Seeing over a colourbond roof?

[el_draco]

Greetings,
Can anyone give me an idea on how much seeing is buggered up by having to observe over a colourbond roof and, how long those things take to cool to roughly ambient at night?

Ta

Rom

[glend]

Both my house and shed are Green colourbond roofed and I can say they cool off pretty quickly once the sun is no longer hitting them. They actually cool off much quicker than concrete tile roofs. In the evening the dew always forms on my roofs before anywhere else and this confirms for me that they are cooling faster than other materials. Basically the roof will cool down faster than your scope mirror most of the time.

In my opinion, your more likely to get heat affected seeing (shimmering, etc) from ground radiation where heat builds up during the day and then takes some time to cool off during the night. To give you an example, the last time I was out at Bretti for a astronomy weekend the daytime temps approached 35C, once the sun went down seeing was affected for about and hour as the ground heat disapated.

[el_draco]

Thanks for the info Glen. Somewhat relieved
Rom

[rogerg]

Agree with what Glen said. Cool down times don't get much better than that of tin/colourbond.