[g__day (Matthew)]

Gary,

No I am not auto-guiding at all as I want to see the drift and measure it. I have done PEC - its down to around +/- 3 to 4 arc seconds. I am on my second shooting run now.

The first shooting run tracked Achernar from 9:30am - 11:30am in Sydney. So it moved for two hours when it was about elevated about 30 degrees above the horizon until it got to about 60 degrees. In the first hour it drifted maybe half a star diameter due East and down (RA was too fast) about 2 star diameters. In the second hour at higher elevation it drifted the same in DEC but I would say 1.5 star diameters in RA (again mount too fast)

Now I am tracking a star (Zarauk) which is almost due East about 30 degrees elevation - so any drift will be much more apparent. This star is 1 mm across in my shots. After 30 minutes its drifted 0.5mm in DEC and 5mm in RA (mount is still too fast). At 45 minutes the drift is around 7mm in RA and still under 1 mm in DEC. By an hour it had moved around 10 mm.

To give you my precise scale - I shot the Moon yesterday - on this monitor it is 293 mm in diameter equating to about 31 arc minutes (by comparison Achernar was 3mm and Zarauk a bit less than 2mm on my shots).

Day 2 - Imaging Atria on Celestial Equator near the Meridian

After a very slight adjustment East tracking now shows DEC in drift about 1 star diameter per half hour and minimal RA drift - so stars look slightly stretched on a 10 minute unguided shot.


Matthew