The photometer has 1 ms resolution, and is used for occultations, remote planet photometry, and variable star work.
telescope coupler has 8 selectable apertures (with illuminated reticles), and
U, B, V and Clear filters. The PMT is a 1P21. The apertures range from 0.34 mm to 4 mm, giving FOV values from 35 " to 405 ".
The primary photometer
is the Pacific Photometric Instruments model 110. The PPI Model 401 Photometric Telescope Coupler
with the Model 50B PMT housing is mounted on the Celestron 8" SCT.
The PPI Model 110 Laboratory Photometer has 11 input ranges from 10 microA
to 100 pA, with 1 pA resolution. Dark current cancellation is switchable
to 1 microA, 100 nA, 10 nA, 1 nA, 100 pA, and OPEN. The Sensitivity control
allows 3X expansion on all but the two least sensitive ranges, to set
any light level to full scale. Accuracy is 1% on the meter, and 0.2% on
the analog output. The regulated high voltage is variable from -50 to