Kochab Observatory

43.3 N - 93.3 W

Celestron Micro Guide Eyepiece Calibration

My first calibration was done over a year ago as I began my double star project. At that time my separation measurements were close to published data. With more experience, I decided to do another calibration.

A second calibration was done 8/27/06 by timing the transit of Altair using my 12”LX200 SCT. Transparency and seeing were very good. Eleven measurements were taken and averaged between 1:00 – 2:00 AM on 8/27/06. The new calibration was then tested on 5 known pairs whose separation and position angle have changed little in the last 100 years.

The declination of Altair is 09 38 34. The average time of eleven transits was 26.512 seconds. Using the formula s=(15.0411) (t) (cos of dec) / d a calibration of 6.557 per division on the linear scale.

Calibration data detail

Transit times in seconds: 26.38 26.72 26.31 26.37

26.43 26.59 26.28 26.97

26.50 26.53 26.56

Average transit time 291.63/11 = 26.512

Cos of 9.3834 dec = .98661

s=(15.0411)(26.512)(.98661)/60

s=6.557

Test Pairs PAo Sep”

STF 39 AB 150 45.9

My measure 150.5 45.89

STF 37AB-CD 174 210.5

My measure 174.5 213.1

STF 43 Aa-B 54 34.4

My measure 53 34.42

STF 307 AB 302 28.7

My measure 301.5 29.5

STF 331 86 12

My measure 86.5 12.45