is tickled to host:

Canada/USA Astronomical Seeing Observation Program


What is Seeing

Seeing is the term astronomers use to describe an image formed by a telescope that is jiggling, wiggling, swarming, blobbing or otherwise moving in a manner that destroys visible detail.

It's really quite annoying.

The cause is a combination of temperature difference and turbulence in the atmosphere that the light travelled to get to the eyepiece. That means it can be anywhere from the high atmosphere to the air in the telescope.

Bad seeing caused by temperature and turbulence in a telescope tube is properly called tube currents. Bad seeing caused by local effects, like a hot driveway, is properly called ground seeing. Bad seeing caused by temperature and turbulence in the atmosphere, for example the jet stream, is properly called atmospheric seeing. But astronomers tend to use the term seeing to mean just the appearance of bad seeing.

This website prefers to use seeing to mean atmospheric seeing.

Why make records of Seeing

A night of exceptionally good seeing, a night where the detail seen on Jupiter causes observers to swoon and swear, is thought to be rare. It would be boon to know in advance when good and bad seeing might occur.

Recently Allan Rahill, meteorolgist of the CMC and amateur astronomer, created a numerical weather model of atmospheric seeing.

Allan previously created an astronomical transparency forecast which is the basis of the the Clear Sky Charts. Allan's transparency forecast is getting known to be more accurate than all other predictors of clear skies (80% to 90%). However, Allan is still tuning his seeing model.

The best way for Allan to tune his seeing forecast is for him to compare with real observations of seeing conditions, made by experienced amateur astronomers. (Pros are welcome too, they just tend to be rare.) Allan needs records of seeing conditions, or seeing observations from all over Canada and the USA. is tickled to be the respository for seeing observations that might help Allan advance the science of weather forecasting for astronomers.

Who can play?

Anyone who knows the difference between seeing and tube currents, has a telescope 6 inches or larger, can rate seeing on one any of 5 semi-standard scales, and can tolerate typing into html forms is encouraged to participate. (A sense of humor helps too.)
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Clear Sky Chart Homepage is Attilla Danko's website.