Comparison of Crater Timing Reductions by Jiri Bouska

 with those by Byron Soulsby

 

Isabella Plains Lunar Observatory Australia

Introduction

 

Jiri Bouska and associated astronomers have observed and analysed ten lunar eclipses from 1943 to 1968.

 

These crater timings were extracted from the Bulletin of the Astronomical Institute of Czechoslovakia (1950 – 1970)  and reported by the author in The Australia Journal of Astronomy, Vol 3 No 3, April 1990 No 11, pp 105-112.

 

Re-analysis of these lunar eclipse have been completed . A comparison of  Bouska's umbral enlargement (%E) findings and the author's values is given below:

 

Date of Eclipse

Number of Observers

Number of Timings

Type of Timings

Bouska

%E

Soulsby

number, %E, + mean error

 

% Change

 

 

 

 

 

 

 

19430815

1

0

Immersion

 

 

 

 

 

15

Emersion

2.333

7 , 2.2798, 0.3025

 

19451219

1

13

Immersion

1.854

combined

13

2.1836

0.1449

 

 

 

5

Emersion

5

1.6359

0.1073

18

2.0315

0.1345

 

19461208

4

95

Immersion

2.809

combined

48, 2.3819, 0.1934

 

 

 

 

Emersion

61, 2.0801, 0.1924

total 109, 2.213, 0.1928

 

19491007

9

78

Immersion

3.678

combined

37, 2.7472,  +/-0.2777

 

 

 

 

Emersion

 

 

19500926

13

271

Immersion

2.235

combined

171, 2.4277,  +/-0.1755

 

 

 

 

Emersion

 

 

19520805

13

237

Immersion

1.896

combined

37, 2.5026, +/-0.3548

 

 

 

 

Emersion

 

 

19570513

8

100

Immersion

2.0 (E)

26, 2.2493, +/-0.2183

 

 

 

 

Emersion

1.560 (W)

59, 1.7159, +/-0.2620

 

19590324

8

170

Immersion

2.59

40, 2.6899, +/-0.2218

 

 

 

 

Emersion

2.03

67, 2.1773, +/-0.1734

 

19650614

2

10

Immersion

2.44

10, 2.5177, +/-0.4343

 

 

 

 

Emersion

 

 

 

19680413

3

26

Immersion

2.774

21, 2.5754, +/-0.3306

 

 

 

 

Emersion

 

 

 

 

Bouska reported his analyses in detail and for his second eclipse produced a plot of the change in umbral semi-diameter with position angle of the craters observed, as shown here. For his first eclipse a similar plot has been prepared by the author and is shown here

The values of  %E found by Bouska and those of the author are compared in the bar chart here.

There are many reasons for the differences between the two authors findings, such as the origin of the crater coordinates, here Bouska used his own catalogues (1953), the reductions were done using Kosik's (1940) method and positions of the Moon were computed from the Astronomical Ephemeris for the relevant eclipse years.

My catalogue of  lunar craters is a Gazetteer of Named Lunar Features by the Positional Astronomy Section, Division of National Mapping, ACT .

The reductions were conducted with my suite of computer programs based on my BAA paper of 1990, Improved Lunar Eclipse Ephemerides, the positions of the Moon were derived from David Herald's Occult Version 4  daily polynomial coefficients, and the solar data from the USNO Interactive Computer Ephemeris (ICE) .
Produced by the Isabella Plains Lunar Observatory Australia, 2008 March 14.