Add ccd/camera simulator

franco

A ccd simulator like the one that's already in the indi library, when combined with the existing mount simulator (Demo mount) would be really cool... I'm sure you must use one when testing new code!

franco

Here's a few shots of the ASIAir running indi_simulator_ccd. Plate solving seems to be a bit fussy about noise, had to dial it down from the default settings. I tried a polar align but got quite a big error which I thought must be wrong. Can't quite work out why it doesn't get the exact focal length I set in the simulator (1000), seems to think it's closer to 900.

This is Stellarium tracking the simulated telescope

The 2 images used for the polar align

w7ay

franco I tried a polar align but got quite a big error which I thought must be wrong.

Nope, you are not wrong. ZWO is. See

https://bbs.astronomy-imaging-camera.com/d/13850-all-sky-polar-align

Chen

w7ay

franco

By the way, @franco, Akismet keeps flagging your posts (all of them) as spam. I needed to constantly unflag your posts.

Perhaps you can check your account information to see what could be wrong (perhaps a bad email address?).

Akismet is an automatic spam detecting service, and ZWO apparently uses it to check this forum.

(I don't work for ZWO, but some time ago, ZWO had bumped my account privileges to include semi-moderator status. So I end up seeing flagged postings, and I usually make the corrective actions; that is why your posts are getting through, albeit with a delay until I see them.)

Chen

franco

w7ay I've been getting email notifications so don't understand the spam thing.

I did see your posts about polar alignment but seem to remember you saying the old N/SCP method was accurate to within 10 arc seconds? Of course indi_simulator_ccd may be getting it wrong - it uses GSC (Guide Star Catalogue) and a little program also called gsc to extra the relevant data. Gotos seem to be spot on though according to Stellarium and Kstars. I use the old PA a lot - lots of clear skys down here - but assumed it was doing a good job, my tracking is mostly ok.

w7ay

franco old N/SCP method was accurate to within 10 arc seconds?

Yes, the original polar alignment gave about 10 arc seconds error (increasing to a few arc minutes when the declination angle is 30 degrees away from the pole). The Beta all-sky method gave 8 arc minutes of error, so much worse -- basically useless, unless you use short exposures, or use a very small sensor or crop.

By the way, Akismet again flagged this post of yours. See the spam count at the bottom of their page? Your post is probably one of them :-)

https://akismet.com

Chen

franco

Still trying to get my head around why the simulator doesn't give a perfect alignment. The simulator generates a precise star field and so the plate solving should work perfectly, given both use similar star catalogues, n'est-ce pas?

I know that the Air uses a low res image for plate solving during PA, so maybe that's contributing to the error.

I uploaded the 2 images (low res) taken 60 degrees apart to astromtery.net and the results are similar to the local plate solving but not that close. It's basically the same software being used.

The PA error is always around 6 to 8 arc minutes.

franco

I repeated the polar align test using the telescope and ccd simulators in Ekos and got the same result as above.