Dave's Book? LOL
"It is not uncommorn for equipment out at night to cool below the air
temperature by radiation into the nearly absolute zero emptyness of space."
Brent,
If I didn't know that you sold your 22", I'd say you'd been stargazing from atop the 20th step of your ladder to reach the 'nearly absolute zero emptyness of space'.
Bernson used to tell a tale about you having people at SPOC look 'with both eyes' at the first quarter moon with the 22" unobstructed/unfiltered while on the same said ladder years ago. Any truth or just a good story for Dave's book?
Dave Bennett
On Nov 29, 2011, at 10:48 AM, Brent Watson <brentjwatson@yahoo.com> wrote:
It isn't necessary for the air temperature to be below the dew point. All that is required is for the equipment to be below the dew point. It is not uncommon for equipment out at night to cool below the air temperature by radiation into the nearly absolute zero emptyness of space. When the equipment cools down below the dew point then frost forms on the equipment.
________________________________ From: "Hutchings, Mat (H USA)" <mat.hutchings@siemens.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Tuesday, November 29, 2011 8:43 AM Subject: Re: [Utah-astronomy] Saturday observing report
The dew point was higher, but it did eventually get about that cold.
Mat
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Don J. Colton Sent: Monday, November 28, 2011 7:27 PM To: 'Utah Astronomy' Subject: Re: [Utah-astronomy] Saturday observing report
I haven't been to Pit-N-Pole for several years but since it is near the local valley floor it is particularly susceptible to frost and dew. I was out observing in Sandy and no frost appeared all night long but the skies were light polluted. The weather forecast said the dew point was 13 deg. F. I suspect the dew point was much higher at Pit-N-Pole or did it get that cold.
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of Hutchings, Mat (H USA) Sent: Monday, November 28, 2011 4:56 PM To: Utah Astronomy Subject: [Utah-astronomy] Saturday observing report
Several of us (Jay, Jeff, Jorge, Mark, my 2 young daughters and I) made it out to Pit-N-Pole for an observing session last Saturday evening. It was a bittersweet time. Sweet because the skies were really clear and steady. Bitter because frost started settling by around 7:00 pm. That seems really early for frost like we got, but that's what happened. Of course it did not get any better after that.
The frostiness continued but I was able to use my newly acquired 12V hair dryer to heat my eyepiece to the point that it would not fog over as soon as my eye was close to it. Each heating session would last for about 30 minutes or so then I would have to apply more heat. Anyone considering this option to dew management should know that it worked well for me and it is hard to beat the $15.00 price tag. You have to be able to power it with something that has a cigarette lighter power connection. I use my jump starter battery. If your car is close, you can use the cigarette lighter or any similar accessory power connection. If you are considering dew busting devices, feel free to use my hair dryer anytime we are observing together. Just don't try to dry your hair, as there is very little heat and air that comes from that dryer. I don't think it would work well for a SCT type telescope as the corrector plate is just too large to heat with the dryer. But again, try mine out, then you'll know.
Anyway, back to the observing session, we called it a night after 11:00 or so. We had good times enjoying the night skies, but the frost got to us early. As usual for this hobby, observing the night sky is only part of the enjoyment, good conversation with like minded people makes the evening a good time. Mark's heater made it a great time, especially for my daughters!
Keep looking up!
Mat
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