First Astronomical Light with TIMMI2, ESO's 2nd-Generation Thermal Infrared Multimode Instrument at the La Silla 3.6-m Telescope
TIMMI, featuring a 64 × 64 gallium doped silicon array and mostly ger-manium refractive optics inside a solid-nitrogen/liquid-helium dewar, was in constant use until its decommission-ing in 1999 (cf. Stecklum et al. 1999). By then, the development of detectors had progressed so rapidly, that the instrument no longer appeared competitive. In fact, in 1993 ESO joined a consortium of French institutes to develop, based on the array used e.g. in TIMMI, a next-generation device (cf. e.g. Lucas et al. 1994). Already the format of this device (128 × 192 pixel) suggested that it would be desirable to build a new camera, rather than trying to use the new device in the existing setup. Even larger arrays were announced by US suppliers. To that end ESO had developed some basic ideas for the optics of a next-generation instrument for the La Silla 3.6-m telescope (cf. Käufl & De-labre, 1994). As a result of the La Silla 2000 questionnaire (see Anderson 1994) in The Messenger 78, ESO received a proposal from the A s t r o p h y s i k a l i s c h e s Institut und Sternwarte of the Friedrich-S c h i l l e r-Universität (FSU) in Jena, Germany, to build TIMMI2. This proposal , reflecting ESO's optical concept, was based on a modern cryostat cooled by a Closed Cycle Expansion Cooler Machine and was also featuring a polarimetric option (not available in TIMMI). Personnel cost and capital investments could largely be covered by funds raised by the Institute in Jena. The PI in Jena was Hans-Georg Reimann. After some negotiations , a Memorandum of Understanding was signed and the work began in early 1996. The design sketch of ESO (see above) was first transformed into a FEM 1 certified conceptual design, both for the optics and mechanics, by the company Jena-Optronik GmbH. Based on this work, the final design and the detail design of the instrument were done at the physics department of the FSU. To the extent that this was feasible, all mechanical parts were manufactured in the workshops of the FSU. In the course of the project, the group at the FSU could enlist a team from the Sternwarte der Universität Wien f o r
Image quality of the 3.6-m telescope (Part VI). Now diffraction limited at 10 microns at the f/35 focus.
The images at the f/35 Cassegrain focus of the 3.6-m telescope have never been excellent. As the system (c.f. [1]) was initially installed and used to do only aperture photometry, this was never an issue of major concern. In fact, it could not even be measured directly. Only with the advent of mid-infrared cameras (here TIMMI [2],[3]) the image quality could be measured easily and systematically. Several reports state that the avEMMI is now working smoothly and reliably. Through a well-deserved recognition of his merits, Pierre has now been hired as staff astronomer at the CanadaFrance-Hawaii Telescope. I take advantage of this occasion to welcome the newcomers, and to wish success in their new activitities to those who have left us. Erratum
Immersion grating for infrared astronomy.
An immersion grating with high refractive index n increases spectral resolution n-fold over that of a surface reflection grating of equal length.