Celestron CPC Telescope alignments

[WarpedSpacer]

Hi all


I recently bought a Celestron CPC 8 inch Delux HD GPS computerized telescope but Im finding that each time I turn it on it requires me to do a star alignment all over again. Every time. Is that right?


Can anyone familiar with Celestron CPC computerised telescopes please advise me if that is the case; namely that I must do a star alignment every time I turn the scope on even if Im always at the same location. I would have though that a computerised telescope could store my location and default to "my particular night sky" every time I start up the telescope unless I instruct it to do otherwise. I assume there's something Im not doing to store my position.



If anyone has any advice for me on this I would be most grateful :help:



Thanks in advance
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[mental4astro]

Hello Claude,

I also have a CPC Deluxe HD GPS mount that I use very extensively from home for my planetary and lunar work. Yes, you need to do a star alignment every time you switch on the mount.

The mount will not know if you had taken it down and set up again. It also cannot assume that you had not changed the position of the scope between set ups, say by unlocking the clutches to align the finder scope. Also there are small errors in the functioning of most mounts, and over the course of a night you will see the goto accuracy diminish slowly. If you've been using the mount for several hours, it is not uncommon to even do a new alignment process to reset the mount.

Really it is not an onerous process to do a two star alignment. I certainly don't find it so, and I know that if I take my time to do a very accurate alignment that the goto can be very accurate so as to leave the object centred. By also doing an alignment every time, I make sure that the goto is functioning at its very best accuracy and best tracking quality.

For what it's worth, I align the finder first with a 25mm eyepiece and fine tune it with a 5mm. I then carry out the two star alignment with the 5mm, but with the image of the star as a very large doughnut as this doughnut is very easy to gauge when it is centred in the field of view of the eyepiece. I find this method to be very quick and very, very accurate. This is just one way of achieving a good alignment accuracy. The more care you take with the alignment, the better the results will be for you :thumbsup:

Some mounts do store the final position of the mount (such as the Park Position), but unless the mount/handset has a built in clock that keeps running while the mount is switched off, you will find that nearly all mounts will require some sort of input from you, be it time or date or location. Even if it stores the location, it will still ask if you are using that position or a different one. The CPC mount does not have a final Park Position, so it cannot store such alignment details.

By the way, my CPC is a modified one! It came from an 1100 Deluxe HD GPS like your mount. I got the mount without the scope (the original owner had deforked the OTA), and I removed the non-mechanised arm, fit a dual Losmandy/Vixen dovetail clamp to the other, and the CPC mount is now a monster one arm mount! The single arm mod is even strong enough to take the original 11" scope. My CPC takes a 9" Mak which is as heavy as an 11" SCT. I had looked at the Evolution mount that can also take a 9.25 SCT, but the arm is not long enough to take the 7" or 9" Maks I've used. The arm length is significantly longer of the CPC 9.25 and 1100 (same arm length mounts).

Another CPC tip: A two star alignment also has its limitations for goto. If you find that the accuracy is not as good as you hoped, don't forget about the "Precise goto" function. It will ask you to select a bright star that is close to the object in question (the handset will present a series of named stars in increasing distance from the object). You hit the goto button and the mount will move to that star. You then centre the star in the scope, re-hit enter, and the mount will then move to the object with incredible accuracy. I found this function very useful when I did my planetary nebula marathon a couple of weeks ago, as some of the PN's were very, very difficult to identify if the goto was not so accurate. It took me a little while to get used to it, but now find it a very handy ace card when I'm struggling to spot a very difficult object

[WarpedSpacer]

Thanks for this Alexander. I'm just glad Im not actually doing something wrong in having to align the scope every time & Im sure Ill find the star alignments less onerous the more experience I get under my belt. And thanks also for your extra tips. Regards
Claude

[Camelopardalis]

Also, if you don’t move your scope in between sessions (and of course, protect it from the weather) you can use the park/hibernate function. This will preserve your previous alignment.

However, this is absolutely NOT useful if you move your scope between sessions, as it’ll have the onboard computer thinking stars are in places that they are not.

If you’re finding the judgement of which alignment stars to pick, choose Sky Align...you can then pick any three bright stars to align on, and you don’t have to know what their names are :)

[mental4astro]

Hibernate!?

Well I'll be.

Need to think of an even more cryptic term for a project I have in mind... Repose? Stand down? HAS to be something really archaic or obscure...

[Camelopardalis]

Snooze?

[Allan_L]

Yes Claude, as Dunk said, the CPC does have a Park function, called Hibernate.
As per your manual...


It's been a while since I owned a CPC1100, I don't recall if the scope keeps track of the time once powered down. (ie if the hand controller has a battery or such)

[The_bluester]

The GPS versions look after that bit for you.


From my time with a CPC925 GPS, the two things I would say are, take care to get the tripod base level (Get a small spirit level and ignore the built in one) and either use an eyepiece with a reticle or the highest power EP you have and take care to center the alignment stars really well. It is the difference in my experience between OK gotos and a gradual fall off in performance over the night and nicely centered targets and good tracking until you give up out of fatigue. The best night I got out of mine I was still getting accurate gotos at 3AM after aligning it as soon as enough stars were visible.