Thanks Andrew,
Yeah ice packs taping up on the back of the mirror works well (and my home-made SCT cooler
I added silica-gels in a bag as dehumidifier recently). Saturn - Sorry I was sloppy to clean up that artifact. I always get this artifact after derotated with Winjupos. I tried PS's Healing Brush Tool to touh up and reposted in my orginal post. Do you know better methods?
Hisanori