Polar Alignment causes murder of a Telescope

[BlackWidow]

Night 3. I have read and read and gone red. I am not able to get this scope aligned at all. I have tried every method I have found on the net. I think I have alighnment but when I use a reticle and drift test I am not getting what I am reading. I start with mey east west drift only to find the star just travels down my eypeice without any East west movement at all. I think its back to the De-Rotator for me as I have had a gut full of it. Next step will be telescope murder if I keep this up. I have got my head around the software for photograpy, processing and got some good shots with the de-rotator. However getting polar alignment is proving to be the bigest challenge I have had so far. I just can't get it.....

If thier is anyone from the ASSA that would be happpy to help it would be greatly appreciated.

Seeing Star
Mardy
:help::help:

[batema]

Hi Mardy,

I am no expert but I do have this drift alignment down thanks to the method 1Ponders showed me that requires the use of a web cam or guide camera and a free program K3CCD Tools. I can now align my scope from start of the process to ready for photography in about 20 minutes but initially the same process would take a couple of hours and by the time I was ready I had given the clouds time to build up. I almost think like all things in this hobby you will look back in a couple of months and wonder how rediculous that was. I wrote an outline of this method at the following web page that a mate and I set up for teachers but am still dealing with red tape.
http://www.qastronomy.org/index.php?page=readarticle&id=122
Keep going and don't murder the scope. It will all come together.

Mark

[Rigel003]

Mardy
You need to ignore left right movement of the star in the eyepiece and only focus on movement up or down from the centreline of the reticle, so what you describe is correct. This applies to both azimuth (east west) adjustments for a star in the north, and altitude (up down) adjustments for a star low in the east. Adjust your mount knobs and see if it makes it better or worse. Start with larger adjustments and then fine tune. When you turn an adjustment knob, the star will move both left right and up down. With each adjustment you'll need to reposition the star in the eyepiece on the horizontal reticle line, somewhere near the centre of the field.

I'm in Adelaide and can help if needed although I'm not familiar with SCTs on wedges. pm me if you like. You could try ASSA chat too.

[bloodhound31]

Mardy, can you please post a picture of your rig?

[BlackWidow]

Thanks Guys. I will post a picture of my rig. I will set it up tonight and then post some images tomorrow. I do have K3ccdtools reg version and webcams so I will try that also tonight. What I do is set the wede to face south using a compas. I allow for 8 degrees veriation east as that is the magnetic variation for Adelaide, I know this from being a pilot. Then I make sure my wedge is a 35 degrees using an electronic Protractor. When I am setup I am pretty well on the mark as I have done a Startrails and can see from my picture that I am in the right place. My scope is also setup pretty well in the same spot I took the startrails images. My main concern is that I can't see the correct stars for aligning to the SCP. I have looked at images and spent time with the bino's but can't seem to make head or tail. If I just assume I am pretty close and turn on the LX200 and tell it I am im polar home position it then slews to Sirius. I center that in the eypeice and press ok. The slew to Sirius is way out however. I them get a alignment success. I then slew to a star overhead of me and put in the reticle. I RA back and forth usint the hand controller so that I can get the Cross hairs so that the star moves along the east west line. I then center the star and watch. the star drifts to the bottom of my eypeice but stays on the verticle line. No matter what I do to the Az adjustment on the wedge this star movement does not seem to stop moving down the eyepiece. This is my problem that I don't seem to be able to get past... If I still have trouble usint software tonight I may contact you Rigel003. I am happy to take my stuff to site for help. I have every software package know on the net and every webcam combo you care to name. So whatever way is best I am sure I will have whats needed. I am also going to try PHD tonight as this has a drift alignment method. I think I am getting most of it correct, but am missing one small process somewhere and a whole lot of hair.


Seeing Stars
Mardy

[BlackWidow]

Hey Mark I gave you method a try tonight. I have a little trouble to start with but spen a lot of time setting up the scope before hand to get as close to the SCP as I could. I used the drift method and it seemed to work. What I did do is that each time I made an adjustmet I would Re-center the star and reset the drift target. I had a little trouble getting a star in the east as I have trees in the way so this part I was not able to get the best result. However I have an electronic Protractor so I was happy my Dec was pretty good.. I have just been taking some shots of Eta and the results look good apart form the light sky from the moon.. I think I am getting on to of this thaks to all your help.

I have never added pictures before so I hope I have got it correct. But here are some images of my setup and how I had it prior to Drift Aligning..

Thanks f
guys for all your help, it's working :thanx:

Seeing Stars
Mardy

[batema]

I'm glad it helps. As I said it took me sometimes a couple of hours but I also found it helpful that when I got a guide star and K3CCD drift align started showing drift due to the graph I would adjust my mount only enough so the star stayed on the screen then recentre it and adjust so I would not have to look through the finderscope every time I made adjustments. I have never looked back since doing this method. I look forward to seeing some of your shots.

Mark

[GrampianStars]

Mardy
First of I notice you have the scope pointing South very wrong by your compas reading.
Adelaide Magnetic Variation is aprox. 8° East
You have your scope compass pointing aprox 10° West,
so your scope is already pointing 18° West azimuth before you have started!
To correct line up the scope with the needle pointing 8° towards the West side of the compass!
which means the Magnetic Variation is now adjusted to aprox. 8° East.
Tip: adjust the centre compass so the correct needle setting lines up with a point on the knob.
See attached image
Should make polar aligning a bit quicker. :D
The rest of your setup looks O.K. :thumbsup:

[floyd_2]

Hi Martin,
where I set up I have found that most compasses are very untrustworthy. They're easily affected by the mount, my nearby fence, the ground and who knows what else. I ended up making a true north-south line on my observing pad by tracing the shadow of a plumb bob string at solar noon onto the ground. It's spot on, and a lot more reliable than the built-in Meade compass ;)

Dean

[BlackWidow]

thanks for that Rob. It's a funny thing with the compass. I thought the same as what you advised, however when I did that it seemed way off. I had a look at a star trails I took from the ssame location on my pathway and when I set the AZ the way I had it setup it seemed on targe. However when I set it to how you have show it, it seemed off?? That was one of the problems I was having. I though that logic would suggest that 8 Deg East would suggest the scope would face slightly 8 east of the compass reading and 8 west of the south compass reading. However when I did that I did not seem to be lined up... Need to have another look. I just looked at the adjustments made to the AZ when i got alignment lat night and it does seem that the adjustment was to get the mount more east..

I do thank you all for your comments and advice. It seems I have a better understanding and will be able to keep doing this to get the process second nature. I can't really see the Southern Cross or crux early in the night as my house roof blocks my view. I can however see the rough area of the missing polar star LOL. How could we get some sort of sat up thier :question:. So drift align is my better option..


Thanks again
Mardy

[BlackWidow]

Hi Dean.. Tell me more. I have found a site for local solar noon times, and I think it's in my GPS.. So you are telling me that if I hold a plumb bob and let it hang down from whatever. I then trace the shadow and that faces SCP? Will I get a shadow when the sun is overhead, or is solar noon not totaly overhead?


Regards
Mardy

[GrampianStars]

Mardy
Youv'e got the drift pretty close it seems.
(1) Polar align LX200 GPS scope on the south pole.
The base control panel point south, the forks horizontal, (point south).
To level, use a spirit level across the top.
(2) Scope tube with the finder underneath points south.
Perpendicular to the forks. The setting circle now reads 90 degrees.
Mardy you seem to have this done o.k.
(3) Do 1 star align. (DO NOT Adjust the wedge), Now "ENTER" when asked if Sigma Octanis is in viewfinder, (you don't even have to look or see it).
(4) Slew AutoStar to any known star, Loose both the clutches, (DO NOT use AutoStar), manually centre star in eyepiece, (use reticle if possible)
(5) Tighten clutches, slew AutoStar to another known star, USE AutoStar to centre and sync.
(6) GPS ON at startup, (go to telescope settings) also
pec RA =ON (very important it stops a slow slew at start-up when in the south)
(7) Edit your "SITE" with your local settings ie; LONGITUDE & LATITUDE
A finer drift align is up to you!

Good to GOTO :thumbsup:
Tip: PARK scope even on a tempory setup- Remember to place tripod pointing south before startup - saves the align process again - just follow the proceedure's (4 & 5)

[BlackWidow]

That sounds pretty simple Rob. I will give this a try. Just one question on the last comment

(7) Edit your "SITE" with your local settings ie; LONGITUDE & LATITUDE

would the GPS not do this part for me on start up 1 star align? The rest I understand fine.

Regards
Mardy

[GrampianStars]

Mardy
The GPS receiver gets the precise date & time from the satelites
NOT your exact location.
by editing the site it is stored for you
Helps in calculating exact star positions :thumbsup:
It uses this information, along with the date and time, to determine which GPS satellites will be in the sky at a given time.
i.e. rise and set times etc.
The general rule of thumb for this is when a GPS is moved about from where it was last turned-on,
it helps dramatically speed up the aquisition process if you help it by telling it the general area of the location.

[AndrewJ]

Gday Rob

Partly incorrect.
If the GPS gets a fix, it sets the date and time
AND, it also adjusts the sites coordinates to the gps acquired ones.
This change is saved in EEProm hence is retained across boots.
Soooo, If you can get a fix, there is no need to edit coords.

Mardy,
if you want to get a true celestial NthSth line,
another way is to set up yr scope alt az.
Do a 2 star align and verify your gotos work reasonably well.
Now do a goto to AZ = 180deg, Alt = say 5deg
( You can do this via the hold mode menu in the hbx.
ie press and hold mode for 3 secs to bring up the display screens.
When in the Alt/Az display, hit "goto".
The handbox goes into edit mode, so change the data as noted to set your target, then hit enter )
Once it finishes its slew,
it will revert to terrestrial mode and the motors will stop.
Once it goes there, the tube is pointing at True Sth, not magnetic.

Andrew