UCLES Slit Area & Iodine Cell

The Anglo-Australian Planet Search (AAPS) is a long-term program being carried out on the 3.9m Anglo-Australian Telescope (AAT) to search for giant planets around more than 240 nearby Solar-type stars with V<8. We use the "Doppler wobble" technique to search for these otherwise invisible extra-solar planets, and achieve the highest long-term precision demonstrated by any Southern Hemisphere planet search.

UCLES Slit Area - Automating the I2 cell

The I2 cell used to sit between SF1 (slit filter wheel 1) and the entrance to the UCLES spectrograph room. In order to mount it in this location, SF2 (slit filter wheel 2) was removed.

However in 2007, the cell was moved into another wheel in the optical train - the focal modifier wheel. This holds small optical elements in barrels which modify the f-ratio of the beam after the slit. This wheel used to hold just two sets of optics, and had 4 blank positions in it.

Modification of this wheel has allowed a new barrel to hold and insulate the cell, a mechanism to halt complete rotation of the wheel, and software effort to integrate with the UCLES ODC.

The insertion of the cell is now under control from the UCLES ODC interface. No more running up and down the stairs to insert and remove the cell when doing templates. Hooray!

The image to the left is a compressed view of the area behind the slit, but before light enters the UCLES spectrograph room. Click on the image for a larger view.


The view below is an expanded view of the focal modifier wheel itself.


Contact Information

•AAT Control Room +61 48 42 6279

•AAT FAX +61 68 84 2298

•AAT Co-ordinates

•Geodetic coordinates:

•Longitude = 149:03:57.91 = 9h56m15.861 East

•Lattitude = 31:16:37.34 South

•Altitude = 1164 m