Brian COLVILLE #235

Letters to the Editor


from Brian COLVILLE in CMO #235
@ . . . . I have attached a set of IR and a single methane band image taken on the morning of the 28th. Seeing was pretty good, 7/10 and it improved a bit towards the end of the session.
(28 Aug 2000 email)

 
@ . . . . I have attached a set of IR and Methane images taken 01 September 2000. At the beginning of the session, I was experimenting with an AO setup which yielded a rather high focal ratio (f45), and the resulting image was very close to the edge of the CCD chip. I took a sequence through the IR filter in both 2x2 and 3x3 binned modes. A good amount of detail was visible, and the shorter exposures in the 3x3 binned mode appear the sharpest. The methane image was taken in the 3x3 binned mode due to the very long exposures needed.
  I later switched back to my traditional planetary mode (f35) and removed the AO unit. The bottom row of images were shot in this setup.
  Oval BA is easily visible in the methane images, at the CM in the first image and approaching the limb in the second. Ganymede transit is just beginning at the start of the imaging session. There appears to be some irregularity in the NTeB and STeB, with a sudden change in darkness and/or thickness in both belts near the CM. The NTeB is dark/thick following the CM and the STeB is dark/thick preceding the CM. They are much like a mirror image of each other. The effect is most pronounced in the 3x3 binned image taken in the IR at 08:20 UT. (I am not 100% sure of the belt divisions, they could be the NNTeB and the SSTeB, any confirmation would be most welcome - please see the belts.jpg file for my interpretation).
Note, the sequence at f45 were dark but not flat field calibrated due to some file problems. The f35 set were dark and flat calibrated.
  I need to work on modifying my optical setup to make use to the AO unit. Will post some results shortly, weather permitting.
(4 Sept 2000 email)
Brian COLVILLE (Cambray, Ontario, Canada) : maple@quicklinks.on.ca
Maple Ridge Observatory
WWW : www.quicklinks.on.ca/~maple