Hi All,

Well, I finally got out in the garage today and drilled the 3/4" x 12" round base plate for my pier. I think I will end up purchasing a Pier-Tech 3 since I don't have a lot of time to be building. My thought was to have Pier Tech attach my plate to the bottom of the mount for me and then ship the completed unit.

Does anyone know if the pier tech's pier and/or mounting base is aluminum or steel? Obviously, we can't weld aluminum to steel.

I also have a question on Polar Alignment. It seems to me that with a robotic, programmable mount like the Paramount that it would not be necessary to orient the pier to true north. Couldn't a guy find true north after the telescope and pier is mounted, and then set something in the program so that the software would always know where true north is? Am I missing something?

Sorry, if the polar alignment question might be a silly question. I haven't had time to look at astronomy stuff since last fall and I've already forgotten a lot. I'm just trying to get back up to speed starting today!

Thanks,

Dave

Dave:
I don't have a Paramount, but my Atlas is at least somewhat similar. I believe it is still necessary to mechanically find true North with the mount. True, the thing is computer controllable, and it will do a great go-to when it's connected to a computer running The Sky (and maybe Starry Night Pro also). The software will do PEC (periodic error correction) for you, but you still have to point it to the North celestial pole. You'll have to do a drift alignment to get it there.

Here is a website to help with drift alignment:
http://www.andysshotglass.com/DriftAlignment.html

I'll have to climb this learning curve myself when I get my act together and build my observatory...
Rich

Hi Rich,


I guess its to align the axis of the mount with the earth's axis so that you don't get star trails. I asked earlier today on the Paramount forum.

I talked to Pier Tech and they are saying 10 weeks to get a PT3. I'd have ordered one if it was two weeks but I don't have the kind of patience to wait 10 weeks. Not to mention it will be a lot colder in 10 weeks and I'd rather work now while it's relatively warm. I may work on building the pier tomorrow.

Dave

I'm reminded of the ad on TV....."Welcome Back, your dreams missed you". At least I did. I've been wondering what happened to you and how your astronomical adventures have been progressing. I's good to have you back, kind of stir up the nest so to speak.
Too bad about Pier Tech....There's GOT to be other pier manufacturers aren't there? YES!! Here's a couple!

http://www.advancedtelescope.com/

http://www.astropier.com/

Teah, I use the drift method according to andys....I even paid for "StarTarg...
http://www.andysshotglass.com/StarTarg.html
It works quite nicely as far as I'm concerned.

Dave, if you build your pier to point to the pole star using a compass set with the offset, there ought to be enough adjustment in the mount to zero in on the pole itself. Can't say for sure, I'd have to check the Paramount "How to's".

Let's not forget to post pictures of EVERY step along the way. You'll be glad you did. (and so will we)

Steve

If you did not polar align you would have the same problem that alt-azimuth mounts have. Field Rotation.
It would work visually but not photographically

Make the pier very sturdy, then double that to make sure for best imaging performance. My 70 lb fork mount SCT is on a 30 inch pier of 7 inch heavy wall aluminum pipe sections. That is adequate, but not overkill by any means.

I would like to add to the question of polar alignment. Although I do not have computerized equipment, I will likely someday have rather large motorized equipment with pier mounts and such. I currently have my portable tripod set at 43 degrees because that's my latitude. But that means that the north star is at 43 degrees only at 1st day of spring and fall equinox when the equator is level facing the sun. 1st day of winter it is higher than 43 degrees and 1st day of summer it is lower because of solstice, correct? What is the range of more or less? Is there a chart that can be followed to compensate this throughout the year? My NIGHTWATCH book doesn't get this technical into it.
Am I crazy, or did I once see a 'figure 8' of the months within a scale of degrees to compensate with the middle of the 8 on the spring and fall equinox?
What's Jack Horkheimer's phone number? He, he, he.

Once properly aligned (on any day of the year) you will not have to realign your mount unless it is moved.

The Earth's axis always points (for all intents and purposes) exactly at the same spot, just off of Polaris. Not to worry

Ok, after MUCH research it finally made sense to me. Mostly to blame is HOW this phenomenon was taught to me. My whole life I've been told the earth (tilts) on it's axis and the earth is leaning toward then leaning away from the sun... terminology that led me to think my whole life that the earth 'wobbled' and it's axis changed. Actually, it's fixed angle changes in relation to the sun throughout the orbit, but the axis is permanently tilted and does not change. Being told that the earth 'tilts' on it's axis, means ongoing tilting to me like a teeter toter. Wow! my whole life and better than average understanding of the solar system, and this little detail was mislead to me. I'm one of those guys who has to use CORRECT termanology. Like when people ask "Where are the directions?" when assembling something. Makes no sense to me since directions tell you where to go, instructions tell you what to do.
Man, this is like being corrected on a song lyric you've been singing wrong your whole life! <blush>

This illustration is the best explanation I can find






Notice the pole in June and December are still going in the same direction.

In June the northern end of Earth (northern hemisphere) is more directly exposed to the global warming rays of the sun while in December the southern hemisphere is more directly exposed.

As a user of trigonometry myself, I would make the point that while there is approximately 186,000,000 miles between our position in summer and winter, compared to the approximately 430 light-years between Earth and Polaris the angular amount is pretty small (although still there).

Lucky us. 

Yes, I got it before. What infuriates me is I distinctly remember being taught in grade school that the earth's axis TILTS. Not 'is tilted' but tilts. Our globe even had a mount that adjusted the angle of the axis. What kind of educational tool is that? Instead of bringing the tilted globe around the light to show how the angle differs, the globe itself tilted it's axis.
I watch Jaywalking and am amazed that people don't know how long an orbit around the sun is, an Earth rotation, a moon orbit, etc... But this is a misconception that I was taught in school. Grrrrr. I'll have to ask my brother and sister if this is what they were taught as well.

Hi All,

Well, I finally got out in the garage today and drilled the 3/4" x 12" round base plate for my pier. I think I will end up purchasing a Pier-Tech 3 since I don't have a lot of time to be building. My thought was to have Pier Tech attach my plate to the bottom of the mount for me and then ship the completed unit.

Does anyone know if the pier tech's pier and/or mounting base is aluminum or steel? Obviously, we can't weld aluminum to steel.

I also have a question on Polar Alignment. It seems to me that with a robotic, programmable mount like the Paramount that it would not be necessary to orient the pier to true north. Couldn't a guy find true north after the telescope and pier is mounted, and then set something in the program so that the software would always know where true north is? Am I missing something?

Sorry, if the polar alignment question might be a silly question. I haven't had time to look at astronomy stuff since last fall and I've already forgotten a lot. I'm just trying to get back up to speed starting today!

Thanks,

Dave
[/quote]

Dave:
I am sure you have discovered in the past 2.5 years or so since your post, that there are some things about alignment to the true pole that no amount of robotics software can hide. True, software can compensate for pointing errors in GoTo slews. These could be caused by mount construction error (not perpendicular between axles and optics is common). Also, atmospheric refraction could be entered for compensation. But most programs like this for tracking and guiding do not try to correct the effects of polar alignment angle error, as far as I know.
Most serious of these is field rotation. This is most severe with alt-azimuth mounts, where the amount of misalignment to the true pole is the distance from true pole to local zenith. Antarctica's Scott Station observers at the pole can get away with a zero error, but everyone else will see field rotation to some degree. How much depends upon the error.
Field rotation causes stars, even if perfectly tracked at the center of the picture, slowly to revolve around that center. Amount depends upon error angle and duration of an exposure, and also upon effective focal length. And sometimes there is minimal effect in some areas of the sky, even for alt-azimuth mounts. But rotation errors can show up as smeared stars over multiple pixels in the corners of the CCD chip even after a few seconds at high magnification.
Also there is declination axis drift caused by an error of alignment. Some expouse purposeful misalignment to take care of backlash in DEC axis corrections. Some think this is solving one problem by creating another.
Ideally, as one images around the meridian at near overhead pointing, there should be no DEC correction needed at all with a properly aligned mount. And only atmospheric refraction, PEC for the driving gearing in RA axis, and wind or optical axis shifting should be the things that need to be considered.
I have built various types of equatorial mounts, and used commercial GoTo mounts with remarkable software, but I still have found no substitute for close polar alignment in the last 50 years. Gregg

Hi dave I have a PT 3 pier. the plates are aluminum . Pier tech should have an adapter for the mount which Vito will include with the pt 3.
polar alignment is easy. Just orient the mount as close to true North as possible. I have found the drift method the most accurate and it is really not that hard to do.
Regards,
Doug.