Finally success with 3 star alignment

[M4lcs67]

After an absolute age and countless attempts, I finally got my 127 SLT to do a reasonably accurate 3 star alignment for the first time. I'm sure it helped that I used my new Baader Hyperion 10mm with 14mm ftr combo (which gives 8.4), so I could centre my chosen stars more accurately in order to get a better result. And the fact that I recently found out that not all stars in the 127 SLT database can be used as alignment ones (they don't tell you that in the instruction booklet), so at least I knew which stars to aim for. Well now i've nailed it, it should get better each time.

[vphotographic]

So which stars ?

[euphony]

I couldn't get my CPC1100 to align to anything last night even on repeated attempts, yet Friday it did it perfectly, with no fuss whatsoever.

i suspect that as it didn't appear to be really dark that I was struggling to get a bright star centered, so the scope probably thought I was taking too long (over a minute for each) so thought I was pointing at something else

[laser_jock99]

A useful accessory is an illuminated reticule eyepiece. These allow you to centre the telescope on the star at fairly high power. I found previously that my guesstimate of where the centre was variable to say the least.

[M4lcs67]

Hello vphotographic, Stars I used were Vega, Arcturus and Regulus. Follow this link to get the full list of alignment stars:

http://www.celestron.com/c3/support3/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=2415&nav=0,227

They don't tell you in the instruction book that all stars can't be used as alignment stars. Took me flipping ages to find this out. Just got this list by accident while commenting on a thread and someone mentioned this list.

[M4lcs67]

Laser_jock99. Which illuminated reticule do you use????

[JamesM]

Illuminated reticules are great and of course accurate but they come at a price. Alternatively, when you can see the chosen alignment star with your 10mm eyepiece, you can always adjust your focuser to put this star out of focus, thereby making it easier to centre a larger (defocused) star concentrically within the confines of the eyepiece/field of view. Hope that helps.

James

[Mark1970Vintage]

.... you can always adjust your focuser to put this star out of focus, thereby making it easier to centre a larger (defocused) star concentrically within the confines of the eyepiece/field of view. Hope that helps.

James

I like that idea, will try it tonight if I get chance.

[Dunkster]

Glad to hear you've nailed the alignment Malc, I've only had it barf a couple of times, but the alignment star list makes sense in some ways as at least with LP there's a chance of seeing them LOL I've normally pre-selected my alignment stars for the altitude and visibility from my garden (mostly east), one being over the meridian.

I've also found the approach improves things a bit, on mine it likes approaching from the below left, i.e. moving right and up to centre the star. Minimises backlash apparently.

De-focussing a star is a great helper in centering too.

[M4lcs67]

Thanks James. That defocussing technique seems a great idea. I'll give it a go.

Yeah, Dunk. The approach is crucial as well, but I had difficulty in locking onto the second star last night. Ended up slewing all over the place until I found the star and centred it, so maybe it was beginners luck. Also I did use my new Hyperion 10mm and 14mm ftr combination which gives 8.4. Perhaps I may do better using the 24mm (either focussed or de-focussed) to align then swap for the 10mm. I'll try both ways next time I am out. I am certainly glad I found that alignment star list. Gives you a fighting chance anyway.

[Dunkster]

Might be worth trying aligning with the bundled 9+25... they're narrower FOV so easier to centre (for me at least!) because you can easily see the field stop.

[M4lcs67]

Blimey. I didn't think about that, but you are right, thanks. By the way. What happened to your 127SLT??????? Are you out tonight? Clouds have rolled in up here and it is rather windy. Unless the weather improved considerably i'll be saying indoors tonight. Although the success I had last night should make up for it.

[Ags]

I find that a 2 star alignment works best for me - the three star alignments often fail, and the mount only uses two out of the three anyway. Also, you can swap alignment stars later in a session, and at least with my 4SE the swapped in alignment objects can be anything - I've used M31, M37 for example. This helps because errors in alignment seem to build up during a session so refreshing the alignment can help. Also your goto gets a boost if you have an alignment star near your targets.

[Dunkster]

LOL the 127 is still with me, just thought my sig would get a bit silly with that little lot in there

Forecast says it will clear here tonight but it'll be a bit windy - it is out there now. But, it's reckoning tomorrow night might be a go, albeit the eyelids fighting with the late dark and early starts

[euphony]

Hello vphotographic, Stars I used were Vega, Arcturus and Regulus. Follow this link to get the full list of alignment stars:

http://www.celestron.com/c3/support3/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=2415&nav=0,227

They don't tell you in the instruction book that all stars can't be used as alignment stars. Took me flipping ages to find this out. Just got this list by accident while commenting on a thread and someone mentioned this list.

Fantastic, I was going put a post up asking about this and now you've saved me the trouble. Thanks for that, that's just what i wanted

[euphony]

I find that a 2 star alignment works best for me - the three star alignments often fail.

Garrrggh, why didn't I try that last night?!?!?!? darn it...I spent 3 hours doing very little due to the 3 star alignment failing every time and the least I could have tried is that! I'll remember that for next time.

The mount only uses 2 out of the 3 aligned stars?

Why on earth do you need to align 3 then?