3 or 2 or Polar?

[Probablynot]

Is the three-star (or two-star) alignment process supposed to be done instead of, or as well as, Polar alignment?

(Darn it, I will get to grips with this CG-5 GoTo! I WILL!)

[old_eyes]

Ah yes, I know this one! Took me ages to understand what was going on with my CG5GT.

My process, and someone will probably explain exactly what is wrong with it is as follows.

After setting up scope (I have to set up and break down each observing session):

1. roughly align mount with pole through polar scope (or by squinting down the hole if no polar scope),

2. check mount level (using bubble level)

3. power up mount

4. do a 2 star alignment with two additional calibration stars

5. go to Align - Polar Align in menu and follow process to acheive polar align.

6. now there is a choice depending on how much you had to adjust the alignment bolts on the mount. You can leave things alone, in which case your Go-To will be off, but the scope will be polar aligned, or you can replace some of the origianl calibration stars. If I want go-to as well as polar alignment accuracy, I usually go-to each alignment star and replace it - realigning to correct any errors.

Seems to work OK.

Now balancing!!

old_eyes

[Capricorn]

As well as.

[Probablynot]

As well as.

But why? Isn't the point just to align the telescope with the heavens? If I align it with two (or three) other stars, why do I have to (also) align it with Polaris before the GoTo will do its job?

(Sorry - I'm really showing my ignorance here!)

[RikM]

You should do both alignments. You are aligning the mount with polaris and the telescope with the skymap in the GoTo. If the mount is not accurately polar aligned, the GoTo map will be off and your GoTo accuracy will suffer as a result.

[Probablynot]

OK Rik, I get that. I think. How accurate does the polar alignment have to be for the GoTo to work properly?

Blimey, it's a contortionists's work to see through the polar alignment scope! The CG-5 tripod isn't the same as an EQ - It's 60° away, so the south leg gets in the way! And Polaris isn't always visible anyway.

I've got spraypaint spots on my patio for where the tripod legs go. I don't change the settings of the tripod legs. The mount is level when set up on the spraypaint spots, and I know my exact lat/long, and I've fed them into the GoTo.

If I do the polar alignment once (properly), is that enough? Or do I have to do it every time I set up? How much of the Synscan setup routine do I have to perform every observable night?

I'm beginning to think that GoTo might be more trouble than it's worth! And I haven't yet viewed a single star/planet as a result of it!

[Tinker1947]

I Polar aligned my mount, got the drill out and drill some indents in the patio slabs, that was late last year, its been good ever since, all the Messiers in my list, have been found with a Telrad and Stellarium, never used the GoTo....

[RikM]

My NEQ6 tripod was dilivered with the peg set for a south facing leg, but I unscrewed it and swapped it to a North facing leg. It's more stable that way and the legs dontt get in the way of the polar scope. I would be surpirised if you couldn't do the same for your CG-5.

How good your PA needs to be depends on how acurate you want your GoTo and tracking. Since I only use my GoTo mount for imaging, I want pretty good GoTo alignment and as best tracking as I can get without spending too much time on it. So I align the mount using the (Properly centred and calibrated) polarscope every time, but I don't drift align or use the Software PA tools. I can get 10min subs with round stars so that's good enough for me.

For just visual use with an EQ mount, I didn't even bother with the polarscope, just looked up through the hole in the mount where the polarscope should be and if I could see Polaris, that was good enough. (But I didn't have GoTo on that mount).

[Probablynot]

My NEQ6 tripod was dilivered with the peg set for a south facing leg, but I unscrewed it and swapped it to a North facing leg. It's more stable that way and the legs dontt get in the way of the polar scope. I would be surpirised if you couldn't do the same for your CG-5.

Thanks for that, Rik. Yes, it worked on the CG-5 too. So now the spraypaint markers on my patio (for the tripod legs) are all 60° out of true.

Now I just need a sky clear enough to see Polaris, a cushion on the patio, some sandpaper and that spraypaint can! Or a drill, if I follow Tinker's example.