Drift Alignment

[Nifty]

Hi all
I have been doing a bit of reading on drift alignment and there seems to be a plethora of info on the subject.
In a lot of cases an illuminated graticle eyepiece is recommended and I was wondering if it can be successfully achieved using an astrophotography camera. It would appear to be a lot more comfortable than having your eye glued to the EP for ages.

Am I right or am I wrong. All suggestions appreciated.

Cheer
Nev

[rogerg]

You're right, a camera can be used no problem.

As with all methods make sure you know the correct direction the star is drifting otherwise it gets confusing.

I find a using a fast frame rate camera (Q-Guider in my case) is better in the long run than a taking only 2 shots every 5 minutes because you get a feel for tracking & drifting behavior.

When using a camera or eyepiece, but more so a camera, I would recommend making Alt & Az adjustments of a size that you still keep the star in the FOV such that you don't need to hunt for the star again or a new star. That's not to say your limited in how big an adjustment you make per itteration, you just might need to move the Alt/Az, adjust RA/Dec, Move Alt/Az, adjust RA/Dec to retain the star in the FOV. Anyhow, keeping the star in FOV is important to minimising the time drift alignment takes you, by allowing you to quantify the adjustments you are making in Alt & Az and compare that to the drift occurring.

Roger.

[Nifty]

Thanks Roger
I had an idea it would work.
I have just discovered a piece of software called WCS that seems to be made for drift alignment. I must investigate fully. It seem you have cough up to register within 30 day or it blows up or something. Maybe it disappears into a black hole!

Cheers
Nev

[DeanoNZL]

Nev,
you could try Eqalign http://eqalign.sourceforge.net/index-en.html
Works with EQ6 and most cameras, does a great job & best of all, is open source(free):thumbsup:

[Nifty]

Thanks Deano, I'll have a look. All info is welcome.

cheers
Nev

[batema]

Hi,

I use a Philips toucam through my scope and use a program called K3CCDtools. This programs allows you to see the star you are focussing on your laptop monitor but also allows you to select the star and the program will graph the motion of the star. If the numbers relating to the star near the eastern horizon increase then I make adjustments to my altitude until the numbers stop increasing. I use big adjustments to start with so that if the numbers start to decrease in the negative direction I know I have gone too far and start going the other way. Same goes with looking at a star overhead. We were put onto this method by Paul(1ponders) and after a little getting use to we find we can align so we have vertually no star movement within about 20 to 30 minutes.

Mark

[allan gould]

Funny that this should come up at this time. I have been manually drift aligning for quite some time as its my prefered method. Ive tried K3CCDTools, bought WCS and tried EQAlign. All are great programs except for one thing. They need a long time - at a minimum 10-15 mins in both North and East/West to align to the pole. Then a repeat itteration to make final adjustments. Slow tedious and booooooring especially as in most programs have to use a webcam, know the lat of your observing site, the dec of the star (in North) etc etc and it can take 30-40 min to properly polar align for imaging.
I got quite good manually as I knew instinctively how much to adjust the star by looking at the drift.
But now I have just tested a beta version of a program that gets you precisely polar aligned - using an illuminated reticule, laptop and not a camera or anything else except a scope and your eye- in 5 min max (to do two itterations but one is generally enough). This product should be available soon and works brilliantly in the Southern Hemisphere which most forget about. And guess what its stupidly simple to do. Each step is almost done for you (especially if you use EQMOD or a planetarium program - or you have a goto system).
You dont have to worry if you are using a reflector, refractor, right angle prism or what ever.
It just works and works just out of the box.
When its available Ill let the forum know. Sorry to be a tease but its best people know that this is great, simple program before they purchase some other thing.
Regards, Allan

I should add that my last alignment put me within under 30" from the pole (1 iteration) and less than 10" in both alt and az in 2 iterations.

[pmrid]

http://www.andysshotglass.com/StarTarg.html (http://www.andysshotglass.com/StarTarg.html)

[Tandum]

http://wcs.ruthner.at/index-en.php
I've used this one for a while and it works ok with my meade DSI.

[troypiggo]

I've just been using PHD guiding. Start looping (but not guiding), turn on the grid overlay, spin the guide camera so it's parallel to the RA and DEC axes, watch for drift off axis, adjust mount etc, then you can start guiding.

[Nifty]

Thanks everyone.
It just goes to show there is more than one way to skin a cat!
Alan Gould, I look forward to the program you mentioned.
Once again, thanks all.
Nev

[g__day]

I like PEMPro's polar align wizard, when you want to get within a few arc seconds of the SCP

[gregbradley]

Sounds good.

Greg.

[Moon]

So many ways to achieve the same goal... I think it's best to try as many methods as possible as see what works for you. You'll learn a lot in the process.
I would say an illuminated reticle eyepiece is a good long term investment, no matter which way you go.

[bluescope]

I downloaded this FREE polar alignment program PoleAlignMax after finding it when browsing Jase's website in his resources links .... haven't tried it yet but I figure if it's good enough for Jase it's probably good enough for me and you too .....................

Here's the link ....

http://users.bsdwebsolutions.com/~larryweber/

:thumbsup:

[jase]

PolarAlignMax does not use the drift method so is quite different to many of the tools previously mentioned. If you're not familiar with astrometric star catalogues or the act of plate solving, you're going to be in for a steep learning curve. It should be noted that plate solving requires the output image to be in FITS format. This is due to the FITS format header having RA and DEC coordinates in which the plate solve software will use to reference the appropriate catalogue as it attempts to match the star pattern of the image FOV. This implies that you are using software that;
a) supports the FITS format
b) supports the camera you're using
c) you've got the appropriate star catalogue installed
d) platesolving works fine (may sound easy, but it usually doesn't work "out of the box" requiring configuration of magnitudes to search etc.)

Despite its overhead's i.e. quatity of dependant software, it is very efficient at getting close polar alignment within a short period of time. In the past, i've got approximately 40 arcsec alt/25 arcsec azimuth from the pole within 10 minutes. The speed/accuracy of the tool makes it appealing for portable set ups in the field, though you'll obviously need a laptop to drive it. In short the PolarAlignMax process is a cut down version of TPoint operations in that it maps a few points across the sky via plate solving, then calculates the pointing error based on the map points, this in turn translates to how far off you are from the polar axis. Not as advanced as TPoint as it does not store modelling parameters, but effective at sole function of streamlined polar alignment.

I've not had much exposure to WCS, eqalign etc, but used PEMPro extensively. Works similar to the other tools in that a camera monitors the drift. PEMPro makes it a breeze. Even if you move the mount considerably in either Alt or Az, it will automatically re-acquire a star to continue the drift process. For permanent set ups, drift alignment is the most accurate, but yes, it takes time. However, it need not be as it depends on your goals. No point ensuring there no drift over a 30min period if you're only going to take 10min subs. Clearly for a permanent set up, you can really get the mount dialled into the pole...and its worth your effort. Again, PEMPro has some software dependancies, so check the requirements. It works fine with web cams and its desirable to have an ASCOM compatible mount...these days there aren't many computerised GOTO mounts that aren't ASCOM ready. The ironic item with PEMPro is that its Polar Align Wizard is really an after thought given the primary purpose of the software is to reduce your mounts periodic error. This makes the investment in such software easier to swallow. Its like a swiss army knife to tune your mount to the best of its ability.

Much of what I've stated is probably off topic for many, so apologies. I only own one eyepeice - a dusty, scratched, but trusty illuminated recticle eyepeice. It does the trick when high tech methods fail.

[RB]

I'm keen to try out this method using my DSLR.
Sounds like a quick and accurate way to drift align.

http://www.astrophotoinsight.com/node/568

:)

[jase]

An alternative is to simply log your auto guider corrections. A few have documented this process, but I've found Brad Moore's instructions easy to follow (available here (http://southern-astro.com.au/php/guides/lx200gpspreciseCCD.php)). Clearly, there are plenty of options to dial in your mount to the polar axis. Depends on how much time you're willing to invest and your goals. If you're only doing visual work, you can almost plonk the mount down with roughest of alignments.