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Hi there! New ASIAIR Mini user here - purchased for imaging from a spot in my yard with no view of Polaris. The all-sky align has been working OK, but I've run into an issue trying to establish the mount's position post-alignment, so that I can slew to my target:
I feel like I'm missing a setting or a step here. I have no other serious issues with the app - the camera and mount communicate well, and I have successfully completed several nights of imaging. What I've had to do is aim the telescope where the erroneous platesolve thinks it is aimed, and then slew to my target. At that point, platesolving while auto-centering works flawlessly and I'm able to image. Thanks for any help with this one - it's the single biggest issue I've had with the ASIAIR since switching from Astroberry. The first time it happened, I didn't realize anything was wrong - my telescope collided with the mount while slewing and took a few years off my life! CS, Mark |
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Hi Mark, AsiAir has issues with plate solving near polar region and it is generally not recommended to do so! The errors to calculate the exact position are too high near the pole. Imaging the polar coordinate grid near the pole and the field of view you have. There used to be an error message regarding this issue in AsiAir Pro don’t know about the mini version. My workflow is always go back to zero after PA, go to a star/region far from Pole (best near polar equator) and plate solve, perfect. That‘s it. You might never get a perfect hit, after PA, because of the general plate solving problem near pole. Don’t mix PA and an exact plate solve to calibrate the polar coordinate system. regards Markus PS.: Oops, did not read your post right. You do all sky alignment without view to Pole… to be safe here I would make a rough manual PA, a plate solve and sync to mount, then goto Zero, then PA by asiair going back to zero. The first positioning after this might be not the best, but it will not be completely wrong to crash your mount. be aware that when doing first plate solve and not sync to mount, the mount does not know where it is positioned. When do a goto, it can end anywhere. The positioning is done by the mount not by the asiair. Asiair just tells the mount -> goto this position. |
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Hi! I've never had a problem plate solving with ASIAIR Plus while performing polar alignment using my 100mm and 130mm refractors. How is it possible to PA if you don't plate solve first? Isn't plate-solving an inherent routine of polar alignment? I have however had trouble plate solving when polar aligning with an Edge 8" 203mm telescope. Not sure why. It might have been a focusing issue. Jerry |
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Hi @Jerry Gerber, thanks for your reply! The ASIAIR is able to platesolve during PA, but the issue is that it doesn't update the mount's location after PA is complete, and the mount still thinks the telescope is pointed straight at the celestial pole, even after taking more images and platesolving them, it wouldn't report the actual position of the telescope. I was able to work around this problem by returning the mount to home position so that the reported position would be closer to the actual position, and then slewing to my target from there. It would platesolve and re-slew and everything would be fine after that. Thanks again, and CS! |
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Mark Germani: Hi Mark, That's exactly the same problem I discovered. After plate solving and polar aligning, it's necessary to slew back to the home position and then choose a star to fine tune focus and start guiding calibration. If after the PA I don't go back to home position, the mount doesn't go to whatever object I tell it to slew to. I don't know if this is a bug, I should tell ZWO about it. In any event, if you go to home position, the mount knows where it is and will guide successfully for the remainder of the night. Jerry |
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Jerry. Mark G's original post was regarding Polar Aligning without a clear view of Polaris, his situation and work around is unique to his situation. Jerry, I'm curious , what have you been using as home position when you start? If you have a permanent set up or especially if you are setting up every night you should be make your home position pointing at Polaris if you have a clear view By having your mount level and balanced and your elevation set properly for your latitude with the ASIAIR synced to your mount, the ASIAIR will do the PA and then use the focus star as a 2nd plate solve and then go perfectly to anywhere you want it to go. I have 5 ASIAIR Pro's and Pluses and have never had the problem you describe. Do this in order: 1 set up gear generally pointing north with your elevation, time, date and Lat/Lon coordinates set correctly 2 move gear to point as close as possible to Polaris and balance 3 power up gear and take a 1-3 second image depending on darkness, and longer if you are using a filter 4 run a PA and do what the ASIAIR wants you to do 5 after you get the azimuth position tweaked, goto Vega or another bright seasonally related star and focus 6 goto target, if the ASIAIR does not go exactly to the target you have done something wrong , not the devise. Set Guiding... hope this helps, scott |
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Jerry. Mark G's original post was regarding Polar Aligning without a clear view of Polaris, his situation and work around is unique to his situation. Hi Scott, I do not have a permanent setup, but I do have access to Polaris from my backyard and use a compass to align the mount (visually) to true north. When it's dark enough I begin PA. With my refractors, PA and plate solving goes well, in fact I get my azimuth and altitude within arc-seconds of accuracy. The problem both Mark and I seem to be having is after successfully polar aligning the mount, I have to go to home position, which for me is, as I just mentioned, with the mount pointing accurately to true north. If I don't slew to home position after PA and tell the mount to go to, say, Arcturus or some other bright star I use for focusing, the mount seems to get confused and doesn't slew to that object, but rather in the vicinity of that object. But if I go first to home position, it will then slew very accurately and get the chosen object precisely centered. This problem may have started with the latest 1.3 AM5 mount software update, or it might be the 2.1 version of ASIAIR Plus. I'm going to write to ZWO tonight and see if it's a known issue. Your 1-6 steps above are pretty much exactly what I do. And once I slew to home position after PA, the mount guides beautifully for the remainder of the evening, often within .35" on either RA or DEC, with a total error of no more than .5". Jerry |
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| I just wrote to ZWO support and also posted on their forum regarding this issue of having to slew to home position after PA to ensure accurate Go-To. |
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Jerry. What is the position you use for home position and why? It sounds like you are saying you plate solve from a home position and then go to Polaris to do a PA. I have never done that, But I have STARTED OUT pointing at Polaris as home position, then doing a PA and then slewing to targets with out fail, literally hundreds of times with 5 different AIRS over 5 years, including models with the latest firmware. |
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Jerry Gerber: Thanks @Jerry, it would save me some trouble when doing an all-sky align if I could go straight from PA to my target. I have only ever used > 2.0 so I don't know where this bug would have crept in. @wsg thanks for the comments. I think my problem (and I'm not sure if Jerry also did this) was I disengaged the clutch to slew the mount to the starting position for the all-sky PA. I thought that surely after all the platesolving it did during PA that it would update the mount's position, but this was perhaps expecting too much, and none of the subsequent preview-shot-platesolving would work either (this bit seemed buggy). Lesson learned - don't disengage the clutch, and slew with the hand-controller! When I PA using the polar scope from the little corner of my backyard where I CAN see Polaris, none of this is an issue. I don't use the ASIAIR for PA at all, my optical PA is fast and accurate after years of using the SkyGuider Pro, and the telescope always starts slewing from home position anyway. But no southern sky from this position! Clear skies to both of you, and thanks again! Mark |
