results

The observations were made on 2 October 2008 at 37 Bindea Street Como, NSW. They were done using a Wild T2 theodolite, between the hours of 20:30 hours and 22:30 hours. The weather was fine, temperature of approximately 25C and at an approximate pressure 1020hPa.

 

The vertical circle refraction error was calculated (see Table 1).

Table 1: VCIC for Wild T2

 

The refraction correction for the observations was determined using the data. On 2 October 2008 the estimated pressure was 1020hPa for Sydney and temperature 25C for the time of observations. The Star Almanac for Land Surveyors 2008 (2007, p.63) provides a refraction factor relating to the pressure and temperature of f = 0.96.

 

Azimuth orientation was made to α Centauri and ε Sagittarii. The position of α Centauri was calculated to be 2103553˝ (azimuth) and 672600˝ (altitude) at 22:50 hours (AEST). Then ε Sagittarii was predicted for 22:55 hours (AEST), this was different to the observed position (see Table 2).

Table 2: Observed and Calculated Azimuth and Altitude for ε Sagittarii

 

None of the stars observed to for the determination of latitude and longitude were known. They were deemed appropriate because of their position on the celestial sphere. Before position could be determined the stars observed had to be identified.

Table 3: RA and Dec of Unknown Star 1, Achernar

Table 4: RA and Dec of Unknown Star 2, θ Scorpii

Table 5: RA and Dec of Unknown Star 3, Altair

Table 6: RA and Dec of Unknown Star 4, α Andromedae

Table 7: RA and Dec of Unknown Star 5, α Trianguli Australis

Table 8: RA and Dec of Unknown Star 6, σ Sagitarii

 

For the determination of longitude and latitude the corrections to the timed altitude observations had to be made. These adjustments corrected the altitudes for VCIC and refraction. Then the longitude and latitude could be calculated using the time altitude method, along with the standard deviation for the observations. As directed by Bennett (1979) each star has been paired with another and these pairs have one star north and south of the ecliptic. The resulting longitude and latitude for these pairs are in tables 912.

Table 9: Latitude and Longitude from Achernar and Altair

Table 10: Latitude and Longitude from θ Scorpii and α Andromedae

Table 11: Latitude and Longitude from θ Scorpii and Altair

Table 12: Latitude and Longitude from Achernar and α Andromedae

 

This can be compared to other coordinates for the place of observation. The coordinates taken for comparison are from Google Earth and the results are in tables 13 15.

Table 13: Google Earth Coordinates for place of observations (2008)

Table 14: Mean Coordinates of Star Pairs

Table 15: Difference between Calculated and Google Earth coordinates

Last Update 29/10/2008

POSITIONAL ASTRONOMEY THROUGH THE AGES

BY

BENJAMIN JACKSON

Face Left

Face Right

VCIC

861019˝

2735007˝

-13˝

900722˝

2695301˝

-11.5˝

 

Mean

-12˝

 

Observed

Calculated

Difference (O-C)

Azimuth

2544704˝

2544637˝

+27˝

Altitude (Adjusted)

410212˝

410258˝

-46˝

Unknown Star 1

RA

Dec

Star

32

Achernar

(α Eridani)

M 0.6

1h38m05.7s

S 571118˝

Unknown Star 2

RA

Dec

Star

482

Theta (θ) Scorpii

M 2.0

17h37m57.3s

S 430023˝

Unknown Star 3

RA

Dec

Star

548

Altair

(α Aquilae)

M 0.9

19h51m13.6s

N 85337˝

Unknown Star 4

RA

Dec

Star

1

α Andromedae

M 2.1

0h08m52.3s

N 290832˝

Unknown Star 5

RA

Dec

Star

451

α Trianguli Australis

M 1.9

16h49m35.3s

S 690254˝

Unknown Star 6

RA

Dec

Star

522

σ Sagittarii

M 2.1

18h55m49.4s

S 261714˝

Star 32 and 548

 

Latitude

34 0' 35"S

5.9"

Longitude

10h 04' 17"

0.7"

Star 482 and 1

 

Latitude

34 0' 46"S

2.63˝

Longitude

10h 04' 19"

0.99˝

Star 482 and 548

 

Latitude

34 0' 43"S

5.12˝

Longitude

10h 04' 18"

0.60˝

Star 32 and 1

 

Latitude

34 0' 38"S

3.27˝

Longitude

10h 04' 18"

1.04˝

Google Earth Coordinates

Latitude

34 00 29˝S

Longitude

151 03 49˝E

Mean Coordinates of Star Pairs

Latitude

34 00 40˝S

Longitude

151 04 18˝

Difference between Coordinates

Latitude

-11˝

Longitude

-29˝