Orion 6/6I D. Locating Deep-SkyObjects by Catalog, The Messier Catalog, The New General Catalog

planet’s orange-colored hue. Like Venus, Mercury sometimes appears as a crescent, rather than as a full disk.

VENUS At its brightest, Venus is the most luminous object in the sky, excluding the Sun and the Moon. It is so bright that sometimes it is visible to the naked eye during full daylight! Ironically, Venus appears as a thin crescent, not a full disk, when at its peak brightness. Because it is close to the Sun, it never wanders too far from the morning or evening horizon. No surface markings can be seen on Venus, which is always shrouded in dense clouds.

MARS The Red Planet makes its closest approach to Earth every two years. During close approaches you’ll see a red disk, possibly some light and dark regions, and maybe the polar ice cap. To see surface detail on Mars, you will need a high power eyepiece and very steady air!

JUPITER The largest planet, Jupiter, is a great subject for observation. You can see the disk of the giant planet and watch the ever-changing positions of its four largest moons – Io, Callisto, Europa, and Ganymede. Higher power eyepiec- es should bring out the cloud bands on the planet’s disk and maybe even the Great Red Spot.

SATURN The ringed planet is a breathtaking sight when it is well positioned. The tilt angle of the rings varies over a period of many years; sometimes they are seen edge-on, while at other times they are broadside and look like giant “ears” on each side of Saturn’s disk. A steady atmosphere (good seeing) is necessary for a good view. You will probably see a bright “star” close by, which is Saturn’s brightest moon, Titan.

URANUS Uranus is a faint planet, and requires high powers (at least 100x) before it starts to show any detail that distin- guishes it from stars. Uranus will appear as a pale, blue-green disk.

NEPTUNE Like Uranus, Neptune will require high pow- ers before showing anything to distinguish itself from stars. Neptune will appear as a bluish-colored disk, possibly with a very faint moon nearby if you are using a larger-aperture IntelliScope.

PLUTO Smaller than our own Moon, Pluto is very, very faint and shows little more than a point of light similar to a star. Even the Hubble Space Telescope is unable to show much detail on Pluto. Many amateur astronomers note how Pluto moves with respect to background stars (over several nights) in order to confirm their observation of our most remote planet.

D. Locating Deep-Sky Objects by Catalog

Catalogs are groups of deep sky objects of interest that have been assembled and given designations. Very often a deep- sky object will have a catalog number, as well as a “common” name. For example, the Orion Nebula is listed in the Messier catalog as “M42.” The controller has three catalogs built-in: The Messier catalog (M), the New General Catalog (NGC), and the Index Catalog (IC). Many of the objects in the Messier catalog also have NGC catalog designations.

The Messier Catalog

The Messier catalog contains 110 galaxies, nebulas, and star clusters identified by the famous French astronomer Charles

Messier and his colleagues in the late 1700’s. These are some of the most popular celestial attractions observed by amateur astronomers.

To view an object from the Messier catalog, press the M but- ton. Then enter the number of the Messier object you wish to view using the numeric buttons and press the Enter button. For example, to view Messier 57, also known as “the Ring Nebula,” you would press the M button, then press the “5” button, then press the “7” button, followed by the Enter button. If the number of the Messier object you wish to view contains three dig-its, it is not necessary to press Enter after inputting the third digit.

The object’s catalog designation will be shown in the upper left corner of the display screen, with the guide arrows in the upper right. The lower left will display the constellation the object resides in and the object’s common name (if it has one) or a brief description of the object. Move the telescope in the corresponding directions shown by the guide arrows to locate the object.

You can get more information about the selected object by pressing the Enter button. The second line of the LCD display will then cycle information about the object you are viewing such as its celestial coordinates (R.A. and Dec.), magnitude (brightness), size (in arc-minutes or arc-seconds), and a brief scrolling text description.

When you are finished viewing the selected Messier object, you may scroll to another Messier object by using the arrow buttons, or you can select another Messier object to view by pressing the M button again.

The New General Catalog

The New General Catalog, or NGC, is a catalog of some 7,840 deep-sky objects compiled by the Danish astronomer J. L. E. Dreyer more than 100 years ago. It contains hundreds of excellent examples of each type of deep-sky object and is the most well known and used catalog by amateur astronomers beyond the already mentioned Messier catalog. To be more precise, the version of the New General Catalog used in the IntelliScope Computerized Object Locator is an improved ver- sion known as the “Revised New General Catalog”; this ver- sion has many corrections from Dreyer’s original list.

To view an object from the NGC catalog, press the NGC but- ton. Then enter the number of the NGC object you wish to view using the numeric buttons and press Enter. For example, to view the Andromeda Galaxy, which is listed as NGC224, you would press the NGC button, then the “2” button twice, then the “4” button, followed by the Enter button. If the number of the NGC object you wish to view contains four digits, it is not necessary to press Enter after inputting the fourth digit.

The object’s catalog designation will be shown in the upper left corner of the LCD screen, with the guide arrows in the upper right. The lower left will show the constellation the object resides in, and the object’s common name (if it has one) or a brief description of the object will be shown in the lower right. Move the telescope in the corresponding directions shown by the guide arrows.

You can get more information about the selected object by pressing the Enter button. The second line of the LCD display

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