Part Xii : Using A Synscan Gps Module - SKY-WATCHER NEQ3 Instruction Manual

PART XII : USING A SYNSCAN GPS MODULE

Users may purchase a SynScan GPS module to acquire accurate local geographical coordi-
nates and local time; it will help improve the accuracy of the mount alignment and the polar
alignment.
12.1 Initialization of the Hand control with a SynScan GPS Module
The initialization process of the SynScan hand control with a SynScan GPS plug-in differs
from a regular one.
Plug the SynScan GPS module into the multi-purpose port (the 6 pins RJ-12 port) located
1.
at the bottom center of the SynScan hand control. Place the GPS module on a horizontal
surface and turn on the power of the mount.
If the SynScan hand control detects the connection of a GPS module, it will ask for the
2.
local time zone:
• Use the left and right direction keys to move the cursor on the screen.
• Use the scroll keys to change or switch the sign for the time zone. Use "
zones in the Eastern Hemisphere, use "
sphere.
• Use the numeric keys to fill the time zone value in
• Press ENTER to confirm and proceed.
The hand control will then ask the user whether to use the Daylight Saving Time. Use the
3.
YES
scroll keys to select between " " and "
ceed.
The screen will now display " GPS fixing...
4.
the GPS satellites.
After the SynScan GPS module fixes to the satellites, the SynScan hand control will con-
5.
tinue the initialization process.
12.2 Checking GPS Information
Plug the SynScan GPS module into the multi-purpose port (the 6 pins RJ-12 port) located
1.
at the bottom center of the SynScan hand control. Place the GPS module on a horizontal
surface.
UTILITY FUNCTION \ GPS
Access the menu "
2.
GPS fixing...
3. The screen will now display "
the GPS satellites.
4. After the SynScan GPS module fixes to the satellites, the screen will display "
mation: ". Use scroll keys to browse through the following information. Press the
to exit.
M.O.V:
• Local magnetic declination
Lat: Local latitude
•
Lo:
• Local longitude
Date
• : Local date
• UT: Greenwich Mean Time
LT:
• Local time
+
" for the time
-
" for the time zones in the Western Hemi-
±hh:mm
format.
NO ENTER
" and press the key to confirm and pro-
". It means that the GPS module is trying to fix to
ENTER
" in the menu and press the key.
". It means that the GPS module is trying to fix to
GPS Infor-
ESC
TimeZone:
• Local time zone
LST: Local sidereal time
•
Elevation:
• Local elevation
Quality:
• Quality of GPS fixing
• Number of SV: Number of GPS satellites in view
SV(fix) Nr:
• Number of GPS satellites fixed
40
APPENDIX I : ELIMINATING CONE ERROR
If the telescope's optical axis is not perpendicular to the declination axis of the equatorial
mount, then there is cone error in the telescope-mount system. The cone error might lower the
accuracy of locating an object or the accuracy of the Polar-Alignment process.
Testing for Cone Error
Perform a precise polar alignment on the equatorial mount, and then perform a two-star
1.
alignment. The alignment stars should be located on the same side of the meridian and
their declination deviation should be within 10 to 30 degrees.
Use the SynScan hand control to locate a few objects on the same side of the meridian as
2.
the alignment stars. The pointing accuracy should be quite good.
Use the SynScan hand control to locate a few objects on the other side of the meridian as
3.
the alignment stars.
• If the pointing accuracy is still good, then the mount system has small or no cone error.
• If the pointing accuracy becomes poor, and most of the error is on the R.A. axis (that is,
the object can be brought back to the center of the eyepiece using the left or right di-
rection keys), it means that the cone error of the telescope-mount system is quite large.
Eliminating Cone Error
1. Rotate the R.A. axis to level the counterweight shaft.
Center the Polaris in the polar scope.
2.
Point the telescope to the Polaris, rotate the Dec. axis to bring the Polaris as close as pos-
3.
sible to the center of the finder scope or the telescope's eyepiece.
Fine tune the azimuth and latitude of the mount to center the Polaris in the telescope's
4.
eyepiece.
Rotate the R.A. axis 180 degrees. (the counterweight shaft should be leveled and pointed
5.
to the other side of the mount). If the Polaris can be put to the center of the eyepiece by
rotating the Dec. axis only, it means the cone error is small and no further adjustment is
needed; otherwise, continue to the following steps.
Rotate the Dec. axis to bring the Polaris as close as possible to the center of the finder
6.
scope or the telescope's eyepiece.
Slightly push the eyepiece end of the telescope in a HORIZONTAL direction while looking
7.
into the eyepiece, find the direction which will bring the Polaris closer to the center of the
eyepiece. In this way, a user can determine the direction in which he/she should re-position
the telescope on the saddle or the mounting bar to reduce the cone error.
Use a shim (or other method) on the proper side of the saddle or the mounting bar to raise
8.
the telescope. Look into the eyepiece while applying the shim. Reduce the deviation be-
key
tween the Polaris and center of the eyepiece to HALF.
Repeat
9. Steps 4 and 5
if necessary.
8
Tips:
• It is recommended to use a reticle eyepiece and align the track of the Dec. movement with
one of the lines of the reticle.
• This adjustment can be done in day time by using a distant point object to replace the
Polaris.
to check whether the cone error is acceptable, repeat
41
Steps 6, 7 and