Brief History

• 1910 construction of refractor begins, from donation by State Senator Sproul
• 1912 continuous operation of Sproul refractor begins in January
• 1966-7 refractor overhauled for 7 months, tracking & setting motors installed, new electronic console
• 1998 Apogee AP-6 CCD camera attached to refractor, cables run to observing alcove at dome entrance

• Specifications:
• aperture 0.61 m
• focal length 11 m
• focal ratio f/18

• favorable for precise measurement of positions & motions of stars
• has advantage that instrument not much affected by background campus & suburban lighting

• minimum seeing disk on photographic plates ~ 1.0¢ ¢ (typical ~ 1.5¢ ¢ )
• minimum visual resolution ~ 0.1¢ ¢ (typical ~ 0.3¢ ¢ )

• practical limiting visual magnitude ~ 13
• practical limiting photographic magnitude ~ 14
• sky background magnitude ~ 15

• photographic observations to determine distances of stars, especially nearby faint dwarfs
• micrometer observations of visual binary stars, their orbits & masses

• Sproul plate archive contains probably largest astrometric plate collection from one telescope:
• 90,000 photographic plates since early 1900s:
• used to make 1400 parallax (distance) determinations

• Visual observations, mainly by W.D. Heintz since 1967:
• 500 binary star orbits
• 900 newly discovered binaries
• study of low-mass binaries, including first "brown dwarf" candidates (Wolf 424 in 1972)

• Photographic program terminated in 1994
• Micrometer observations terminated in 1998

• reviewed in CCD Astronomy, Summer 1996 (then Axiom AX-6)
• very large chip yields workable field of view with f/18 refractor

• 1024 x 1024 pixel array, 24.6 x 24.6 mm square
• 24 m square pixels
• front-illuminated, no antiblooming
• linear well depth 170Ke
• dark count ~ 1.0 e/sec at -25° C (doubles for every ~6° C warmer)
• pixel binning 1x1 to 8x8

• download > 45K pixels/sec, total frame 24 sec
• readout noise < 24 e (19e typical)
• system gain 3.5 e/ADU nominal
• exposure time 0.03 sec to 10,400 sec
• frame size full frame, subframe, focus mode

• thermoelectric cooler with forced air.
• minimum 35° C below ambient at 25° C (remote boost unit adds 5-8° C cooling)
• 20 min temperature transition time for sensor safety
• Software programmable temperature

• 8061-T6 aluminum body, hard blue anodized
• BBAR coated silica windows
• camera head is 6x6 in x 1.3 in thick (heat sinks & fans add 1.2 in)
• 3 lbs

• yields 8¢ x 8¢ field of view with 24-inch at f/18
• pixel scale 0.45¢ ¢ per pixel at focal plane
• 16-bit images, each takes up ~ 2 Mb of space

• constructed by ISI Systems, Santa Barbara, CA
• contains eight, 2-inch square slots
• standard B, V, R filters, 5 mm thick, from Omega Optical,

• full version

• PowerSpec PC
• 233 MHz Pentium II processor
• 64 Mb RAM

 
Short Period Variables

• Delta Scuti Variables
• SX Phoenicis Variables
• Eclipsing Binaries – Algols & W UMa

• Extragalactic Supernovae
• RV Tauri and Semiregular Variables
• Possible Identification of Flare Stars