Last updated: 27 December 2005
Ultimate Astronomy sent me an Astralign-light (ultimateastronomy.com/ca/products/astralignlight.htm) for use with ETX telescopes. It comes in a small case (see photo on the right). It is actually two accessories in one: a magnetic compass to help you find North (left photo below) on one end of a 1.25" tube and an illuminated bubble level to assist in leveling the scope (right photo below) on the other end.
The Astralign-light is placed into the ETX eyepiece as seen in the photos below:
You turn the ring with the green dots to turn on the red illumination to assist in leveling in the dark. This illumination is very handy but unfortunately it does not also illuminate the compass so you will still need a red flashlight to see the compass dial.
To make leveling easier you line up the three dots with your tripod legs and then adjust the leg(s) nearest the out-of-level condition indicated by the direction of the dots. This works well and is a nice touch that other leveling accessories don't have. That is, it works well if your Optical Tube Assembly (OTA) is parallel to the ETX base in all directions. Normally this is the case for a left-right (through the fork arms) direction but not for a forward-backward (OTA altitude) unless the OTA is parallel to the ETX base.
So, how to check that the OTA and base are exactly level and so parallel? Place a level on the base. You will need a second level to do this as the Astralign-light compass cover is a dome and so it doesn't sit flat on the base, as you can see in this photo:
The above limitations notwithstanding, the Astralign-light works well to assist finding level and north. Remember, that as with all magnetic compasses, you will need to correct for your location Magnetic Variation (see the Astronomy Links page for some sources) as well as any local magnetic interference. Even though I can see Polaris from my local observating site and I normally just "eyeball" the OTA Home Position and base leveling and get good results, I was able to improve the accuracy of the initial alignment star GOTOs using the Astralign-light.
Do you need an Astralign-light? The Autostar is very forgiving of leveling errors and if you know the night sky well enough to identify the alignment stars (if they are not hidden by obstructions), then you might not. But if you don't have a bubble level nor a compass and you want them, or you want to improve the accuracy of the initial alignment star pointing, then the Astralign-light makes a convenient, well made package to add to your telescope accessories.
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