Lost to cloud

Compare a bad sub with a good one. Fewer stars in the bad sub, and the ones that remain are no larger.

1. 01

   Cloud

   Cloud dims the field, so fainter stars drop below detection while star size does not change.

   FixCheck cloud and transparency for the hours you will image, and drop the affected subs before stacking.

   Session Checklist

• Bloated, soft stars

  Focus drift makes the stars larger as the count falls. Cloud leaves their size alone.

• Dew on the optics

  Dew softens stars and cuts the count together, gradually. Cloud drops the count without changing star size.

One frame cannot show this. It takes star count and HFR for each sub, from the capture software's log or a stacking tool's frame statistics.

The cloudy subs flagged and left out of the stack.

No outside source is cited here. The signature, the causes and their order are the atlas’s own, from imaging experience. The order is a judgment of likelihood; no measured frequency is behind it.