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skychart (Carte du Ciel) star alignment question


AstroRookie

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Hello,

Mount: EQ6-R Pro, QHYCCD PoleMaster, software Couldmakers Indigo-server, skychart (on OS X). Applied procedure:

  • Leveled the tripod
  • Polar aligned with PoleMaster, so I suppose I can assume that it's decently polar aligned
  • Star alignment using skychart, direct connection to EQ6-R (no Synscan handcontroller, AstroRookie's hubris 😉 )
    • First star synced: Arcturus
    • Second star synced: Dubhe
    • Slew back to Arcturus: nicely centered
    • Third star Vega, which was close to the zenith: completely off
    • Slew back to Dubhe and Arcuturus, every thing still hunky dory

Question: what can cause this "error"; is it because I took 2 stars west of the meridian? Is it better to take stars in "opposite positions" of the meridian?

Thanks for clarifying!

AstroRookie

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I guess that the more points you take - and the more spread apart they are - the better your mount modelling of the sky would be. From some videos I saw about the subject, it seems that if you align with 3 stars, every slew inside the "triangle" made by putting those stars at the vertices should be pretty much spot on. Outside the "triangle", things start to be more off the further you go.

Another pointer I could give you is to try with the hand-controller alone, just to see if the behavior is similar: this would rule out any software related problems.

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3 hours ago, endlessky said:

I guess that the more points you take - and the more spread apart they are - the better your mount modelling of the sky would be. From some videos I saw about the subject, it seems that if you align with 3 stars, every slew inside the "triangle" made by putting those stars at the vertices should be pretty much spot on. Outside the "triangle", things start to be more off the further you go.

Another pointer I could give you is to try with the hand-controller alone, just to see if the behavior is similar: this would rule out any software related problems.

Hello endlesssky,

thanks for the advice; concerning the hand controller, I have the impression that it's always quite far off; but as up to now I always used the hand-controller with eyepieces, it was for a rookie like me easier to get the star in the field of view; with a dslr attached to the main scope and a guide camera to the guide scope it's a completely different ball game, at least for

AstroRookie

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1 hour ago, stash_old said:

Post the question on Indigi Forum site as it depends on the mount driver / alignment subsystem and has nothing to do with CDC (other than it send the sync command). Dont think many here will be using Indigo server and its not that close to Indi in a lot of aspects.  https://github.com/indigo-astronomy/indigo/issues

 

Hello stash_old,

thanks for the advice; I'm using Indigo-server because I'm to stubborn to use windows (I only use operating systems based on unix), and I'm fully aware that there is more and better software available for astrophotography  on windows.

But I will have a look in a coming session to the alignment functionality in Indigo-server, if I experience the same, I'll post my question on the forum you kindly pointed out for me.

AstroRookie

 

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1 hour ago, AstroRookie said:

with a dslr attached to the main scope and a guide camera to the guide scope it's a completely different ball game

If you have cameras, you can take advantage of plate-solving. To me, after I discovered it, there's nothing better and I have never done star alignment ever since.

Also, does the KStars/EKOS suite work on OS X? If you want to abandon Windows - which I don't blame you for - consider using KStars and EKOS. It's a spectacular package. KStars is a planetarium and works pretty much the same as Cartes du Ciel. EKOS is a controller for every and any piece of gear astrophotography related that you can think of or own.

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2 hours ago, endlessky said:

Also, does the KStars/EKOS suite work on OS X? If you want to abandon Windows

He already has - Indigo (specialiality Cloudmaker is mainly Apple oriented) is from the same camp as Indi . Indigo can use Indiserver devices. 🙂

 

4 hours ago, AstroRookie said:

thanks for the advice; I'm using Indigo-server because I'm to stubborn to use windows

You missed my point or I didn't explain myself (most likely me !)  - there are very few "Pure" Indigo users on SGL -  so direct Indigo knowledge would be limited. Hence my pointer to look on Indigo forum for help where you should get a better informed answer to your query and as far as I am aware no Indigo author frequents SGL (unlike Indi Forum) . 🙂

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On 08/08/2020 at 17:49, endlessky said:

If you have cameras, you can take advantage of plate-solving. To me, after I discovered it, there's nothing better and I have never done star alignment ever since.

Also, does the KStars/EKOS suite work on OS X? If you want to abandon Windows - which I don't blame you for - consider using KStars and EKOS. It's a spectacular package. KStars is a planetarium and works pretty much the same as Cartes du Ciel. EKOS is a controller for every and any piece of gear astrophotography related that you can think of or own.

Hello endlessky,

I have KStars/EKOS installed on my macbook and it is really very impressive and for a rookie a bit overwhelming, it has everything: planning, capturing, guiding and even plat solving. Cloudmakers Indogo-server is simple and fairly straightforward, but I'll try some "dry-runs" with KStars/EKOS. As for plate solving, I wonder if that is possible with a Canon 500D dslr, as it is not possible to have Live-view in combination with my slow F/10 sct (I have to be honest reduced to F/6.3 with a 63% ocal reducer). I admit, AstroRookie's first step in astrophotography is on a tight budget.

Kind regards,

AstroRookie

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I have done plate-solving with my Nikon D5300 and any combination of the focal lengths I have available: from 18mm to 2032mm. As long as you install the required indexes - and specify what focal length you are using, in the telescope tab of EKOS - plate-solving works fine, even with a DSLR. The exposure just needs to be long enough to show a few stars - usually anywhere between 1s-10s.

Edited by endlessky
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4 hours ago, AstroRookie said:

Hello endlessky,

I have KStars/EKOS installed on my macbook and it is really very impressive and for a rookie a bit overwhelming, it has everything: planning, capturing, guiding and even plat solving. Cloudmakers Indogo-server is simple and fairly straightforward, but I'll try some "dry-runs" with KStars/EKOS. As for plate solving, I wonder if that is possible with a Canon 500D dslr, as it is not possible to have Live-view in combination with my slow F/10 sct (I have to be honest reduced to F/6.3 with a 63% ocal reducer). I admit, AstroRookie's first step in astrophotography is on a tight budget.

Kind regards,

AstroRookie

If using DSLR you dont need to use any index's as such but look at ASTAP (runs on Linux(RPI etc) ,Win,Mac) and only requires 1 index file normally. It is also the fastest "near" platesolving piece of software if not 100% reliable for "blind Solving". E.G  AZEQ6 + C9.25 + Canon 100d regularly gets <6 secs solve time depending how good you slews are. It is also intergrated into Ekos/Kstars.  Just a thought:-)

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On 10/08/2020 at 12:16, stash_old said:

P.S. Unless Indigo developers have corrected the problem it will not do exposures with DSLR above  55secs https://github.com/indigo-astronomy/indigo/issues/220

Hello stash_old,

thanks for the info; I only use indigo-server to connect skychart with to control the mount. The github issue even indicates that dslr's are not support. I have to say Peter Polakovic is very helpfull.

Kind regards,

AstroRookie

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