A brief history is presented of the Bosscha Observatory in the 1950s, when the plans for a Schmidt telescope in Lembang materialized.

The implementation of CCDs on Schmidt telescopes is discussed, including the capabilities of such systems and the new types of observations that they facilitate. An analysis of the demand for and use of the CCD system on the Burrell Schmidt is presented. Some examples of scientific investigations accomplished with Schmidt CCD systems are given. The future evolution of CCD capabilities on Schmidt telescopes is discussed.

Current users only use CCDs to cover a small fraction of the Schmidt fields. We discuss what kind of Schmidt astronomy is more efficient and the advantages of Schmidt telescopes over reflecting telescopes. The BAO CCD multi-object light curve survey system and the BATC 15 colour survey are introduced.

We report on the status of the CCD cameras for the Kiso 105-cm Schmidt telescope. We have two types of cameras – single-chip and mosaic. The single-chip camera is available for common use. At present about 90 % of the telescope time is allocated to observations with CCD cameras.

A wide field CCD camera has been developed for asteroid searches and has been used at our Schmidt telescope since September 1993. This paper describes this camera and its software as well as the changes it introduced in the type of programs that were requested on the telescope, and changes introduced in the way the telescope is operated.

The Automated Patrol Telescope (APT) is a wide-field CCD imaging telescope operated by the University of New South Wales at Siding Spring Observatory in Australia. The optical design employed resembles that of a Schmidt, but uses a 3-element lens to achieve a wide, corrected field of view. The APT was developed by extensively modifying the optical, mechanical and electronic systems of a Baker-Nunn satellite tracking camera. Telescope motion and operation of the CCD have been placed under computer control, allowing automated observations for longterm survey and monitoring projects. The APT has 0.5 m aperture f/1 optics which produce a 5° flat field, of which a 2°×3° field is covered by the CCD currently installed. The telescope is being used for studies of stellar activity in open clusters and regions of star formation, and comet and minor planet investigations. A number of other projects for the APT are being considered, including searches for novae, supernovae in clusters of galaxies, and brown dwarfs.

We have carried out imaging observations in the near-infrared (J, H and K’ band) with a large format array camera attached to the prime focus of the 105 cm Schmidt telescope at Kiso Observatory. The image resolution, limiting magnitudes and effect of thermal radiation are presented, based on observations of nearby galaxies. Considering the results, we are constructing a new larger near-infrared camera optimized for use with the Kiso Schmidt.

A multi-object camera for the Tautenburg Schmidt Telescope (134/200/400) was developed and constructed in cooperation with the Max-Planck-Institut für Astronomie in Heidelberg and the Thüringer Landesstemwarte Tautenburg. The experience with the “Spaltspinne” for the 3.5 m Telescope of the Calar Alto Observatory (Pitz 1993) was the foundation of TAUMOK. The technical concept was given by Pitz et al. (1993).

Thirty six rods controlled by a processor can be moved in an area with a diameter of 16 cm. This area covers a field of 2.3° in the focal plane which is flattened by a plano-convex lens. Each of 34 rods carry two fibres with diameters of 100/µm with one fibre for the object and another for the background light. The fibres have a length of 7 m and their opposite faces form the entrance slit of a spectrograph. At present, reciprocal dispersions of 3.4, 10, 20 and 40 nm/mm can be realized. A CCD camera with a chip-size of 1152 × 770 pixels (pixel size 22.5/µm) is used as detector. Two of the 36 rods are equipped with image bundles for telescope guiding.

The University of Michigan’s Curtis Schmidt Telescope at CTIO has recently been equipped for CCD imaging at the Newtonian focus. A review is presented of the current status of this telescope, future upgrades, and some of the science being conducted.

From the middle of 1993, a ST-6 CCD Camera (375 × 242 array with 23 × 27 microns pixel size) was mounted at the Newtonian focus (f/3) of the 70 cm meniscus telescope of the Abastumani Observatory. The photometer is now equipped with various sets of narrow-band interference, intermediate and wide band standard niters. Some pilot observations were carried out in direct imaging mode and in combination with an 8° objective prism (166 Å mm−1 at Hγ). Spectrophotometric standard stars with absolute calibrations were observed in the 8° mode to determine the CCD spectral response. Some other observations were performed with a prism-interference filter combination to estimate the observational mode efficiency.

The use of Schmidt telescopes in their traditional mode for the detection of stellar flares and for the UV and PG photometry of these stars proved to be very productive. The fast optical system and reliable sensitivity of modern photographic emulsions resulted in a photometric time-resolution of several minutes even in the case of distant objects. One of the most important characteristics of flare stars may be the tendency for coexistence with more massive and more luminous member stars of young stellar aggregates (mainly open clusters). Although the vast majority of flare stars discovered seem to belong to clusters, a great many of them are neighbours of our sun. These can be investigated in depth because a sufficient number of their photons can be collected and recorded in narrow photometric bands or even in spectra of good resolution. The direct comparison of solar vicinity flare stars with flare-active members of distant clusters has been almost impossible. However recent developments in silicon-based photon-detecting technology offer the advantage of incredibly high detector quantum efficiency (DQE) in many spectral regions where photographic materials never reached an acceptable level. Hα emission is one of the most characteristic features of flare stars, and the wavelength of Hα photons fits extremely well with the peak of the spectral sensitivity curves of silicon photon detectors. CCD chips placed in the focal surface of Schmidt telescopes seem to be very promising for the future investigation of Hα emission of flare stars.

The Schmidt telescope (360/333/625 mm) of the Abastumani Observatory is used for photographic observations. It provides a field of 7.3° (80 mm) and a non-vignetted field of 4° (44 mm). For an astronomic film of medium sensitivity (DIN 20, ASA 70) the limiting exposure time is 7–8 m and the limiting magnitude is 16.5. For fine grain emulsions, a 15 m exposure time provides the limiting magnitude of 18.0. Since 1961 systematic photographic (mainly photovisual) observations have been carried out, within the International Cooperation Program of the Supernova Patrol in the direction of 24 selected fields. During a night an average of 10 exposures are taken. About 10,000 exposures have been obtained up to now and 30 Supernovae discovered, of which 10 were first identified in Abastumani (Chuadze 1967; Kimeridze 1971, 1979; Kimeridze et al. 1984, 1988, 1989a, b) In parallel with the patrol observations, photovisual and photographic (sometimes UBV) photometry was performed for 9 discovered Supernovae. The observations are still continuing.

Large Schmidt telescopes are peculiarly well-suited to multifibre spectroscopy. The extent to which the small aperture is compensated by the wide field is illustrated by the fact that the total photon throughput of the 1.2 m UK Schmidt Telescope (UKST) is almost identical to that of the 3.9 m Anglo-Australian Telescope (AAT) in its new 2-degree field (2dF) mode. In the implementation of the technique, Schmidt telescopes have a number of practical advantages, while there is no shortage of scientific problems that can be addressed. However, the instrumentation required to capitalize fully on this potential is costly and, because Schmidts are perceived as “small” telescopes with a specialist following, the required funding is likely to remain elusive.