Date
1 - 20 of 21
Guide star lost after dithering
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yanzhe liu
Not sure what the issue is and whether it is mount related, hope someone can help me out. I have been using SGPro + PHD2 + AP mount without any issue for years, but recently PHD2 often loses guide star after dithering. It happens to mach2 mount only (so far so good for AP1100), but it did not happen until I upgraded PHD2 to 2.6.10 (and 2.6.9dev4 for multi-star guiding). One strange thing is that whenever the guide star is lost, there is always a big spike on DEC guiding (and the spike is always 12 pixels), even though I enable PHD2 "RA only" dither. Changing SGP settings does not help either (except disabling dither).
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Hi yanzhe liu Your question is probably better answered in the PHD user forums, but either way, you will need to upload your guidelogs Brian
On Tue, Nov 23, 2021 at 1:28 PM yanzhe liu <liuyanzhe@...> wrote:
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Roland Christen
One strange thing is that whenever the guide star is lost, there is always a big spike on DEC guiding (and the spike is always 12 pixels), You will need to look at your PHD log file to see what PHD is sending to the mount. I assume your dither is set to move the mount at 1x sidereal for a fraction of a second, is that correct? If you are sending a co-ordinate move, you may be sending the mount in both axes to a previous location.
Rolando
-----Original Message-----
From: yanzhe liu <liuyanzhe@...> To: main@ap-gto.groups.io Sent: Tue, Nov 23, 2021 3:27 pm Subject: [ap-gto] Guide star lost after dithering Not sure what the issue is and whether it is mount related, hope someone can help me out.
I have been using SGPro + PHD2 + AP mount without any issue for years, but recently PHD2 often loses guide star after dithering.
It happens to mach2 mount only (so far so good for AP1100), but it did not happen until I upgraded PHD2 to 2.6.10 (and 2.6.9dev4 for multi-star guiding).
One strange thing is that whenever the guide star is lost, there is always a big spike on DEC guiding (and the spike is always 12 pixels), even though I enable PHD2 "RA only" dither. Changing SGP settings does not help either (except disabling dither). -- Roland Christen Astro-Physics
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yanzhe liu
Here is the log:
https://openphdguiding.org/logs/dl/PHD2_logs_xGZF.zip I have not used the log before but I think this is the dither causing issue. I then restarted the sequence by turning dither off. 19:29:39.383 00.003 2112 PhdController::Dither begins
19:29:39.386 00.003 2112 dither: size=1.00, dRA=-0.61 dDec=0.00
19:29:39.389 00.003 2112 MountToCamera -- mountTheta (3.14) + m_xAngle (-1.59) = xAngle (1.55 = 1.55)
19:29:39.392 00.003 2112 MountToCamera -- mountX=-0.61 mountY=0.00 hyp=0.61 mountTheta=3.14 cameraX=0.01, cameraY=0.61 cameraTheta=1.55
19:29:39.395 00.003 2112 setting lock position to (121.19, 18.76)
19:29:39.398 00.003 2112 Mount: notify guiding dithered (0.0, 0.6)
19:29:39.401 00.003 2112 MultiStar: stabilizing after lock position change
19:29:39.403 00.002 2112 Status Line: Dither by -0.61,0.00
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yanzhe liu
Since both SGP and PHD2 have been used by many customers, I am looking for suggestion on Mach2 mount debug.
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yanzhe liu
I also posted the same question on PHD2 forum.
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Are you doing 15 minute exposures? The dither distances and settling look fine from a PHD perspective, although I can see a big spike in guidestar SNR roughly every 900 seconds
On Tue, Nov 23, 2021 at 5:49 PM yanzhe liu <liuyanzhe@...> wrote: Here is the log: --
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yanzhe liu
Yes, exposure time was 900s.
On Tue, Nov 23, 2021 at 6:25 PM Brian Valente <bvalente@...> wrote:
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Regarding your image download when exposure complete, are you still guiding while image is downloading? Does download take a while?
On Tue, Nov 23, 2021 at 6:28 PM yanzhe liu <liuyanzhe@...> wrote:
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yanzhe liu
Download takes 10-20s. Yes, guiding is still on during download, but not during auto focus.
On Tue, Nov 23, 2021 at 6:31 PM Brian Valente <bvalente@...> wrote:
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You might try pausing guiding during download and see if that helps.
On Tue, Nov 23, 2021 at 6:39 PM yanzhe liu <liuyanzhe@...> wrote:
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Roland Christen
A dither move is normally the same as a guide move command, except typically bigger. If the mount guides normally and properly, then it is responding to the PHD external commands in the proper manner. I don't see how the mount would, on its own, move the Dec axis by 12 pixels unless instructed to do so.
If the camera is angled by 45 degrees then both X and Y will move although only RA is commanded to move. We don't have enough information at this point as to what really moved. Did the Dec actually move or did the Y axis of the camera move? The two are not the same. People often mix up the X and Y axes, thinking they are the RA and Dec axes. This is not the case unless the camera is exactly rotated to a null position with respect to RA and Dec. That is usually never the case.
Rolando
-----Original Message-----
From: Brian Valente <bvalente@...> To: main@ap-gto.groups.io Sent: Tue, Nov 23, 2021 8:30 pm Subject: Re: [ap-gto] Guide star lost after dithering Regarding your image download when exposure complete, are you still guiding while image is downloading? Does download take a while?
On Tue, Nov 23, 2021 at 6:28 PM yanzhe liu <liuyanzhe@...> wrote:
-- Roland Christen Astro-Physics
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Roland Christen
Mounts will be instructed to move by two different methods. One is by coordinate moves, the other is by timed move where a 1 second move command corresponds to a 15 arc sec move. Coordinate moves are tricky because they are subject to a different protocol and can cause problems when the mount is in counterweight up position. Timed moves are preferred for all guide and dither commands. I cannot tell by the log below which one is being used. Delta RA = .61 means nothing to me, but perhaps our PHD gurus can clarify.
Rolando
-----Original Message-----
From: Roland Christen via groups.io <chris1011@...> To: main@ap-gto.groups.io <main@ap-gto.groups.io> Sent: Tue, Nov 23, 2021 8:44 pm Subject: Re: [ap-gto] Guide star lost after dithering A dither move is normally the same as a guide move command, except typically bigger. If the mount guides normally and properly, then it is responding to the PHD external commands in the proper manner. I don't see how the mount would, on its own, move the Dec axis by 12 pixels unless instructed to do so.
If the camera is angled by 45 degrees then both X and Y will move although only RA is commanded to move. We don't have enough information at this point as to what really moved. Did the Dec actually move or did the Y axis of the camera move? The two are not the same. People often mix up the X and Y axes, thinking they are the RA and Dec axes. This is not the case unless the camera is exactly rotated to a null position with respect to RA and Dec. That is usually never the case.
Rolando
-----Original Message-----
From: Brian Valente <bvalente@...> To: main@ap-gto.groups.io Sent: Tue, Nov 23, 2021 8:30 pm Subject: Re: [ap-gto] Guide star lost after dithering Regarding your image download when exposure complete, are you still guiding while image is downloading? Does download take a while?
On Tue, Nov 23, 2021 at 6:28 PM yanzhe liu <liuyanzhe@...> wrote:
-- Roland Christen Astro-Physics -- Roland Christen Astro-Physics
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There's one other thing you can test disable dithering and take a few images, but leave everything else the same (i.e., continue guiding during download). If the issue persists, you know it's unrelated to dithering If that's the case, you could then try imaging without guiding and downloading and see what happens
On Tue, Nov 23, 2021 at 6:39 PM yanzhe liu <liuyanzhe@...> wrote:
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Roland Christen
Autofocus can shift the camera which will cause the star to jump. Try turning off Autofocus and see if you still get the jump.
Rolando
-----Original Message-----
From: Brian Valente <bvalente@...> To: main@ap-gto.groups.io Sent: Tue, Nov 23, 2021 10:52 pm Subject: Re: [ap-gto] Guide star lost after dithering There's one other thing you can test
disable dithering and take a few images, but leave everything else the same (i.e., continue guiding during download). If the issue persists, you know it's unrelated to dithering
If that's the case, you could then try imaging without guiding and downloading and see what happens
On Tue, Nov 23, 2021 at 6:39 PM yanzhe liu <liuyanzhe@...> wrote:
-- Roland Christen Astro-Physics
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yanzhe liu
Last night I turned off guiding during download and it worked. I will test more in the next few days. Thanks everyone for the help.
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Howard Ritter
Idle question: Whatever happened to the 3600GTO “El Capitan" mount? Looking at photos of it on its massive portable pier, carrying a PlaneWzve 24”, I realized it’s the ideal solution to my notional dream semipermanent home installation. Any plans (that can be mentioned) to produce it again, or for a successor?
—howard
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Roland Christen
Possibly, but not this year.
Rolando
-----Original Message-----
From: Howard Ritter via groups.io <howard.ritter@...> To: main@ap-gto.groups.io Sent: Wed, Nov 24, 2021 10:28 pm Subject: Re: [ap-gto] Guide star lost after dithering Idle question: Whatever happened to the 3600GTO “El Capitan" mount? Looking at photos of it on its massive portable pier, carrying a PlaneWzve 24”, I realized it’s the ideal solution to my notional dream semipermanent home installation. Any plans (that can be mentioned) to produce it again, or for a successor?
—howard -- Roland Christen Astro-Physics
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Howard Ritter
If the notification list doesn’t go live soon, I’m gonna be too old!
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—howard
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yanzhe liu
That is good to hear, thanks for the update What camera were you using, and does it have the built-in SBIG guider? I'm glad it solved the problem, but i'm not entirely sure what's going on during image download such that it would cause a large spike in Dec Brian
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