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
TIMMI, ESO’s new 10 μm camera/spectrometer☆
Abstract TIMMI stands for Thermal Infrared Multi Mode Instrument. TIMMI allows for imaging (at present 16 filters available) with variable magnifications as well as limited long-slit spectroscopy in the l0 μm atmospheric window. The instrument was built by the Service d'Astrophysique (SAP) according to ESO's specification in a period of 2 years. At the telescope the instrument is using the ƒ35 chopping configuration in conjunction with the special adaptor unit. TIMMI control and primary data-acquisition is performed by an VME-based computer (under OS9) while final data storage and online data processing with ESO's image processing system MIDAS is done using an UNIX workstation. While TIMMI will provide new observational possibilities for the ESO users community it is also supposed to become a test-bed to gain experience for similar instrumentation at the VLT.
X-rays and photocarcinogenesis in hairless mice
It is well known that excessive X-ray radiation can cause non-melanoma skin cancers. With the increased incidence of sun-related skin cancer there is a need to investigate the combination of sunlight and X-rays. Immunocompetent C3.Cg/TifBomTac mice (n = 298) were divided into 12 groups. Mice were irradiated with 12, 29 or 50 kV X-rays. The mice received a total dose of 45 Gy. They were irradiated with 3 SED simulated solar radiation (SSR) either before or after irradiation with X-rays. The groups irradiated with X-rays alone, 0, 3, 9 and 10 mice (0, 12, 29 and 50 kV, respectively) developed squamous cell carcinoma. In the groups irradiated with SSR after X-rays the development of tumours was significantly faster in the 50 kV group than in the corresponding control group (175 vs. 194 days, p < 0.001). In the groups irradiated with SSR prior to the X-ray radiation the development of tumours was significantly faster in the 29 and the 50 kV groups than in the corresponding control group (175 vs. 202 days, p < 0.001 and 158 vs. 202 days, p < 0.001, respectively). In conclusion, X-ray radiation alone is a weak carcinogen in hairless mice. There is an added carcinogenic effect if X-ray radiation is given on prior sun-exposed skin or if the skin is sun-exposed after X-rays. We still believe that X-ray radiation is a safe and effective therapy for various dermatological diseases but caution should be observed if a patient has severely sun-damaged skin or has a high-risk sun behaviour.