RE: [ap-gto] 1100 GTO guiding problem.


Sep 27, 2014

 


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#45199 Sep 27, 2014

I am using a separate guide scope with an STi. Everything seems to be rock solid. Calibration is not a problem. There is good star movement. I am using The Sky X Pro. Alignment is excellent. The N/S switch is in the N position. I will have to wait until tonight to see what happens when it is in the S position. The problem has always been there since I received the mount ��3 months ago. I wanted to rule out other possibilities first. Unguided images ��are pretty much the same as guided. Maybe even better since the guider is struggling. I will say too that after slewing to a point before guiding and zooming in on the field of view, there can be ��some East West shaking of the point which can be stopped by small manual movements of the mount. I am using relays and cable to the GTOCP3 from the STi. ��From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] Sent: Saturday, September 27, 2014 11:36 AMTo: ap-gto@yahoogroups.comSubject: RE: [ap-gto] 1100 GTO guiding prblem.



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#45214 Sep 29, 2014

I mean the mount is moving west. The star drifts east. Using TSX and T Point, the Alignment is excellent both on altitude and azimuth. T Point was done with over 50 plate solves. The tracking speed is set to Sidereal guiding at x1. The mount is being controlled by TSX. I am guiding on axis with an 80 ED and an STi. There was no problem with calibration. The scope is a C11 with a Feathertouch focuser. I have tried a different cable between the STi and the mount. There is no change. Everything has been checked and rechecked for something loose but all is solid. The drift is always the same regardless of the position of the mount in the sky. The guider always yields to the mount and the mount moves too fast. ��From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] Sent: Monday, September 29, 2014 10:39 AMTo: ap-gto@yahoogroups.comSubject: Re: [ap-gto] 1100 GTO guiding prblem.



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#45218 Sep 29, 2014

You can do a timing of the motor gears, which is quite easy to do. Call either Howard or George, and he can advise you how to do it. You will probably find that the mount is tracking at the exact sidereal rate, however, if it is not, then you will see it right away. All you need is a watch with second hand or other timer.



Rolando







-----Original Message-----From: 'Steve Wiencek' swiencek@... [ap-gto] ap-gto@yahoogroups.com>To: ap-gto ap-gto@yahoogroups.com>Sent: Mon, Sep 29, 2014 11:26 amSubject: RE: [ap-gto] 1100 GTO guiding problem.



I mean the mount is moving west. The star drifts east. Using TSX and T Point, the Alignment is excellent both on altitude and azimuth. T Point was done with over 50 plate solves. The tracking speed is set to Sidereal guiding at x1. The mount is being controlled by TSX. I am guiding on axis with an 80 ED and an STi. There was no problem with calibration. The scope is a C11 with a Feathertouch focuser. I have tried a different cable between the STi and the mount. There is no change. Everything has been checked and rechecked for something loose but all is solid. The drift is always the same regardless of the position of the mount in the sky. The guider always yields to the mount and the mount moves too fast.��From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] Sent: Monday, September 29, 2014 10:39 AMTo: ap-gto@yahoogroups.comSubject: Re: [ap-gto] 1100 GTO guiding prblem.



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#45219 Sep 29, 2014

One other thing that trips up the tracking might be the connection to the guider port. Often people will attach the guider cable from the camera to the guide port, and if one of the wires, the west wire in the guide cable is shorted the mount gets a continuous Go West signal which basically runs the tracking rate westward at 2x rate. This of course cannot be guided out. The advise is to go back to basics, remove all connections from the mount from any and all external sources, except for the keypad. Start the mount with the keypad, turn on your CCD camera, and record the drift in RA and Dec. You may find that the mount is tracking correctly, and any small RA drift will be due to polar misalignment, scope flexure, atmospheric refraction, etc. You should see no more than about 2 - 3 arc sec drift in a 5 minute period in RA.



BUT YOU MUST disconnect all external cables from the mount. One of those cables is probably at fault.



Rolando







-----Original Message-----From: chris1011@... [ap-gto] ap-gto@yahoogroups.com>To: ap-gto ap-gto@yahoogroups.com>Sent: Mon, Sep 29, 2014 12:37 pmSubject: Re: [ap-gto] 1100 GTO guiding problem.



You can do a timing of the motor gears, which is quite easy to do. Call either Howard or George, and he can advise you how to do it. You will probably find that the mount is tracking at the exact sidereal rate, however, if it is not, then you will see it right away. All you need is a watch with second hand or other timer.

Rolando





-----Original Message-----From: 'Steve Wiencek' swiencek@... [ap-gto] ap-gto@yahoogroups.com>To: ap-gto ap-gto@yahoogroups.com>Sent: Mon, Sep 29, 2014 11:26 amSubject: RE: [ap-gto] 1100 GTO guiding problem.



I mean the mount is moving west. The star drifts east. Using TSX and T Point, the Alignment is excellent both on altitude and azimuth. T Point was done with over 50 plate solves. The tracking speed is set to Sidereal guiding at x1. The mount is being controlled by TSX. I am guiding on axis with an 80 ED and an STi. There was no problem with calibration. The scope is a C11 with a Feathertouch focuser. I have tried a different cable between the STi and the mount. There is no change. Everything has been checked and rechecked for something loose but all is solid. The drift is always the same regardless of the position of the mount in the sky. The guider always yields to the mount and the mount moves too fast.��From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] Sent: Monday, September 29, 2014 10:39 AMTo: ap-gto@yahoogroups.comSubject: Re: [ap-gto] 1100 GTO guiding prblem.







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#45288 Oct 7, 2014

Rolando, ��Last night I disconnected all cables including the Encoder. The only connected cables were the power and the hand control. I pointed the mount toward Altair. The tracking is set to sidereal, PEM is None. I centered the star in the guiding eye piece crosshairs. The mount drifts west faster than sidereal by about .5 arc sec per minute. This occurred when tracking on both sides of the mount. ��Remember also that when guiding, the guider attempts to make corrections but the drift continues. ��Also recall that we had to replace the chip in the controller because of gear oscillation when setting backlash. Last night the backlash was set to 0. ��Steve �� ��From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] Sent: Saturday, October 04, 2014 3:14 PMTo: ap-gto@yahoogroups.comSubject: Re: [ap-gto] 1100 GTO guiding problem.



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#45292 Oct 7, 2014

With the refracted pole at approximately .-62 arc sec what do you recommend as ideal? ��At this point I suspect flexure. Can this be guided out? The guider has not been able to compensate. I use a guide scope attached to the main OTA. Do I have to use off axis guiding? ��SteveFrom: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] Sent: Tuesday, October 07, 2014 10:53 AMTo: ap-gto@yahoogroups.comSubject: Re: [ap-gto] 1100 GTO guiding problem.



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#45294 Oct 7, 2014

"With the refracted pole at approximately ��-62 arc sec what do you recommend as ideal?"��What I would do is to minimize RA drift at the meridian with a scope pointed at a star somewhere near half way between equator and zenith. Raise or lower the polar axis until RA drift is minimized at that point. Dec drift of course is��zeroed out��at the equator and meridian with the azimuth adjusters. Once you have done that, you will have minimum drift over most of the sky. I would NOT use an SCT or RC or Cass for this critical adjustment. I would use a small refractor directly mounted to the DEC mounting plate, and use the Guider graph in Maxim to determine drift in the two axes. Alternatively you can use PEMPro very effectively to zero out drift in both axes. It is easy, intuitive and extremely accurate. Once you have done that, the mount goes away as an issue, and what you have left is the mechanics of your telescopes.��Rolando����-----Original Message-----

From: 'Steve Wiencek' swiencek@... [ap-gto] ap-gto@yahoogroups.com>

To: ap-gto ap-gto@yahoogroups.com>

Sent: Tue, Oct 7, 2014 11:52 am

Subject: RE: [ap-gto] 1100 GTO guiding problem.





With the refracted pole at approximately ��-62 arc sec what do you recommend as ideal?��At this point I suspect flexure. Can this be guided out? The guider has not been able to compensate. I use a guide scope attached to the main OTA. Do I have to use off axis guiding?��SteveFrom: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com]

Sent: Tuesday, October 07, 2014 10:53 AM

To: ap-gto@yahoogroups.com

Subject: Re: [ap-gto] 1100 GTO guiding problem.



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#45296 Oct 7, 2014

I always ask my wife if it's plugged it in. Not a stupid question. It was one of the first things I checked. ��From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] Sent: Tuesday, October 07, 2014 10:12 AMTo: ap-gto@yahoogroups.comSubject: [ap-gto] Re: 1100 GTO guiding prblem.



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#45297 Oct 7, 2014

And that's why I always use off-axis (radial) guiders with compoundtelescopes!����Christopher EricksonConsultingEngineerSummit KineticsWaikoloa, HI96738www.summitkinetics.com

��



From: ap-gto@yahoogroups.com[mailto:ap-gto@yahoogroups.com] Sent: Tuesday, October 07, 2014 6:59AMTo: ap-gto@yahoogroups.comSubject: Re: [ap-gto] 1100 GTOguiding problem.



I'm betting that your guide scope is doingjust fine, but you still get oval stars in your imaging camera. So because starsare oval, you believe the mount is not tracking or guiding. Most likely it isguiding just fine - on the guide scope, but guide scope and main scope do notpoint identically over time. They are flexing differentially. This is always thecase when you have a separate guide scope attached to a mount. The only way Ihave seen this work successfully is when the guide scope is attached directly tothe tube assembly of a refractor. Refractors work because the optics do not flexwith respect to the tube. Reflectors never work because the optics do flex quitebadly with respect to the tube and or mounting plates.��Rolando����-----OriginalMessage-----From: 'Steve Wiencek' swiencek@... [ap-gto]ap-gto@yahoogroups.com>To: ap-gtoap-gto@yahoogroups.com>Sent: Tue, Oct 7, 2014 11:52 amSubject:RE: [ap-gto] 1100 GTO guiding problem.



With therefracted pole at approximately ��-62 arc sec what do you recommend asideal?��At this pointI suspect flexure. Can this be guided out? The guider has not been able tocompensate. I use a guide scope attached to the main OTA. Do I have to use offaxis guiding?��SteveFrom: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com]

Sent: Tuesday, October 07, 2014 10:53 AMTo: ap-gto@yahoogroups.comSubject:Re: [ap-gto] 1100 GTO guiding problem.



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#45298 Oct 7, 2014

I ordered one earlier today. Just got an Email saying it shipped. ��From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] Sent: Tuesday, October 07, 2014 3:07 PMTo: ap-gto@yahoogroups.comSubject: RE: [ap-gto] 1100 GTO guiding problem.



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#45299 Oct 7, 2014

Hi Steve,

I am curious, what main and guide scopes are you using? Also what main camera are you imaging with? I know from one of your posts is you use SBIG ST-i guide camera but you did not specify the scopes.

Thanks,Peter

---In ap-gto@yahoogroups.com, swiencek@...> wrote :

I ordered one earlier today. Just got an Email saying it shipped. ��From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] Sent: Tuesday, October 07, 2014 3:07 PMTo: ap-gto@yahoogroups.comSubject: RE: [ap-gto] 1100 GTO guiding problem.







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#45302 Oct 8, 2014

I have a C11 and am guiding with an 80ED. The camera is a Canon 7D. ��From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] Sent: Tuesday, October 07, 2014 6:56 PMTo: ap-gto@yahoogroups.comSubject: RE: [ap-gto] 1100 GTO guiding problem.



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#45304 Oct 8, 2014

Kent ��I spoke to George this morning and said the same. It may be a time saver for both us and AP. ��This is the last chapter. Last night I took the main scope off the mount and mounted the 80ED refractor with no cables attached. I used a high magnification graduated guiding eye piece and a 2x Barlow centering it Altair. Three hours later I came back and the star was still dead center. ��Steve Wiencek �� ��From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] Sent: Wednesday, October 08, 2014 9:37 AMTo: ap-gto@yahoogroups.comSubject: [ap-gto] Re: 1100 GTO guiding prblem.



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#45306 Oct 8, 2014

I can't say possible mirror flop alone. It is what took place between the guide camera and the mount, mirror flop and or flexure. I have a feathertouch focuser and as good of a product that it is, I know that adding it reduced my pointing ability by a few arc sec. I going to off axis guiding and hope that it will solve or reduce my problem. . ��From: ap-gto@yahoogroups.com [mailto:ap-gto@yahoogroups.com] Sent: Wednesday, October 08, 2014 12:32 PMTo: ap-gto@yahoogroups.comSubject: RE: [ap-gto] Re: 1100 GTO guiding problem.



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#45308 Oct 8, 2014

Thanks Steve. I re-read your thread and found your third posts stated your main and guide scopes. This thread is getting long.

Anyway,I also have A-P1100GTO and use TEC 140 APO (980mm focal length) mainscope with Baader 10x60 Vario guide scope using A-P bracket mounted onFeatherTouch 3.5" focuser's body. My main camera is QSI660wsg and guidecamera is Superstar. I also have a V chip. I use PHD ASCOM guiding.I do not have any issues with my current setup. I also have used OAG aswell but guide scope mounted on focuser's body does a decent job andit's easier to find guide stars especially when automation (SequenceGenerator Pro) is used including auto focusing and automatic MeridianFlip.

I think you are asking for trouble using a guide scopeguiding a SCT scope with moving primary mirror (mirror flop differentialflexure). Been there, done that. OAG would do a better job. There is no way a guide scope can monitor for main scope's mirror flop while keeping the guide star locked where it's supposed to be.

Correctme if I'm wrong. Are you saying that you are seeing tracking issuethrough the refractor guide scope? Your guider is having difficultykeeping the guide star where it's supposed to be? Did you check yourmount's latitude scale and compare to your location's latitude usingGPS? Does the star drift in Declination as well? I personally have seenRA drift (very small after 30 minutes) while Dec stays pretty stable dueto refraction in the sky. My polar alignment method is A-P Quick DriftAlignment using Meridian Delay and Finderscope and use RAPAS from thenon.

There is another thread in ap-ug Yahoo Groups having similar issues and may have solved the problem by remeshing RA gears. He said the meshing was too tight. Maybe check your gear mesh. See this thread at:

groups.yahoo.com/neo/groups/ap-ug/conversations/topics/69193

Peter



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