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Hi All, I've been imaging for a year now and noticed a weird tracking error on most nights...usually before the Meridian flip. It self corrects either frame to frame or sometimes after a few frames. It manifests as a small nodule, nubbin or bubble next to the imaged stars...tried to take a pic of it below (sorry for the bad iPhone picture). AM5 tracking error? I've been deleting these frames but was curious if it was correctable. Mount AM5 Cam 2600MC Guide scope Orion 60mm Guide cam: ZWO 224  |
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What does your guiding look like? Have you also checked your meridian flip settings on the AM5?
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Michael Jarvis: Guiding is usually very good.....like around .5 or less. Which Mount settings would correct this? |
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How's your scope balancing, cable management etc? I had issues at one point due to those 2 things, which manifested themselves around the meridian flip as well—my starts looked somewhat different, though. |
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Christian Bennich: Thanks for the response...scope is on an AM 5 mount which they say you dont need to balance but I've got it pretty centered although now you have me wondering if the slightly heavier rear end (filter wheel/camera) dont add to small guiding errors as you get closer to the Meridian which would cause this? Cable management is sound...no issues there. |
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Not exactly sure what the issue is, but try heavy duty mode and/or change times before and after meridian flip. Hope this helps.
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Michael Jarvis: Thanks...I find it very odd that I dont see it after the flip...will give those a try |
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Could be because of the high PE of the AM5 and/or flexure? What are your guiding settings? |
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Tobiasz: 2000ms Calibration Step 500ms Max Dec and RA Duration RA Aggr 70% Dec Aggr 55% Dec Mode Auto |
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Chris:Tobiasz:Chris:Tobiasz: To combat the high PE of HD mounts I recommend you to reduce the guide exposures to max. 1s and try an aggressiveness of 20-40% depending on your load. ZWOs version of PHD2 should be able to multistar guide, so seeing should not be much of a problem. |
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This dont look like guiding error at all. What is your imaging scope? You listed everything but that. you get this only on or after the meridian flip ? |
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Karl Theberge: Orion 60mm guide scope with a 224MC as a guide cam. And this predominantly happens before the flip |
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I agree that this does not look like a guide error at all. Is this "print screen" coming from the guide or the main camera? What is your imaging scope? AM5 typically requires 1 second of exposure time. |
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Sorry if I missed this in the conversation, Chris, but what primary imaging scope are you using? Greg |
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What are your meridian flip settings? Looks like a short exposure near a longer one?
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Greg Erianne: No worries...thx for responding! Askar FRA 500 with a .7 reducer |
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Krzysztof Gaudy: Thx mate...this super crappy iPhone pic was taken on a zoomed in pic on one of my subs from last night's imaging...I tried to find a few representative stars that showcased the error...but obviously this occurs across the image. The stars come out with small "nubbins" (for lack of a better word)...always to the right of the star...and only before a flip. |
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What are your meridian flip settings? Looks like a short exposure near a longer one? Stop tracking 5 min before Meridian Auto flip 5 min after Meridian Recalibrate Guiding after AMF is off (havent needed this and again...the error is before the Meridian anyway). Honestly I dont think this is a Meridian problem per se...but it is odd it only occurs before the flip. I start out the night...usually get about 10-12 subs in and the first error manifests....the error will ruin a sub or two (or more)...self correct and then keep popping up on and off again (sometimes losing several subs) before it flips. Then after the flip...dont get this error. |
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I have that when my cables stuck… similar shapes.
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Istvan Tomasovszki: Exactly, I have seen similar behavior and stars in the same situation |
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What is the clearance between your camera/cables/EAF thermometer probe/or whatever else might be hanging down from the lower end of your telescope just before the meridian? If one of these starts touching the tripod, it can cause all kinds of interference with tracking and guiding. This woud be more so just before the meridian than after because afterwards the tension is getting less and less whereas on the opposite side it gets worse. Do you use a Pier Extension (like the PE-200)? Also the nubbins are all reddish (the other part of a star is bluish), which is a sign of chromatic aberration, and then maybe the proximity to the meridian plays some role in causing the reddish "nubbins" to appear. I'm just guessing here. So my 2 cents. |
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Chris:What are your meridian flip settings? Looks like a short exposure near a longer one? I have seen this before a few times, but I cannot recall the situation. Seems it was early in a session, when first setting up. I would think it has something to do with the flip because of when it happens. Do you have a photo of your setup? |
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Wild guess but maybe stopping x amount of time before meridian flip, but camera still exposing?
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