Subject: 3.5m Optics and Seeing: Good News!

From: Alan Watson

Submitted: Wed, 29 Jan 1997 01:07:25 -0700

Message number: 120 (previous: 119, next: 121 up: Index)

For a short period of time tonight I had 0.5 to 0.6 arcsec FWHM seeing
with the APO 3.5m. I believe this is the best seeing that has been
seen. The instrument was GRIM II with the f/20 camera, so the seeing
was well sampled. The exposures were 5 seconds long in J, H, and Ks
and were taken near the zenith.

Ah, you're saying, this idiot screwed up and really had 1.0 to 1.2
arcsec FWHM seeing with the f/10 camera. Well, no: I was taking images
of an astrometrically calibrated field in M67 to check the plate
scale, so I can independently confirm that I was using the f/20
camera.

The images match my previous experience of good seeing images in short
exposures: they have a tight core with irregular wings. If anyone is
interested, the images are in ftp://oldp.nmsu.edu/pub/alan/970129/.
The first pair are in J, the second pair in H, and the third pair in
Ks.

I think this is very encouraging news!

Alan Watson
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