Photometry with the Lowell 20-inch telescope.

Abstract

view Abstract Citations (1) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Photometry with the Lowell 20-inch telescope. Hardie, Robert Abstract Photoelectric observations of a number of faint objects were undertaken recently using the 20- inch reflector of the Lowell Observatory. The equipment used consisted of a photomultiplier of high sensitivity kindly furnished by A. Lallemand of the Paris Observatory which was employed unrefrigerated, and an AC amplifier built by Johnson with which is associated a rotating sector which occults half the light. Therefore the results correspond with those of a i4-inch telescope using a DC amplifier. The recording was made by the conventional constant deflection method with a time constant of two seconds. For the majority of the observations a diaphragm of 25" diameter was used, although it became necessary unfortunately to use one of 50" when the objects passed beyond the visibility limit and the centering became a matter of luck. The resulting measures of the planet Pluto, reduced to the UBV system of Morgan and Johnson, are as follows: Date (mean) V B-V U-B s~54May6.2UT 14.50 o.8s 0.29 Average deviations: .02 ~ .03 ~ .05 The three observations which form this set of means were made on May 5.2, 6.2, 7.2 and for each color the time used per observation was about 15 minutes of which about half was on sky and half on the planet. Observations of the eclipsing system RV Lyn were made through the range 13 to 15 visual magnitude and 13 to 16 blue magnitude.' The average deviations at the different brightness levels are consistent with those of the Pluto measures considering that the observations were 3 minute rather than 15 minute readings. At V = 15 and B = 16 the average deviations were about + .o6 magnitude. It is felt that with an offset device, a smaller diaphragm, refrigeration of the multiplier, and a DC amplifier, measures may be carried to beyond 16 magnitude with reasonable precision in reasonably short times. An integrating device might also be of value in eliminating some of the uncertainties of reading a noisy tracing. I.Pub. A. A. S. 10, 53, `939 and A. J. 51, 200, `945. Lowell Observatory, Flagstaff, Aris. Publication: The Astronomical Journal Pub Date: 1954 DOI: 10.1086/107085 Bibcode: 1954AJ.....59R.323H full text sources ADS |