Sunday, July 5, 2015

Paramount MyT - Day 10 - Further tweaks to PHD2, SGPro and the MyT driver & Rotating base plate!!!

Carried my scope out after our vacation. I set the scope in roughly the same place where I had it before our vacation, but could immediately see that the polar alignment would be completely off in Azimuth. Apparently, what happened when I carried the scope outside, I rotated the base plate (I noticed this earlier that it's not completely sticky). I asked on the Software Bisque forum about that.

Next, I needed to calibrate my model and redo my polar alignment. I connected the scope, homed it and then slewed it to Arcturus. I put the red dot finder on the scope, turned the base plate until Arcturus was close to center. Then I ran a model with 37 points. did an accurate polar alignment, ran another model and had my PA at 19.1 arcsec Azimuth and -67.3 arcsec Altitude. Pretty good.

As GSSP is in 10 days(!!) I decided to use the MyT mount without relying on T-Point slewing and tracking accuracy. I.e. I unchecked the "Inhibit Sync to protect TPoint model" setting in SGPro. This would allow SGPro to do proper center commands. Before doing that, I exported my current model to make sure that I still have it (not sure if adding syncs from SGPro would have any effect on the stored model).

I then calibrated PHD2 and wanted to do some manual tests. Noticed for the first time that PHD2 does not seem to notice when the MyT mount slews (I verified that the "Stop guiding when mount slews" setting is checked). So, I have to remember to manually stop it if I want to slew the mount.

First, I wanted to see how the mount is tracking without guiding:

The measured PA error of 1.21arcmin is consistent with the one from TPoint (19.1 arcsec Azimuth and -67.3 arcsec Altitude = 1.16arcmin). Good at least I don't have these inconsistencies between TPoint and PHD2 anymore. It's hard to see what the tracking accuracy is with the slope, but it seems to be below 1 arcsec...

Then the next surprise: suddenly, PHD2 corrected the DEC axis wrongly... Turns out, I need the "Reverse DEC output after meridian flip setting" in PHD2. With that, everything worked.

By now it was late again and I wanted to see how guiding would work. I setup a sequence on SGPro to image the core of NGC 7822. Here is the PHD2 guiding output:

There are the usual dithering spikes. In between, both RA and DEC are mostly below 1 arcsec - which is typical for seeing in our backyard. And the guide box shows that corrections were applied at >0.6 arcsec but maybe not aggressive enough and/or often enough. Need to work on calibrating PHD2 now.