Version 0.70
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Part IV
Measuring the Distance of Asteroid 1992JB by
Parallax:
In this section we’ll use our new-found skill in measuring
coordinates to determine the parallax of asteroid 1992JB. For
this purpose, we took two images of 1992JB simultaneously
from observatories at opposite sides of the United States.
One image, you have already seen: Image 92JB12, which we
have also stored under the name ASTWEST. It was taken by
Dr. Laurence Marschall using a 0.8m diameter telescope at
the National Undergraduate Research Observatory in
Flagstaff, Arizona. The other image ASTEAST was taken by
Dr. Thomas Balonek using an 0.4 m telescope at the Foggy
Bottom Observatory of Colgate University in Hamilton, New
York.
D
1992JB
Nuro
Colgate
DQ
Time of Observation at Both Sites
06 57 00UT 23 May, 1992
Site
Latitude
Longitude
Image File
Exposure
Foggy Bottom Observa tory,
Colgate University
Hamilton, NY
42° 48' 59.1"
W 75° 31'59.2"
ASTEAST
120
National Undergraduate
Research Observatory
Flagstaff, AZ
(Tele sc ope Operated byLowell Observatory)
35° 05' 48.6"
W111° 32' 09.3"
ASTWEST
120
Because the asteroid is much closer than the stars, it appears in a different position on the two images with respect to the
background stars. This is called its parallax. By measuring the position with respect to reference stars on both pictures,
we can determine the parallax, which is just the angular difference, , in arc seconds, between its position on the image
taken from the eastern site and from the western site. Using simple trigonometry (see Figure 7 as the example), if B, the
baseline, is the distance between the two telescope sites in kilometers, then :
Using our program, then, the measurements can be done rather quickly.
Dq
(
)
Dist of the Asteroid
.
,
= 206 265
BDq
Figure 14
Parallax Observations
1992JB
