Daniel Schmid Posted September 29, 2014 Report Share Posted September 29, 2014 Does anyone know if the performance of MLTP is affected by the general pointing model in use or if MLTP is only using the local pointing measurements? I am quite happy with MLTP with exposures of up to 6 minutes. For longer exposures (10 and more minutes) it seems to be a bit less reliable sometimes but not always. Therefore it would be nice to know if there is a chance of improvement with a larger general pointing model. Link to comment Share on other sites More sharing options...
lukepower Posted September 29, 2014 Report Share Posted September 29, 2014 Hi Daniel, I experienced bad mlpt runs with bad pointing files. I am not sure, but I gues MLPT is jet another parameter of the pointing correction, so if the overall correction is quite good, MLPT makes it better. But if it is quite bad, it makes it better only that much... Not sure if this is always the case, though. Link to comment Share on other sites More sharing options...
robertp Posted September 29, 2014 Report Share Posted September 29, 2014 Hi Daniel, I use MLPT without any pointing-file (despite the three-star pointing-file used for polar alignment). I would recommend to try that first before using a new/larger pointing file in case you have inconsistent tracking. Please keep us posted with regards to your findings, Robert Link to comment Share on other sites More sharing options...
MarkS Posted September 30, 2014 Report Share Posted September 30, 2014 Hi Daniel, I have had no trouble using MLPT for up to 20min subs with only the 3 star config from the PA routine. Regards, Mark Link to comment Share on other sites More sharing options...
lukepower Posted September 30, 2014 Report Share Posted September 30, 2014 Robert, Mark, I'm gonna try this, seems to actually make more sense than a big pointing file plus MLPT... Thanks Link to comment Share on other sites More sharing options...
MartinN Posted October 1, 2014 Report Share Posted October 1, 2014 Lukas, Daniel, I can confirm to statements given by Robert and Mark, I often use only the 3 star PA routine, too. Out in the fields, a big pointing file delays the start of intended imaging, and MLPT works precise, even when comet tracking is activated in addition. Flexure changes, due to temperatures falling, might be the cause of tracking problems during long exposures, when MLPT is setup for more than 60 minutes. Daniel, did you ever check for changed flexure after 10 degrees lower environmental temperature ? Regards Martin Link to comment Share on other sites More sharing options...
Jay Posted October 1, 2014 Report Share Posted October 1, 2014 (edited) I'm using rather large pointing model (200 points) and MLPT at the same time with no problems. Corrections made by the MLPT seem to be rather small but still have an effect. I did try the 3-star PA routine + MLPT when setting up the system this fall with excellent results. Tried first how well it would track with just the 3-star model, and the results were not very good. Then added MLPT (120 min/10 points) and the tracking was excellent after that. Jay Edited October 1, 2014 by Jay Link to comment Share on other sites More sharing options...
Daniel Schmid Posted October 1, 2014 Author Report Share Posted October 1, 2014 Thanks to all of you for your inputs! Still not clear if the general pointing model is added to MLTP but likely this is not the case. I will disable the pointing model next time and only use the 3-star PA routine. Let's see! Link to comment Share on other sites More sharing options...
Jay Posted October 2, 2014 Report Share Posted October 2, 2014 Just to be clear ....I never disable the general pointing model when using the MLPT. I have a feeling that the MLPT works better (you need less MLPT points for a good result) if there is a solid general pointing model used at the same time. That would mean that the MLPT points are added to the general model. However, that is just a feeling because have never really made any comparison. Link to comment Share on other sites More sharing options...
afesan Posted October 2, 2014 Report Share Posted October 2, 2014 (edited) Welll.. I just image with MLPT and Sequencer all over the night in a remote-robotic observatory ....without any problems at all. I always use a full model of the sky and MLPT.. , but this is just a personal taste.. I like to have always a previous model for the whole Sky. My subframes are always into the range of 10-15 minutes LRGB and 20-30 minutes narrowband. No problems at all. Perfect round stars. If you experience problems I will re-check the hardware area ( balance, counterweights, motors parameters) and , of course... mirror movements or focuser sights... Most of my initial problems came for movements of primary mirror (in case of a reflector).... Just my two cents... CS ¡ Antonio Edited October 2, 2014 by afesan Link to comment Share on other sites More sharing options...
RamaSpaceShip Posted October 2, 2014 Report Share Posted October 2, 2014 My understanding of MLPT is that it creates a pointing model with points along the path followed by the imaged target. This target-specific pointing model is then used during the imaging session in place of the existing pointing model. The better is the existing pointing model, the closer from the best trajectory are the points found by MLPT, the best accuracy is got for the tracking. Hope this helps your understanding. Bernard Link to comment Share on other sites More sharing options...
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