CDC - Issues With 1st point in 3 star Alignment Process

[Stickfarm8]

I wasn't sure this is "normal" when starting the 3-star alignment process or not. I am relatively new, having been imaging (or should I say attempting to) since early July. I have a Skywatcher EQ6 -R mount and a Esprit 120  ED scope.  I do not use the hand controller - everything is done via laptop PC using a Lynx ASTRO FTDI cable and EQMod software.

After the initial polar alignment using the scope in the mount , I  use Polemaster to fine tune the polar alignment.  I always park the scope in the home position before shutting down EQMod. I start CDC up. Connect the telescope. Unpark it. Then start the alignment process. When picking the first object to align to, and telling the scope to slew to that object it frequently isn't close. I have to spend quite a bit of time getting that first object positioned and sync'd. The second is usually much better; but occasionally not.

When the moon is out, that makes it easy as the first object. But when it's not, it can be very time consuming on that first object.

I have check the setup information - it is all correct.

Is this normal - or is there a better way or other settings I can adjust in CDC to make that first alignment go quicker?

Thanks for any help,

Rich

[Merlin66]

 

Check out the above thread for some ideas.

 

[Stickfarm8]

I had seen this earlier when I searched.

But let me ask what might be a stupid question.  I have to completely taken down my mount/OTA setup each time I finish imaging. I have the spots marked on the driveway for the three legs.  I had ASSUMED I could not save the 3 point alignments - that I had to redo that each time. Can I keep them and count on them finding the points the next time I set up ? 

Any help is appreciated !

Rich

[Merlin66]

Rich,

If re-positioning the mount is repeatable and accurate then it would certainly be worth trying.

you never know, you may be lucky.

Ken

 

[Stickfarm8]

Three no imaging nights now - VERY frustrating. Last night was clear at the start - the haze-humidity of the previous two nights gone - but the three star alignment, again took over 45 minutes to get done and by the time I was ready to start capture, the high level thin cloud layer was building.

So I tried getting the placement of the mount and OTA exactly where it had been Friday night. The polar initial polar alignment thru the scope on the mount required no adjustment (time was close to the same - Polaris at exactly 10 oclock), and very minor adjustment required when I ran Polestar .  I took that as a hopeful sign. The alignment data was definitely present in EQMod when it was fired up for Polestar rotation, and by CDC when I restarted it and connected to the mount.

A little better last night - but not by much.

I know distances on a PC screen can be relative depending on zoom - but once I've got the object centered in the eye piece, that first alignment might be as much as a half inch different on the laptop (with the view in the default - not zoomed in or out). 

Putting it another way - at times, when aligning to  that first object, it won't even be in the finder scope. I'm using a keypad to slew with, but it can still be time consuming getting that first object sync'd.

The second is always much closer - but not always. The third is usually very close. 

My question to everyone is one of expectations. Am I expecting too much on that first slew to an object for alignment of CDC - i.e., is this your normal experience? 

If not typical, i.e., when CDC is slewed to the first alignment object, is the object at least in the finder scope, does anyone have any suggestions where to start troubleshooting ?

Thanks - any help or suggestions would be most appreciated !

Rich 

 

[stash_old]

You could try :-

If you look thru SGL you will see the check list with CDC - one important issue is to make sure that Epoch (base date pointers) is the same in each piece of the software - e.g. j2000 in EQMOD then CDC must be j2000 (except it called something slightly different)  - and any software such as APT which has a mount interface (e.g. Ascom EQMOD).

Plus check the advance development settings in EQMOD has the "Secondary encoders" is disabled. Again search SGL to find exactly what.

🙂

[Stickfarm8]

Stash,

Thanks for the suggestions. Epoch data base pointers were both the same., and the secondary encoders  was disabled.

I have a hunch my issue is "newbie ignorance"  in not verifying that the scope is indeed pointing at the NCP.   As I was trying to search thru the threads for the checklist, I came across a thread "C du C Not  Playing Ball" that hit me like a brick.  I'm going to visually verify the scope and the view scope are centered on the NCP the next time I setup and I suspect my issues will be resolved. Several comments emphasized that (almcl and Steppenwolf's) . I had used a technique that I saw in a video from AstronomyShed which I thought was supposed to gets things positioned correctly  - assuming the tripod was perfectly level and a good polar alignment using a level on the weight extension rod and the mount saddle to set the home points but I'm not so sure its doing that - or that I'm not botching it up somehow.  

There is a TON of good information on this site - I could read through it for hours and hours.  At some point I need to dig into plate solving as an alternate but I want to get these fundamentals down pat before I add anything else to get in trouble with <s>.

Thanks,

Rich

[Look left]

Just a suggestion to reduce the setup time until someone gives you the answer on the technical issues.

give first star alignment on a bright star Capella ,Rigel etc let mount go where it thinks it is then MANUALLY move scope so you see star on screen it in eyepiece. Then adjust using the key pad then confirm alignment. It cuts down loads of heartache and frustration. Second alignment willl be much better.

i do this in Synscan app then into APT then plate solve,sync ,Goto++ so done in mins . Well less than 10 mins.

as I say just a suggestion mate.

[stash_old]

3 hours ago, Look left said:

i do this in Synscan app then into APT then plate solve,sync ,Goto++ so done in mins

He is using EQMOD so will not (cannot) be using Synscan App 🙂

@Stickfarm8

I think if all your settings are correct and you are reasonably Polar aligned and you have NOT saved the previous alignment points in EQMOD you would be close - IMHO there is no point in saving the EQMOD alignment data between sessions if you have a mobile set up - as I say my opinion. 

However even with Polar alignment its not guaranteed to be  "accurate" every time all over the sky hence why many use Platesolving to speed positioning and centring  of objects. I can blind Platesolve in under 1 min  and there after normally under  20  secs (my best about 6 secs). Platesolving cuts out most of the frustrations (not all 🙂 ) of getting objects centred quickly - ok some would say lazily . BUT Platesolving involves a camera (DSLR,CCD etc) and so is not much use to visual only users. 

 

 

[Merlin66]

@stash-old,

Which platesolving package are you using?

I've successfully used astrometry.net  ASPS, and AstroArt in the past but they occasionally give me problems - I consistently use the same efinder and camera, so no changes between sessions.

 

[stash_old]

10 hours ago, Merlin66 said:

@stash-old,

Which platesolving package are you using?

I've successfully used astrometry.net  ASPS, and AstroArt in the past but they occasionally give me problems - I consistently use the same efinder and camera, so no changes between sessions.

 

I have used Astrotortila,ASPS,Platesolve2 (ASPS/PS2 only via APT) ,Local Astrometry via Ansvr,ASTAP(latter two via CCDciel and Kstars/Ekos Astrometry.net local.

All have problems and are never 100%.

I am currently moving to CCDciel for my DSLR which has access to 4/5 platesolvers(most of the above) and a very nice Sequencer. Main problem with CCDciel is it depends on the FITs file containing the RA/Dec info to do Platesolving - so my older CR2 files when converted to FITs do not have this info. Not a big problem for new images taken via CCDciel.  With CCDciel i have decided to stick with ANSVR which is pretty good.  

[Merlin66]

Thanks for that.

I downloaded Ansvr, but it seems to need an up front program to access it......

[stash_old]

On 02/10/2019 at 12:13, Merlin66 said:

Thanks for that.

I downloaded Ansvr, but it seems to need an up front program to access it......

I dont know as I have always used it via an application - Ekos CCDCiel etc. I assumed that there was a Web interface ,as per Astrometry.net, only local IP - e.g. 127.0.0.1:8080 but I have never tried that route.   But it does have a simple

http://127.0.0.1:8080/api/config for configuration 

Besides ASPS  ,Platesolve2 and Astrotortilla both have their own application front end.

NOTE ASTROTORTILLA does seem to be able to use ANSVR version of Astrometry- never noticed before always assumed it was yet another version of Astrometry - So there's a front end!

P.S. Had a quick look at Ansvr developer notes you could create a simple script as it seems putting an image in %LOCALAPPDATA%\cygwin_ansvr\temp\ folder and running Solve-field with parameters (see developes notes at adgsoftware.com)  will provide a stars.wcs (fits) format file which includes RA/DEC I guess. Perhaps an email to the author will help you with a more "user friendly" application.

Real example attached - well just the start up 🙂

Sorry thats not too helpful.

new 1.txt

Edited October 4, 2019 by stash_old