Orion ASTROVIEW 9827 - Manual (Page 9)

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4. Loosen the R.A. lock lever and rotate the mount about
the R.A. axis until the March 1 indicating mark (the long line
between the “2” and the “3”) on the date circle lines up with the
4 PM mark (the long line above the “16”) on the R.A. setting
circle. You may find it convenient to remove both the counter-
weights and the telescope optical tube to do this.
5. Now, loosen the three thumbscrews on the polar finder
housing and rotate the polar finder so the small circle where
Polaris will be centered is located straight down from the inter-
section of the crosshairs. Retighten the thumbscrews.
The polar axis finder scope is now properly set in its initial
position. Next, you must align it so that it is exactly parallel to
the mount’s R.A. axis:
6. Look through the polar finder at a distant object (during the
day) and center it in the crosshairs. You may need to adjust
the latitude adjustment T-bolts and the tripod position to do
this.
7. Rotate the mount 180° about the R.A. axis. Again, it may
be convenient to remove the counterweights and optical tube
first.
8. Look through the polar finder again. Is the object being
viewed still centered on the crosshairs? If it is, then no further
adjustment is necessary. If not, then look through the polar
finder while rotating the mount about the R.A. axis. You will
notice that the object you have previously centered moves in
a circular path. Use the three thumbscrews on the housing
to redirect the crosshairs of the polar finder to the apparent
center of this circular path. Repeat this procedure until the
position that the crosshairs point to does not rotate off-center
when the mount is rotated in R.A. Once this is accomplished,
retighten the thumbscrews.
The polar axis finder scope is now ready to be used. When
not in use, replace the plastic protective cover to prevent the
polar finder from getting bumped, which could knock it out of
alignment.
using the Polar axis Finder
When using the polar finder in the field at night, you will need
a red flashlight to illuminate the finder’s reticle. Shine the
flashlight at an angle into the front opening in the R.A. axis.
Do not shine it directly into the opening, or the light will be too
bright, and you will also obstruct the view of the polar finder.
It may be helpful to have a friend hold the flashlight while you
look through the polar finder.
For most accurate polar alignment, you will need to know the
approximate longitude of your observing site. This information
can be obtained by looking at a local map. Now, figure the
difference between the longitude of your observing site and
the closest standard time meridian. The standard time merid-
ians are 75°, 90°, 105°, and 120° for the 48 continental states
(150° and 165° for Hawaii and Alaska). Choose the standard
time meridian that is closest in value to your local longitude,
and then calculate the difference. If your local longitude has
a value less than the closest standard time meridian, you are
east of the standard time meridian by the calculated amount.
If your local longitude has a value greater than the closest
standard time meridian, you are west of the standard time
meridian by the calculated amount. For example, if you are
in Las Vegas, which has a longitude of 115°, the closest stan-
dard time meridian is 120°. The difference between these two
numbers is 5°. Since Las Vegas’ longitude value is less than
the standard time meridian value, you are 5° east of the clos-
est time meridian.
Take your calculated difference from the closest standard
time meridian and rotate the date circle so that the merid-
ian offset scale line that corresponds to your calculated differ-
ence lines up with the engraved time meridian indicator mark
on the polar finder housing. Each line of the meridian offset
scale represents 5° of longitude. Lines to the left of the “0” on
the meridian offset scale indicate east of the closest standard
time meridian, while lines to the right of the “0” indicate west
of the closest standard time meridian.
Continuing with the prior example of observing in Las Vegas,
you would rotate the date circle so that the first line to the left
of the “0” on the meridian offset scale lines up with the time
meridian indicator mark.
Make sure that the “0” mark on the R.A. setting circle lines
up with the pointed indicator cast into the mount, and that
the large thumbscrew just above it is tightened. Now, rotate
the mount about the R.A. axis of the mount until the line on
the R.A. setting circle that corresponds to your current local
time lines up with the line on the date circle that indicates
the current date. If you are on daylight savings time, subtract
one hour from your current local time. For example, if it was
November 1 at 9 PM, standard time, you would rotate the
telescope in R.A. until the line above the “21” (9 P.M.) on the
R.A. setting circle lines up with the long line between the “10”
and “11” on the date circle. The long line indicates the first day
of the higher numbered month, i.e. the line between “10” and
“11” marks November 1st.
Finally, look through the polar alignment finder scope while
shining a red flashlight at an angle down the front opening
of the R.A. axis, and center Polaris in the small circle. Adjust
the tilt of the altitude up-or-down with the latitude adjustment
T-bolts and use the azimuth fine adjustment knobs (Figure 7)
for final positioning. To do this, you will first need to loosen the
big tripod attachment knob directly underneath the base of the
equatorial mount. The fine adjustment knobs work by loosen-
ing one and then tightening the other. When done, retighten
the tripod attachment knob to firmly secure the mount and
tripod. If the fine adjustment knobs do not allow the mount to
move far enough to center Polaris, you will need to rotate the
entire tripod left or right to get it within the fine adjustment’s
range.
Once Polaris is centered in the small circle, you are done.
The telescope is now accurately polar aligned, and can be
used for advanced observational applications, such as astro-
photography or precise use of the manual setting circles. As
mentioned before, only move the telescope along the R.A.
and Dec. axes; if you move the tripod, or change the tilt of the
equatorial mount, you will need to polar align again.