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8 Imaging
8.9.3 Observing
1. It is best to turn up at the observatory well before the transit is due so that you
can make sure that everything is set up and that you are in focus and pointing
correctly.
2. Start imaging your target about 15 min before the event is due, but there is no
need to record at this point. Remember that you will be unable to autoguide the
telescope, and even with tracking on, the target will move in the field. Hence, you
will need to track the target manually.
3. You should see the two bodies involved in the occultation or transit in the frame
and be able to make a reasonable judgment as to how close you are to the event
occurring. Start recording when you think you are about 10 min from the transit.
Make a careful note of when you started recording. Try to determine accuracy to
about a second and the frame rate at which the camera is running. Depending on
your object, the event could be delayed by as much as an hour from that reported
by Stellarium.
4. Once you are happy that you have captured the event you wished to observe, stop
and save the video file. Back it up and transfer it to another medium for removal
from the camera control computer before shutting the observatory down.
8.9.4 Analysis
1. Using the video file, play the video until the moment that the transit or occultation
occurs. You might need to rewind and play the video a number of times in order
to identify the frame number.
2. Dividing the frame number by the frame rate gives the number of seconds after
recording started that the event occurred. using your starting time and this figure,
along with the uncorrected time and distance from Stellarium, you can calculate
the speed of light.
3. As with previous practicals, you should write up your report in standard laboratory
style. You should include notes about the camera and software used in addition
to any problems you may have encountered. You should also include details of
your preparation, especially details concerning the occultation or eclipse and
its expected, ucorrected, predicted time. Pay special attention to how your result
compares to other more modern methods of determining c, what your uncertainties
are, where they come from, and what you would do differently if you were to repeat
this experiment.
8 Imaging
8.9.3 Observing
1. It is best to turn up at the observatory well before the transit is due so that you
can make sure that everything is set up and that you are in focus and pointing
correctly.
2. Start imaging your target about 15 min before the event is due, but there is no
need to record at this point. Remember that you will be unable to autoguide the
telescope, and even with tracking on, the target will move in the field. Hence, you
will need to track the target manually.
3. You should see the two bodies involved in the occultation or transit in the frame
and be able to make a reasonable judgment as to how close you are to the event
occurring. Start recording when you think you are about 10 min from the transit.
Make a careful note of when you started recording. Try to determine accuracy to
about a second and the frame rate at which the camera is running. Depending on
your object, the event could be delayed by as much as an hour from that reported
by Stellarium.
4. Once you are happy that you have captured the event you wished to observe, stop
and save the video file. Back it up and transfer it to another medium for removal
from the camera control computer before shutting the observatory down.
8.9.4 Analysis
1. Using the video file, play the video until the moment that the transit or occultation
occurs. You might need to rewind and play the video a number of times in order
to identify the frame number.
2. Dividing the frame number by the frame rate gives the number of seconds after
recording started that the event occurred. using your starting time and this figure,
along with the uncorrected time and distance from Stellarium, you can calculate
the speed of light.
3. As with previous practicals, you should write up your report in standard laboratory
style. You should include notes about the camera and software used in addition
to any problems you may have encountered. You should also include details of
your preparation, especially details concerning the occultation or eclipse and
its expected, ucorrected, predicted time. Pay special attention to how your result
compares to other more modern methods of determining c, what your uncertainties
are, where they come from, and what you would do differently if you were to repeat
this experiment.