SharpCap Forums

Hi,
I have been trying for a while now to try and get my mount set up with sharpcap and stellarium so I can use the plate solve feature in sharpcap.
So far I have been unsuccessful.
I have a SkyWatcher az gti mount and a Windows laptop.
The software I have downloaded is synscan pro, stellarium, sharpcap, allsky plate solver, ascom and the ascom driver for synscan.
I have installed this software and filled in the field of view option in allsky plate solver in order to install the indexes
In theory, I think I've done what is needed to be able to plate solve but when I click to plate solve it starts searching and comes up with only 1 star found and says to higher exposure/gain. The camera screen shows around 13 other stars.
I would appreciate any help on this as its getting a bit frustrating and I'd like to do plate solving as my mount never seems to find the target I'm aiming at!
Thanks.

Hi,

so, the most obvious thing to do is to turn down the 'sigma' setting in the SharpCap plate solving settings page - that increases the sensitivity of the star detection by the plate solving application.

However, the fact that you only see 13 stars on screen is a bit of a concern (particularly if you are seeing those by using a SharpCap display stretch). You can also consider turning up the exposure and/or gain to get a few more stars to be visible. A good number for plate solving is 50 to 100 being detected by the plate solver, so you have a bit of a way to go. An exposure of 4s and a gain value somewhere between half and three quarters of the maximum is usually a pretty good be for camera settings for plate solving.

There is no need to worry about the settings within ASPS itself - SharpCap bypasses all of those settings and just uses the plate solving engine that ASPS installs. Aside from the installation of the data files, all of the relevant settings are in the SharpCap plate solving settings page.

If you continue to have problems, please let us know what camera and telescope combination you are using, which will let us check your field of view and possibly give more detailed suggestions on settings.

cheers,

Robin

Thanks for your reply Robin,
Does sigma value mean the amount of stars to detect? For example, if I can find only 13 stars I should therefore set the sigma value to 10?

I was using 4 second exposures and the gain was on 370 I believe, I can try turning that number up and see if this works.

I'm using the skywatcher heritage 130p on an az gti mount and a zwo asi178mc camera.

Thanks.

Hi,

no, the sigma setting is a measure of statistical significance that needs to be exceeded for a bright area to be considered a star. Basically (and very roughly), if it is set to 10 then a bright area needs to be 10 times brighter than the average random bright area (due to random background variations) to be flagged as a star. Normally somewhere in the range 20 to 70 works fine.

The 178 camera is notable for having small pixels - might be worth trying 2x2 binning to see if that helps.

cheers,

Robin