Table of Contents
General Information on the VATT
Optical System : aplanatic Gregorian, f/9
Focal Length : 16.48 m
Primary Mirror : f/1.0, Diameter 1.83 meters
Secondary Mirror : f/0.9, Diameter 0.38 meters
Back Focal Distance : 50.80 mm (effective)
Vignetting-Free Field : 72 mm diameter (15 arcmin)
Image Scale : 12.52 arcsec/mm
Image quality : 0.1 arcsec throughout 6.8 arcmin diameter flat FOV
Mount : altitude-azimuth with derotator
Geographical Location of VATT
Latitude : 32° 42' 04.69“ N
Longitude : 109° 53' 31.25” W
Altitude : 3191 meters
Driving time from Tucson : 3.5 hours in good conditions
IAU Observatory Code number : 290
Sky Conditions at VATT
The sky surface brightness for low-airmass (sec z < 1.2) observations averaged 22.00, 22.53, 21.49, and 20.88 mag arcsec2 in U, B, V, and R, respectively. These were measured during relatively high solar activity. The darkest run achieved 21.72 in V, close to theoretical minimum of 22.0 mag arcsec2.
The FWHM seeing for median R-band focus images per run ranged from 0.97“ to 2.15”, with values occasionally as low as 0.65“. While this is very good, please note that the VATT's height and location do not give the best seeing achievable at MGIO.
(These values were determined by Violet Taylor, ASU)
Computer Systems at VATT
HP Server System and Terminals running on a 1 gigabit private network with a TCP/IP link to the Steward Obs. network via microwave connection
VME instrument computer running VxWorks
Linux for TCS interface, Xephem utility, and autoguider control
IRAF reduction software and AzCam data aquisition software
