Using the Advanced Astromaster

Alignment is required before using the AAM. The computer module has to know where it's pointing before it can keep track of the encoder motions. Alignment is a 2 step process.

1. Using the remaining setting circle, set the telescope to point to 0 degrees. Hit the enter button on the AAM module.

2. Point the telescope at one of the alignment stars (most of the brighter stars in the sky are alignment stars) and press enter. Move to a second alignment star and repeat the procedure.

It is suggested that you select alignment stars as widely separated as possible and, for the fork mount, that the stars not be between Polaris and the northern horizon. Now you are ready to bounce from deep sky object to deep sky object. Or are you?

I used the iron circles on the C-8 for 20 years with great results. By using a bit of imagination, it was possible to point the RA circle to 1 minute accuracy (.25 degrees) and the dec circle to about 20 minutes accuracy. Once the scope was polar aligned using a couple iterations of the 2 star method, I could usually put an object in the field of view of a low power eyepiece.

Using the digital setting circles can be a much more frustrating experience! There are nights when they are dead on all across the sky and other nights when I can't use them to zero in on M42. Here are some of the techniques I've found that seem to make using the AAM easier.

Before taking the scope out into the field, check to make sure the scope is level when pointing to 0 degrees declination. Set the drive base on a flat, level surface when checking level. You can either point the scope straight up with a level across the front of the tube and set the dec circle to 90 degrees or point it to the horizon and set a level across the top of the tube and set the circle to 0.

While polar alignment is not necessary (you can specify in the AAM setup menu whether you are roughly or accurately polar aligned) I find it beneficial to take the few minutes and do a good 2 star polar alignment. While this may not increase your pointing accuracy, it will keep the scope tracking well.

Use a moderately high power eyepiece while doing the AAM alignment procedure. Some people advocate using a cross-hair eyepiece, but I find it pretty easy to estimate when a star is close to the center of the field of view. I have used a Celestron Microguide eyepiece to set the stars in the center of view, but didn't find any significant increase in pointing accuracy when compared with my estimate.

Synching allows you to center an object in your field of view and then telling the AAM that the object is centered. For example, you used the AAM to move you to M57 - the Ring Nebula in Lyra. It was necessary to hunt around a bit to find M57, but you finally have it dead center in the field. Change the AAM mode to SYNC (or ALIGN) and press enter. Synching can be very useful if you keep in mind the fact that centering on a fuzzy patch is not as easy as centering on a star. I prefer using planetary nebulae or stars for synching, but will use the center of small galaxies as well.

Here's a technique to let you synch on any of the alignment stars. Point the scope at an alignment star - say Regulus - and use the IDENTIFY mode to search for any star brighter than mag 2. Regulus should pop up on the display. Center it and synch. You can use the CATALOG mode to do the same thing, but this will require looking for the ST (star) number for Regulus in the AAM user guide. This technique works well on bright stars that are not in the alignment catalog.

The best method of gaining almost perfect pointing accuracy is to work a small area of the sky. Find a bright object in the area you wish to work, synch on it and you will be able to put any object within about 20 degrees of declination or 1 hour of right ascension into the field of view.

When all else fails:

The night will come when you can not get the digital setting circles to find ANYTHING in the sky. You have aligned until you can't align no more. You have synched on everything in the sky, but as soon as you try moving from one object to the next... all you end up with is black sky in the eyepiece.

Change the battery! I know the 9 volt batteries are supposed to last 20 or 30 hours (with display brightness down low), and the computer should tell you when the battery is low. If the thing is acting weird, change the battery. I keep a handful of 9v batteries in my observing case and usually swap out the AAM battery after 2 nights observing.

If the battery doesn't cure your problems, chances are something is loose. On the RA encoder, make sure the set screw that holds the encoder shaft is tight. If you have the small, knurled coupler that screws into the RA axis, check to see if this is tightly screwed into the axis. The DEC encoder is held to the declination trunnion by a small collar. The encoder shaft goes into the collar and is held in place by another set screw. The collar itself is held to the trunnion by 2 very small screws. If these screws loosen up, there will be a lot of play in the connection. This was my problem using the 2 plastic washers (see the installation section.) Pull the protective cover off the declination encoder assembly and make sure the collar and set screw are tight.

Are your cables hooked up right? If you reverse the paddle boards at the encoders, you will usually get an encoder error on the display. However, if you reverse RA and DEC cables, you won't get an error, but your WARP factor will be astronomical.

 

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