Methods to Setup a Telescope and to Find Objects Close to the Horizon
Submitted by Bernard Friberg
Viewing objects close to the horizon shortly after sunset can often
be a problem. The time between the object just becoming visible and the
time it touches the tree line or horizon is very short making it very desirable
to find the object as quickly as possible. The following suggests ways
to accomplish this with an alt-az or equatorial telescope.
1. If Venus is near the horizon, it can be used to accurately orient
- Determine the exact RA and Declination of Venus.
- Use a compass or setting circles to orient the telescope so that the measurements
coincide with the RA and Dec values.
- Adding angular measurements to an Alt-Az scope using measurement rings,
markings or some other method is recommended if your scope does not have angle
- Many equatorial mounts have setting circles installed so all that
is necessary is to orient the scope to known azimuth and altitude angles and/or
RA and Dec values. If your scope has a clock drive with RA measuring
capability (this includes computers), initialize your scope to the above values.
The orientation of your telescope can be easily checked and/or fine tuned
by locating Serius, Capella or another bright star or known object.
- The telescope can then be used to locate comets or any other known object.
2. Another method to orient an equatorial mount with RA measuring capability
is to set it to the local sidereal time.
- First orient
the azimuth using one of the above methods if the
telescope is not mounted in a fixed position such as a pier or in an
observatory thus making this step unnecessary.
use a bubble level to orient the scope to the meridian. Then initialize
the RA value to the sidereal time.
- A bright object
can then be used to check and/or fine tune the setting.
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