Brief summary of Klet photographic search programme for minor planets

J. Ticha, M. Tichy, Z. Moravec
Klet' Observatory, Zatkovo nabrezi 4, CZ-370 01 Ceske Budejovice, Czech Republic, e-mail : klet@klet.cz
August 23, 1998

Abstract A long-term photographic search programme for minor planets was begun at the Klet' Observatory at the end of seventies using a 0.63-m Maksutov telescope, but with insufficient respect for long-arc follow-up astrometry. More than two thousand provisional designations were given to new Klet' discoveries. Since 1993 targeted follow-up astrometry of Klet' candidates has been performed with a 0.57-m reflector equipped with a CCD camera, and reliable orbits for many previous Klet' discoveries have been determined. The photographic programme results in more than 350 numbered minor planets credited to Klet', one of the world's most profilic discovery sites. Nearly 50 per cent of them were numbered as a consequence of CCD follow-up observations since 1994.
This brief summary describes the results of this Klet' photographic minor planet survey between 1977 and 1996. The majority of the Klet' photographic discoveries are main belt asteroids, but two Amor type asteroids and one Trojan have been found.

Key words: minor planets - survey - discovery - astrometry

1. Searching

Telescope

0.63-m f/3 Maksutov telescope has been used
the field of view is nearly 20 square degrees
the limiting magnitude of moving objects is 16.2^m - 16.9^m

Searching strategy

ORWO ZU-21 or KODAK 103a-O plates
double exposure of 20 and 20 minutes, 3 arcminutes shift in the declination
plate microscope
in the course of this Klet' survey nearly 5000 plates have been obtained from 1977 to 1996
the majority of them cover fields within 10 degrees of the ecliptic and were taken near the opposition point
the minor planet discovery frequency by months shows a first maximum in February and March and the main maximum (more than twice as high) in August, September and October

2. Follow-up

The Klet' photographic survey brought hundreds of new discoveries credited to Klet' since 1977, but without an aim to improve their orbits. Since 1992 substantial modifications of observational techniques and subsequent methods were made. In the framework of these improvements we have started in 1994 targeted follow-up astrometry of minor planets with provisional designations credited to Klet' using:

0.57-m f/5.2 reflector equipped with CCD camera SBIG ST-6, replaced by SBIG ST-8 in 1996
Klet' software library for reduction of CCD images, identification of stars with GSC and USNO-SA1.0 catalogues, determination of equatorial coordinates and magnitude of objects, residual calculation, identification of known minor planets and comets, ephemeris calculation, preliminary orbital elements calculation
Klet' minor planet catalog, which contains information about orbital elements and discovery circumstances

From the beginning of 1994 to 1998 August 176 minor planets received permanent numbers as a result of CCD follow-up astrometry at Klet'. This indicates that nearly 50 per cent of all Klet' numbered discoveries obtained reliable orbits during last five years.

This work has contributed to the improvement of the orbital solutions of Klet' discoveries and have helped us to complete the results of Klet' photographic search programme. Further astrometric observations at further oppositions are necessary for the rest of the Klet' unnumbered discoveries. Moreover, some discoveries were also made by chance on CCD images (including high eccentricity asteroid 1998HZ₇, Mars crosser 1997AN₁₇, Trojans 1997TB₁₂ and 1997VB₁) in the course of this follow-up programme.

3. Results of Klet' photographic search programme

359 Klet' discoveries have been numbered up to this time (including 16 CCD discoveries which have been found in the course of follow-up astrometry of photographic discoveries)
Klet' Observatory ranks in sixth place among the world's most prolific discovery sites (together with Siding Spring)
the majority of these Klet' discoveries are of main-belt asteroids
- semi-major axis in the range of 2.2 - 3.3 AU
- eccentricity <= 0.3
- inclination <= 20 degrees
several interesting discoveries were made
- Amor-type asteroids (3102) Krok, (5797) Bivoj
- Trojan asteroid (3451) Mentor
- Hilda asteroids (3571) Milanstefanik, (4317) Garibaldi
- Hungaria asteroids (3022) Dobermann, (4142) Dersu-Uzala
- higher inclination asteroids (2544) Gubarev, (2696) Magion, (7498) Blanik, (7695) Premysl
the majority of discoveries have absolute magnitude H in the range of 12.0^m -14.5^m. The largest object, with H=8.1^m, is the Trojan (3451) Mentor, and the smallest object with H=19.1^m is the Amor type (5797) Bivoj.
there are 132 unnumbered Klet' discoveries with multiple-opposition orbits and 104 unnumbered Klet' discoveries with one-opposition orbits observed over arcs longer than 30 days

Acknowledgements.
This work has been supported by the Grant Agency of the Czech Republic No. 205/93/1296 and No. 205/96/0042.
The authors thank the observers and assistants who contributed to the Klet' photographic search programme untill 1991, mainly L. Brozek, J.Kveton, M. Mahrova, A. Mrkos, J. Prusova, R. Petrovicova, Z. Vavrova.

References

Minor Planet Center IAU, Minor Planet Discovery Sites, 1998, http://cfa-www.harvard.edu/cfa/ps/lists/MPDiscSites.html
Ticha, J., Tichy, M., Moravec, Z.:1995, Earth, Moon, Planets 68, 579
Ticha, J., Tichy, M., Moravec, Z.:1998, Planet. Space Sci.Vol. 46,No.8, pp.887-891

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