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INDI Library v1.8.1 Released (09 Sep 2019)

Monthly maintenance release INDI v1.8.1

First time autoguiding

1 month 3 weeks ago
wbarsuhn
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First time autoguiding #44696
Last weekend was my first attempt to use the internal autoguider since I usually use PHD2. I saw that I could export the guiding data so being the geek that i am, i downloaded the from the 100 minutes of capturing M27. During the imaging session I was capturing 1 minute subs. When i opened the data and charted it in Excel I noticed there was a significant spike in the RA error every 10 minutes of the capture session. Any idea what I should be doing to correct or at least minimize this? I am using an older Meade LXD55 mount if that helps.

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1 month 3 weeks ago
Ihoujin
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First time autoguiding #44697
You can understand much more of what is in the guide log if you open it in PHD Log Viewer.
adgsoftware.com/phd2utils/
Those could simply be dither pulses, and this application will show that. It will also filter them out and show you a detailed frequency analysis of your periodic error.

INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
PHD2
Adafruit Motor Hat shield
Adafruit GPS Module
Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.

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1 month 3 weeks ago
wvreeven
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First time autoguiding #44707
Can you post the settings used for the internal guider? Maybe a screenshot of the tab would be easiest. That would help us advise you how to possibly correct this.


Wouter

ASI1600MM-Pro Cooled and filter wheel with a SkyWatcher Esprit 80 ED on a SkyWatcher HEQ5-Pro

ASI1600MM-Pro Cooled and filter wheel with an 8" TS Ritchey-Chrétien on a SkyWatcher EQ6-R

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1 month 3 weeks ago
wvreeven
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First time autoguiding #44708

Ihoujin wrote: You can understand much more of what is in the guide log if you open it in PHD Log Viewer.
adgsoftware.com/phd2utils/
Those could simply be dither pulses, and this application will show that. It will also filter them out and show you a detailed frequency analysis of your periodic error.


Can the PHD Log Viewer also be used for the internal guider?


Wouter

ASI1600MM-Pro Cooled and filter wheel with a SkyWatcher Esprit 80 ED on a SkyWatcher HEQ5-Pro

ASI1600MM-Pro Cooled and filter wheel with an 8" TS Ritchey-Chrétien on a SkyWatcher EQ6-R

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1 month 3 weeks ago
Ihoujin
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First time autoguiding #44732

wvreeven wrote: Can the PHD Log Viewer also be used for the internal guider?
Wouter


I don't know, probably not. And I do not have any internal guide logs to test it with because I've mainly stuck with PHD2.

INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
PHD2
Adafruit Motor Hat shield
Adafruit GPS Module
Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.

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1 month 3 weeks ago
khobar
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First time autoguiding #44737
Every 10 minutes? I *think* that may be periodic error.

"Even quality machined mount parts like worms, worm gears, shafts are not absolutely perfect. The parts are machined in micrometer precision at best. We must realise that in astrophotography we require tracking precison up to arcseconds. That means, that e.g. teeth of teeth on perimeter of wheel with diameter of 8cm must be machined with accuracy of hundreeds of nanometers!
As mount's shaft rotates, any error in its surface and shape and also in worm and worm gear surfaces and shapes causes a periodic bump in tracking. The most observable is so called periodic error of the mount which is caused by inaccuracy of of worm. The period of this error takes one revolution of gear (usually 5-10 minutes for common mounts)." ~http://www.pk3.org/Astro/index.htm?astrophoto_mount_errors.htm

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1 month 3 weeks ago
wbarsuhn
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First time autoguiding #44739
Unfortunately I won't be home until Saturday to review what my settings were for this run. I'll post it then.

As far as the periodic error, I wondered about that at first but I thought that would be demonstrated by a gradual drift in one direction followed by a drift in the opposite direction as the worm wheel rotates. That doesn't appear to be the case here.

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1 month 3 weeks ago 1 month 3 weeks ago by Ihoujin.
Ihoujin
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First time autoguiding #44799
You are correct, looking at the raw guide data would not create a such a regular peak due to periodic error, unless maybe there is some physical grit in the gears or something.
I'm inclined to say they are dither pulses, but that only makes sense of your images are 10 minutes long, or if dither ever N frame, a factor of 10.
Upload the original guide log, that will make it much easier to see what is happening.

INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
PHD2
Adafruit Motor Hat shield
Adafruit GPS Module
Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.

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1 month 3 weeks ago
El Corazon
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First time autoguiding #44934
There is another possibility.

I experience something similar when using the ASI120MM (USB2 version).

That camera does not work well with Linux. Without the firmware update it did not connect at all and with the firmware update it keeps dropping frames intermittently.
What I noticed is that it drops frames or only receives part of a garbled frame every time a new image is being downloaded from the main camera. That results in the guide star being lost/displaced and the guider frantically starts looking for it, resulting in a huge deflection. Unless the guide star is reacquired right away, the next exposure is ruined by star trails.

Bottomline: The ASI120MM is useless under Linux and should not be used or sold to Windows users.

Atlas Pro AZ-EQ, ASI1600MM-Pro, ASI120MM-S, ES102ED, WO-Z61, Nikon D3300, ASI-EFW, ZWO LRGB,Ha,O3,S2 filter set
The following user(s) said Thank You Herrhausen

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