Celestron NexStar 8i manual Object Catalog, EQ North / EQ South Alignment, NexStar Re-Alignment

EQ North / EQ South Alignment

EQ North and EQ South Alignments assist the user in aligning the telescope when polar aligned on an optional equatorial wedge. Just as with the Altazimuth alignments described earlier, the EQ alignments gives you the choice of performing an AutoAlign or a Two-Star alignment.

•The EQ AutoAlign follows many of the same steps as the Alt-Az Auto Two-Star Align, except it will ask you to position the tube so that the index markers are aligned, and then rotate the telescope base until the tube is pointed towards the Meridian (see figure 2-2).

•The EQ Two-Star Align requires the user to locate and align the telescope on two bright stars. When selecting alignment stars it is best to choose stars that, a) have a large separation in azimuth and b) both are either positive or negative in declination. Following these two guidelines will result in a more accurate EQ Two-Star alignment.

NexStar Re-Alignment

The NexStar has a re-alignment feature which allows you to replace either of the two original alignment stars with a new star or celestial object. This can be useful in several situations for example:

Figure 2-2

The Meridian is an imaginary line in the sky that starts at the North celestial pole and ends at the South celestial pole and passes through the zenith. If you are facing South, the meridian starts from your Southern horizon and passes directly overhead to the North celestial pole.

If you are observing over a period of a few hours, you may notice that your original two alignment stars have drifted towards the west considerably. (Remember that the stars are moving at a rate of 15º every hour). Aligning on a new star that is in the eastern part of the sky will improve your pointing accuracy, especially on objects in that part of the sky.

To replace an existing alignment star with a new alignment star:

1.Select the desired star (or object) from the database and slew to it.

2.Carefully center the object in the eyepiece.

3.Once centered, press the UNDO button until you are at the main menu.

4.With NexStar Ready displayed, press the ALIGN key on the hand control.

5.The display will then ask you which alignment star you want to replace. Use the UP and Down scroll keys to select the alignment star to be replaced. It is usually best to replace the star closest to the new object. This will space out your alignment stars across the sky.

6.Press ALIGN to make the change.

Object Catalog

Selecting an Object

Now that the telescope is properly aligned, you can choose an object from any of the catalogs in the NexStar's extensive database. The hand control has a key (4) designated for each of the catalogs in its database. There are two ways to select objects from the database: scrolling through the named object lists and entering object numbers.

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