Congratulations on getting your new telescope! Or maybe you are about to get a new telescope? You are about to discover and explore the hidden treasures in the night sky up close.
You probably have a few questions like how do I set up a telescope? In this blog update, lets review some basic terms that you need to know, and some general steps on how to to set up a telescope. My name is Erik, and I am an amateur astrophotographer.
Before we get started, a good place to start is with the manufacture's instruction manual or any videos they may provide online.
ALTITUDE AND AZIMUTH
So let's start first with some general terms. Altitude and Azimuth.
ALTITUDE and AZIMUTH are part of a local coordinate system on how we find the apparent location of celestial objects in the night sky. All measurements are expressed in degrees.
ALTITUDE, or ALT for short, stands for the altitude or elevation axis. On the horizon is the zero degrees altitude or elevation on the axis. Directly overhead is the zenith at 90 degrees altitude. Halfway in-between is 45 degrees.
AZIMUTH is "the direction of a celestial object from the observer, expressed as the angular distance from the north (Oxford Dictionary)."
In the northern hemisphere, we use Polaris to help find the celestial north pole, denoted as zero degrees north. Go clockwise 90 degrees from the celestial north, you will reach the 90 degree point, or East. Another 90 degrees clockwise is south at 180 degrees. Another 90 degrees clockwise is 270 degrees or West.
This coordinate system works best with Alt-Azimuth mounts. After initializing and star-aligning your mount, armed with your local position and time, you are able to slew your telescope to the apparent location of celestial objects that are potentially viewable from your location that is above the horizon.
For example, if the Moon is halfway up the horizon, by telling your APP or hand-controller to find the moon, its apparent position may be 210 degrees in azimuth and 45 degrees in altitude.
DEGREES
Before we move on, lets talk about degrees. It is helpful to know that degrees are further divided into arc-minutes. There are 60 arc-minutes to a degree.
And there are 60 arc seconds to a 1 arc-minute. So the apparent location of a celestial objects have a precise location that is always moving, due to the rotation of the Earth, or their own movement in space. So going back to our moon location, its apparent azimuth position tonight at this very moment might be 210 degrees, 30 minutes, and 29.5 seconds.
We also express the apparent width of objects in the night sky in degrees as well - like the Sun, Moon, planets, galaxies, nebulas, constellations, etc..
So far example, the Sun is approximately 1/2 degree apparent width or 32 arc minutes.
The moon has an apparent width of 29.4 and 33.5 arcminutes depending on its orbit, similarly at 1/2 a degree wide. As we just recently witnessed across North America, the moon was at the right spot in its orbit to give us a total eclipse on April 8th.
MORE ON CELESTRIAL NORTH
It is important to note that celestial north is not the same as true north or magnetic north. Celestial north is around 1 degree off of true north. However, magnetic north varies greatly due to your location on Earth due to magnetic declination. Magnetic declination is the angular difference between true north and magnetic north. Here just south of Atlanta, magnetic north is over 5 degrees west of true north.
CELESTRIAL SPHERE
Lets talk about another coordinate system that is used by astronomers and equatorial mounts. Let's start with the coordinate system we use here on Earth, Latitude and Longitude.
Latitude measures the distance north or south of the equator. It is expressed in degrees. 0 degrees latitude is equal to the equator. 90 degrees North is equal to the true north pole. 90 degrees South equals to the true South pole. The poles are where the Earth spins on it's axis.
Longitude measures distance east or west from the prime meridian. The prime meridian is an imaginary line from Greenwich, England, dividing the Earth into two hemispheres - West and East. It is measured in degrees, minutes, and seconds.
For astronomy, the sky has a similar coordinate system. There is a celestial north pole and a celestial south pole. Halfway in-between the north and south poles is the celestial equator.
DECLINATION
To help find objects in the night sky with this system, we describe celestial objects either north or south of the celestial equator in degrees. If the object is south, we use negative degrees. So for example, Antares is negative 26 degrees and 29 minutes, south of the celestial equator.
RIGHT ASCENSION
Right ascension is similar to longitude on Earth and the prime meridian and Greenwich, England. The "meridian" on the celestial sphere is determined on where the Sun falls on the celestial equator at the Spring equinox. The 360 degrees circle around the sphere is subdivided into 24 parts called hours. So as each hour passes, one hour advances on the celestial sphere. Actually slightly a little less at 10 seconds each hour. One solar days is 24 hours where one sidereal day is short 4 minutes of that. This is why the constellations are just a little further west at the same time each night, unless you live at the true north or south poles.
Equatorial mounts are polar aligned with the celestial poles. One the telescope has slewed to its declination location and right ascension location, the mount can track the object on one axis, adjusting for the rotation of the Earth.
So in astronomy, we use altitude (ALT) and azimuth to find objects in the sky. Based on your exact location and time, this coordinate system is used by your telescope mount to find objects in the night sky.
TELESCOPE MOUNTS
Telescope mounts fall in two categories. Alt-Azimuth (Alt-Azi) and Equatorial mounts (EQ).
ALT-AZIMUTH MOUNTS
Alt-Azimuth mounts are great for observation and planetary imaging. They are perfect for beginners. Some companies sell their telescopes that are attached with these types of mounts - like the Celestron Nexstar series. Some alt-azimuth mounts come with a hand controller. Others utilize an app from your mobile device. And still others like my Sky-Watcher SolarQuest alt-azimuth Solar Mount use both GPS and a HelioFind solar finder to locate and track the sun during the day. And more basic mounts are moved manually by adjusting knobs or through cables.
After providing power to your mount, go through the set-up process on your hand-controller or app. After performing a basic star alignment process, you are ready to go and explore the night sky.
If you are getting into this hobby, I recommend alt-azimuth mounts. They are mostly affordable and easy to setup. Strain-wave mounts like the ZWO AM3, AM5, the new Sky-Watcher Wave 100i and 150i and many others can operate in both alt-azimuth and equatorial modes.
Equatorial mounts (and strain wave mounts operating in equatorial modes) are for both astronomers and astrophotographers. Once polar aligned, these mounts are able to track objects in the night sky for an extended period of time with higher accuracy. Depending on the mounts, they can also be moved through a app, hand-controller, or manually through knobs and/or cables.
I hope this episode was helpful. If your interested in learning more about astronomy and astrophotography, be sure to subscribe to my YouTube channel. Be sure to check out my video on this very topic.
Also, if your like me, there are no telescopes stores my area, not even in my state. I purchase all my astronomy gear and solar viewing gear from High Point Scientific. They have a huge inventory of astrophotography cameras, solar telescopes, solar eclipse viewing glasses, and more. By using the High Point Scientific link below in the description, you can help this channel. Thank you for your support.
High Point Scientific
https://www.highpointscientific.com/?rfsn=7755489.66ed8e
"Astronomy compels the soul to look upwards and leads us from this world to another". Until next time, take care.
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