Wednesday, June 22, 2016

Mars--Seeing is Everything...

Last night's imaging session also gave me the opportunity to compare my image of Mars taken 3 weeks ago from the Isle of Palms in SC (using the 6 inch RC scope) with one taken here in Indiana with the 14 inch. The expectation, of course, is that the 14 inch would produce a much superior image. The 14 is perfectly collimated (as is the VRC 6) and, operating at about the same f/ratio with a barlow, produces a much larger image on the DS 2.3+ imaging ship.

However, my previous experience indicates that is not the case. I have never been able to get as good an image of Saturn as that I achieved in Cape Cod 3 years or so ago with my ETX 125. The 14 inch was not even close.


The answer is seeing. In Indiana, we tend to have either hazy, steady seeing, or very transparent but very unsteady seeing conditions. Transparent and steady almost never happens (although around 3:30 in the morning seems to be the best bet!).

Last night was no exception. To me, it seemed I was looking at Mars though quickly rippling water. The image was almost impossible to focus as it quivered and danced. There's a reason Percy Lowell set up his observatory in Flagstaff, AZ...

For comparison, here's the best image of Mars I could achieve last night with the 14. Syrtis Major is very visible--but that's about it:

By comparison, here's the image I took with the 6 inch scope in SC. Although the image scale was much smaller than in the 14 and I had to crop and enlarge it considerably, the much better seeing conditions in SC resulted in a more detailed image of the area of Mars presented at that time (see my Mars Through the Palms post for more details).

Conclusion: size isn't everything!