16.2 The Proper Motion of Asteroids
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16.2.2 Planning
Using the Minor Planet Centre (MPC) website http://www.minorplanetcenter.net/
iau/MPEph/MPEph.html, you should identify an asteroid at or near opposition that
is bright enough and in the right position to be observed. You should download the
ephemeris for this target to be sure that you have the position for the days and time
you will be observing. Create finder charts for each night as usual.
16.2.3 Observing
• On each night of observing, cool the camera as usual and start up the telescope.
As we are undertaking astrometry, we don’t need dark or bias frames.
• Move the telescope to a bright star, focus up, and ensure that the pointing is good.
Make any adjustments as needed.
• Move to the target (make sure you have the right RA and Dec for that night)
and take a short image, using your finder chart to ensure that you are in the right
location.
• Take several longer-exposure images to ensure that your stars in the image have
Gaussian PSF.
• Plate solve the images, using either a local program such as Pinpoint or an online
program such as astrometry.net.
• Save your images to a portable medium and shut down the observatory.
16.2.4 Reduction and Analysis
You will need to open your images in pairs is SAO DS9 with tiled frames and then
blink the frame so you can identify the object.
• Open DS9 and from the frame menu select Tile Frame and then New Frame.
• Click on the left-hand frame, and from the file menu select Open and open your
first image. Select the right-hand tile and load your second image into it.
• You will now have two FITS images displayed. On each tile, in turn, select Zoom
Fit to Window and then scale 99.5%.
• From the frame menu select frame match WCS. This will orient the two frames
so that they match. You should have some like those displayed in Fig. 16.1.
• Select Frame Blink, and the two frames will be displayed alternately every half
second. Your object should be seen moving against the background stars.
• Make a note of its location in each frame. Repeat the procedure for all your frames
until you have located the asteroid in all your images.
219
16.2.2 Planning
Using the Minor Planet Centre (MPC) website http://www.minorplanetcenter.net/
iau/MPEph/MPEph.html, you should identify an asteroid at or near opposition that
is bright enough and in the right position to be observed. You should download the
ephemeris for this target to be sure that you have the position for the days and time
you will be observing. Create finder charts for each night as usual.
16.2.3 Observing
• On each night of observing, cool the camera as usual and start up the telescope.
As we are undertaking astrometry, we don’t need dark or bias frames.
• Move the telescope to a bright star, focus up, and ensure that the pointing is good.
Make any adjustments as needed.
• Move to the target (make sure you have the right RA and Dec for that night)
and take a short image, using your finder chart to ensure that you are in the right
location.
• Take several longer-exposure images to ensure that your stars in the image have
Gaussian PSF.
• Plate solve the images, using either a local program such as Pinpoint or an online
program such as astrometry.net.
• Save your images to a portable medium and shut down the observatory.
16.2.4 Reduction and Analysis
You will need to open your images in pairs is SAO DS9 with tiled frames and then
blink the frame so you can identify the object.
• Open DS9 and from the frame menu select Tile Frame and then New Frame.
• Click on the left-hand frame, and from the file menu select Open and open your
first image. Select the right-hand tile and load your second image into it.
• You will now have two FITS images displayed. On each tile, in turn, select Zoom
Fit to Window and then scale 99.5%.
• From the frame menu select frame match WCS. This will orient the two frames
so that they match. You should have some like those displayed in Fig. 16.1.
• Select Frame Blink, and the two frames will be displayed alternately every half
second. Your object should be seen moving against the background stars.
• Make a note of its location in each frame. Repeat the procedure for all your frames
until you have located the asteroid in all your images.