Aligning fork/wedge mounted telescopes
Rough initial setup.
Note: This can be done at home and should only
need to be done once.
You're just using it to get your scope
'close' so that you can do a finer adjustment in the field.
1. Set the wedge at it's lowest latitude possible.
2. Mount the telescope.
3. Place a level on the wedge and using a wooden wedge
adjust the 'north' leg so that the telescope's wedge
is horizontal.
4. Mount the telescope and rotate it in declination so that
if's pointing roughly 'up'.
5. Put your carpenter's level across the top of the tube in a
north/south orientation (perpendicular to the plane of
the fork) and use the declination slow motion to get the
bubble level.
6. Rotate the declination setting circle to 0.
7. Remove the wooden wedge from under the 'north' leg.
8. Use a bubble-level to level the tripod.
9. Place the forks roughly parallel to the ground.
10. Place a carpenter's level across the forks and adjust in RA
until the forks are level.
11. Rotate the telescope so that your observing site's latitude
is set on the declination setting circle.
12. Place the carptenter's level across the tube perpendicular
to the forks.
13. Adjust the wedge's altitude until the carpenter's level
shows the bubble centered.
14. Lock the wedge and head to the observing site.
Polar Alignment
Note: The following is a manual implimentation of the computerized
'one-star' alignment
routines in many GoTo scopes.
1. Setup the tripod and level it with the 'north' leg and
wedge roughly north.
2. Mount the scope and level the forks with your carpenter's
level so that they're parallel to the ground.
3. Rotate the tube in declination so it reads '90'.
3. Using the wedge's adjustments center Polaris. If your
finder scope is 'pretty damned close' you can use the
North Pole finder diagram to get your setup 'pretty damned
close' then continue.
4. Find a star with an RA of about 8 hours or 18 hours.
5. Slew the telescope so that the star is centered.
6. Adjust the setting circles so that they match the star's
position.
7. Slew the telescope to 2h31m RA and 89.15 declination.
8. Use the wedge adjustments to move the telescope 2/3
of the way to Polaris.
9. Repeat steps 4-5 as many times as you want using the same
alignment star. Each iteration will get you closer.
Drift method of polar alignment (prime focus photography)
Note: I'm using the terms up and down in the instructions. They
assume you're using a diagonal.
1. Rough align as above.
2. Put your reticle eyepiece in the scope and make sure
that it's aligned north/south east/west using the
slow motion controls.
3. Find a star near the meridian at about +20 declination.
4. Center the star in the crosshairs and adjust the reticle
so that slow motions in RA move the star directly along
the horizontal crosshair. It's easier when the star is
slightly defocused.
5. Start your drive.
6. Watch for the drift of the star over time. If the star
drifts up tweak your wedge a bit in azimuth to
move the star to the right in your field.
If the star drifts down tweak your wedge
to move the star to the left in your field.
Stop when the star ceases to drift off the horizontal
crosshair over 5 minutes (ceases means CEASES.. no drift).
Even one star diameter is too much (and stars are pretty
small )
7. Find a star near the eastern horizon along the celestial
equator.
8. Center the star as above so that adjustments in RA move
the star along the horizontal crosshair.
9. Start the drive.
10. Watch for declination drift again. If the star drifts up
then tweak your wedge in altitude to move the star down
in your field. If the star drifts down then tweak your
wedge to move the star up in your field.
Stop when the star ceases to drift off the horizontal
crosshair over 5 minutes.
11. Changing the north/south will upset the east/west. A
couple of iterations will get you increasingly
closer to true alignement.
Polaris Finder Chart
Limiting magnitude 10.0