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 Post subject: Frage zu PHD2
PostPosted: 08. July 2017, 20:32:42 PM 
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Hey Leute,

ich habe angefangen mit PHD2 zu guiden. Dort ist mir aufgefallen, dass die Dithering Funktion (scheinbar?!) nicht auszuschalten ist. Weiß jemand, was man dort einstellen muss bzw., wie ich das zu verstehen habe?
Attachment:
Screenshot 2017-07-08 20.21.13.png
Screenshot 2017-07-08 20.21.13.png [ 88.17 KiB | Viewed 908 times ]
Viele Grüße und CS
Christoph


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 Post subject: Re: Frage zu PHD2
PostPosted: 08. July 2017, 21:41:14 PM 
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Hi Christoph,

Dither is controlled by the imaging application, not PHD2. PHD2 will only dither the guide position if the image application sends a command to dither.

Cheers
Robin


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 Post subject: Re: Frage zu PHD2
PostPosted: 09. July 2017, 06:40:36 AM 
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Mir ist auch nicht klar , was ich mit diesem Parameter beeinflusse und was der bewirkt. Das Übersetzen von " to dither " ins Deutsche hilft mir leider auch nichts.

Wie heißt die neueste Version von Phd2 bitte?

berthold


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 Post subject: Re: Frage zu PHD2
PostPosted: 09. July 2017, 10:41:40 AM 
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Hi Robin,

thank you! I got a little frightened... .

Hey Berthold,

Dithern ist eine Funktion für pretty pictures. Dort wird jede neue Aufnahme absichtlich um einen bestimmen Pixelwert in x und/oder y verschoben. Dies soll der Rauschreduzierung dienen und so die Bearbeitung der Aufnahmen erleichtern.


By the way, Im not satisfied with the SNR of my data. Setup is a 5 inch SCT, Lhires equipped with 1800 grating and the ATIK 428. For 3x5min Deneb there is only a SNR of about 200. One point is to find the accurate focus, I know. Now its slightly better.

I thought that I have a seeing of 3. Therefore I used the 19um slit. But I'm not longer sure. The seeing is rather 4, so that the 23um slit will pass through more light. I attach a sreenshot of the guiding. There the star is only little distorted of the slit. Has anyone a picture how a star have to look like, if the slit width is right chosen?

Indicates the little number on the right in the starprofile box the seeing?
Attachment:
Screenshot 2017-07-09 01.36.48.png
Screenshot 2017-07-09 01.36.48.png [ 279.02 KiB | Viewed 882 times ]
Viele Grüße und CS
Christoph


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 Post subject: Re: Frage zu PHD2
PostPosted: 10. July 2017, 11:50:39 AM 
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Hi Berthold,

vergessen: Die aktuelle PHD2 Version ist die 2.6.3 => https://openphdguiding.org/

Christoph


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 Post subject: Re: Frage zu PHD2
PostPosted: 14. August 2017, 10:40:29 AM 
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Hallo,

weiß jemand, ob man in PHD2 irgendwie auf zwei Helligkeitsschwerpunkten guiden kann?

Durch das Seeing haben ich in der Dec immer das Problem, dass der Schwerpunkt mal auf die Seite vom Spalt hüpft und mal auf die andere.

Ich habe natürlich schon die Empfindlichkeit der Kamera verringert und dafür länger belichtet, um das Seeing zu mitteln und auch an der Pixelabweichungsschwelle rumgestellt, aber so richtig sauber wie die Ra- Achse bekomme ich es nicht!

Zudem habe ich kein fest aufgestelltes Equipment und muss immer wieder neu Aufbauen. Darunter leidet natürlich die Einnordung.

Viele Grüße und CS
Christoph


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 Post subject: Re: Frage zu PHD2
PostPosted: 14. August 2017, 12:29:02 PM 
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Hallo Christoph,
Du solltest es mit einem Graufilter oder besser noch mit einem IR-Passfilter versuchen, das Du in den Guidingstrahlengang bringst. Als passende Stelle bietet sich der Guidingkameraanschluss an. Ein IR-Passfilter ist deshalb nützlich, da die längeren Wellenlängen weniger gebrochen werden als die kürzeren.
Viele Grüße
Christian


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 Post subject: Re: Frage zu PHD2
PostPosted: 14. August 2017, 13:37:06 PM 
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Na ja, aber erst einmal sollte Christoph es ohne Filter versuchen. :) Ich glaube, die meisten, wenn nicht alle, Tolls sollten das schaffen. Gruß, Thomas


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 Post subject: Re: Frage zu PHD2
PostPosted: 14. August 2017, 21:16:51 PM 
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Hello Christian.

Be careful if using an IR pass filter on the guider camera. If there is any atmospheric dispersion, the light from the star that you are trying to measure might miss the slit :(

Cheers
Robin


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 Post subject: Re: Frage zu PHD2
PostPosted: 14. August 2017, 21:27:41 PM 
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Hello Christoph,

I use PHD. This is a well known problem. The guider moves the star backwards and forwards across the slit as it locks on each half of the split image. It reduces the throughput a bit but does have the advantage that the whole of the star image is sampled evenly which removes problems with continuum shape due to chromatism and improves radial velocity measurement accuracy.
If there is a field star you can guide on that instead. The program Astro Art has a special function for guiding on a slit which I know some people have used with success . I have not tried it yet though.

note that I guide with the slit along the Dec axis. The control of the star on the slit is better for me in this direction and atmospheric dispersion is along the slit so less of a problem when measuring near the meridian at low altitude

Cheers
Robin


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 Post subject: Re: Frage zu PHD2
PostPosted: 15. August 2017, 08:39:23 AM 
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Quote:
Hello Christian.

Be careful if using an IR pass filter on the guider camera. If there is any atmospheric dispersion, the light from the star that you are trying to measure might miss the slit :(

Cheers
Robin
Hello Robin,
as long as the the star is not too close to the horizon and you take a Ha line it works fine. I suggested this to find out whether the the mounting is eligible for guiding. I used an IR pass filter for a while for very bright stars with 0 mag with good success.
Cheers
Christian


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 Post subject: Re: Frage zu PHD2
PostPosted: 16. August 2017, 10:32:41 AM 
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Hi,

okay I will try an IR-Pass, but as Robin pointed out, it seems not necessary!
By the way, did anyone asked the developers for an algorithem for spectroscopy?

Thank You all!
Christoph


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 Post subject: Re: Frage zu PHD2
PostPosted: 21. August 2017, 02:59:32 AM 
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Location: St Leonards, Vic, Australia
Christoph,
I and other have been in constant dialog with the developers of PHD2 regards the needs of spectroscopy.
This resulted in the availability of the nudge to X-Y option - to better bring the target onto the slit.
I also worked with Fabio (AstroArt) to also improve the spectroscopic acquisition/ guiding.

_________________
" Astronomical Spectroscopy for Amateurs" - Springer


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 Post subject: Re: Frage zu PHD2
PostPosted: 21. August 2017, 09:39:15 AM 
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Hi Ken,

cool, good to know! I thought first about to asked the developers if it is possible to write and implement an algorithm for guiding on two center weights (I think e.g. the Mgen can do this).

Astroart isn't avilable for Linux?!


I tried guiding with an lent IR pass and it worked slightly better. But don't think that it is worth to buy one.

Cheers
Christoph


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 Post subject: Re: Frage zu PHD2
PostPosted: 22. August 2017, 12:59:51 PM 
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Hello Christoph
Quote:
Astroart isn't avilable for Linux?!
For Linux you could try Audela which has a special feature for guiding on a slit
http://www.audela.org/dokuwiki/doku.php ... d=en:start
I have not tried it though

Cheers
Robin


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 Post subject: Re: Frage zu PHD2
PostPosted: 31. August 2017, 10:45:04 AM 
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Hi Robin,

I tried it, but it worked not very well! I think at the Moment PHD2 is (for me) the best solution!

Cheers
Christoph


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