Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Alignment Stars Ambiguous

  • Please log in to reply
18 replies to this topic

#1 Dennis Persyk

Dennis Persyk

    Mariner 2

  • *****
  • topic starter
  • Posts: 239
  • Joined: 16 Mar 2010

Posted 09 August 2019 - 11:42 PM

I have a new LX200-ACF.  After going through the level north, tripod tip, ... setup, it slews to a star and requests I center the brightest star and press ENTER. 

 

Tonight both initial slews were in a region where there were 3-4 stars in the FOV of a 40 mm Ploessl eyepiece and they were all pretty much the same brightness.  I made my best guess and result was "Align Successful". I did a goto to the Moon and the moon was about 20 degrees off.

 

What do you suggest?

 

Thanks.
Dennis



#2 OzAndrewJ

OzAndrewJ

    Mercury-Atlas

  • *****
  • Posts: 2930
  • Joined: 30 Nov 2010

Posted 10 August 2019 - 12:21 AM

Gday Dennis

a) What firmware does it have loaded?

b) There is a menu setting to force the real star name to be shown

 

The moon can have odd calcs at times but not 20deg

I would redo the alignment with the correct stars selection and try again.

If you know the main bright stars, you are better off just doing a manual 2star

as you get to select your own stars ( and its much faster )

Andrew Johansen Melbourne Australia



#3 havasman

havasman

    Cosmos

  • ****-
  • Posts: 9952
  • Joined: 04 Aug 2013
  • Loc: Dallas, Texas

Posted 10 August 2019 - 12:38 AM

Yes, pick your own stars. Use a shorter focal length eyepiece.


Edited by havasman, 10 August 2019 - 12:39 AM.

  • ShaulaB likes this

#4 sg6

sg6

    Fly Me to the Moon

  • *****
  • Posts: 6069
  • Joined: 14 Feb 2010
  • Loc: Norfolk, UK.

Posted 10 August 2019 - 01:35 AM

First I would check how level and North the scope actually is - do not use magnetic North as that can be several degrees off and so therefore will the first slew. Thinking that the scope has slewed the required amount but as the start position was a bit off you have ended up looking at where the first alignment star was not present.

 

Assuming the 8" then with a 2000mm focal length you get 50x, and that gives 0.8 degree field. The catch then is that you need to be aligned to North by a maximum error of 0.4 degrees - not 0.8, things get halved.

 

So if more then 0.4 degrees off of North your first alignment star will not (OK may not) be in the field of view. That all means you have top be very accurate. One of the catches with an SCT.

 

An accuratelt set up finder will help, but accurate means checked at each outing to be confident of accuracy.

 

Easy way to envisage it is a star at 90 degrees to North. You set up scope to L&N, and then scope will slew 90 degrees to the first star. If your North is 1 degree off the final slew position is 1 degree "wrong", and in the field you have there is no alignment star in view. You have a field of view of +/-0.4 degrees and the star is off to one side by 1 degree = not in view.

 

Selecting your own is a good option as the best idea I have come across is to select red/orange stars at least for the first one. The color makes them stand out easier.

 

But I think the real problem will be the initial Level and North simply as you have a narrow FoV.

 

I do think that with an SCT (Meade and others) that Level and North although easy is maybe not a great idea. A start position of centering Polaris would make more sense. That is defined and can be read from data and it removes the "How level and how North?" is the scope question.



#5 OzAndrewJ

OzAndrewJ

    Mercury-Atlas

  • *****
  • Posts: 2930
  • Joined: 30 Nov 2010

Posted 10 August 2019 - 03:13 AM

Gday sg6

 

I do think that with an SCT (Meade and others) that Level and North although easy is maybe not a great idea. A start position of centering Polaris would make more sense.

No good for me :-)

Also, whilst the instructions say Level and North ( as its easy to understand ),

you are really setting the mount to Alt = Az = 0.

In a one or two star process, the mount assumes it is at alt = az = 0

"when you tell it to start the align" process ( ie it gives you a chance to put it into home first )

It then does a dead reckoning slew to the first star.

If you put the mount in the home position in AltAz,

and then turn it on and set the date/time you are actually aligned.

Just set tracking to astronomical and you could do a goto.

Slew to a known star and synch and you have effectively done a one star align.

 

Andrew Johansen Melbourne Australia


  • EdIII likes this

#6 carolinaskies

carolinaskies

    Surveyor 1

  • *****
  • Posts: 1689
  • Joined: 12 Dec 2014
  • Loc: Greenville SC

Posted 10 August 2019 - 07:02 AM

I have a new LX200-ACF.  After going through the level north, tripod tip, ... setup, it slews to a star and requests I center the brightest star and press ENTER. 

 

Tonight both initial slews were in a region where there were 3-4 stars in the FOV of a 40 mm Ploessl eyepiece and they were all pretty much the same brightness.  I made my best guess and result was "Align Successful". I did a goto to the Moon and the moon was about 20 degrees off.

 

What do you suggest?

 

Thanks.
Denni

You should be knowledgeable about the alignment star the mount is using, whether it picks it or you do.  Check on the hand control which star it has chosen and using a star chart (hand held or on your phone/tablet/computer)  Then looking at the sky where the scope is pointing does it appear to be generally pointed in the right constellation and location in the sky?  If it is then using the finder scope you should be able to see the alignment star is brighter than other stars.  Adjusting the mount hand control to bump the alignment star to the center of the finder again you should have a pretty good idea which star is the alignment star.  At 40mm your scope is seeing around .75-1 degree of the sky so you may want to drop to the 25/26mm which will put you close to 1/2 degree and the alignment star should be in that field of view.   

My bet though is you have something off, date, time, or location wise so your initial field is wrong because normally alignment stars are pretty easy to identify even in a 40mm widefield eyepiece. 


  • EdIII likes this

#7 decep

decep

    Vostok 1

  • *****
  • Posts: 114
  • Joined: 19 Aug 2018
  • Loc: Griffin, Georgia

Posted 10 August 2019 - 11:57 AM

The LX200GPS mount has been a frustrating experience for me, as well.  smile.gif  It is considerably more complicated than I had assumed when I bought mine... especially without some guidance.

 

I have an older one that has not been updated for the recent GPS rollover, so I have my GPS disabled.

 

  1. Make sure date and time is right
  2. Verify GMT offset
  3. Verify Site (longitute/latitude)
  4. There is another GMT offset in the Site
  5. Verify Alt/Az or Polar config

 

Assuming you do not have a permanent pier.... Make sure every time you power it on, you calibrate sensors before you perform an alignment.  The end of the calibrate sensors routine should try to align on polaris.


  • LFORLEESEE likes this

#8 dcaponeii

dcaponeii

    Lift Off

  • -----
  • Posts: 11
  • Joined: 01 Sep 2019

Posted 01 September 2019 - 03:18 PM

This thread as well as others reference picking your own stars for the two-star alignment.  The Meade customer support folks said the same thing. My challenge is that no where in the manual shows HOW to do that.  The Autostar II always picks for itself. Can someone please explain the sequence of keypad entries that allow me to pick my own two stars for two star alignment in polar mode? Thanks.

 

Don Capone

Waxahachie, TX



#9 Dennis Persyk

Dennis Persyk

    Mariner 2

  • *****
  • topic starter
  • Posts: 239
  • Joined: 16 Mar 2010

Posted 01 September 2019 - 04:06 PM

P 39 in the Manual

 

Two-Star Alt/Az Alignment
Two-Star Alignment requires some knowledge of the night sky. AutoStar II provides
a library of bright stars and two stars from this library are chosen by the observer
for alignment. In this procedure, AutoStar II does not automatically find home, level,
or North.
1. Select Alignment. Select “Align: Two Star” from the Setup menu. Press ENTER.
2. Set Home Position. Place the telescope in the home position.
3. To Set the Home Position Manually:
a. See Figs. 19 and 20. Loosen the telescope’s Dec. lock (Pg. 7, Fig. 1, 17).
Set the optical tube to 0° on the Dec. setting circle (Fig. 1, 20).
b. Tighten the Dec. lock (Fig. 1, 17) to a firm feel only.
c. Level the tripod base.
d. Move the base of the telescope so that the computer control panel
(Fig. 1, 13) approximately faces South.
e. Unlock the R.A. lock (Fig. 1, 12) and turn the telescope’s optical tube
horizontally until it points North.
f. Re-lock the R.A. lock (Fig. 1, 12). Press ENTER.
g. Press ENTER.
4 . Star Alignment. “Select Star” displays. AutoStar II then displays a library of stars
for the observer to choose from. Use the Scroll keys to scroll to a star on the list
that you wish to align upon—select a star that you can easily locate in the night
sky. Press ENTER.
5. Center Star. The telescope slews to the star. Use the Arrow keys to move the
telescope until the star is centered in the eyepiece. Press ENTER.
6. Center Star. Repeat procedure for a second alignment star. Once ENTER is
pressed, the telescope is aligned and you are now ready to use AutoStar’s II GO
TO capabilities for a night of observing.

 

Best regards,

Dennis  www.dennispersyk.com



#10 dcaponeii

dcaponeii

    Lift Off

  • -----
  • Posts: 11
  • Joined: 01 Sep 2019

Posted 01 September 2019 - 04:33 PM

Thanks Dennis but my scope is on an X-Wedge so it needs to start out on Polar Home.  I don't know how to get the equivalent settings should be for this home position.  I've tried releasing the RA Lock to compensate for the offset but it didn't seem to help at all.



#11 Dennis Persyk

Dennis Persyk

    Mariner 2

  • *****
  • topic starter
  • Posts: 239
  • Joined: 16 Mar 2010

Posted 01 September 2019 - 04:48 PM

Wow, Don, that is a problem.  My scope's gotos for default alignment stars are usually 20 degrees off and it has nothing whatsoever to do with level, north or site

.
What has helped me is to look up the alt/az and RA/Dec of the star(s) in my planetarium program and use the calibrated altitude scale to get me to the proper elevation to within +/- 2 degrees.  I haven't figured out how to use the settings circle because it is not fixed but rather rotates freely.  Perhaps other group members can help me out with the proper use of the Meade setting circle.

I don't know if these tips apply to a wedge mount.

Good luck.

Dennis



#12 dcaponeii

dcaponeii

    Lift Off

  • -----
  • Posts: 11
  • Joined: 01 Sep 2019

Posted 01 September 2019 - 05:00 PM

I tried to use the published RA and Dec last night to correct the offset but it didn't seem to help. Calibrate home didn't work the scope just kept running in RA to the hard stop.  Ill get there with some additional work I hope.  I'd hope to have purchased a $5000 yard ornament.



#13 SkipW

SkipW

    Messenger

  • -----
  • Posts: 498
  • Joined: 03 Feb 2011
  • Loc: Oklahoma, USA

Posted 01 September 2019 - 06:12 PM

I've received a ton of help using an old RCX400 on a newly-installed wedge in the other thread you replied to. I've still got a lot to learn, but maybe I can offer some tips from one newbie with a similar system to another.

 

This presumes the basics of the RCX are similar to yours.

 

1 - Polar Home position: this is at declination 90° (telescope pointing exactly away from base, where the celestial pole would be if it were correctly polar aligned), and hour angle 0h (telescope points at the meridian; bottom of fork horizontal, midway between hard stops). In this position, the tube is upside-down with the finder on the bottom.

 

2 - To find HA = 0h, rotate the fork so that the inner and outer reference marks point are aligned with each other. Once you get close, rotate the hour circle and move the telescope so that one of the hour lines is lined up with both. 

 

3 - 2-star alignment should allow you to pick your stars, just like it does for alt-az. It will show a star when you start the process, but use the Scroll Up and Scroll Down buttons to select a different one.

 

4 - My understanding is that Calibrate Home isn't used for polar alignment. Your experience suggests that this is correct.

 

5 - So far, our attempts to do alignment have been somewhat successful. Final pointing has been close, but not as accurate as we'd like, or think it should be if we were doing everything correctly. It usually lands something like 1/2 degree off our go-to target.

 

6 - When we power up the telescope from the home position after being Parked at the end of the last session, it slowly rolls about 25° (1h 40m) in RA and stops there - with emphasis on the word "slowly". I still haven't figured out why it's doing that. If it's powered up after it had not been Parked before being powered down, it moves both directions in RA before settling at, I think, the same position. Before beginning an alignment, I use the direction buttons to drive it back to 0h HA.

 

Why it's doing that last bit still needs to be investigated, but for now, we want to put more time working with the equipment. It's at our club's observatory about an hour's drive away, so it's not easy to just experiment with it a lot, which is usually how I get used to using complicated systems.



#14 dcaponeii

dcaponeii

    Lift Off

  • -----
  • Posts: 11
  • Joined: 01 Sep 2019

Posted 01 September 2019 - 07:44 PM

Thanks that's a great summary of what I've read today so far. I will have another go this evening.



#15 dcaponeii

dcaponeii

    Lift Off

  • -----
  • Posts: 11
  • Joined: 01 Sep 2019

Posted 01 September 2019 - 10:05 PM

Another two hours wasted although I think this time I screwed up.  After two hours of fighting with worse RA issues than ever I gave up before the hard stops gave out. Then while putting covers back on everything I noticed I had never removed the caps from the Starlock scopes. I'm pretty sure they are part of the pointing system cause if not then I have no idea what is wrong.  I was so optimistic when I did a simple GOTO Arcturus and hit it spot on.  Then tried a star in the eastern sky well above the horizon and missed by a mile. Scope pointing at the floor miss!! Please tell me the wide field Starlock scopes looks for the bright stars during the slew.  Also does seeing degrade the performance for the GOTO?  I've got both RA and DEC set on 66.  Maybe too much 7n hazy skies like tonight. Less than 3rd magnitude with unaided eye this evening was tough.

 

Don Capone

Waxahachie, TX



#16 SkipW

SkipW

    Messenger

  • -----
  • Posts: 498
  • Joined: 03 Feb 2011
  • Loc: Oklahoma, USA

Posted 04 September 2019 - 12:20 PM

I've been on the road and haven't checked in for a few days. 

 

We don't have Starlock, so I can't begin to help you with that. In my opinion, if you're having difficulty, and can do it, I'd recommend eliminating everything extra, and with just the basics ('scope, finder, mount, standard hand control, and wedge), get that working reliably before adding another layer of automation (i.e. another "black box" doing who knows what) to the system. If the system is tightly integrated with Starlock and cannot be used without it, I'm way out of my league.



#17 OzAndrewJ

OzAndrewJ

    Mercury-Atlas

  • *****
  • Posts: 2930
  • Joined: 30 Nov 2010

Posted 04 September 2019 - 04:53 PM

Gday Don

 

Please tell me the wide field Starlock scopes looks for the bright stars during the slew.

If HiPrecision is on,then yes, the mount slews to a nominated nearby bright star.

The camera then tries to centre it and does a soft synch and slews to the final target.

If the covers were on and Starlock was ON, i have no idea what would have happened,

but several people have reported problems that ended up being the cameras were out of focus

so maybe you need to check that first.

 

If the system is tightly integrated with Starlock and cannot be used without it

It can be used without Starlock, but it uses different firmware in certain areas and there are bugs in some of this.

 

Andrew Johansen Melbourne Australia



#18 BessAmaral

BessAmaral

    Lift Off

  • -----
  • Posts: 1
  • Joined: 01 Oct 2019
  • Loc: Little Elm, Texas

Posted 17 October 2019 - 09:45 PM

Is there some way for Dennis Persyk to contact Bess Amaral regarding my Meade LX200 GPS 10 inch purhases 20 years ago. I live in the Dallas area and have read his responses on this forum. Would like to ask him a questions directly. 

Bess Amaral



#19 Starman27

Starman27

    Cosmos

  • *****
  • Moderators
  • Posts: 7982
  • Joined: 29 Jan 2006
  • Loc: Illinois, Iowa

Posted 18 October 2019 - 09:52 AM

Bess, Click on his avatar and then send him a PM.




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics