NavList:

   

Reply

The Skyscout just has two flat lenses, through which you observe the object. 
You are expected to observe the object in the center of the objective, a 
reticle would have been nice, but is not part of the kit.

When we talk about pointing accuracy, I think we must bifurcate the discussion 
to azimuth and elevation.  Since the inclination of the Skyscout is far more 
readily obtained than the azimuth, I would suggest that the elevation is of a 
very high accuracy, much finer than the 0.5 degrees.  There are several 
electronic devices which can provide inclination, here are several 
http://www.leveldevelopments.com/inclinometer-sensors.htm Note that the 
quoted resolution is on the order of 1/100 th of a degree.

The azimuth is a far different matter.  The internal magnetic variation map 
(absolutely required for the device to work) cannot be infinitely fine in 
resolution, leading to an approximation right from the start.  Why is it 
required?  Since the variation of the compass will clearly affect object 
identification, we have no choice but to account for it. If your variation 
was 10 degrees, then the object pointed at would be wrong by 10 degrees, thus 
mis-identification would occur. Next, we must sense the local magnetic field, 
determine (via gps) where in the variation map we are, and then compare to 
see if we are in range (yielding that 'magnetic error message') and finally 
determine azimuth by correction.

To me, this azimuth solution sounds much like the longitude method whereby the 
longitude would be found by the variation of the compass.   If the variation 
was mapped to a very fine level AND we had a way to sense azimuth, then we 
probably could get a fairly good approximation to longitude.  Problems: the 
variation map changes all the time, the sensitivity isn't there and local 
disturbances would yield some highly wrong results.

------

On the topic though, of attracting Celestial Navigators because they have the 
Skyscout or a Smart Phone is upside down.  If you have a Skyscout, you have a 
GPS, no need for Celestial.  If you have a Smart Phone, between the cell 
tower localization and the probable on board GPS, you have no need for 
Celestial.

They may make the connection that it is Celestial turned inside out, but they may not.

But that can be turned to our advantage.  Suppose the display would show a 
graphic, explaining how the object's light intersects the earth's sphere and 
showing that classic circle of equal altitudes.  Then click on the next 
object, with its circle of equal altitudes shown super-imposed on the same 
sphere, showing the intersection!  In other words, Sumner's Lines of 
Position, graphically, based on the objects the user selects!  That brings 
the attention to how celestial "could" have shown the same thing...

Best Regards
Brad








-----Original Message-----
From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of frankreed@HistoricalAtlas.com
Sent: Friday, May 22, 2009 1:53 PM
To: NavList@fer3.com
Subject: [NavList 8381] Re: Learn the stars, by phone


I wrote previously that the SkyScout has a pointing accuracy of 0.5-1.0 
degrees. George found a FAQ saying 2-3 degrees. If we were talking about a 
sextant or other measuring instrument, those statements would be 
contradictory, but we're not.

Under good operating conditions, I wouldn't be surprised if the SkyScout has a 
pointing accuracy at the high end of accuracy. And under marginal operating 
conditions (for example, just before its software complains about magnetic 
interference), I wouldn't be suprised if the pointing accuracy is near the 
low end of accuracy. For a device with no magnification, none of this makes 
any difference, of course.

It will be interesting to see if the mobile phone engineers who are attempting 
to add this pointing capability to a device with a more hostile environment, 
both internally and externally, can get reasonable accuracy out of it. They 
have a lot more money than Celestron (now there's an understatement!), and 
they've had a few more years to work on it, but we will have to wait and see.

-FER






"Confidentiality and Privilege Notice
The information transmitted by this electronic mail (and any attachments) is 
being sent by or on behalf of Tactronics; it is intended for the exclusive 
use of the addressee named above and may constitute information that is 
privileged or confidential or otherwise legally exempt from disclosure. If 
you are not the addressee or an employee or agent responsible for delivering 
this message to same, you are not authorized to retain, read, copy or 
disseminate this electronic mail (or any attachments) or any part thereof. If 
you have received this electronic mail (and any attachments) in error, please 
call us immediately and send written confirmation that same has been deleted 
from your system. Thank you."

--~--~---------~--~----~------------~-------~--~----~
Navigation List archive: www.fer3.com/arc
To post, email NavList@fer3.com
To , email NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---

   

Reply