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Back to the Future-Manual Setting Circles

Started by youngb, 06/21/2008 02:35PM
Posted 06/21/2008 02:35PM Opening Post
I've found the manual setting circles on my Orion SVP mounts to be a big help in locating objects under hazy/brightly lit skies. I find a bright star in the vicinity of my desired object, center it in the e.p. and set the circles to its RA/Dec coordinates (RA drive running). Then unlock the axes and move the scope until the object's RA/Dec coordinates are at the pointers. If done carefully the object is almost always in the FOV, often well centered.

The process is dependent upon having accurate, up-to-date coordinates for the initial bright star. Sometimes these are hard to come up with if the star isn't double or unique in some way. Where would I find printed coordinates for all the bright (1st Mag or brighter) stars? Picking coordinates off the chart just introduces another potential source of error.
Bob

Having a big time on a small scale grin
Posted 06/21/2008 04:40PM #1
The process is dependent upon having accurate, up-to-date coordinates for the initial bright star. Sometimes these are hard to come up with if the star isn't double or unique in some way. Where would I find printed coordinates for all the bright (1st Mag or brighter) stars? Picking coordinates off the chart just introduces another potential source of error.
Bob


Bob: Here's what I do, I use a Palm Handheld running Planetarium and PleiadAtlas. This gives me accurate coordinates for just about any star or object bright or not.

Used Palms are available various places (Craigslist is good) for $25 on up... Color is nice so you can turn on the night screen function.

http://www.aho.ch/pilotplanets/

http://astro.isi.edu/pleiadatlas/

Both are shareware that are fully functional in the freeware mode and have a single nag screen. I registered both of em but lost the key for PleiadAtlas...


Jon

Posted 06/22/2008 07:40AM #2
Bob Young said:

I've found the manual setting circles on my Orion SVP mounts to be a big help in locating objects under hazy/brightly lit skies. I find a bright star in the vicinity of my desired object, center it in the e.p. and set the circles to its RA/Dec coordinates (RA drive running). Then unlock the axes and move the scope until the object's RA/Dec coordinates are at the pointers. If done carefully the object is almost always in the FOV, often well centered.


I frequently used the analog circles on my Ultima 8 (before I performed a forkectomy and put it on a CG5), and was almost always able to get within a degree of my target just by "syncing" on a star in the area of the sky I was working in (the large RA circle of the SCT helps). I also STILL make my freshman astronomy students learn to use analog circles. Not because I think they will likely ever use them much as an amateur astronomer or at all as a professional, but because learning to use them teaches them the realities of the celestial coordinate system better than me and my powerpoints can.

Me? These days you'll pry my Sky Commander DSCs outa my cold, dead hands... grin

Uncle Rod

Time on your hands?
Waste it with Uncle Rod's Astro Blog!

http://uncle-rods.blogspot.com/
Posted 07/10/2008 06:17PM #3
Is there any best way to calibrate a declination circle? it seems to be quite accurate but I'd like it to be as right on as possible. If I use, say the typical example of Vega => M57 thisngs look really good, but shouldn't I be trying about three such reference star/target pairs? Once this is really acurately done I will be able to completely tighten the tiny dec, screw. Right now it's a bit loose so that I can move the Decl. circle for calibration. The problem is that, when the screw isn't tightened all the way, the decl movement has some rougher areas, at ~180* apart. So, i want to finish this little project, tonight?