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Thank you everyone for the helpful insights. Next time I will play a bit with altitude/density.
In the long term I will also update the mirror cell from Orion UK to my design. It should be a step further to control differential flexures. a bit off topic but it is my baby :-)
Il giorno sab 19 nov 2022 alle ore 05:49 Bill Long < bill@...> ha scritto:
The modeling really is as good as people say it is. Here is a snip from my last OIII frame that just came in. This is 1:1 zoom, and as you can see these stars are excellent. 5 minute unguided subs, Mach 2 + Epsilon 160ED. Bravo to Ray and AP for making the
best modeling and unguided experience there is in Astrophotography.
+1 for min altitude. Don't spend time on points in parts of the sky you will not be using for Dec Arc mode.
>>>Andrea, I am sitting out at my remote site right now running a 3-Dec line mapping run (2 degree Dec spacing and 5 degree RA spacing) as I am waiting for the temperature to stabilize and my object to get high enough.
nice update.
I would also point out setting an appropriate minimum altitude helps to minimize the number of mapping points. i used to do 30 degrees altitude until i realized i never really shot anything below 45 degrees
“Do you think that one single arc centred on the objects but very dense can work also better?
3 arcs for 3-5 degrees RA spacing is probably the best in terms of performance but time required is also important to me.
I'd like to keep the modeling within 30 minutes to maximize imaging time
In any case next time I will go for 3 arcs/5 deg spacing as suggested, so I can have also a good benchmark.
I will try to go unguided so any bias in the analysis can be eliminated.”
Andrea, I am sitting out at my remote site right now running a 3-Dec line mapping run (2 degree Dec spacing and 5 degree RA spacing) as I am waiting for the temperature to stabilize and my object to get high enough. The run is nearly complete and it has been
running for about 25 minutes. The software/mount can map 3 points in a little over a minute - slew, settle, image and solve. So it doesn’t really take very long. I would just be sitting here waiting for it to get dark and for the scope to cool down anyway.
So no imaging time is lost.
The big up side of going unguided for me is that I have eliminated the significant time overhead of the dither-settle cycle that happens when guiding. For me it was 15 or 20 seconds, or more per dither. That time starts to add up when you dither every image
as I do. With unguided imaging I just set the settle time to 3 seconds and the mount will dither, settle and start the next image in about 5 seconds or less. Thus I can pack more subs into a given time period.
Last winter I was using my old school Takahashi MT-160 - f/6 1000mm fl - to take unguided images. It works great.
--
Dean Jacobsen
Astrobin Image Gallery -
https://www.astrobin.com/users/deanjacobsen/
--
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|
|
It's not just there for folks with encoders. 🙂 After all the king of the throne about 5 years ago was T-Point, ProTrack, and Bisque's seemingly massive stranglehold on the unguided market with their "robotic" mounts.
Ray and AP just passed them in the left lane with a midwest quality wave goodbye with the latest APCC tech over the last year or so. While it is easier with encoders, everyone can join on on this -- just refresh your PEM if you dont have encoders.
toggle quoted message
Show quoted text
From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Dean Jacobsen <deanjacobsen@...>
Sent: Friday, November 18, 2022 9:14 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
Yes, the Mach2 and the software that unlocks unguided imaging is indeed a wonderful thing.
If you have a Mach2 or an 1100 or 1600 with encoders you should give unguided a try.
I agree with the recommendation to not bother with collecting mapping points below the actual altitude you plan on imaging. It’s just a waste of time.
--
Dean Jacobsen
Astrobin Image Gallery -
https://www.astrobin.com/users/deanjacobsen/
|
|
|
Dean Jacobsen
Yes, the Mach2 and the software that unlocks unguided imaging is indeed a wonderful thing.
If you have a Mach2 or an 1100 or 1600 with encoders you should give unguided a try.
I agree with the recommendation to not bother with collecting mapping points below the actual altitude you plan on imaging. It’s just a waste of time.
--
Dean Jacobsen
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/
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The modeling really is as good as people say it is. Here is a snip from my last OIII frame that just came in. This is 1:1 zoom, and as you can see these stars are excellent. 5 minute unguided subs, Mach 2 + Epsilon 160ED. Bravo to Ray and AP for making the
best modeling and unguided experience there is in Astrophotography.
toggle quoted message
Show quoted text
From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Bill Long <bill@...>
Sent: Friday, November 18, 2022 8:39 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
+1 for min altitude. Don't spend time on points in parts of the sky you will not be using for Dec Arc mode.
From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Brian Valente <bvalente@...>
Sent: Friday, November 18, 2022 8:28 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
>>>Andrea, I am sitting out at my remote site right now running a 3-Dec line mapping run (2 degree Dec spacing and 5 degree RA spacing) as I am waiting for the temperature to stabilize and my object to get high enough.
nice update.
I would also point out setting an appropriate minimum altitude helps to minimize the number of mapping points. i used to do 30 degrees altitude until i realized i never really shot anything below 45 degrees
“Do you think that one single arc centred on the objects but very dense can work also better?
3 arcs for 3-5 degrees RA spacing is probably the best in terms of performance but time required is also important to me.
I'd like to keep the modeling within 30 minutes to maximize imaging time
In any case next time I will go for 3 arcs/5 deg spacing as suggested, so I can have also a good benchmark.
I will try to go unguided so any bias in the analysis can be eliminated.”
Andrea, I am sitting out at my remote site right now running a 3-Dec line mapping run (2 degree Dec spacing and 5 degree RA spacing) as I am waiting for the temperature to stabilize and my object to get high enough. The run is nearly complete and it has been
running for about 25 minutes. The software/mount can map 3 points in a little over a minute - slew, settle, image and solve. So it doesn’t really take very long. I would just be sitting here waiting for it to get dark and for the scope to cool down anyway.
So no imaging time is lost.
The big up side of going unguided for me is that I have eliminated the significant time overhead of the dither-settle cycle that happens when guiding. For me it was 15 or 20 seconds, or more per dither. That time starts to add up when you dither every image
as I do. With unguided imaging I just set the settle time to 3 seconds and the mount will dither, settle and start the next image in about 5 seconds or less. Thus I can pack more subs into a given time period.
Last winter I was using my old school Takahashi MT-160 - f/6 1000mm fl - to take unguided images. It works great.
--
Dean Jacobsen
Astrobin Image Gallery -
https://www.astrobin.com/users/deanjacobsen/
--
|
|
|
+1 for min altitude. Don't spend time on points in parts of the sky you will not be using for Dec Arc mode.
toggle quoted message
Show quoted text
From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Brian Valente <bvalente@...>
Sent: Friday, November 18, 2022 8:28 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
>>>Andrea, I am sitting out at my remote site right now running a 3-Dec line mapping run (2 degree Dec spacing and 5 degree RA spacing) as I am waiting for the temperature to stabilize and my object to get high enough.
nice update.
I would also point out setting an appropriate minimum altitude helps to minimize the number of mapping points. i used to do 30 degrees altitude until i realized i never really shot anything below 45 degrees
“Do you think that one single arc centred on the objects but very dense can work also better?
3 arcs for 3-5 degrees RA spacing is probably the best in terms of performance but time required is also important to me.
I'd like to keep the modeling within 30 minutes to maximize imaging time
In any case next time I will go for 3 arcs/5 deg spacing as suggested, so I can have also a good benchmark.
I will try to go unguided so any bias in the analysis can be eliminated.”
Andrea, I am sitting out at my remote site right now running a 3-Dec line mapping run (2 degree Dec spacing and 5 degree RA spacing) as I am waiting for the temperature to stabilize and my object to get high enough. The run is nearly complete and it has been
running for about 25 minutes. The software/mount can map 3 points in a little over a minute - slew, settle, image and solve. So it doesn’t really take very long. I would just be sitting here waiting for it to get dark and for the scope to cool down anyway.
So no imaging time is lost.
The big up side of going unguided for me is that I have eliminated the significant time overhead of the dither-settle cycle that happens when guiding. For me it was 15 or 20 seconds, or more per dither. That time starts to add up when you dither every image
as I do. With unguided imaging I just set the settle time to 3 seconds and the mount will dither, settle and start the next image in about 5 seconds or less. Thus I can pack more subs into a given time period.
Last winter I was using my old school Takahashi MT-160 - f/6 1000mm fl - to take unguided images. It works great.
--
Dean Jacobsen
Astrobin Image Gallery -
https://www.astrobin.com/users/deanjacobsen/
--
|
|
|
>>>Andrea, I am sitting out at my remote site right now running a 3-Dec line mapping run (2 degree Dec spacing and 5 degree RA spacing) as I am waiting for the temperature to stabilize and my object to get high enough.
nice update.
I would also point out setting an appropriate minimum altitude helps to minimize the number of mapping points. i used to do 30 degrees altitude until i realized i never really shot anything below 45 degrees
“Do you think that one single arc centred on the objects but very dense can work also better?
3 arcs for 3-5 degrees RA spacing is probably the best in terms of performance but time required is also important to me.
I'd like to keep the modeling within 30 minutes to maximize imaging time
In any case next time I will go for 3 arcs/5 deg spacing as suggested, so I can have also a good benchmark.
I will try to go unguided so any bias in the analysis can be eliminated.”
Andrea, I am sitting out at my remote site right now running a 3-Dec line mapping run (2 degree Dec spacing and 5 degree RA spacing) as I am waiting for the temperature to stabilize and my object to get high enough. The run is nearly complete and it has been running for about 25 minutes. The software/mount can map 3 points in a little over a minute - slew, settle, image and solve. So it doesn’t really take very long. I would just be sitting here waiting for it to get dark and for the scope to cool down anyway. So no imaging time is lost.
The big up side of going unguided for me is that I have eliminated the significant time overhead of the dither-settle cycle that happens when guiding. For me it was 15 or 20 seconds, or more per dither. That time starts to add up when you dither every image as I do. With unguided imaging I just set the settle time to 3 seconds and the mount will dither, settle and start the next image in about 5 seconds or less. Thus I can pack more subs into a given time period.
Last winter I was using my old school Takahashi MT-160 - f/6 1000mm fl - to take unguided images. It works great.
--
Dean Jacobsen
Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/
|
|
|
Dean Jacobsen
“Do you think that one single arc centred on the objects but very dense can work also better?
3 arcs for 3-5 degrees RA spacing is probably the best in terms of performance but time required is also important to me.
I'd like to keep the modeling within 30 minutes to maximize imaging time
In any case next time I will go for 3 arcs/5 deg spacing as suggested, so I can have also a good benchmark.
I will try to go unguided so any bias in the analysis can be eliminated.”
Andrea, I am sitting out at my remote site right now running a 3-Dec line mapping run (2 degree Dec spacing and 5 degree RA spacing) as I am waiting for the temperature to stabilize and my object to get high enough. The run is nearly complete and it has been running for about 25 minutes. The software/mount can map 3 points in a little over a minute - slew, settle, image and solve. So it doesn’t really take very long. I would just be sitting here waiting for it to get dark and for the scope to cool down anyway. So no imaging time is lost.
The big up side of going unguided for me is that I have eliminated the significant time overhead of the dither-settle cycle that happens when guiding. For me it was 15 or 20 seconds, or more per dither. That time starts to add up when you dither every image as I do. With unguided imaging I just set the settle time to 3 seconds and the mount will dither, settle and start the next image in about 5 seconds or less. Thus I can pack more subs into a given time period.
Last winter I was using my old school Takahashi MT-160 - f/6 1000mm fl - to take unguided images. It works great.
-- Dean Jacobsen Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/
|
|
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Dean Jacobsen
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Dean Jacobsen
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I have tried many times just one Dec arc modeled instead of 3. It works very well. This assumes that your polar alignment is good and doesn't have much Dec drift.
Rolando
-----Original Message-----
From: Andrea Lucchetti <andlucchett@...>
To: main@ap-gto.groups.io
Sent: Fri, Nov 18, 2022 5:59 pm
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
Thank you Roland for the analysis.
I try to comment to your points:
1)I have no answer to point one: i think I am missing something in the PHD analysis and how the two data match
2) can be seeing in both cases?
3) got the point: I think the major contribution is tied with mirror support in my case. lateral supports must be fine tuned to avoid astigmatism. At this point I suspect the mirror was too loose. I designed a new cell but it will take time for me to build it.
4) got the point, also Ray pointed out the same. I need to find a better balance between density, # of arcs and duration
I don't think I can go with an OAG, backfocus is too short.
Next time I will try to improve the model and to go unguided: of course I can invest more time in modeling if time is shaved from guiding, calibration, set up, etc
Thank you again for your kind support
Andrea
So the 0.26"/min (15.6"/h) should be the drift without any guiding (in my case with model applied) 1) The screen shot of the 4 hour run shows .077 arc sec per minute, 4.6 arc sec per hour, not what you wrote above.
2) The Dec data appears to be guided in both cases.
3) You made the model with the main scope and then tested the model with a different scope attached somehow to the mount with different rings etc. The model has in it not only the motion of the stars with atmospheric refraction, but also the differential motion of the main scope, which includes flex in the scope rings. The model applies only to the main scope, not to the guide scope which does not have the main scope flex. So just from this I would conclude that the test is invalid. Between a guide scope and main scope there is always differential flexure, which can easily be 10 - 20 arc seconds over 4 hours.
4) Even if there is no differential flex between guidescope and main scope, the Dec is sampled with 1 degree spacing, but the RA spacing is quite rough at 14 degrees. This will also impact the overall accuracy of the model.
I have checked the records of the tests we did with your mount and we measured a maximum error of only 7 arc seconds in the RA encoder over a 24 hour period, 0.29 arc seconds per hour of tracking error at the sidereal rate. Therefore the mount's contribution to any drift is essentially zero. Even if it was 10 times this value, any modeling will compensate for that, and it will never show up in the data.
The only way to test the accuracy of any model is to use the same scope/camera system to create the model and then measure the resulting tracking with that same scope/camera. The model can account for some differential flexure between the scope and the mount, but in a lot of cases the differential flex is non-linear and can be variable between one run and the next. This is especially true if the temperature changes, if the focuser is not fully locked down (flex in the focuser tube), if the mirror shifts differently between runs, etc etc etc. There are so many variables possible here. Having a model taken with one scope and then applied to another scope is invalid in any case.
Bottom Line: There will always be an order of magnitude difference between the tracking error in RA and the Dec, simply because the Dec doesn't move much at all during the 4 hours (1% error of zero = zero). The RA tracking error must be accurately modeled over ~70 degrees of sky motion, but the Dec perhaps only 1/2 degree of motion. The error budget in RA is an order of magnitude higher, so much finer spacing in RA is needed to get similar results. And finally, you cannot model with one scope and measure the result with another scope.
Rolando
-----Original Message-----
From: Andrea Lucchetti < andlucchett@...>
To: main@ap-gto.groups.io
Sent: Fri, Nov 18, 2022 3:23 am
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
Hi Roland,
the drift reported by PHD in the main panel is the drift "before" the corrections are applied, that is my understanding.
So the 0.26"/min (15.6"/h) should be the drift without any guiding (in my case with model applied)
Then, you can analyze the data in the guided form or, the "raw RA form" (extrapolated subtracting the guider corrections).
PHD gives you the two options. I am attaching the two analysis here ( the Raw RA is the one already sent before).
I can understand we are relying heavily on PHD data analysis, I am ready to collect new data you think are needed to run an unbiased analysis.
Thank you again,
Andrea
RA is -0.26"/min (15.6/"h): this is measured by PHD. The picture you posted shows a max drift rate of 7 arc sec over 1.5 hrs (4.6/hr) and a secondary rate of 7 arc sec per 2.6 hrs (2.7/hr). See attached picture below.
From your answer below, with the guider running, you experienced a long term drift in the guide star of 15.6 sec per hour. That's impossible unless you were not guiding (you say you were guiding).
So we have 2 things that do not make any sense.
Rolando
-----Original Message-----
From: Andrea Lucchetti < andlucchett@...>
To: main@ap-gto.groups.io
Sent: Thu, Nov 17, 2022 5:24 pm
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
Hi Roland, thank you for finding the time to help me.
You are probably the only dentist I can stand :-)
I collected the info requested through the terminal:
$RS# time: 0.337 Received 10#
$RA# time: 0.319 Received 40#
$RN# time: 0.318 Received 8#
$GOS# time: 0.325 Received 1110000000#
$GR# time: 0.329 Received +162° 37:59.5#
$GD# time: 0.358 Received: +01° 53:26.7#
data collected just after initialization at park3.
then the answer to the questions below:
Time period 4 hrs (yes, no): YES, 4hours 43' . I have also the run after meridian flip (3h 48') from the same session
Guided (yes, no): yes
Modeled (yes, no): yes
Dec Arc modeled or All Sky modeled: dec arcmodeled , 3arcs , dec spacing 1deg, RA spacing 14 deg for a total of 26 points
Guide exposure time (seconds, plus delay between exposures) 3seconds, 4 seconds delay
Guide camera with off-axis guider on main instrument (yes, no) No
Guide camera on separate guide scope (yes, no) yes, it is a takahashi Fs60
How are the cables attached from the camera to your computer? short cables from camera to USB hub and rig runner (mouted on top of OTA), then USB cable from here to Pc. Power goes from rigrunner through the mount
What is the minimum and maximum drift in arc seconds per hour in that guider: average DEC drift is 0.00"/min, RA is -0.26"/min (15.6/"h): this is measured by PHD. I am not sure what you mean for "minimum" and "maximum" drift
Can you show a guider graph of 10 minutes and 60 minutes unguided? no, not a recent one: I think I tried once and verified the PE was basically covered by seeing.
What I wanted to check with this thread is the effect of the model in RA (in DEC was clearly very good).
I understand it would be better to first check native PE before add complexity to the analysis, I can collect the 10/60 min runs next week if the weather cooperates.
Andrea
Please correct me if I am wrong, but I need to understand exactly how you are taking the data shown on your picture of the guider graph.
Time period 4 hrs (yes, no)
Guided (yes, no)
Modeled (yes, no)
Dec Arc modeled or All Sky modeled
Guide exposure time (seconds, plus delay between exposures)
Guide camera with off-axis guider on main instrument (yes, no)
Guide camera on separate guide scope (yes, no)
How are the cables attached from camera to your computer?
What is the minimum and maximum drift in arc seconds per hour in that guider graph?
Can you show a guider graph of 10 minutes and 60 minutes unguided?
I know it's like pulling teeth but I'm the dentist and I have to find out if there is an owie there.
Rolando
-----Original Message-----
From: Andrea Lucchetti < andlucchett@...>
To: main@ap-gto.groups.io
Sent: Tue, Nov 15, 2022 5:38 pm
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
Roland,
my be I've jumped one post? sorry for that if it is the case.
Regarding the commands: do I need just to power up and connect the mount right?
I don't have the mount with me now, but can answer in 1-2 days.
thank you
I guess my post went out into the vapor-sphere and got lost.
Andrea, if you don't mind, please use APCC Terminal mode and type in the following commands. Let me know what the responses are:
$RS#
$RA#
$RN#
$GOS#
$GR#
$GD#
Thanks. It will go a long way to perhaps explain what might be happening.
Rolando
-----Original Message-----
From: chris1011@...
To: main@ap-gto.groups.io < main@ap-gto.groups.io>
Sent: Tue, Nov 15, 2022 4:59 pm
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
You attached a picture in your last post. Please explain what this is. Scale, time period, etc.
Rolando
-----Original Message-----
From: Andrea Lucchetti < andlucchett@...>
To: main@ap-gto.groups.io
Sent: Tue, Nov 15, 2022 4:06 pm
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
Thank you Brian.
if you look at the RA line in the guiding plot you see that is almost always below zero.
The scatter diagram too is not centered.
I am trying to understand if this could be caused by drift, but I am not sure.
I had to increase aggressiveness to try to compensate for this.
if you click on "drift " on the box you posted, you see that drift in DEC is 0, pol align error is zero, but RA drift is -0.26 arcsec/min.
The same is visible in the plot of raw RA (see photo attached), where you can see the cumulated drift over the 4 hours.
the difference between DEC and RA is clear.
My eccentricity is reported to be 0.55 on average at the center of the field.
This eccentricity is about the same in different nights, sky objects and with different rotation of the camera
Il giorno mar 15 nov 2022 alle ore 22:49 Brian Valente < bvalente@...> ha scritto:
Hi Andrea
Great that worked
Looking at your 4 hour run, your total RMS is 0.45" with RA RMS 0.30" and Dec RMS 0.28".
this should result in nice tight round stars
it looks pretty good to me. Can you point out what concerns you?
thank you for your patient :-)
Il giorno mar 15 nov 2022 alle ore 22:24 Brian Valente < bvalente@...> ha scritto:
getting closer :)
that is the debug log, i'm looking for the guidelog
if you just want to upload the one file here that would be great
I am so sorry. try this last one:
I've verified the link, it should be there.
let me know if it doesn't work
thank you
Il giorno mar 15 nov 2022 alle ore 22:12 Brian Valente < bvalente@...> ha scritto:
sorry I still don't see a guidelog in there?
I am sorry, try this one:
https://www.dropbox.com/t/DO1UyH8HNE7xvyyG
by the way, the RA rates are noted in the APPC log.
if you take the PHD log and check the raw data, you see a long period oscillation
Thank you
Andrea
--
--
--
--
Roland Christen
Astro-Physics
--
Roland Christen
Astro-Physics
--
Roland Christen
Astro-Physics
--
Roland Christen
Astro-Physics
-- Roland Christen Astro-Physics
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Thank you Roland for the analysis. I try to comment to your points: 1)I have no answer to point one: i think I am missing something in the PHD analysis and how the two data match 2) can be seeing in both cases? 3) got the point: I think the major contribution is tied with mirror support in my case. lateral supports must be fine tuned to avoid astigmatism. At this point I suspect the mirror was too loose. I designed a new cell but it will take time for me to build it. 4) got the point, also Ray pointed out the same. I need to find a better balance between density, # of arcs and duration
I don't think I can go with an OAG, backfocus is too short. Next time I will try to improve the model and to go unguided: of course I can invest more time in modeling if time is shaved from guiding, calibration, set up, etc Thank you again for your kind support Andrea
So the 0.26"/min (15.6"/h) should be the drift without any guiding (in my case with model applied) 1) The screen shot of the 4 hour run shows .077 arc sec per minute, 4.6 arc sec per hour, not what you wrote above.
2) The Dec data appears to be guided in both cases.
3) You made the model with the main scope and then tested the model with a different scope attached somehow to the mount with different rings etc. The model has in it not only the motion of the stars with atmospheric refraction, but also the differential motion of the main scope, which includes flex in the scope rings. The model applies only to the main scope, not to the guide scope which does not have the main scope flex. So just from this I would conclude that the test is invalid. Between a guide scope and main scope there is always differential flexure, which can easily be 10 - 20 arc seconds over 4 hours.
4) Even if there is no differential flex between guidescope and main scope, the Dec is sampled with 1 degree spacing, but the RA spacing is quite rough at 14 degrees. This will also impact the overall accuracy of the model.
I have checked the records of the tests we did with your mount and we measured a maximum error of only 7 arc seconds in the RA encoder over a 24 hour period, 0.29 arc seconds per hour of tracking error at the sidereal rate. Therefore the mount's contribution to any drift is essentially zero. Even if it was 10 times this value, any modeling will compensate for that, and it will never show up in the data.
The only way to test the accuracy of any model is to use the same scope/camera system to create the model and then measure the resulting tracking with that same scope/camera. The model can account for some differential flexure between the scope and the mount, but in a lot of cases the differential flex is non-linear and can be variable between one run and the next. This is especially true if the temperature changes, if the focuser is not fully locked down (flex in the focuser tube), if the mirror shifts differently between runs, etc etc etc. There are so many variables possible here. Having a model taken with one scope and then applied to another scope is invalid in any case.
Bottom Line: There will always be an order of magnitude difference between the tracking error in RA and the Dec, simply because the Dec doesn't move much at all during the 4 hours (1% error of zero = zero). The RA tracking error must be accurately modeled over ~70 degrees of sky motion, but the Dec perhaps only 1/2 degree of motion. The error budget in RA is an order of magnitude higher, so much finer spacing in RA is needed to get similar results. And finally, you cannot model with one scope and measure the result with another scope.
Rolando
-----Original Message-----
From: Andrea Lucchetti < andlucchett@...>
To: main@ap-gto.groups.io
Sent: Fri, Nov 18, 2022 3:23 am
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
Hi Roland,
the drift reported by PHD in the main panel is the drift "before" the corrections are applied, that is my understanding.
So the 0.26"/min (15.6"/h) should be the drift without any guiding (in my case with model applied)
Then, you can analyze the data in the guided form or, the "raw RA form" (extrapolated subtracting the guider corrections).
PHD gives you the two options. I am attaching the two analysis here ( the Raw RA is the one already sent before).
I can understand we are relying heavily on PHD data analysis, I am ready to collect new data you think are needed to run an unbiased analysis.
Thank you again,
Andrea
RA is -0.26"/min (15.6/"h): this is measured by PHD. The picture you posted shows a max drift rate of 7 arc sec over 1.5 hrs (4.6/hr) and a secondary rate of 7 arc sec per 2.6 hrs (2.7/hr). See attached picture below.
From your answer below, with the guider running, you experienced a long term drift in the guide star of 15.6 sec per hour. That's impossible unless you were not guiding (you say you were guiding).
So we have 2 things that do not make any sense.
Rolando
-----Original Message-----
From: Andrea Lucchetti < andlucchett@...>
To: main@ap-gto.groups.io
Sent: Thu, Nov 17, 2022 5:24 pm
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
Hi Roland, thank you for finding the time to help me.
You are probably the only dentist I can stand :-)
I collected the info requested through the terminal:
$RS# time: 0.337 Received 10#
$RA# time: 0.319 Received 40#
$RN# time: 0.318 Received 8#
$GOS# time: 0.325 Received 1110000000#
$GR# time: 0.329 Received +162° 37:59.5#
$GD# time: 0.358 Received: +01° 53:26.7#
data collected just after initialization at park3.
then the answer to the questions below:
Time period 4 hrs (yes, no): YES, 4hours 43' . I have also the run after meridian flip (3h 48') from the same session
Guided (yes, no): yes
Modeled (yes, no): yes
Dec Arc modeled or All Sky modeled: dec arcmodeled , 3arcs , dec spacing 1deg, RA spacing 14 deg for a total of 26 points
Guide exposure time (seconds, plus delay between exposures) 3seconds, 4 seconds delay
Guide camera with off-axis guider on main instrument (yes, no) No
Guide camera on separate guide scope (yes, no) yes, it is a takahashi Fs60
How are the cables attached from the camera to your computer? short cables from camera to USB hub and rig runner (mouted on top of OTA), then USB cable from here to Pc. Power goes from rigrunner through the mount
What is the minimum and maximum drift in arc seconds per hour in that guider: average DEC drift is 0.00"/min, RA is -0.26"/min (15.6/"h): this is measured by PHD. I am not sure what you mean for "minimum" and "maximum" drift
Can you show a guider graph of 10 minutes and 60 minutes unguided? no, not a recent one: I think I tried once and verified the PE was basically covered by seeing.
What I wanted to check with this thread is the effect of the model in RA (in DEC was clearly very good).
I understand it would be better to first check native PE before add complexity to the analysis, I can collect the 10/60 min runs next week if the weather cooperates.
Andrea
Please correct me if I am wrong, but I need to understand exactly how you are taking the data shown on your picture of the guider graph.
Time period 4 hrs (yes, no)
Guided (yes, no)
Modeled (yes, no)
Dec Arc modeled or All Sky modeled
Guide exposure time (seconds, plus delay between exposures)
Guide camera with off-axis guider on main instrument (yes, no)
Guide camera on separate guide scope (yes, no)
How are the cables attached from camera to your computer?
What is the minimum and maximum drift in arc seconds per hour in that guider graph?
Can you show a guider graph of 10 minutes and 60 minutes unguided?
I know it's like pulling teeth but I'm the dentist and I have to find out if there is an owie there.
Rolando
-----Original Message-----
From: Andrea Lucchetti < andlucchett@...>
To: main@ap-gto.groups.io
Sent: Tue, Nov 15, 2022 5:38 pm
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
Roland,
my be I've jumped one post? sorry for that if it is the case.
Regarding the commands: do I need just to power up and connect the mount right?
I don't have the mount with me now, but can answer in 1-2 days.
thank you
I guess my post went out into the vapor-sphere and got lost.
Andrea, if you don't mind, please use APCC Terminal mode and type in the following commands. Let me know what the responses are:
$RS#
$RA#
$RN#
$GOS#
$GR#
$GD#
Thanks. It will go a long way to perhaps explain what might be happening.
Rolando
-----Original Message-----
From: chris1011@...
To: main@ap-gto.groups.io < main@ap-gto.groups.io>
Sent: Tue, Nov 15, 2022 4:59 pm
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
You attached a picture in your last post. Please explain what this is. Scale, time period, etc.
Rolando
-----Original Message-----
From: Andrea Lucchetti < andlucchett@...>
To: main@ap-gto.groups.io
Sent: Tue, Nov 15, 2022 4:06 pm
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
Thank you Brian.
if you look at the RA line in the guiding plot you see that is almost always below zero.
The scatter diagram too is not centered.
I am trying to understand if this could be caused by drift, but I am not sure.
I had to increase aggressiveness to try to compensate for this.
if you click on "drift " on the box you posted, you see that drift in DEC is 0, pol align error is zero, but RA drift is -0.26 arcsec/min.
The same is visible in the plot of raw RA (see photo attached), where you can see the cumulated drift over the 4 hours.
the difference between DEC and RA is clear.
My eccentricity is reported to be 0.55 on average at the center of the field.
This eccentricity is about the same in different nights, sky objects and with different rotation of the camera
Il giorno mar 15 nov 2022 alle ore 22:49 Brian Valente < bvalente@...> ha scritto:
Hi Andrea
Great that worked
Looking at your 4 hour run, your total RMS is 0.45" with RA RMS 0.30" and Dec RMS 0.28".
this should result in nice tight round stars
it looks pretty good to me. Can you point out what concerns you?
thank you for your patient :-)
Il giorno mar 15 nov 2022 alle ore 22:24 Brian Valente < bvalente@...> ha scritto:
getting closer :)
that is the debug log, i'm looking for the guidelog
if you just want to upload the one file here that would be great
I am so sorry. try this last one:
I've verified the link, it should be there.
let me know if it doesn't work
thank you
Il giorno mar 15 nov 2022 alle ore 22:12 Brian Valente < bvalente@...> ha scritto:
sorry I still don't see a guidelog in there?
I am sorry, try this one:
https://www.dropbox.com/t/DO1UyH8HNE7xvyyG
by the way, the RA rates are noted in the APPC log.
if you take the PHD log and check the raw data, you see a long period oscillation
Thank you
Andrea
--
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--
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Roland Christen
Astro-Physics
--
Roland Christen
Astro-Physics
--
Roland Christen
Astro-Physics
--
Roland Christen
Astro-Physics
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Thank you Ray, I got the point. Do you think that one single arc centred on the objects but very dense can work also better? 3 arcs for 3-5 degrees RA spacing is probably the best in terms of performance but time required is also important to me. I'd like to keep the modeling within 30 minutes to maximize imaging time In any case next time I will go for 3 arcs/5 deg spacing as suggested, so I can have also a good benchmark. I will try to go unguided so any bias in the analysis can be eliminated. Thank you Andrea
Il giorno ven 18 nov 2022 alle ore 14:45 Ray Gralak < iogroups@...> ha scritto: Hi Andrea,
> Dec Arc modeled or All Sky modeled: dec arcmodeled , 3arcs , dec spacing 1deg, RA spacing 14 deg for a total of 26 points
Assuming you are also using Dec Arc Tracking with your "Dec Arc Model", using an RA spacing of 14 degrees is not going to provide the best Dec Arc tracking performance. As recommended, try something in the range of 3-5 degrees RA spacing. That will produce a denser set of data points.
Also, the RMS and Max pointing errors for the East and West models only apply to the All-Sky model. The Dec Arc Tracking model is different, so those values do not apply to it.
-Ray
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Chris White
Kirby,
I've been making a model using three declination arcs spaced 1 or 2 degrees apart with RA spacing of 7 degrees. For my horizons that gives me about 60 points and takes less than 25 minutes while still duck. I don't move my mount and use that same model if I image the same target several nights.
Going unguided is really a luxury that you don't "understand" until you've done it. No fiddling with phd settings. No guidestar issues. No cloud issues, etc etc.
I'd say try going unguided with a robust model and see if it works for you. I love it. In fact I just acquired a mach1 (to go with the mach2) and it's my goal to try to image unguided with it as well. No encoders, but with a good PEC curve and robust model I am hopeful.
I dont see why you would use your guide camera for the model run. Has that been officially advised? I'd stick with the main camera.
As far as re-entering, your capture software should allow you to force a recent after a specified amount of time. I use voyager with single star focusing so every hour I slew to a bright star, focus, then slew back to target... so I effectively recenter frequently.
I also dither every frame. Takes about 3 to 4 seconds.
You have a wonderful mount. Enjoy it!
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Dean Jacobsen
On Fri, Nov 18, 2022 at 01:35 PM, Roland Christen wrote:
You will want to dither, even if you go unguided, so you will naturally get some movement of the image.
Ah, yes. Dithering is a really good idea Kirby. So, your re-centing during unguided imaging question is applicable here. In my experience re-centering is a non-issue because I do dither every frame. -- Dean Jacobsen Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/
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Dean Jacobsen
On Fri, Nov 18, 2022 at 12:52 PM, Kirby Collins wrote:
2. If I do guide, use an OAG to at least eliminate the error from the separate guidescope, and build the model with the guide camera, not the imaging camera. (p.s. OAGs have always been a pain in the neck for me)
Kirby, Guiding with an OAG is a good idea. I don't see why using the main imaging camera to build a model wouldn't be the best course though. It is what is being seen through the main imaging camera that you are trying to characterize with the model creation in the first place. I don't use an OAG because I don't guide but the APPM data that that is used for my abbreviated point mapping runs - three declination lines at, above and below the declination of the object I am going to image that night - is acquired with my main imaging camera. I'm not sure about your #4... If your model isn't working for some reason and the tracking rate model isn't accommodating for whatever drift you are thinking about, then your stars probably won't be round in the first place. -- Dean Jacobsen Astrobin Image Gallery - https://www.astrobin.com/users/deanjacobsen/
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You will want to dither, even if you go unguided, so you will naturally get some movement of the image.
You will want to refocus occasionally, so if you don't guide you will get some offset at the end of the focus run. It's not because of the mount or model, it's because you have moved the camera sensor back and forth and also side to side due to focuser lateral motion.
Off-axis guiders work wonderfully well, even with long focus instruments. The reason - because the encoders on the mount won't require you to do active guiding, so you can take fairly long exposures to find guide stars. It's very rare that I can't find a guide star in a 10 second guide exposure.
https://www.astrobin.com/full/p8jrgv/0/ This image was taken with an AP175F8 refractor using the off-axis guider built in to the QSI683 camera. This guider is the most robust system ever manufactured and has zero differential flex. No way I would have used a separate guide scope to shoot with this long scope, there is just too much chance for differential flexure and oval stars.
I did some tests with this camera/guider system on the refractor and 1600 AE mount. I varied the guide exposure from 1 second to 5 sec, 10 seconds and 20 seconds. There was no difference in the guide accuracy on any of them, nor was there a difference in star image FWHM. So, with an encoder mount you can safely use long guide exposures along with models to get accurate results. The only issue used to be the long guide exposures ate into the settle time after a dither. This is no longer the case I believe, with PHD2? If you guide with Maxim DL, you're out of luck, they will probably never get around to modernizing that Model T software.
Rolando
-----Original Message-----
From: Kirby Collins <kirbycollins80@...>
To: main@ap-gto.groups.io
Sent: Fri, Nov 18, 2022 2:52 pm
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
As someone new to the Mach2, I think I'm going to have to reset a bunch of the assumptions I've built up with previous mounts. Here is what I think I'm hearing:
1. Don't guide. Build a detailed model and let the mount do its thing. Is there a rule of thumb for when guiding is unnecessary (for instance, if the image scale of the guide camera/scope is say 1.0"/px, but the mount and the model I've built is accurate to 0.25", guiding is unlikely to help? (I understand seeing is a part of this too, but that's highly variable so not sure how to factor that in)
2. If I do guide, use an OAG to at least eliminate the error from the separate guidescope, and build the model with the guide camera, not the imaging camera. (p.s. OAGs have always been a pain in the neck for me)
3. Are there rules of thumb to set my expectations for how accurate the mount is under different conditions? For instance, more points in the model are obviously better, but I'd like to have a sense for the time versus accuracy tradeoff. Is it worth doing the kind of experiment discussed here with my imaging camera, under different conditions and model densities to characterize how it behaves with my equipment under the conditions at my site? Do people do a quick tracking check at the target before starting a sequence to get a sense for how accurate it is?
4. If I'm imaging unguided, is it worth recentering periodically just to catch any drift?
Sorry to beat on this, but I'm learning a lot from this thread.
-- Roland Christen Astro-Physics
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Hi Kirby
I am away from my desk to not easy to write a detailed response, but this AP video may help add some perspective on this topic;
As someone new to the Mach2, I think I'm going to have to reset a bunch of the assumptions I've built up with previous mounts. Here is what I think I'm hearing:
1. Don't guide. Build a detailed model and let the mount do its thing. Is there a rule of thumb for when guiding is unnecessary (for instance, if the image scale of the guide camera/scope is say 1.0"/px, but the mount and the model I've built is accurate to 0.25", guiding is unlikely to help? (I understand seeing is a part of this too, but that's highly variable so not sure how to factor that in)
2. If I do guide, use an OAG to at least eliminate the error from the separate guidescope, and build the model with the guide camera, not the imaging camera. (p.s. OAGs have always been a pain in the neck for me)
3. Are there rules of thumb to set my expectations for how accurate the mount is under different conditions? For instance, more points in the model are obviously better, but I'd like to have a sense for the time versus accuracy tradeoff. Is it worth doing the kind of experiment discussed here with my imaging camera, under different conditions and model densities to characterize how it behaves with my equipment under the conditions at my site? Do people do a quick tracking check at the target before starting a sequence to get a sense for how accurate it is?
4. If I'm imaging unguided, is it worth recentering periodically just to catch any drift?
Sorry to beat on this, but I'm learning a lot from this thread.
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As someone new to the Mach2, I think I'm going to have to reset a bunch of the assumptions I've built up with previous mounts. Here is what I think I'm hearing:
1. Don't guide. Build a detailed model and let the mount do its thing. Is there a rule of thumb for when guiding is unnecessary (for instance, if the image scale of the guide camera/scope is say 1.0"/px, but the mount and the model I've built is accurate to 0.25", guiding is unlikely to help? (I understand seeing is a part of this too, but that's highly variable so not sure how to factor that in)
2. If I do guide, use an OAG to at least eliminate the error from the separate guidescope, and build the model with the guide camera, not the imaging camera. (p.s. OAGs have always been a pain in the neck for me)
3. Are there rules of thumb to set my expectations for how accurate the mount is under different conditions? For instance, more points in the model are obviously better, but I'd like to have a sense for the time versus accuracy tradeoff. Is it worth doing the kind of experiment discussed here with my imaging camera, under different conditions and model densities to characterize how it behaves with my equipment under the conditions at my site? Do people do a quick tracking check at the target before starting a sequence to get a sense for how accurate it is?
4. If I'm imaging unguided, is it worth recentering periodically just to catch any drift?
Sorry to beat on this, but I'm learning a lot from this thread.
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Dean Jacobsen
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So the 0.26"/min (15.6"/h) should be the drift without any guiding (in my case with model applied) 1) The screen shot of the 4 hour run shows .077 arc sec per minute, 4.6 arc sec per hour, not what you wrote above.
2) The Dec data appears to be guided in both cases.
3) You made the model with the main scope and then tested the model with a different scope attached somehow to the mount with different rings etc. The model has in it not only the motion of the stars with atmospheric refraction, but also the differential motion of the main scope, which includes flex in the scope rings. The model applies only to the main scope, not to the guide scope which does not have the main scope flex. So just from this I would conclude that the test is invalid. Between a guide scope and main scope there is always differential flexure, which can easily be 10 - 20 arc seconds over 4 hours.
4) Even if there is no differential flex between guidescope and main scope, the Dec is sampled with 1 degree spacing, but the RA spacing is quite rough at 14 degrees. This will also impact the overall accuracy of the model.
I have checked the records of the tests we did with your mount and we measured a maximum error of only 7 arc seconds in the RA encoder over a 24 hour period, 0.29 arc seconds per hour of tracking error at the sidereal rate. Therefore the mount's contribution to any drift is essentially zero. Even if it was 10 times this value, any modeling will compensate for that, and it will never show up in the data.
The only way to test the accuracy of any model is to use the same scope/camera system to create the model and then measure the resulting tracking with that same scope/camera. The model can account for some differential flexure between the scope and the mount, but in a lot of cases the differential flex is non-linear and can be variable between one run and the next. This is especially true if the temperature changes, if the focuser is not fully locked down (flex in the focuser tube), if the mirror shifts differently between runs, etc etc etc. There are so many variables possible here. Having a model taken with one scope and then applied to another scope is invalid in any case.
Bottom Line: There will always be an order of magnitude difference between the tracking error in RA and the Dec, simply because the Dec doesn't move much at all during the 4 hours (1% error of zero = zero). The RA tracking error must be accurately modeled over ~70 degrees of sky motion, but the Dec perhaps only 1/2 degree of motion. The error budget in RA is an order of magnitude higher, so much finer spacing in RA is needed to get similar results. And finally, you cannot model with one scope and measure the result with another scope.
Rolando
-----Original Message-----
From: Andrea Lucchetti <andlucchett@...>
To: main@ap-gto.groups.io
Sent: Fri, Nov 18, 2022 3:23 am
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
Hi Roland,
the drift reported by PHD in the main panel is the drift "before" the corrections are applied, that is my understanding.
So the 0.26"/min (15.6"/h) should be the drift without any guiding (in my case with model applied)
Then, you can analyze the data in the guided form or, the "raw RA form" (extrapolated subtracting the guider corrections).
PHD gives you the two options. I am attaching the two analysis here ( the Raw RA is the one already sent before).
I can understand we are relying heavily on PHD data analysis, I am ready to collect new data you think are needed to run an unbiased analysis.
Thank you again,
Andrea
RA is -0.26"/min (15.6/"h): this is measured by PHD. The picture you posted shows a max drift rate of 7 arc sec over 1.5 hrs (4.6/hr) and a secondary rate of 7 arc sec per 2.6 hrs (2.7/hr). See attached picture below.
From your answer below, with the guider running, you experienced a long term drift in the guide star of 15.6 sec per hour. That's impossible unless you were not guiding (you say you were guiding).
So we have 2 things that do not make any sense.
Rolando
-----Original Message-----
From: Andrea Lucchetti < andlucchett@...>
To: main@ap-gto.groups.io
Sent: Thu, Nov 17, 2022 5:24 pm
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
Hi Roland, thank you for finding the time to help me.
You are probably the only dentist I can stand :-)
I collected the info requested through the terminal:
$RS# time: 0.337 Received 10#
$RA# time: 0.319 Received 40#
$RN# time: 0.318 Received 8#
$GOS# time: 0.325 Received 1110000000#
$GR# time: 0.329 Received +162° 37:59.5#
$GD# time: 0.358 Received: +01° 53:26.7#
data collected just after initialization at park3.
then the answer to the questions below:
Time period 4 hrs (yes, no): YES, 4hours 43' . I have also the run after meridian flip (3h 48') from the same session
Guided (yes, no): yes
Modeled (yes, no): yes
Dec Arc modeled or All Sky modeled: dec arcmodeled , 3arcs , dec spacing 1deg, RA spacing 14 deg for a total of 26 points
Guide exposure time (seconds, plus delay between exposures) 3seconds, 4 seconds delay
Guide camera with off-axis guider on main instrument (yes, no) No
Guide camera on separate guide scope (yes, no) yes, it is a takahashi Fs60
How are the cables attached from the camera to your computer? short cables from camera to USB hub and rig runner (mouted on top of OTA), then USB cable from here to Pc. Power goes from rigrunner through the mount
What is the minimum and maximum drift in arc seconds per hour in that guider: average DEC drift is 0.00"/min, RA is -0.26"/min (15.6/"h): this is measured by PHD. I am not sure what you mean for "minimum" and "maximum" drift
Can you show a guider graph of 10 minutes and 60 minutes unguided? no, not a recent one: I think I tried once and verified the PE was basically covered by seeing.
What I wanted to check with this thread is the effect of the model in RA (in DEC was clearly very good).
I understand it would be better to first check native PE before add complexity to the analysis, I can collect the 10/60 min runs next week if the weather cooperates.
Andrea
Please correct me if I am wrong, but I need to understand exactly how you are taking the data shown on your picture of the guider graph.
Time period 4 hrs (yes, no)
Guided (yes, no)
Modeled (yes, no)
Dec Arc modeled or All Sky modeled
Guide exposure time (seconds, plus delay between exposures)
Guide camera with off-axis guider on main instrument (yes, no)
Guide camera on separate guide scope (yes, no)
How are the cables attached from camera to your computer?
What is the minimum and maximum drift in arc seconds per hour in that guider graph?
Can you show a guider graph of 10 minutes and 60 minutes unguided?
I know it's like pulling teeth but I'm the dentist and I have to find out if there is an owie there.
Rolando
-----Original Message-----
From: Andrea Lucchetti < andlucchett@...>
To: main@ap-gto.groups.io
Sent: Tue, Nov 15, 2022 5:38 pm
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
Roland,
my be I've jumped one post? sorry for that if it is the case.
Regarding the commands: do I need just to power up and connect the mount right?
I don't have the mount with me now, but can answer in 1-2 days.
thank you
I guess my post went out into the vapor-sphere and got lost.
Andrea, if you don't mind, please use APCC Terminal mode and type in the following commands. Let me know what the responses are:
$RS#
$RA#
$RN#
$GOS#
$GR#
$GD#
Thanks. It will go a long way to perhaps explain what might be happening.
Rolando
-----Original Message-----
From: chris1011@...
To: main@ap-gto.groups.io < main@ap-gto.groups.io>
Sent: Tue, Nov 15, 2022 4:59 pm
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
You attached a picture in your last post. Please explain what this is. Scale, time period, etc.
Rolando
-----Original Message-----
From: Andrea Lucchetti < andlucchett@...>
To: main@ap-gto.groups.io
Sent: Tue, Nov 15, 2022 4:06 pm
Subject: Re: [ap-gto] APPC & Mach2: Dec Arc model results and RA drift connection? #APCC #Mach2GTO
Thank you Brian.
if you look at the RA line in the guiding plot you see that is almost always below zero.
The scatter diagram too is not centered.
I am trying to understand if this could be caused by drift, but I am not sure.
I had to increase aggressiveness to try to compensate for this.
if you click on "drift " on the box you posted, you see that drift in DEC is 0, pol align error is zero, but RA drift is -0.26 arcsec/min.
The same is visible in the plot of raw RA (see photo attached), where you can see the cumulated drift over the 4 hours.
the difference between DEC and RA is clear.
My eccentricity is reported to be 0.55 on average at the center of the field.
This eccentricity is about the same in different nights, sky objects and with different rotation of the camera
Il giorno mar 15 nov 2022 alle ore 22:49 Brian Valente < bvalente@...> ha scritto:
Hi Andrea
Great that worked
Looking at your 4 hour run, your total RMS is 0.45" with RA RMS 0.30" and Dec RMS 0.28".
this should result in nice tight round stars
it looks pretty good to me. Can you point out what concerns you?
thank you for your patient :-)
Il giorno mar 15 nov 2022 alle ore 22:24 Brian Valente < bvalente@...> ha scritto:
getting closer :)
that is the debug log, i'm looking for the guidelog
if you just want to upload the one file here that would be great
I am so sorry. try this last one:
I've verified the link, it should be there.
let me know if it doesn't work
thank you
Il giorno mar 15 nov 2022 alle ore 22:12 Brian Valente < bvalente@...> ha scritto:
sorry I still don't see a guidelog in there?
I am sorry, try this one:
https://www.dropbox.com/t/DO1UyH8HNE7xvyyG
by the way, the RA rates are noted in the APPC log.
if you take the PHD log and check the raw data, you see a long period oscillation
Thank you
Andrea
--
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Roland Christen
Astro-Physics
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Roland Christen
Astro-Physics
--
Roland Christen
Astro-Physics
-- Roland Christen Astro-Physics
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