The Parallax of Asteroid 2000 QW7

On the night of September 5/6, 2000, astronomers at RIT and the US Naval Academy joined forces to observe the asteroid 2000 QW7. Simultaneous observations from the two sites reveal an apparent shift in the position of the asteroid: parallax. If one knows the distance between the observing sites, one can use this shift to calculate the distance to the asteroid.

Observations at RIT

The RIT Observatory is located in Rochester, New York, at latitude 43.0747 degrees North, longitude 77.6644 degrees West. Astronomers Michael Richmond, Tracy Davis and Stacey Davis used a Meade 10-inch telescope (at f/6.3) and Pictor 416 CCD camera (without filter) to take 30-second exposures of asteroid 2000 QW7. Here are several of their pictures. In all cases, North is up, East to the right, and the field of view is about 15 x 10 arcminutes. The pictures are centered near RA = 01:40:46, Dec = -03:44:26 (J2000). The bright star near middle bottom has magnitude R=12.2, and the fainter star immediately to its right R=14.0.

Image29: a 30-second exposure starting at 04:34:00 UT.

Image37: a 30-second exposure starting at 04:50:00 UT.

Image43: a 30-second exposure starting at 05:02:00 UT.

Can you spot the asteroid in the pictures above? Perhaps it will be obvious if you "blink" the pictures. Click on this link to blink.

You can download these images in 16-bit integer FITS format. If your browser tries to display the image data when you left-click on the links below, try right-clicking and choosing the "Save" option.


Observations at the US Naval Academy

Deborah Katz-Stone and midshipmen Brooke Massie and Aaron Fielder observed 2000 QW7 at the Michelson Observatory on the grounds of the US Naval Academy in Annapolis, Maryland (latitude 76.49 degrees West of Greenwich, latitude ?? North). They used a DFM 20-inch f/11 telescope with CCD camera to take 30-second exposures of the asteroid. Here's one of their images, taken at 04:34 UT: the orientation is the same as that in the RIT pictures (North up, East left), but the field is somewhat larger.

You can see from blinking a set of USNA pictures that the asteroid is visible in these images, too.


Parallax -- another point of view

If one compares two images of the asteroid, taken at exactly the same time at each observatory, one finds a shift in its position relative to the stars. In the pair below, each taken at 04:34 UT, the first is from RIT, the second from USNA:

Try blinking these two images and watch the asteroid (near the center of each picture) closely.