) time with squaring things up really well, and leveling the tripod/mount, then all that's left is some tiny residual to tweak.  I guess that with practice this will become pretty fast (at least at home).

 

Compared to decades ago, SkySafari to name what you see, and a goto mount to get them in field is terrific.

 

Thanks all!

 

-Bob

Hi Bob

 

Welcome to CN! We all have a member name (stars1111 for you) and a kind of ranking label based on number of posts, in your case "Lift Off". The member name is above in bold.