Add hour angle to polar Alignment

[aston]

I seem to have to offset my polar latitude to get round stars suggesting my polar alignment is off. I don't suspect Sharpcap is the problem but it would help diagnose the problem if Sharpcap indicated the hour angle of Polaris as it sees it so I could compare it to the known value. This could be done with a graphic reticle on the star field screen like you see in a polar scope or with a number somewhere on the screen. Thanks.

[admin]

Hi,

I'm afraid I'm struggling to see how this would be any advantage over using a phone app to calculate and show the hour angle of Polaris – for example https://play.google.com/store/apps/deta ... k&hl=en_GB

Can you explain a bit further how putting these details on the polar alignment screen would be advantageous?

Cheers, Robin

[aston]

It would allow me to verify that the Sharpcap hour angle agrees with the the app derived hour angle and that something had not gone wrong with the plate solving. It would let me remove another variable when trying to diagnose an alignment problem.

[admin]

Ah, I see…

Actually, SharpCap has no idea of the hour angle of Polaris as it doesn't use that information to perform the polar alignment calculations. The alignment is entirely based on the captured images – plate solving let's SharpCap work out the coordinates of the pixel that represents the north celestial pole (even if it is out of view) and the rotation allows SharpCap to work out the coordinates of the pixel that all the stars appear to rotate around (which is where the RA axis is currently pointing). Once the code knows those two things it simply a matter of prompting the user to adjust the altitude and azimuth until the two pixels representing the NCP and the RA axis are both in the same place.

You may find that the information on this page is helpful if you are having difficulty with the polar alignment – https://www.sharpcap.co.uk/sharpcap/fea ... leshooting

Cheers, Robin