Hi Dogstar,
Regarding scintillation recalculations for winter and summer.
Scintillation can vary by large amounts on minute time scales (doubling), but time average fluctuation levels are fairly predictable using dependencies on air mass, site, telescope aperture, wavelength and exposures.
There is a difference between winter and summer with the change in jet streams which would have an effect on scintillation noise. You can reduce scintillation fluctuations of a star's intensity by decreasing exposure time. For example, a 4 minute exposure will exhibit half the scintillation of a one minute exposure.
However, the smaller the telescope aperture, the greater the scintillation. the naked eye's aperture is so small that an additional componenet of scintillation is produced by temperature and humidity inhomogeneities near the ground level ( where atmospheric seeing degradation is produced).
Ideally, a large telescope aperture will reduce scintillation and in fact improve resolution which is really important when it comes to resolving millimag transit of a planet.
Seanie,
I was surprised as well how it got an NGC designation. Another cluster group M103 has similar features and has also got an NGC designation. You're right the stars could be sharpened a bit more. The transparency ie. RH levels seem to determine the sharpness.
Eamonn A
MPC J62
www.kingslandobservatory.com
  