The Photoelectric Micrometer for the Bergedorf Meridian Circle

Summary

A photoelectric micrometer for the meridian circle will be ready for testing in August 1962. The micrometer mainly consists of a fixed focal grid and a pulse counting photometer with digital output on punched tape. The indication of the counter is punched every 100 ms of time on the tape from which a computer can later deduce the transit time and also the declinationcomponent. Using the known power spectrum of seeing it has been shown that the accuracy decreases very little for stars of high declination although at 84° of declination only 3 slits are crossed during an observing time of 20 seconds.

We will be able to measure stars down to about 10th mag., Sun, Moon, and planets, and the brightest stars also at daytime. The micrometer permits the measurement of collimation, nadir, and of mire.

We will try to read the declination circle (with 3′ divisions) by making a microphotometry of 6′ of the circle projected onto reference lines. This registration will be done on the punched tape after the observation of each star.