maxmirot Posted September 19, 2016 Report Share Posted September 19, 2016 I am getting bad errors in RA and this has increased . https://www.dropbox.com/s/jb4r1oji9g28kha/PointingErrors7.pox?dl=0 Have a look at the autopoint file and tell me what you think. Thanks Max Link to comment Share on other sites More sharing options...
lukepower Posted September 19, 2016 Report Share Posted September 19, 2016 Max, I didn't look at your file, however there is a remote possibility that the axis is not tracking well due to mechanical reasons, like a defective bearing, a strong hit during operations or transport, and the likes... This is something you should discuss with ASA support... Link to comment Share on other sites More sharing options...
maxmirot Posted September 19, 2016 Author Report Share Posted September 19, 2016 Max, I didn't look at your file, however there is a remote possibility that the axis is not tracking well due to mechanical reasons, like a defective bearing, a strong hit during operations or transport, and the likes... This is something you should discuss with ASA support... RA is bad, this what it looks like to me. Btw. there has been no transport since I got the mount. RA errors was always a little worst than DEC but this got worse. I am able to get balance perfect in DEC in all positions using CWs in including radial adjustment. RA is never perfect in all positive. Please load the the file and tell me what you think. Max Link to comment Share on other sites More sharing options...
MarkS Posted September 19, 2016 Report Share Posted September 19, 2016 Hi Max, I've looked at your file, and compared the figures to a 21 star pox file from my DDM60. I see no significant differences. What is showing you that the RA pointing is off? Mark Link to comment Share on other sites More sharing options...
maxmirot Posted September 20, 2016 Author Report Share Posted September 20, 2016 The errors are spread out along the RA in a non random manor. RA error is about 8-10x greater. Also this over 100+ stars. This suggests to me something wrong. Link to comment Share on other sites More sharing options...
lukepower Posted September 20, 2016 Report Share Posted September 20, 2016 Max, hm, what about polar alignemnt and radial balancing? What kind of OTA do you have on your mount? Link to comment Share on other sites More sharing options...
maxmirot Posted September 20, 2016 Author Report Share Posted September 20, 2016 Polar alignment is less than 3 min. (The models that are coming out now vary so much it hard to show that). I have a radial balance. I null balance using a CW along the tube and a radial CW. When I am done DEC is in balance in all positions. I can't get RA to balance in all positions. The residual pointing errors show up in RA. The OTA is an Astrophysics Riccardi Honders 305mm with Optec Gemini focuser-rotator which supports up to 25 lbs. I checked the scope for loose components. The back of OTA opens for cooling so I was able checked the mirror and rear corrector. It is all rock solid. The AP OTA is not user adjustable. I am sure they set all optics as firmly possible without pinching them. Max Link to comment Share on other sites More sharing options...
tbaehnck Posted September 20, 2016 Report Share Posted September 20, 2016 Hi Max, could you quote a picture of your setup. I didn't understand why RA should be not balanced in all positions. Normally it much easy then DE because you have no off axis weight. Thomas Link to comment Share on other sites More sharing options...
maxmirot Posted September 20, 2016 Author Report Share Posted September 20, 2016 Exactly! It should be much easier to do than DEC. It is giving problems and that shows it the pointing data along the RA axis. Max Link to comment Share on other sites More sharing options...
maxmirot Posted September 20, 2016 Author Report Share Posted September 20, 2016 Have a look at the errors. That tells me there something wrong. Link to comment Share on other sites More sharing options...
maxmirot Posted September 20, 2016 Author Report Share Posted September 20, 2016 Or how about this one. Note the polar aliment and collimation were not adjusted. One this one is over 40 stars the last one over 110 star. Result should be constant unless the OTA or mount has loose components. Everything is rock solid from the ground up. Would a loose optical component favor one axis??? I make remove the AP RH OTA and put my TEC a refractor as a experiment. However, the errors might be only present with a heavier weight OTA. Max Link to comment Share on other sites More sharing options...
RamaSpaceShip Posted September 20, 2016 Report Share Posted September 20, 2016 Hi Max, Did you check your cables? If you have a cable that does not go through the mount, it may influence the balance and create some errors. Such a cable must be attached in a way where it does not create any extra effort to the motors. Best regards. Bernard Link to comment Share on other sites More sharing options...
maxmirot Posted September 20, 2016 Author Report Share Posted September 20, 2016 Yes, I have very great cabling. Power and USB all comes through the mount. Nothing to drag on the mount or it's bearings. Max Link to comment Share on other sites More sharing options...
lukepower Posted September 20, 2016 Report Share Posted September 20, 2016 Hm interesting.. What about motor tuning? Maybe the tuning on RA is too aggressive? Or the slew settle time is too short? Link to comment Share on other sites More sharing options...
Waldemar Posted September 20, 2016 Report Share Posted September 20, 2016 How about vibrations of the pier or tripod? I experienced some problems with vibrations caused by a 'rat-cage' on my pier. Waldemar Link to comment Share on other sites More sharing options...
MarkS Posted September 20, 2016 Report Share Posted September 20, 2016 Hi again Max, I suggest you shoot some images, say, 5 or 10 min subs, preferably with MLPT, to see how much of a problem you have. Mark Link to comment Share on other sites More sharing options...
pesa Posted October 3, 2016 Report Share Posted October 3, 2016 Max, Since I have the same problem and support suggested to me that hysteresis might be the "villain" in my scenario you might check too what they suggested: Make a new model with random points so that dec isn't always is constant across meridian. Then compare with old model. Or to the same effect (as I see it): make a model on only one side so you dont ever pass meridian when building the model. Then experiment with slews and tracking on that side. Perhaps ricardo-honders have a fixed main mirror but hysteresis could easily come from focuser also. If tube is a bit loose dont tighten too hard or something will break when motor tries to move tube. I did that and now I cant do anything untill ASA sends it back. DAMN! When I get the focuser back I will do this but also keep model area smaller than one whole side. Not only meridian shifts can make focuser change position... pelle Link to comment Share on other sites More sharing options...
maxmirot Posted October 3, 2016 Author Report Share Posted October 3, 2016 I can not see how this the focuser. I am using the Optec Gemini it supports 10kg and is very made very well. Perhaps I am can detect movement in the focuser using a dial indicator. What version of autoslew are you using? Link to comment Share on other sites More sharing options...
pesa Posted October 3, 2016 Report Share Posted October 3, 2016 I'm using 5.2.2.8 pelle Link to comment Share on other sites More sharing options...
maxmirot Posted October 6, 2016 Author Report Share Posted October 6, 2016 Let us know what happens. I am going back to guiding Max Link to comment Share on other sites More sharing options...
maxmirot Posted October 18, 2016 Author Report Share Posted October 18, 2016 I started using Sequence with MLPT imaging the last few nights. ( I still prefer SGP.) However, I am getting round stars on most 20mins images using MLPT. A recent 180 star model still shows the same pattern. Much bigger errors spread out along the RA Everything is rock solid from the foot of the pier, focuser, scope. The source of hysteresis is not obvious. The increased RA error should be a clue. Max Link to comment Share on other sites More sharing options...
pesa Posted November 15, 2016 Report Share Posted November 15, 2016 Max, what is your mount? if it is DDM60 perhaps those are not as sturdy as DDM85? Anyone else (then me) have same problem - rec-error much bgger then dec error? In that case, do you have DDM60 or RRM 85? pelle Link to comment Share on other sites More sharing options...
maxmirot Posted November 15, 2016 Author Report Share Posted November 15, 2016 It is the DDM85. It probably is hysteresis as the MLPT does make improvement it unguided error. If you look at the JPEG I posted , the spread in the residual error after superfit shows a non random pattern along the RA. I wound think this should tell us something . I have not been able to determine a mechanical source yet. Btw, I tried the mount with Bisque's Tpoint . I automapped about 44 points. It shows no pattern in residual error. The pointing is no better also. They have a lot extra terms that autoslew does not use. None of these improve the pointing model. There is always the possible that the pattern is an artifacts on how the autoslew does superfit. There is so little explained with the autoslew modelling here. We should be able to manually adjust the model by removing outliers etc and see if the fit statistics improve. There is a lot in the advance modeling that is undocumented. I wish we knew more. Perhaps some day Dr. Keller or ASA will spend some time on this. Max Link to comment Share on other sites More sharing options...
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