David's Astronomy Pages CCD Image Notes - Session 110 (2006-01-03) Notes (S109)   Notes (Main)   Home Page   Notes (S111)

Goto Images from 2006-01-11

Sky Condition Graph

Sky Conditions Chart (S110)

Notice  1)

See explanation of these graphs

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Impact of light wind on image quality with & without dew shield

A dew shield was installed on the scope at the commencement of the session as a precaution against dew formation, but more specifically to reduce potential glare from a 94% phase moon which was high in the southern sky.   Dew did not in fact cause any problem this particular evening and the benefits in reducing moon glare were completed overwhelmed by the detrimental effect on image quality caused by  additional wind vibration on the scope.  The dramatic difference in image quality immediately before and after removing the dew shield are shown by the two images below.

With Dew Shield (wind catches dew shield and causes vibration of  scope and consequential poor image quality)		Dew Shield Removed  (image quality immediately improved  after taking off dew shield)
CCD Image 2 min exposure,  C Filter 2006-01-11  22:05h UT (#110067)		CCD Image 2 min exposure,  C Filter 2006-01-11  22:09h UT (#110070)

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