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kirkster501

Guiding better after the Meridian Flip...šŸ¤”

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Hi all, any thoughts as to why my guiding is better after the flip because after numerous observations, it most assuredly is.Ā  Mount is MESU 200 and using PHD2 and using a guide scope.Ā  Everything is balanced as far as I can tell - not the easiest of mounts to balance is the MESU.Ā  I do not appear to have any flexture either and in any event, this also appliesĀ when I am using OAG as well.

What tinkering do you guys do with PHD2 settings such as min move, Hysteresis and aggressiveness?

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Unfortunately with my current set up location, I have little need to meridian flip as one hemisphere of the sky is almost completely inaccessible. Guiding performance with the MesuĀ can vary a lot from session to session even though I polar align with Sharpcap to <30ā€ every time (still having movement on the final tighten down).

Last night imaging M106 I was getting total RMS of 0.6ā€, with very few corrections in Dec but RA needing regular corrections in both directions. I reduced the RA aggressiveness setting in PHD (currently at 65%) and this helped a bit as there was an element of over correction happening. But... on nearly every session I get periods of around 60 secs or so with near perfect tracking, with no corrections on either axis. This has to be due toĀ seeing conditionsĀ I presume,Ā but my guiding exposure time is 3.5-4.0 secs which should be enough to smooth these out?

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13 hours ago, kirkster501 said:

Hi all, any thoughts as to why my guiding is better after the flip because after numerous observations, it most assuredly is.Ā  Mount is MESU 200 and using PHD2 and using a guide scope.Ā  Everything is balanced as far as I can tell - not the easiest of mounts to balance is the MESU.Ā  I do not appear to have any flexture either and in any event, this also appliesĀ when I am using OAG as well.

What tinkering do you guys do with PHD2 settings such as min move, Hysteresis and aggressiveness?

Very odd to have better guiding after the flip... Most probably you have some imbalance there.

I always have my MESUĀ on very low aggression and relatively high hysteresis. As of lately, I am using aggression of 45% in RA and 30% in DEC and 32 hysteresis. I found that these values with a 5-second exposure will give me the best results in average seeing conditions at long focal length (I have a 2000 mm FL GSO 10 inch RC on top of the mount now). At low FL should not matter too muchĀ on this mount it will make round stars in any configuration of PHD2.

Balance can be tricky to do on the MESUĀ but I use a hand scale with an attached strap held by a "contraption" I made to help me with the positioning and raising the scale perfectly perpendicular to the end of the OTA and end of the counterweight bar. The only pain with the balance has been shifting the 25+ kgs of OTA in the saddleplate.Ā 

Ā 

Edited by mihaighita
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I like Mihaighita's method of checking balance as it would also highlight any change in the rotation drag of the mount itself. I used to check compressors by wrapping cord round the drive pulley and using a spring balance to measure the start and rotation pull as part of routine checks.

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