Polar alignment for cluttered backyards

[04Stefan07]

My backyard is filled with trees and also the house blocks the bloody SCP so I need to improvise.

I roughly align my tripod true south (I follow a guide on MyAstroShop https://www.myastroshop.com.au/guides/polar-align-basic.pdf) which is 169 degrees East according to the chart. My alignment is off by a bit once I slew to stars.

For those who suffer the same issues in their backyards at home (where they have limited sections of the sky to work with) are there any work arounds or tips to get a more accurate alignment?

[Imme]

Use drift align on phd.....easy as and very accurate

[peter_4059]

+1 for PHD2 drift align.

[DJT]

Hi Stefan
There’s a very simple daylight polar alignment routine on this link

http://www.astro-physics.com/tech_support/mounts/daytime-polar-alignment.pdf

Works for AP mounts and assumes you have their park 2 setup but if you create your own park positions with your flavour of mount then it’s all good. I use this then repeat once a known star appears overhead early evening just to fine tune and also for kicks use pempro which you may or may not be able to do depending on your foliage constraints.

Another link here to another discussion with various ways as well
https://www.cloudynights.com/topic/416367-daytime-polar-alignment/

Cheers

[gregbradley]

What about one of these?

http://www.qhyccd.com/PoleMaster.html#PoleMaster

Greg.

[chuckywiz]

Try Alignmaster and edit the star list. Delete all but the ones you can see and add extras where applicable. I used to use different sets for different locations.

I now use sharpcap tho it has to be pretty dark for my ssag to pick up stars.

Ben

[peter_4059]

Hi David, are you using this with a non-AP mount?

Can you provide a description of the two park positions? Reading the PDF it sounds like Park 1 is CW shaft horizontal - what position is the OTA in? It sounds like the OTA is also horizontal from the Cloudy Nights discussion. Is that correct?

Park 2 sounds like OTA is horizontal in the east-west plane - what position is the CW shaft in? Vertical?

Cheers,

Peter

[traveller]

I use the solar noon method and then PHD drift align, works pretty well.
Bo

[peter_4059]

It needs a view of the SCP.



I've never had much luck with Alignmaster where there are trees obscuring most of the horizon despite adding extra alignment stars. I haven't tried deleting stars though so that migh work. SharpCap needs a view of the SCP.

[jenchris]

Can you ensure that the tripod sits in the same position?
If your scp is behind the house, and with the scope in the same position, mark on the wall where your scope points when aligned. You'll always be pretty close after that.

[04Stefan07]

I have had trouble with Alignmaster as well. For some reason it will pick up one star above the horizon but the second star is always below the horizon.

[DJT]

PDF with descriptions in the link below

http://www.astro-physics.com/images/Park_Positions_Defined.pdf

Counter weights are up and done and EW fro the OTA. Just make sure you have a bubble level

Havnt tried this with a non AP mount but provided you can set your own park positions there shouldn’t be a reason not to

[DJT]

Have also linked to the keypad manual which has a full description with images as well

http://www.astro-physics.com/tech_support/mounts/keypad/keypad-manual.pdf

[peter_4059]

Thanks David. Eqmod lets you define custom park positions so this should be doable with skywatcher mounts using eqmod.

[DJT]

Interested to see if this works so would be good to know how you get on.

[Atmos]

Although certainly not the cheapest way forward, another consideration could be to get TheSkyX and do T-Point models. An automated 16 point model will get you very close reasonably quickly.

Another way would be to use the 2-Star Alignment routine in SynScan. It is just a matter of using two stars in the sky and going back and forth between them until you get close.

[peter_4059]

I'm not familiar with theskyx. How does the tpoint polar alignment work?

[lazjen]

Another solution is provided using Astrotortilla (plate solving software). It has a routine that takes using through PA using plate solving. You don't need to see the SCP for it - lowi(ish) east or west plus zenith to align the axes. Assuming you start out roughly close (using compass, say), it doesn't take too long to dial in the PA with it.

[Atmos]

TheSkyX is a planetarium software package. T-Point is a module within the planetarium that you can use to create a sky model. You can use it to take images of parts of the sky that aren't blocked, the software creates a pointing model and from that it can calculate how far you are from the SCP. It'll also drastically increase the pointing accuracy of your equipment.

[Premordial]

+1 for solar noon and Phd drift align.

[RobF]

I'd be interested to hear more about this option Chris?

As an aside, it is fantastic how many PA solutions people have provided to the community, even in just the last 5 years! What a time to be an astro-nerd :D

[lazjen]

Here's a tutorial on setting up Astrotortilla (AT): http://www.lightvortexastronomy.com/tutorial-setting-up-and-using-astrotortilla-for-plate-solving.html

I'll quote the manual as it describes the process:



I use AT with APT to acquire the images, but there are a few other choices available.

Since I can see SCP, I've switched to using SharpCap's PA routine and will be trying a new PA tool in PHD2 (not the drift align tool) sometime in the future. However I will fall back to this tool if I'm at a location where I can't use SCP.

[RobF]

Thanks Chris - will have to try this.

[gregbradley]

I now use TPoint in the SkyX. It has an accurate polar alignment tool. I haven't found anything that can match it in accuracy. Its really accurate. But it takes about 30 minutes to do and you have to get plate solving to work (it can be fussy to setup but once done it should work every time).

Accurate polar alignment in TPoint will give you a PA that is more accurate than PemPro. Pempro I assume is more accurate than PHD2 (which only uses trend lines on autoguiding graph which Pempro also does but Pempro takes it further.

Accurate Polar Alignment also takes into consideration the fact that there is a refracted SCP.

You could probably get the time down to 15 minutes once you were familiar with it.

I doubt anything out there can match it. Its very refined. But you need Sky X and you need Tpoint.

Greg.

[Atmos]

+1 :thumbsup:

I got it down to 15 minutes with 16-25 point models. Also, as long as you know your pixel scale and get the exposure time right (2s 2x2 bin works brilliantly for me) it’s rsally easy.

The only package I’ve found that will rival it is the software package for the ASA mounts. It’s a little slower than T-Point mostly because TSX plate solves faster than PinPoint but it also doesn’t need as many points for accuracy. Still, TSX is blisteringly fast with its plate solving.

[04Stefan07]

Does the polar alignment need to be within a certain distance for this to work? I gave it a go last night but had no idea what was going on.

Think I need to re watch that tutorial I found online.

[kens]

Its not essential but it helps. The hardest thing is to work out which way to adjust depending on the trendline. The next thing is how much to adjust. Once you work it out (e.g. left knob clockwise 1 turn = 5 arcmin or whatever you can write that in the notes for future reference.
If you are seeing big errors at first its worth making a big adjustment to work out which way to turn. Remember that when you are poiting t the hoizon you adjust altitude and when you are pointing at the meridian you adjust azimuth.

[xelasnave]

Now you tell me:lol:

I had this mixed up the very first time way back years ago.

I have been trying to get polar back since I moved the mount onto a pier and have started building the box ob around it all... but between much cloud:D...and a night or two ago having got it half reasonable:D after further adjustment completly stuffed it:mad2:...

I hope its cloudy tonight so I dont have to bother with it;)...but if its clear I cant help myself..and that is crazy cause the mount will have to moved when I do the next stage of the ob box...

alex