Image of the day

Captured by
Michael Scherman

M17 Swan-Omega Celestron C6 Hyperstar2

My Account

New to Astromart?

Register an account...

Need Help?

N8GPS

Started by jonstot, 09/27/2003 04:04PM
Posted 09/27/2003 04:04PM Opening Post
Hi y'all; this is my first post so go easy on me. Also first-time scope owner (not counting the 90mm xmas scope many, many years ago).
I've had the N8GPS for a few months now, and thought I'd pick a few bones. Nothing nasty, just naggy...
1. Why can't I see galaxies like they're shown in books 'n stuff? (um, just kidding)
2. Vertical alignment marker was MIA (missing on arrival). I haven't bothered to do anything about it yet, but was a little miffed at Celestron QA for a second or two.
3. The finderscope mount is atrocious. The o-ring concept doesn't work at all and the set screws are so tight I can't even turn them by hand. I've thought about taking a pair of ViseGrips to them but have so far resisted the urge.
4. On a particularly dewey night I pointed the OTA straight down when I went inside to take a nap, thinking the dew wouldn't form as quickly on a downwad-facing surface. Big mistake. The dew on the outside of the OTA dripped down and leaked through the corrector mount. Now I have a big water streak running across the corrector. Question: how much grief will I bring down upon myself if I remove the corrector to clean it? (not counting re-collimation, which I assume is a given)
5. Biggest concern: the GPS's first approximation for locating alignment stars is much worse than I would have expected, considering it knows its own position to 5 meters or so. Alignment stars always seem to be at least 5-10 degrees away. Heck, I could do better than that with a protractor and a flashlight! Once the unit is aligned, it's dead-on for the rest of the viewing session, but at that point it's not even using the GPS so where's the payoff? I've checked the GPS coordinates and the clock with a handheld, and it seems to be working fine. Any suggestions? How about the compass? Am I expecting too much to see the alignment stars at least within the viewing radius of the finderscope?
Other than those minor issues, I love my scope.
ps. What's the accepted waiting period before one can start lusting for an 11"?

Posted 09/27/2003 05:36PM #1
Set the scope to true north with a compass. This includes taking in the magnetic deviation. Then set north in the computer. It has a section for this in the book. This will help some with the initial alignments.
Replace the finder mount with a quick mount dovetail type. Better yet replace the whole thing.
Cleaning of the corector plate is not that difficult, but you must put it back together with the shims and plate in the exact same location or it is screwed. You must be cafeful with how you clean it though. It can be easily scratched. You must use a good cleaning fluid as well. I use the Arkansas Observatory's cleaning solution that I make up. They also have a how to on their page for cleaning the corrector plate. If you don't live too far from Celestron, you can take it to them for cleaning.
The verticle alignment mark I assume is the little arrow that just sticks on the fork. Mine also fell off. I can tell you that the two marks should be where the scope tube is level to the ground. Just use a level on the top of the tube and then make a mark with white paint or something easily seen.
You may lust for 11" right after the 8" is completely paid off. Then yuo may begin to lust after the 14". Unfortunantly the lust can become obsessive.
:^)
Floyd

[SIZE="Large"][/SIZE][COLOR="Blue"][/COLOR] Floyd Blue grin
Amateur Imager
Posted 09/28/2003 06:18PM #2
My problem with the GPS was in its leveling capability, but there is a catch-22: you cannot use the leveling utilities program until you have aligned the scope, and alignment is unsatisfactory if the scope's computer contains an inaccurate zero altitude position. My solution: When setting up your equipment, make sure your tripod head is as level as possible, and when you start your observing session, BEFORE alignment, use the compass utilities program to point the scope to true north (this program CAN be run before alignment). Then align the scope using Auto Align, NOT GPS Align; the GPS unit will determine your location and time in either case, the only difference being that Auto Align will ask you to find north and level; and since you have already pointed your scope to true north, you need merely line up the two index markers to the level position and can then proceed with the usual two-star alignment process. I find that this approach will bring the objects I select during the observing session within less than 30 arcminutes of the eyepiece's center (and perhaps closer if great precision is used to center the alignment stars).

NexStar 8i SCT, Orion 80ED APO refractor, Orion 120 mm EQ refractor, 3.5-inch Questar