We report on the results of CCD photometric observations of the open cluster NGC 2539. Eight new variable stars have been found in the observed field of this cluster. However, no γ Doradus-type variability was found among the member stars.

The goals, results and perspectives of the ongoing search for variables in open clusters and associations of the northern hemisphere, carried out at the Białków Observatory of the Wrocław University, are presented.

Results of a search for variable stars in the central region of the Oosterhoff II type globular cluster M92 are presented.

The present observational strategy of globular cluster variables does not favour long observational runs, which are needed to study the modulation properties of Blazhko type RR Lyrae stars. The only globular cluster for which we have enough data (both photographic and CCD) to determine modulation cycles of RRab stars is ω Centauri. Any connection between the modulation periods and other stellar or cluster parameters may serve as a new clue to the explanation of the Blazhko phenomenon.

We have developed and tested a new near infrared camera equipped with a 512 × 512 PtSi CCD and cooled by two independent Stirling Cycle refrigerators. The camera, installed on the 60 cm reflector telescope of the Nishi-Harima Astronomical Observatory (NHAO) since April 2000, has begun regular observations toward infrared objects. Since the reasonable cost and lower maintenance needs of the camera make it more attractive, we introduce it as an alternative to robotic telescopes.

The self-constructed Super-Light telescope of the National Central University is now ready for open use. Systematic studies of RR Lyraes stars and other variables are outlined and some preliminary results are introduced.

For more than a decade a small group of Astronomers has been monitoring variable stars of different types. In the present contribution I will present the observations of chromospheric active binaries and near contact binaries and the results obtained from their analysis.

The discovered population of Near Earth Objects (asteroids and comets) consists of more than 1,300 bodies. Small telescopes provided with a large field of view have played a major role in the field, contributing to the discovery of about 95% of the total known population. We present a brief summary of the steps that have led to the present knowledge and suggestions to improve it. A proposal for accessing archival images to search for previous apparitions is presented.

In 2000, Korea Astronomy Observatory launched the Near-Earth Object Patrol (NEOPAT) program. NEOPAT has conducted follow-up observations of NEOCP (NEO Confirmation Page) objects and discovered 52 new main-belt asteroids during the observation runs. We initiated collaboration with the Yonsei Survey Telescopes for Astronomical Research (YSTAR) team for NEO search. Wide-field of view, fast read-out time, and fully autonomous data pipeline will enable us to detect and track NEOs with a high efficiency. Scheduled to begin active operations in mid-2001, our survey system is going to be the first network of robotic telescopes for NEO search with automatic access to both hemispheres.

There are three wide-field telescopes at the Bisei Spaceguard Center operated by the Japan Spaceguard Association. These telescopes are dedicated to detect near-earth asteroids and produce several tera-byte data per month. Since these data contain many main-belt asteroids, we will use them for an education program that will allow school pupils and the general public to find new main-belt asteroids. We are now developing a new software for its purpose.

We have presented photometric results for two asteroids (895) Helio and (165) Loreley. The observations were performed from 2000 Oct. to 2001 Jan. using the 61cm telescope installed at Sobaeksan Optical Astronomy Observatory in Korea.

The purpose of the TAOS project is to directly measure the number of Kuiper Belt Objects (KBOs) down to the typical size of cometary nuclei (a few km). In contrast to the direct detection of reflected light from a KBO by a large telescope where its brightness falls off roughly as the fourth power of its distance to the sun, an occultation survey relies on the light from the background stars thus is much less sensitive to that distance. The probability of such occultation events is so low that we will need to conduct 100 billion measurements per year in order to detect the ten to four thousand occultation events expected. Three small (20 inch), fast (f/1.9), wide-field (3 square degrees) robotic telescopes, equipped with a 2,048 × 2,048 CCD camera, are being deployed in central Taiwan. They will automatically monitor 3,000 stars every clear night for several years and operate in a coincidence mode so that the sequence and timing of a possible occultation event can be distinguished from false alarms. More telescopes on a north-south baseline so as to measure the size of an occultating KBO may be later added into the telescope array. We also anticipate a lot of byproducts on stellar astronomy based on the large amount (10,000 giga-bytes/year) of photometry data to be generated by TAOS.

The goal of the Taiwan-America Occultation Survey (TAOS) project is to estimate directly the number of Kuiper Belt Objects (KBOs) by measuring the rate of stellar occultations. Occultations of distant stars may also be caused by asteroids and this article describes how both types of occultations can be distinguished on the basis of their shadow ground speed on Earth and the observing angle.

We study the possible humps or deviation from the single-power law for the size distribution of the Kuiper Belt Objects (KBOs). Both the current observational data and theoretical simulations show evidence of such humps. We conclude that this is an imprint of the depletion of the outer Solar System in the Kuiper Belt region.

The existence of a population of large planetoids outside the orbit of Neptune predicted by GP Kuiper, KE Edgeworth and JA Fernandez has been confirmed by ground-based observations.The physical properties of these Kuiper Belt Objects (KBOs) remain elusive. Photometric measurements have indicated that they have diverse color variations. A theoretical model is formulated to simulate the evolution of the surface materials of the KBOs under the influence of cosmic ray irradiation and meteoroid impacts. The long-term goal is to couple this theoretical model to observations and laboratory experiments such as LARA (Laboratory Astrochemistry and Astrophysics).

We have been monitoring comets using the 50-cm telescope at the Mitaka campus of the National Astronomical Observatory, Japan since 1996. Over 20 comets, including bright ones such as comet C/1995 O1(Hale-Bopp), have been observed over long-term periods, namely over large heliocentric distance scales. Our samples show variety of comets in terms of both morphological and temporal variations. Several typical examples of various morphology, probably due to dust, are shown to emphasize the importance of long-term monitoring of comets.

We present a simulation based on the morphology of the inner coma of comet Hale-Bopp(C/1995 O1) in February 1997. The synthetic images can fit the observations well, suggesting a simple spin mode. The rotation parameters, obliquity of orbital plane to equator and argument of subsolar meridian at perihelion, are 71 and 81 degrees respectively.

Comets are known to have a high (2-10 percent) polarization, caused mainly due to dust scattering and resonance fluorescence emission. Since near earth comets are generally bright (integrated visual magnitudes of 10 or even brighter) and as they show high polarization near earth-sun location, one can try to perform imaging polarimetry of such objects with small (40 cm or even smaller) telescopes. By using a dichroic polaroid sheet either in front of the telescope tube or before the imaging detector at the Cassegrain plane, one can record cometary images with a good signal to noise ratio. By rotating the dichroic sheet in three discrete steps and then reducing the corresponding three comet images to a single image, one can determine the linear polarization value at each pixel location on the image. The error in polarization will typically be the inverse of the ‘signal to noise ratio’. Such polarization images of a comet help us to determine its dust properties and also to look for possible dust jet activities. This type of work is possible with small telescopes and minor instruments.

Comet C/1999 S4 (LINEAR) with a maximum magnitude of 6 mag was the brightest comet in 2000. The 24” telescope on NCU campus was used to observe its coma behavior in June and July of 2000 as it approached perihelion. The observations were carried out using the comet filters designed by the European Space Agency for the ground-based observational program of Comet Wirtanen (target comet of the Rosetta mission). Comet C/1999 S4 (LINEAR) ended up disrupting into many small fragments near perihelion. We are in the process of analyzing the time variations of the cometary dust coma and dust tail to examine the physical condition prior to the destruction of the nucleus of this intriguing comet. An image processing method will be developed to trace small-scale structures in the dust tail.

We observed the Leonid meteor storm in 1998 and 1999. The light curves extracted from the 2-dimensional images of the bright Leonid meteors clearly show the sub-structures, which are consistent with the generally accepted dustball meteor model (Hawkes & Jones, 1975).