Jwake2
member
Reged: 06/16/02
Posts: 16
Loc: Bend, Oregon
|
|
Location, location, location....So, when entering in our local viewing site (Lat & Long) .....why isn't our local elevation a factor ? This can vary by several thousand feet.
|
Grizz
Carpal Tunnel
Reged: 04/24/03
Posts: 2172
Loc: Waldwick,New Jersey USA
|
|
I'm thinkin' that the GPS takes care of that when it does its thing. I know my Garmin will give my elevation after it acquires the right amount of sats.
If your doing a 2 or 1 star align and not using the GPS then I suppose elevation is not a factor, since you will be leveling and pointing north manually. Also I beleive that entering the Lat/lon for your site is to help the GPS figure out where to look for the sats so it does not time out.
Craig
--------------------
Craig
LX200GPS 10" UHTC SMT
ETX90EC
Orion ED80 APO
Meade LPI Canon 10d Meade DSI
My Photo Gallery
|
DaveSchwartz
member
Reged: 04/26/03
Posts: 78
Loc: Bamberg, ON
|
|
I believe the reason you would not need elevation data is that the lat/lon/time are sufficient to calculate the relative coordinates of any object. It is very doubtful that your location along the elevation axis, going straight through the zenith, is going to be a factor... a few thousand feet (or miles) is not likely going to cause enough stellar parallax to throw out the calculations.
--------------------
LX200GPS12/SK80ED/ETX90AT LPI/DSI/SolarMax60
DenkII w/dual arm Power x Switch, filter slide diag
Backyard sliding-roof observatory
Edited by DaveSchwartz (05/19/03 09:08 AM)
|
Charles
Post Laureate
Reged: 06/12/03
Posts: 4111
Loc: Enterprise, AL
|
|
I have a Meade GPS 12 inch and I have never been able to figure out whether the scope and software utilize elevation or not. I have looked everywhere and have not found an answer. I agree it is an important factor for pointing accuracy and may be one of the reasons I have never been happy with Meade's pointing accuracy. Think about basic geometry, if I'm looking at the moon at sea level and your standing next to me on a 300 hundred foot roof top your angle and my angle to the moon will be different. I'll keep looking for the answer as to whether elevelation is used or not by a GPS scope.
|
John_Gillies
Vendor - Earthwin Optical
Reged: 04/23/03
Posts: 1385
Loc: Ontario, Canada
|
|
Just speculation because I don't for sure but... Doesn't a GPS acquire satelites by line of sight, therefore the altitude is accounted for when acquiring a fix? Just because the scope doesn't report the altitude, doesn't mean it isn't accounting for altitude. Even my old Eagle Acu-Nav Sport hand held GPS reports the altitude. How accurate is debatable but I believe that it is calculated through line of sight.
--------------------
John Gillies
12” LX200 GPS / Double Stacked PST
EarthWin Optical PFS-D Binoviewer System(s)
Skywatcher ST 80, 102 & 120
|
Charles
Post Laureate
Reged: 06/12/03
Posts: 4111
Loc: Enterprise, AL
|
|
Yes...GPS does give you an altitude by way of trianglation. Whether Meade's software utilizes that reading is not known by me. The GPS meade incorporates into their GPS scopes may not even be capable of determining ALT for all I know. It's Alt determination would be a result of the software within the GPS routine. I have tried to find out the answer to this but have had no luck yet. It would not surprise to see it does not compute Altitude.
|
Grizz
Carpal Tunnel
Reged: 04/24/03
Posts: 2172
Loc: Waldwick,New Jersey USA
|
|
Quote:
I agree it is an important factor for pointing accuracy and may be one of the reasons I have never been happy with Meade's pointing accuracy.
I don't think the GPS has anything to do with pointing accuracy. All it does is tell Autostar where on the planet it is, the date and time, so it can slew to the approximate position of the first alignment star. Then closer still to the second alignment star. Centering the alignment stars (say in a 9mm reticle ep) is the determining factor in pointing accuracy, along with other mechanical considerations, not the GPS.
I could be wrong 
Craig
--------------------
Craig
LX200GPS 10" UHTC SMT
ETX90EC
Orion ED80 APO
Meade LPI Canon 10d Meade DSI
My Photo Gallery
|
John_Gillies
Vendor - Earthwin Optical
Reged: 04/23/03
Posts: 1385
Loc: Ontario, Canada
|
|
No Craig...I think you are right. I use a 9mm reticle ep and after alignment, my go to's are dead centre in my 12.5mm Ortho's every time. Kinda fun watching the target slew into the ep's through the binoviewer.
--------------------
John Gillies
12” LX200 GPS / Double Stacked PST
EarthWin Optical PFS-D Binoviewer System(s)
Skywatcher ST 80, 102 & 120
|
Charles
Post Laureate
Reged: 06/12/03
Posts: 4111
Loc: Enterprise, AL
|
|
I think you are correct also Craig. Because my Meade before I started doing drive training more frequently would just get worst with pointing accuracy even when I would use my 9mm recticle lens for alignment. Your explanation would also explain why you need to do drive training to improve pointing accuracy.
|
LivingNDixie
Lord of Ferrets
Reged: 04/23/03
Posts: 15799
Loc: Hoover, AL
|
|
I wouldn't think that elevation would be a factor in the geometry for the GPS satelites in orbit. From there vantage a few thousand feet ain't going to matter. Even if it was a factor (and extreme small one at that) it shouldn't make a difference to the scope. With my old LX200, I used the same Lat and Long for Birmingham AL and I was over 40 miles away and it worked fine.
Preston
10" F/6 Discovery PDHQ
Birmingham, AL
--------------------
Preston
Celestron 11" Nexstar GPS XLT
Lunt LS60T/Ha 60mm f/8.33 (on order)
It’s not finishing something when your tank is empty that makes you a stronger person. It’s brushing yourself off and refacing the foe that defeated you with the same determination and willingness to fight that you had when you began your journey.
|
Charles
Post Laureate
Reged: 06/12/03
Posts: 4111
Loc: Enterprise, AL
|
|
That's why I agree with Graig that Meade only uses the GPS for the initial star alignment and nothing else. As to the elevation I never thought it utilized that function of GPS. The angle used for the star alignment is probably what Meade uses to determine the telescopes point in 3D space.
|
Previous
Index
Next
Threaded
Edit
Reply
Quote
