Saturday, July 19, 2014

PEPSI spectrograph is on Mt Graham!

PEPSI, the Potsdam Echelle Polarimetric and Spectroscopic Instrument, is a high-resolution echelle spectrograph with two polarimeters to be installed on the LBT.

In the works for many years at the Leibniz-Institute for Astrophysics Potsdam (AIP), the spectrograph made it finally to the mountain in early July.

 Three of the six containers used to transport the spectrograph and its enclosure are seen at the MGIO (Mount Graham International Observatory) base camp near Safford.

The spectrograph is not mounted on the telescope (it is much too big!) Instead, it is mounted on the first floor of the observatory inside the pier supporting the telescope.

The optical bench, freshly installed in the coudé room inside the pier.

The light is sent to the spectrograph through fibers which pick the light from the telescope at two permanently mounted focus units (one per LBT mirror) which have been installed on the telescope central platform, allowing the spectrograph to be permanently available for non-polarimetric spectroscopy. The observer will have a choice of using fibers of three different core diameters, giving resolutions of 32,000, 120,000 and 320,000.

The PFUs (Permanent Focus Units) feeding the spectrograph. Seen as white boxes on the bottom left and right of this picture from last November, the left one is already installed and the right one is being craned to position and secured to the telescope.

PEPSI will be available for science in its spectroscopic in a year or two from now, after months and months of reassembly and testing. You can see below some of the exciting science PEPSI will tackle.

- More information on PEPSI on its web site.
Members of the LBT community, if you are interested in eventually using PEPSI, you are welcome to read the presentation given at the recent LBTO Users' Meeting by Klaus Strassmeier, the Principal Investigator of the project, available here.