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Use a magnetic compass if you are not sure which way north is. 2. Make sure the mount is level. A carpenters level may be helpful. 3. Recheck all hardware and knobs to make sure all are tight. F. To focus the telescope and align the finderscope: 1. Remove the front lens cover (#5). 2. With a low power eyepiece tight in the eyepiece adapter (with its lens cover removed), position the telescope tube to look at any object about one mile or further away during the day. Put the object in the center of the field. To focus, turn the focusing knob (#2) until your chosen object is in sharp focus. Remember to use outdoors only as you should not look through windows which may distort the image. 3. Look through the finderscope (with its lens covers removed). If the object being observed is not visible in the finderscope or is not in the center of the finderscope crosshairs, then you need to align the finderscope. Use the finderscope adjustment screws to align the finderscope with the main telescope by tightening and loosening these screws until the object is centered on the crosshairs. Once the finderscope is aligned with the main telescope, it makes it easy to find celestial objects. You find the desired object in the finderscope first (since it has a wide field) and then look at the narrow field but much more powerful main telescope for detailed views. 4. If the image in the finderscope is not sharp, then turn the finderscope eyepiece until the image is sharp. 5. Do not be alarmed when you look through the finderscope and telescope and the object is upside down and reversed left to right. This is normal with an astronomical telescope. G. Preparation for astronomical observing with the altazimuth models. 1. All that is necessary is to recheck all hardware and knobs to make sure all are tight. 6 4. UNDERSTANDING THE SKY A. The Celestial - Coordinate System. The celestial-coordinate system is an imaginary projection of the Earth's geographical coordinate system onto the celestial sphere which seems to turn overhead at night. This celestial grid is complete with equator, latitudes, longitudes and poles. The Earth is in constant motion as it rotates on its axis. Actually the celestial-coordinate system is being displaced very slowly with respect to the stars. This is called precession and is caused by gravitational influences from the Sun, Moon and other celestial bodies. The celestial equator is a fiill 360° circle bisecting the celestial sphere into the northern celestial hemisphere and the southern celestial hemisphere Like the Earth's equator, it is the prime parallel of latitude and is designated 0°. The celestial parallels of latitude are called "coordinates of declination (Dec.)", and like the Earth’s latitudes they are named for their angular distances from the equator. These distances are measured in degrees, minutes and seconds of arc. There are 60 minutes of arc in each degree, and 60 seconds of arc in each arc minute. Declinations north of the celestial equator are "+" and decimations south are The north pole is +90 and the south pole is -90 . The celestial meridians of longitude are called "coordinates of right ascension (R.A.)", and like the Earth's longitude meridians they extend from pole to pole. There are 24 major R.A. coordinates, evenly spaced around the 360° equator, one every 15°. Like the Earth's longitudes, R.A. coordinates are a measure of time as well as angular distance. We speak of the Earth's major longitude meridians as being separated by one hour of time because the Earth rotates once every 24 hours (one hour = 15°). The same principle applies to celestial longitudes since the celestial sphere appears to rotate once every 24 hours. Right ascension hours are also divided into minutes of arc and seconds of arc, with each hour having 60 minutes of arc and each arc minute being divided into 60 arc seconds. Astronomers prefer the time designation for R.A. coordinates even though the coordinates denote locations on the celestial sphere, because this makes it easier to tell how long it will be before a particular star will cross a particular north-south line in the sky. So, R.A. coordinates are marked off in units of time eastward from an arbitrary point on the celestial equator in the constellation Pisces. The prime R.A. coordinate which passes through this point is designated "O hours O minutes O seconds". We call this reference point the vernal equinox where it crosses the NORTH POLE Figure 2 7 celestial equator. All other coordinates are names for the number of hours, minutes and seconds that they lag behind this coordinate after it passes overhead moving westward. Given the celestial coordinate system, it now becomes possible to find celestial objects by translating their celestial coordinates using telescope pointing positions. For this you use setting circles (if you have the Firstscope 76 EQ - equatorial mount models) for R.A. and Dec. to find celestial coordinates f...

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