Mastering my first GoTo mount CG-5

[g__day]

Well I took my first steps towards more serious astronomy, and it was alot fun but I'm rapidly getting to the a few questions and is this gear working / initialised correctly (particularly star alignment and goto tests).

Achievements:

1. All set up, downloaded NexStar demo from hero, bought a ohine cable, hacked it, crimpped it, converted it to a serial port and tried controlling it - :) huge yah!!!! Sees the scope, reads its co-ordinates, issues go to commnads fine.

Here the Problem:

1. When I think I've aligned it it does strange things on Go To. For example did a one solar body align on Jupiter around 8pm last night, used the controller to shift focus 10 degrees left then Issued a go to Jupiter command. Instead of slewing back (to around the 8pm position high in the sky, it pointed between my feet! ???

2. Did an two star align using Vega and Altair, then used controlledr to slew to Arcturus and issued a Identify command. STraight away it got it right.

3. Then I did a find Spica call. Including slewing along left to Spica it ended up doing a 180 ending up almost horizontal but pointing East not South.

So the GoTo is temperamental for me so far,

What I've tried

1. Reading the instruction book back to back
2. Checking time and date and location to the nearest metre using Google Earth amd using my rpecision location
3. Using an electronic compass to assist point the mount towards Celestial South

The Go To for a few other planets seem strange, can onyone please offer suggestion, tests to do a better. The set up manual usages book then three of operations where, a definite eay of testing the mount

* * *

All suggestions and advice gracefylly accepted!

[OneOfOne]

Boy, are you having fun! The first time I actually aligned my scope, it all went pretty smooth. A few times I have aligned everything and then attempted a GoTo and the whole thing went psycho! Usually it ended up pointing to the wrong hemisphere, ie the ground. Pretty frightening. Usually I hit the super master reset button (turn it off) and start again, always with success.

Unfortuantely, I can't offer any suggestions except to say that I am sure you will get there! You will love the GoTo when you sort out the problems. Hopefully someone will have been there done that.

[g__day]

Yes I am having some WTF oments at present. My joy at having this as a next step up is phenominial. My realisation that I need to know key guide stars before I can validate them and really use capability was my first major learning point. My seeing the scope said it aligned quick and dirtly with Jupiter, then moving it off 5 degrees and executing GoTo and having it say Jupiter appears buried 6 feet under my shoes was dissapointing!

Another question - when you start the scope with both AXIS aligned to 0 degrees (the little triangles pointing at each other on both axes) does it matter which way the telescope is pointing on the Mount (up at the sky or or down at the ground)? Given this position should point directly to the Celestial South Pole you have a choice that your OTA is on this line either pointing up at the sky or down at the ground. I presumed it doesn’t matter but I always having mine pointing at the sky. Is this right / wrong or doesn’t it matter?

[sheeny]

G'Day G__day!

Hmm. I have the same mount, and I have to say I have had 1 or 2 instances where it's done screwy things like you describe... but more than 99% of the time it's fine. I couldn't explain what went wrong on those 1 or 2 occasions. Both times I switched it off and started again.

Most times when it goes stupid, in my experience it's operator error, usually entering data incorrectly to the goto (I haven't tried controlling from the PC yet). Things to watch are:

Date - make sure you get the day and month right way round. I haven't found a way to make it dd/mm/yy, it defaults to mm/dd/yy. Depending on the date, that can make a big difference!
Position (your lat long). Do you have a GPS, or can you get a GPS reading of where you observe? It shouldn't make much difference but I would prefer to use a GPS reading than Google Earth.
Polar alignment. Check you've got your magnetic declination right for your observing location so you have the scope pointing to celestial south. For the alignment procedures you mention that you've used I don't think the goto can calculate the cone error. I think you need to do a three star or auto alignment for that.
The altitude (latitude) scale on the mount is pretty rough. If you can get the goto to behave itself, do a drift align (or partial drift align) to set your latitude.I would suggest going back to basics for a start. Just use your goto till you get a handle on it - just to eliminate any bugs from the computer control.

Set it up as accurately as you can with your compass etc, double check all your data entries, and do an auto alignment. This will calculate the cone error for your scope.

I must say, even when things were all working well for me somethimes I felt the alignment and accuracy of the goto was not as good as I expected. I have since bought the GPS module for it, and now it is great! I think the biggest issue with accuracy before was time. The GPS module keeps accurate time, without it I think the goto fails to account for the time during the alignment procedure.

Hope something out of this helps, and I apologise if some of it sounds like sucking eggs - it's not intended to! Keep us posted with how you get on!

Al.

[casstony]

There is a 'Celestron Advanced Series' yahoo group that will be able to answer all of your questions. They have an extenensive FAQ in the files section.

Tony

[sheeny]

Yes, it does matter. Pointing at the sky is good!;)

Hmmm. You said "My realisation that I need to know key guide stars before I can validate them and really use capability was my first major learning point." How are you going with that? If you do pick the wrong star, it can throw things out significantly. I had that problem between Hadar and alpha centauri my first night out with the scope:( but very quickly learned that Hadar is not a double! (I was pretty rusty after 15 years of no observing!) A good planisphere is a great aid to identifying the bright stars that the goto will use for alignment.

Hang in there, mate!

[g__day]

Agreed,

Basically I run NexStar from here looking for what it suggested as guidestars - 16 choices, of which from my covered balcony I could see 4 (Spica, Arcturus, Vega and Altair).

Tonight I'll try it from my backyard on the tripod rather than my pier, and use a powertank rather than a transformer.

GoogleEarth allows me to see not only my street, but my house to 1 foot of where my scope is!!!

Also knowing the exact published GPS of optus towers you can zoom on these and check findings!

Date and time etc to be checked again tonight...

As to finding which star is which, I printed a star chart with only order 1 magnitude stars of brighter from my location using

http://www.fourmilab.ch/cgi-bin/uncgi/Yoursky

Puzzling!

[OneOfOne]

You may want to invest $20 in a planisphere, mine (Philips) goes to about mag 4, which is all I can see anyway. They are waterproof and can be used anytime. I even use mine when I don't have the scope out just to revise what star is what.

[g__day]

Got one, must say I use the NexStar software to print out a night 8pm, 10pm, midnight series of sky maps showing alignment stars (figuring how many times I'm powering down in frustration and totally re-setting my mount!).

Until you have basic Goto functioning, forget finding anything of any magnitude!