New T - Point and Slewing Problem with the Paramount

On Friday night I spent the entire night working on making a new pointing model, I scrapped the last one after reading the T - Point user manual and finding out that it was not advisable to take samples down near the horizon due to atmospheric refraction that causes offsets between the actual position of an object and it's observed position, I started collecting samples around 9:30 and only stopped collecting samples early in the morning due to the mount making an inexplicably unhealthy noise when it was slewing, I couldn't see any obvious reason why the mount was suddenly making the noise ( sounds like a rattle with clicking or cracking type noises ) so I just put the mount back in the home position and called it a night, by the time this had happened I had collected 82 sample points, the new model showed that we are only off by 2 arc-minutes in azimuth while the altitude was still excellent and we don't need any more adjustments in that area.

After attending the Auckland Astronomical Society council meeting at Andrew's house on Saturday, I thought I'd head out to Kumeu and see if the Slewing was still making that same noise and to also test the new pointing model, The first ten or so slews sounded healthy but then again inexplicably the unhealthy noise started up again, so again I just put the mount back into the home position and called it a night, I've talked to Steve about the problem and he is at a loss to explain it as well so we might need Grant Christie or Tim Natusch to come out and take a look at it, hopefully it's nothing too serious, before this happened I was quite happy with the accuracy of the new pointing model, objects were always just a few arc-seconds from the center of the frame although I didn't get a chance to slew all over the sky so some areas may be worse than others, I still had the same problem with the mount in the area of sky to the South East that I had the first time I attempted a pointing model so I couldn't take samples around Centaurus, Crux or Carina, below is an example image of the Galaxy NGC 1532, the image was a 100 sec long exposure and I was quite happy with how close the galaxy was to the center of the frame, the image exhibits some pretty bad vignetting but I think this was due to the Moon being almost full and very bright.

Posted by Jonathan Green