In the ESA-MUSICOS spectrograph servicing mission in November 1996, some major
improvements have been realized:
Bernard Foing and Eric Stempels inspecting the fibre interface
below the A&G box
- Using a new fibre, the throughput in the red (above 6500 Å) was improved considerably.
- We have commissioned a new wavelength setting, ranging from 4300 to 9800 Å. This large wavelength range is obtained by using the lesser dispersing prism in the red range. Orders are more packed than before, but the small CCD pixel size still allows reduction. It should be noted that this large wavelength coverage can only be realized by making changes to the optical setting of the spectrograph and is not a common operating mode.
The former setting with two wavelength ranges spanning 3800 to 5800 Å and 5500 to 8800 Å is proposed as a standard mode of operation. Switching
between these two settings can be done by flipping a switch in the INT control room.
- The fibre mount under the IDS slit assembly has been tightened, making the
alignment more robust.
- Dekker slides with holes and transparencies were commissioned, making acquisition and alignment much easier.
- The focus of the spectrograph has been improved, yielding a higher resolving power of above 32000. This resolution is nicely matched by the pixel size of the TEK CCD.
- Two flat non-essential glass surfaces were removed from the camera objective. This slightly improved the throughput, and avoids ghosting due to reflection of red light off the TEK detector.
The MUSICOS spectrograph with Eric Stempels and Bernard Foing
The November 1996 MUSICOS servicing was done by Eric Stempels
(Leiden Observatory) and Bernard Foing (ESA/SSD) with local ING
support of John Telting and Nic Walton and other members of ING staff.
Afterwards, observations were conducted with Joana Oliveira (ESA/SSD) and Jeroen
de Jong (University of Amsterdam) as part of the world-wide MUSICOS 96
campaign. The science objectives of the MUSICOS 96 campaign include
Doppler-imaging of a T Tauri star, winds and magnetic structures in Herbig-Ae
and O-type stars and Non-Radial Pulsations in a delta Scuti star.