Jean DIJON #217
Letters to the Editor
in CMO #217
@ . . . . .Please find enclosed my first CCD results on Mars this year.
The weather was very bad during the month of April so it was not possible for me to observe so much the planet for the opposition.
I just begin to make Mars images with my 500mm telescope which is now operational at Champagnier for about one year. In spite of the vicinity of Grenoble town and a terrible turbulence related with the close vicinity of the Alps I am able to do better images than with my 300mm previously installed in the same unfavourable planetary site. Thanks to a lot of light I am able to catch the planet with full aperture with only 0.07s exposure which is a great oint to obtain useful images. Each sent image is a composite of almost two.
During one observing session, I take a huge number of view(one for 10s) and just keep the best(about 100 per observing session). Next day, after processing I just keep the best one. So with this process I select the best available moment and possibly obtain an image resolution equal or better than a visual one. CCD is great for planetary observations in a bad location. It would be far more better with good seeing conditions but most amateurs are not able to select their observing locations, so.
The following observations are enclosed:
The 31-03 image shows limb cloud and probably a rima in the polar cap. Otherwise the general aspect was rather classical.
The 17-04, clouds are evident on Elysium with a cloud brighter in the north. Propontis is very dark. Eridania and Electris are bright while the polar cap wasdull. A brilliant cloud is seen just below Syrtis Major on the limb.
The 30-04 clearly a bright streak is seen on Ophir-Candor. The polar cap is bright, some clouds are present on the limb and Chryse. Mare Acidalium is very dark with Nilokeras and Lunae Palus evident. Ganges is also seen.
The 01-05 about the same view(a little bit better) which confirms the bright streak on Ophir-Candor.
The cap is seen divided in two parts. Solis Lacus is dark and Tithonius Lacus is also seen.
I hope to have more good weather to be able to produce other images.
I must use this letter to thank you for your continuous sending of the CMO which is a good link among Mars observers.
I hope you have clear skies.
(5 May 1999, postmarked)
Jean DIJON (Champagnier, France)