A 20 cm2 CCD mosaic camera for a dark matter search part I : Mechanics,optics and cryogeny

A 20cm ² CCD mosaic camera has been especially built to search for dark galactic halo objects by the gravitational microlensing effect. The sensitive area is made of 16 edge-buttable CCDs developped by Thomson-CTS, with 23×23 µm ² pixels. The 35 kg camera housing and mechanical equipment is presented. The associated electronics and data acquisition system are described in a separate paper. The camera resides at the focal plane of a 40 cm, f/10, Ferson reflector. The instrument has been in operation since December 1991 at the La Silla Observatory (ESO).     

A 20cm 2 CCD mosaic camera for a dark matter search part II : Electronics,data acquisition and performance

Conclusion To summarize, the readout and the control system of the CCD mosaic camera are running since December 1991 at the La Silla Observatory (ESO). The overall performance of the camera has been good. About 12000 pictures (data and flat-fields) have been successfully registered up to now. We will report in the near future preliminary scientific results of the EROS experiment.     

The fiberless multislit spectrograph SFM

We describe the multislit spectrograph SFM. It is designed to obtain simultaneously spectrograms of faint objects over a field of 10 arcminutes for an entrance aperture ratio f/10, or of 15 arcmin for f/8. The SFM makes the dispersed image of the entrance slits directly, without any fiber optics. The number of entrance slits can be as large as a few hundreds, depending on the distribution of the sources on the sky and on the wavelength range. The present reciprocal dispersion is 79Åmm^–1 in the wavelength range 3600 – 6400Å. The SFM is expected to reachm _v22 with a signal to noise ratio of 10 for a spectral resolution of 3.3Å and an integration time of 5 hours, when used with the photon counting detector CP40.Radial velocities can be measured either by using calibration spectrograms or by the objective prism technique.The mask of entrance slits is made photochemically from a plate previously recorded of the field to be observed, taken during the same observing run. The auxiliary equipment Mascograph, specially designed for this purpose, is described.First spectrograms in the field of M15 obtained with the SFM using the Calar-Alto 3.50m telescope are presented.Based on observations collected at the Calar-Alto 3.5m telescope, operated by the German MPIfA (Heidelberg), and at the 3.60m CFHT, operated jointly by the Canadian SRC, the French CNRS and the University of Hawaii