NEAR-EARTH OBJECT TRACKING. The Plaskett Tracking System
D. D. Balam*
Department of Physics and Astronomy, University of Victoria
*Guest Worker, Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada

 

INTRODUCTION

The Plaskett telescope is the largest telescope in the world that is used in a regular program of near-Earth object (NEO) follow-up astrometry, and the telescope is able to detect these objects long after they have faded from the grasp of other observers. Without this work, many of the near-Earth objects would be permanently lost.

The aim of the program is to provide rapid astrometric data for all newly-discovered objects that manifest unusual plane-of-sky motion and could be in close proximity to the Earth-Moon system. In addition, time is allocated for systematic observation of previously-discovered NEO in order to increase their respective observational arc-lengths and therefore to enhance the probability of recovery at subsequent apparitions. This is particularly important for those objects classed as `potentially-hazardous asteroids' (PHAs) as they possess a non-zero probability of impacting the Earth in the future.

Since the NEO discovery programs (Spacewatch, LINEAR, Catalina Sky Survey and LONEOS and NEAT) are now on-line it is not unusual to begin a night in the Plaskett dome with more than a dozen new NEO candidates to confirm and track. Dissemination of NEO discovery data and search ephemerides is accomplished on a daily basis by the Minor Planet Center of the International Astronomical Union via the world wide web NEO Confirmation page. In addition, collaborations are maintained with Spacewatch (University of Arizona), as the Plaskett telescope is well-suited to track the faint and fast objects found by this program, and with the Catalina Sky Survey (University of Arizona).

An overview of the NEO tracking system is presented here as well as the observational throughput for the period from 2000 January - September. The program has adapted to the ever-increasing discovery rate of NEOs by grouping target objects by several factors: minimum Earth orbit intersection distance, apparent magnitude, and rate of motion. Close communication is maintained with fellow observers, the Minor Planet Center and the Central Bureau for Astronomical Telegrams during the course of the program. The observational throughput is further illustrated by a list of IAU publications for the year 2000.

THE NEO TRACKING SYSTEM

The 1.82-m Plaskett telescope of the National Research Council of Canada has been the primary NEO tracking instrument for the past ten years. The Plaskett telescope has a 1.82-m parabolic mirror that feeds an f/5 light cone onto a diamond turned aluminum (optically flat) secondary mirror to illuminate a SITe-5 CCD detector that is mounted on a platform near the Newtonian focus. The SITe-5 detector is a thinned and backside illuminated 1K (1024 x 1024 pixels) CCD with excellent cosmetic quality. The pitch (size of the pixels) of the detector is 0.024 mm and physical size is 24.58 mm % 24.58 mm. The field of view is 560² % 560² (9'.3 % 9'.3). The SITe-5 has a readout noise of 11 electrons and gain of 4.13 electrons/ADU. Quantum efficiency is better than 80% at 700 nanometres wavelength (R filter) and about 70% at 400 nanometres. Typical limiting magnitudes in (Johnson) R band imagery, obtained in ‘stare’ mode, are between R = 20.5 to 20.8. Co-addition of images using the ‘dynamic shift and stack’, i.e. motion-compensated images, has allowed the detection of rapidly moving objects as faint as R = 21.8 (2 sigma detection). The Plaskett telescope was closed for seismic upgrading on Oct. 01 and will not be re-commissioned until Feb. 01, 2001. While the Plaskett telescope has been closed the NRC has replaced the liquid nitrogen cooling system of the SITe-5 CCD detector with an efficient ‘cryo-tiger’ system that will obviate thermal-cycling of the detector and ensure that the detector is stable. In addition, a new optically flat secondary mirror has been ordered to replace the diamond-turned aluminum mirror that has been in use since 1991. It is expected that the new secondary will allow the detection of objects a magnitude or more fainter than the current limit.

Telescope positioning and data acquisition are controlled from a Sparc work station situated in the control room via the DICE (DAO Instrument Control Environment) software. The system has been augmented with a DICE-TCS (telescope control system) graphical user interface that allows the observer to move the telescope using a file of positions. Positioning the telescope on rapidly-moving NEOs is accomplished using an instantaneous ephemeris generator that updates the target positions every 20 seconds. The operator chooses the target object from a list on the DICE-TCS screen, highlights the appropriate line in the file, and the telescope slews to the position. The orbital data for the target objects are maintained daily from the Minor Planet Center and from internal orbital analysis routines. The target acquisition mode is determined by the objects predicted apparent brightness and rate of motion. The effective exposure duration is determined by the nightly FWHM (full width half maximum) of a stellar point-spread function (PSF) that is divided by the target objects (sky plane) rate of motion in arc seconds/second. For example, if the nightly ‘seeing’ is 2².3 FWHM and the target asteroid is moving at a rate of 180 arc seconds/hr (3²/sec) then the object will subtend the ‘seeing-disk’ in 46 seconds. If the object is bright enough for detection using the effective exposure length then a series (3-5) of ‘stare’ images are obtained in rapid succession. Faint and fast-moving objects require motion compensation to allow enough flux to be detected within their seeing-disks. Object motion compensation on the Plaskett system is done using an IRAF routine (DSS_DAO) that first aligns a series of images (at the sub-pixel level) and then shifts each image according to a user supplied rate of motion and position angle. The routine reads the (UT) mid-time of observation of each image, and the interval between the timing of the first image and image N, and shifts each image to maximize the flux within the seeing disk at the position corresponding to the first image. The series of images is then co-added and the background star images become trails (FIGURE 1).

FIGURE 1. Motion-compensated (DSS) images of the Apollo asteroid 1998 SC15. The object is a potentially-hazardous asteroid that may approach the Earth to within 0.001 AU (half lunar distance). These images were obtained 244 days post-discovery when the asteroid was apparent magnitude V = 20.3 and moving at 90² /hour. The time interval between the left and right image is 11 minutes and the asteroid has moved 16² . Each image is the co-addition of six 100 second exposures obtained in rapid succession.

Pre-processing of the CCD images is done as each (object) frame is written to the hard drive in the dome control room. The bias (DC offset) is subtracted from each image using 9-30 zero exposure duration images, obtained at the beginning of each night, and combined with a median filter. Pixel to pixel variation of the detector is corrected using 3-9 twilight sky exposures (per filter) that have been scaled and median filtered together into a master flat-field image. Each object frame is then bias-subtracted and divided by the flat-field and written to the hard disk of the program (tracking) computer.

The final step of the pre-processing involves the astrometric calibration of each science frame using NEURAL_DAO. First, NEURAL reads the (image centre) RA, Dec and Epoch keywords from the image header and precesses the coordinates to J2000. The image is then subjected to a point-source detection routine and a list of the X,Y and instrumental magnitudes of all detected objects is written to a temporary file. The brightest 100 stars are then sorted and the results are used as the input coordinate list for a centroiding routine (CENTER_DIGIPHOT). Simultaneously, the USNO-A2.0 astrometric catalogue (stored on one of the hard drives of the program computer), containing 526,280,881 standard stars, is searched for all stars that fall upon the area of the detector and a second temporary list is constructed of (J2000) RA, Dec and predicted image pixel coordinates. The image and lists are then subjected to a process of cross-correlation and iterative plate-constants solutions until the true image centre coordinates are determined. The results are then written to the image header in the form of an initial world-coordinate system (WCS) containing the RA and DEC keywords and the linear portion of the plate-constants solution. Thus far, we have been concerned with defining the true image centre, as few telescopes point to an accuracy of a few seconds of arc. Finally, the USNO catalogue is read again and the equatorial and predicted pixel coordinates are piped to a temporary file. The predicted pixel coordinates are used by CENTER_DIGIPHOT as initial positions for 2-dimensional Gaussian fitting and the results replace the predicted (pixel) positions. The matched list of celestial and pixel coordinates, of all available stars, is used to calculate a plate solution using a gnomic (tangential) projection geometry including non-linear (distortion) terms. The observed minus calculated residuals of the plate solution are graphically displayed, in the form of four plots (x vs xy and h vs xy) on the tracking screen and the observer can delete bad measurements and re-fit the data. In addition, a sigma-clipping algorithm is included and the process can proceed autonomously. The operator has the option of visually checking the field indentification via a graphical overlay of the catalogue upon the image, although this is generally not necessary. An example of the tracking interface is shown in FIGURE 2. Plate constants solutions, using NEURAL_DAO, have been found to yield RMS solutions to the order of 0².2 - 0².3 across the field. The final (linear) plate solution is written to the image header and the non-linear (distortion) terms are written to a database file for later use. An additional image is copied that contains the WCS information in J2000 ecliptic coordinates while the ecliptic coordinates of the anti-Solar point and the image centre are displayed on the screen. The average time-budget of the NEURAL_DAO task is 30 seconds per image on a Pentium 133 (64 Mbytes RAM) computer.

Processing of the science frames consists of ‘blinking’ the first and last of a series (usually 3-5) of images to detect any objects moving in the field. The middle image serves as a confirmation of objects found from the first and last images. Wide-field discovery systems, such as LINEAR and LONEOS locate moving objects using sophisticated search algorithms on large areas of sky. However, the Plaskett telescope has a long focal length and moderately-small field of view and is well-suited to the systematic follow-up of NEOs when they have faded beyond the grasp of other instruments. An experienced asteroid observer can usually locate all moving objects on a Plaskett field in less than a minute. Once an object is located the observer places the image cursor upon the object and presses the spacebar on the computer keyboard. The routine SOLUTION_DAO will then fit a two dimensional Gaussian to the source. The centroided pixel coordinates are piped to the CCTRAN_IMCOORDS routine that converts the measurements, using the plate solution contained both in the image header and in the database (non-linear terms) to FK5-J2000 equatorial coordinates. SOLUTION_DAO has parsed the values of the UT date, time and length of integration, computed the observation mid-time, and converted the time to a decimal of a day. Both timing and angles-only data are then formatted and appended to a nightly file of astrometry. All observations are in MPC standard format and also contain the object designation and the topocentric observatory code (658) of the instrument.

FIGURE 2. The graphical interface showing catalogue stars (marked in red) and detected moving objects (yellow circles with designation indicated above). The targetted object is the high-inclination Aten asteroid 2000 NL10 on the night of (UT) 2000 July 25. 2000 NL10 was relatively bright (V = 18.0) and moving at 68 arc-seconds/hour. This is a single ‘stare’ image of 60 seconds duration. The object below and left of image centre is 2000 NS11 and was discovered by the author on this series of images. NEURAL_DAO found 298 catalogue stars upon the field. Fifty-six of the standard stars were rejected. The astrometric solution yielded an (RMS) error of 0². 208 in both axes.

 

All astrometric observations are processed through the orbital reduction package (SWATCH) for residuals (O-C) checking during an observing session. Resultant orbital solutions are appended (automatically) to the telescope control file. Short-arc observational data-sets are investigated by comparing the rates of motion (per unit time interval), in both equatorial and ecliptic coordinates, for 3-5 astrometric observations of an object. This is especially helpful when attempting to locate a specific NEO candidate when there are multiple detections in the field and also when there is a spurious observation in the data-set. Multiple-night data-sets are subjected to preliminary orbit determination. A family of orbital solutions are calculated for each object in the form of circular, Väisälä and Gaussian (general) orbits. Each orbital solution is appended to a master file for use by the telescope control interface. Each time that an orbit is refined, the new orbit over-writes the previous entry in the master file. The orbits of objects that have positional data spanning a week or more are refined using special perturbations (Mercury-Pluto) and differential refinement software.

OBSERVATIONAL RESULTS

The tasking of international NEA follow-up programs has changed drastically over the past few years. In Victoria the majority of telescope man-hours are spent in ‘confirmation mode’ in conjunction with the NEO confirmation system of the (IAU) Minor Planet Center. The urgency of the situation is due to the operation of several efficient NEO discovery systems (the LINEAR telescopes, Spacewatch, NEAT and LONEOS) that have taxed the world’s follow-up capability. Fortunately, a number of skilled amateur observers with small telescopes have applied themselves to the observation of brighter NEOs. The tasking of the Plaskett tracking system has been prioritized such that the faintest and most difficult target objects have the highest weight. The observational priorities are (highest to the lowest): un-confirmed NEOs, newly-discovered potentially-hazardous objects (PHAs), newly-discovered NEOs, long-arc observations of all PHAs and NEAs and attempts at recovery of NEAs that were discovered at a previous apparition.

Since observational results are acquired in near real-time, our throughput is a function of the large-angle slew speed of the Plaskett telescope and the sky conditions (length of night and weather). All digital and orbital reductions are performed on our project computer that is located at the University of Victoria and accessed using an X terminal in the Plaskett dome.

Observational results are published in the International Astronomical Union Circulars (IAUC), the Minor Planet Electronic Circulars (MPEC) and the monthly batches of Minor Planet Circulars published at the Harvard-Smithsonian Center for Astrophysics and are listed below. It is of note that about 15% of the objects listed on the NEO Confirmation page did not exist or were non-detectable by the system. The situation improved when the Minor Planet Center added ephemeris uncertainty calculations into their web-based data-stream. We acquired positional data for a total of 137 asteroids and 13 comets and objects that reside in cometary orbits. More than 30% (42) of the former objects have been determined to be potentially-hazardous asteroids, i.e., their orbital characteristics are such that they can pass within 0.05 AU (25 Lunar distances) of the Earth’s orbit. The largest PHA of the sample is 2000 PN9 (2 - 4 km) while the smallest objects, not classified as PHA’s because of their size, were 2000 RF52 and 2000 HP40. The latter objects were both in the 50-100m size range. The statistical composition of the PHA sample is: Aten class - 6, Apollo asteroids - 30, and so-called ‘grazing’ Amor asteroids - 6. The orbital characteristics of three PHA’s suggest that they might be viable candidates for low-DV spacecraft missions: 1994 AW1, 1999 RA32 and 2000 CO101. Grazing Amor 1994 AW1 (diameter ~ 1km) has a near-circular orbit that is slightly larger than that of the Earth and may approach as close as 0.0188 AU at the ascending node of its orbit. Close encounters occur when the object is passing through the ascending node in mid-July. The next close approach of 1994 AW1 will be on July 15, 2015 at a distance of 0.065 AU. Apollo asteroid 1999 RA32 was recovered by this program (MPEC 2000-O35) in the early morning sky in July. It has a diameter of approximately 200m and resides in a near-circular Earth-sized orbit with low inclination (10°). The Earth will encounter this object again in March 2025 at 0.092 AU. The third candidate, 2000 CO101, is a 500m - 1km diameter asteroid that can approach to within 0.0216 AU of the Earth when at its ascending node in September. The next Earth approach will be on September 17, 2009 when at a distance of 0.046 AU. Closer approaches will take place in 2057 (0.025 AU) and 2096 (0.032 AU).

FIGURE 3. A Kresak (a/e) plot of the sample of near-Earth objects. Red symbols denote objects classified as potentially-hazardous (PHA). Estimated diameters are indicated as follows: 5km size (filled circles), 3km (open circles), 2km (filled box), 1km (filled diamond), 700m (filled triangle - up), 500m (filled triangle - down), 200m (cross) and < 200m are shown as asterisks in blue. The plotted curves show the perihelion of the Earth (starting at a = 1 AU, e = 0), Venus and Mercury. If an object falls to the left of a curve it can cross the orbit of the corresponding planet. The solid line from a = 1 AU to the upper left of the graph denotes the aphelion distance of the Earth. An Aten asteroid must fall on or to the right of the line. There are no known objects left of the line as they would be unobservable from ground-based systems. The three objects located near a = 1 and e = 0.1 are possible low-D V spacecraft targets.

Objects that were determined, after careful observation, to not be potentially hazardous to the Earth fall into the following orbit classes: Aten asteroids (6), Apollos (26), Amors (39), Mars-crossers and Mars-grazers (3), comets (9) and objects residing in comet-like orbits (4). The sample of objects is best illustrated in the form of a Kresak (a/e) plot in FIGURE 3. In addition, 20 objects that were observed owing to their unusual plane-of-sky motion vectors were found to be main-belt objects in high-inclination orbits or Flora asteroid family members. Objects marked in red on FIGURE 3 are classified as potentially-hazardous. The three low-DV candidates are located near a = 1 and e = 0.1. Curves are drawn for perihelion distances q (AU) = 1 (Earth), 0.723 AU (Venus) and 0.387 (Mercury). The PHA 2000 BM19 is located (a = 0.74 AU, e = 0.36) on the line marking the aphelion distance Q (AU) = 1. In other words, 2000 BM19 intersects the orbit of the Earth during its passage through aphelion. The current orbit state does not allow passages less than 0.082 AU from the Earth. The encounter will occur in mid-January 2023 at a distance of 0.085 AU.

Modern NEO discovery instruments, such as those used by LINEAR and the Catalina Sky Survey, are short focal length (fast) optical systems with large-format CCD detectors. They lack the contrast required to recognize cometary emission associated with fainter moving objects and often report new comets as asteroidal in appearance. It has been the task of the follow-up programs, with their long focal length instruments, to detect and confirm an objects true nature. It is the Central Bureau for Astronomical Telegrams (CBAT) and the Minor Planet Center that requests specific observers to investigate suspected comets. There are also instances when the discovery program has recognized the cometary nature of a new discovery and reported it as such. The policy of the CBAT/MPC is to obtain independent confirmation of the observation. There were four such requests made to our program during the year 2000. An asteroidal object was reported to the MPC by LINEAR in January that yielded Centaur-like orbital elements. P. Kusnirak at Ondrejov reported the object as slightly diffuse in appearance and a request was made by CBAT for independent confirmation. The object appeared similar on Plaskett images obtained on Jan. 29 and the object was subsequently designated as comet C/2000 B4 (LINEAR) on IAUC 7368. In September, the LINEAR team reported that one of their objects appeared to be cometary. It was recognized, by D. Green and T. Spahr at CBAT, that the object was located 0°.6 north west of the prediction for Comet Shoemaker-Levy 5 (1991 XXII) and could possibly be the same object. Following a request from CBAT, Balam obtained images of the object showing a well-developed coma and fan-shaped tail. Victoria astrometry combined with the LINEAR data secured the object identity as 1991 XXII (IAUC 7488). In the same month LINEAR reported an asteroidal object that was subsequently placed on the MPC NEO confirmation system. Observations obtained with the Plaskett telescope revealed that the object had a 9" diameter coma (IAUC 7492). Independent confirmation was made by M. Tichy at Klet and Robert McNaught at Siding Spring. Finally, an object reported as asteroidal by the Spacewatch program was reported to CBAT as being slightly diffuse in appearance by O. Hainaut and C. Delahodde using 2.2-m ESO/MPI telescope. The nuclear magnitude of the object was V = 21.3 at the time of discovery and it was moving retrograde at a rate of 57"/hr. Balam obtained long motion-compensated images using the 1.82-m Plaskett telescope that revealed a coma of 6" diameter that was extended to a position angle of 260°. The object was designated as COMET C/2000 OF8 (SPACEWATCH) on IAUC 7484.

FUTURE PLANS

Starting in February 2001 we will be taking advantage of the ‘front-line’ nature of the Victoria NEO program and the Plaskett tracking and orbital analysis system capabilities to acquire physical data, in the form of BVRI photometry, of as many newly-discovered NEAs as time permits. The physical characterisation of NEAs has been much neglected during the course of the international Spaceguard Survey. In particular, we will be striving to investigate the taxonomic classifications of those objects that pose a threat to the Earth and its biosphere.

The author wishes to express his sincere appreciation for the kind and generous support provided by the Foundation for International Non-Governmental Development of Space (FINDS), The Watch and the National Research Council of Canada.

Dave Balam is recognized as one of the most sartorially astute of Canadian astronomers and spends countless hours using the Plaskett 1.82 m telescope to hunt for NEO's. He is Co - Investigator of the Near-Earth Space Surveillance (NESS) Satellite (University of Calgary, University of British Columbia, University of Victoria and Dynacon Enterprises Ltd). Supported by the Canadian Space Agency and the Department of National Defence. He is also:

  • Member of the International Spaceguard Foundation
  • Guest Investigator, Dominion Astrophysical Observatory of the National Research Council of Canada
  • Visiting member of Spaceguard U. K.
  • Associate member, Meteorite and Impacts Advisory Committee to the Canadian Space Agency

PUBLICATIONS

Tichy, M.; Moravec, Z.; Kim, S.-L.; Lee, B. C.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Hug, G.; Garradd, G. J.; Marsden, B. G., 2000, Minor Planet Electronic Circ., 2000-S04, COMET P/2000 R2 (LINEAR)

Ticha, J.; Tichy, M.; Moravec, Z.; Kocer, M.; Mikuz, H.; Kornos, L.; Koleny, P.; Griesser, M.; Sarounova, L.; Kusnirak, P.; Lombardi, G.; Toso, A.; Pettarin, E.; Spolaor, M.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Garradd, G. J.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-R43, 2000 RL77

Ticha, J.; Tichy, M.; Moravec, Z.; Kovcer, M.; Griesser, M.; Sarounova, L.; Kusnirak, P.; Lombardi, G.; Toso, A.; Pettarin, E.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Garradd, G. J.; Spahr, T. B., 2000, Minor Planet Electronic Circ., 2000-R40, 2000 RK60

Ticha, J.; Tichy, M.; Moravec, Z.; Kovcer, M.; Griesser, M.; Sarounova, L.; Kusnirak, P.; Lombardi, G.; Toso, A.; Busch, M.; Kluegl, S.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Garradd, G. J.; Spahr, T. B., 2000, Minor Planet Electronic Circ., 2000-R39, 2000 RJ60

Tichy, M.; Moravec, Z.; Lombardi, G.; Toso, A.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Robinson, L.; Sinnott, R. W.; Ikari, Y.; Spahr, T. B., 2000, Minor Planet Electronic Circ., 2000-R34, 2000 RD53

Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Spahr, T. B., 2000, Minor Planet Electronic Circ., 2000-R30, 2000 RF52

Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Spahr, T. B., 2000, Minor Planet Electronic Circ., 2000-R29, 2000 RE52

Kim, S.-L.; Lee, B. C.; Balam, D. D.; Skiff, B. A.; Spahr, T. B., 2000, Minor Planet Electronic Circ., 2000-R28, 2000 RD52

Tichy, M.; Moravec, Z.; Kornos, L.; Toth, J.; Kim, S.-L.; Lee, B. C.; Sicoli, P.; Cavagna, M.; Banfi, M.; Pettarin, E.; Balam, D. D.; Rogers, J. E.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Spahr, T. B., 2000, Minor Planet Electronic Circ., 2000-R25, 2000 RW37

Kim, S.-L.; Lee, B. C.; Balam, D. D.; Comba, P. G.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Spahr, T. B., 2000, Minor Planet Electronic Circ., 2000-R24, 2000 RV37

Gajdos, S.; Toth, J.; Haver, R.; Gorelli, R.; Otuki, N.; McNaught, R. H.; Garradd, G. J.; Kusnirak, P.; Babiakova, U.; Manca, F.; Testa, A.; Balam, D. D.; Rogers, J. E.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Shelus, P. J.; Shelus, J. A.; Warner, B. D.; Robinson, L.; Spahr, T. B., 2000, Minor Planet Electronic Circ., 2000-R21, 2000 RM12

Galad, A.; Toth, J.; McNaught, R. H.; Garradd, G. J.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Shelus, P. J.; Shelus, J. A.; Spahr, T. B., 2000, Minor Planet Electronic Circ., 2000-R20, 2000 RJ12

Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Spahr, T. B., 2000, Minor Planet Electronic Circ., 2000-R19, 2000 RK12

Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Shelus, P. J.; Shelus, J. A.; Spahr, T. B., 2000, Minor Planet Electronic Circ., 2000-R18, 2000 RN12

Gajdos, S.; Toth, J.; Griffin, I. P.; Manca, F.; Testa, A.; Balam, D. D.; Rogers, J. E.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Spahr, T. B.; Nakano , S., 2000, Minor Planet Electronic Circ., 2000-R17, 2000 QL7

Balam, D. D.; Spahr, T. B., 2000, Minor Planet Electronic Circ., 2000-R16, 1994 EF2

Balam, D.; Tichy, M.; McNaught, R. H., 2000, IAU Circ., 7492, Comet P/2000 R2 (LINEAR)

Spahr, T.; Balam, D.; Green, D. W. E., 2000, IAU Circ., 7488, Comet P/2000 R1 (Shoemaker-Levy 5)

McNaught, R. H.; Balam, D. D.; Petit, J.-M.; Delahodde, C. E.; Hainaut, O. R.; Marsden, B. G., 2000, Minor Planet Electronic Circ., 2000-Q43, COMET C/2000 R1 (Shoemaker-Levy 5)

Ticha, J.; Tichy, M.; Moravec, Z.; Jelinek, P.; Tesi, L.; Boattini, A.; Tombelli, M.; Forti, G.; Mikuz, H.; Kandler, J.; Boettcher, F.; Lehmann, T.; Kornos, L.; Koleny, P.; Griesser, M.; Abe, H.; Pravec, P.; Kusnirak, P.; Lombardi, G.; Pettarin, E.; Helin, E. F.; Pravdo, S.; Lawrence, K.; Kervin, P.; Talent, D.; Maeda, R.; Tanner, P.; Spratt, C. E.; Balam, D. D.; Rogers, J. E.; Hug, G.; Robinson, L.; Sinnott, R. W.; Jacques, C.; Duczmal, L.; Magno, C.; Gomez, J. J.; Dupouy, P.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-Q32, 2000 QW7

Debehogne, H.; Elst, E. W.; Ticha, J.; Tichy, M.; Moravec, Z.; Jelinek, P.; Tesi, L.; Boattini, A.; Tombelli, M.; Forti, G.; Mikuz, H.; Lehmann, G.; Kandler, J.; Lehmann, J.; Kornos, L.; Koleny, P.; Griesser, M.; Dawson, M.; Pravec, P.; Kusnirak, P.; Cavagna, M.; Banfi, M.; Busch, M.; Balam, D. D.; Rogers, J. E.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Hug, G.; Lopez, C. E.; Lepez, H. S.; Jacques, C.; Duczmal, L.; Duczmal, J.; Magno, C.; Holvorcem, P. R.; Gomez, J. J.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-Q31, 2000 QV7

Ticha, J.; Tichy, M.; Moravec, Z.; Jelinek, P.; Tesi, L.; Boattini, A.; Tombelli, M.; Forti, G.; Mikuz, H.; Guidetti, D.; Masotti, E.; Bartolini, S.; Lehmann, G.; Kandler, J.; Kornos, L.; Koleny, P.; Griesser, M.; Dawson, M.; Pravec, P.; Kusnirak, P.; Cavagna, M.; Banfi, M.; Pettarin, E.; Busch, M.; Balam, D. D.; Rogers, J. E.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Hug, G.; Jacques, C.; Duczmal, L.; Magno, C.; Holvorcem, P. R.; Wolfe, C.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-Q30, 2000 QU7

Debehogne, H.; Elst, E. W.; Ticha, J.; Tichy, M.; Moravec, Z.; Jelinek, P.; Tesi, L.; Boattini, A.; Tombelli, M.; Forti, G.; Mikuz, H.; Guidetti, D.; Masotti, E.; Bartolini, S.; Lehmann, G.; Kandler, J.; Lehmann, T.; Kornos, L.; Koleny, P.; Griesser, M.; Haver, R.; Anzellini, F.; Calabresi, M.; Panella, M.; Dawson, M.; Pravec, P.; Kusnirak, P.; Manca, F.; Banfi, M.; Lombardi, G.; Pettarin, E.; Busch, M.; Balam, D. D.; Rogers, J. E.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Hug, G.; Robinson, L.; Lopez, C. E.; Lepez, H. S.; Jacques, C.; Duczmal, L.; Duczmal, J.; Magno, C.; Holvorcem, P. R.; Gomez, J. J.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-Q29, 2000 QT7

Tichy, M.; Moravec, Z.; Jelinek, P.; Tesi, L.; Boattini, A.; Tombelli, M.; Forti, G.; Kornos, L.; Toth, J.; Dawson, M.; Kusnirak, P.; Balam, D. D.; Van Ness, M. E.; Koehn, B. W.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-Q20, 2000 QJ1

Tichy, M.; Dawson, M.; Sugie, A.; Garradd, G. J.; Gilmore, A. C.; Sarounova, L.; Kluegl, S.; Busch, M.; Stoss, R.; Balam, D. D.; Rogers, J. E.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Shelus, P. J.; Ries, J. G.; Lopez, C. E.; Lepez, H. S.; Gil Hutton, R.; Vicentela, J. A.; McGaha, J. E.; Jacques, C.; Amancio, J.; Duczmal, L.; Hergenrother, C. W., 2000, Minor Planet Electronic Circ., 2000-P30, 2000 PF5

Tichy, M.; Galad, A.; Koleny, P.; Garradd, G. J.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Shelus, P. J.; Ries, J. G.; Hergenrother, C. W., 2000, Minor Planet Electronic Circ., 2000-P23, 2000 PG3

Tichy, M.; Galad, A.; Koleny, P.; Lukic, B.; Peric, J.; Dermadi, D.; Korlevic, K.; Juric, M.; Garradd, G. J.; Kluegl, S.; Busch, M.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Shelus, P. J.; Ries, J. G.; McGaha, J. E.; Hergenrother, C. W., 2000, Minor Planet Electronic Circ., 2000-P22, 2000 PE3

Tichy, M.; Balam, D. D.; Montani, J. L.; Scotti, J. V.; Tubbiolo, A. F.; Shelus, P. J.; Ries, J. G.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-P20, 2000 OA51

Tichy, M.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Shelus, P. J.; Ries, J. G.; Robinson, L.; McGaha, J. E.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-P15, 2000 OB22

Ticha, J.; Tichy, M.; Galad, A.; Koleny, P.; Sarounova, L.; Tholen, D. J.; Manca, F.; Busch, M.; Stoss, R.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Shelus, P. J.; Ries, J. G.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-P08, 2000 OL8

Ticha, J.; Tichy, M.; Tombelli, M.; Boattini, A.; Tesi, L.; Guidetti, D.; Masotti, E.; Bartolini, S.; Forti, G.; Galad, A.; Koleny, P.; Lukic, B.; Pintaric, S.; Korlevic, K.; Dermadi, D.; Malic, G.; Juric, M.; Rejkuba, M.; Demeautis, C.; Matter, D.; Griesser, M.; Dawson, M.; Griffin, I. P.; Brady, N.; Greatrex, R.; Sarounova, L.; Manca, F.; Busch, M.; Stoss, R.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Shelus, P. J.; Ries, J. G.; Robinson, L.; Lopez, C. E.; Lepez, H. S.; Jacques, C.; Amancio, J.; Weaver, D.; Diniz, J.; Holvorcem, P. R.; Camargo, J.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-P07, 2000 OK8

Ticha, J.; Tichy, M.; Skvarc, J.; Galad, A.; Koleny, P.; Sposetti, S.; Griesser, M.; Dawson, M.; Griffin, I. P.; Brady, N.; Greatrex, R.; Sarounova, L.; Manca, F.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Shelus, P. J.; Ries, J. G.; Robinson, L.; Lopez, C. E.; Lepez, H. S.; Jacques, C.; Duczmal, L.; Weaver, D.; Diniz, J.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-P06, 2000 OJ8

Ticha, J.; Tichy, M.; Skvarc, J.; Galad, A.; Koleny, P.; Griffin, I. P.; Brady, N.; Greatrex, R.; Sarounova, L.; Manca, F.; Lombardi, G.; Toso, A.; Pettarin, E.; Spolaor, M.; Piani, F.; Busch, M.; Stoss, R.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Shelus, P. J.; Ries, J. G.; Robinson, L.; Lopez, C. E.; Lepez, H. S.; Jacques, C.; Duczmal, L.; Weaver, D.; Diniz, J.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-P05, 2000 OH8

Tichy, M.; Galad, A.; Koleny, P.; Klemencic, K.; Pintaric, S.; Bedekovic, T.; Rejkuba, M.; Korlevic, K.; Dermadi, D.; Malic, G.; Lukic, B.; Juric, M.; Sarounova, L.; Manca, F.; Balam, D. D.; Ferris, W. D.; Koehn, B. W.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Shelus, P. J.; Ries, J. G.; Robinson, L.; Holvorcem, P. R.; Camargo, J.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-P04, 2000 OG8

McNaught, R. H.; Griffin, I. P.; Brady, N.; Greatrex, R.; Bredenkamp, T.; Tholen, D. J.; Balam, D. D.; Descour, A.; Larsen, J.; McMillan, R. S.; Scotti, J. V.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-P03, 2000 OF8

Hainaut, O. R.; Delahodde, C. E.; Balam, D. D., 2000, IAU Circ., 7484, Comet C/2000 OF_8 (Spacewatch)

Balam, D. D.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-O35, 1999 RA32

Griesser, M.; McNaught, R. H.; Broughton, J.; Griffin, I. P.; Brady, N.; Greatrex, R.; Pravec, P.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; McGaha, J. E.; Jacques, C.; Duczmal, L.; Weaver, D.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-O31, 2000 ON

Tichy, M.; Moravec, Z.; Jelinek, P.; Griesser, M.; McNaught, R. H.; Broughton, J.; Griffin, I. P.; Brady, N.; Greatrex, R.; Pravec, P.; Balam, D. D.; Rogers, J. E.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Robinson, L.; McGaha, J. E.; Jacques, C.; Duczmal, L.; Weaver, D.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-O30, 2000 OM

Ticha, J.; Tichy, M.; Skvarc, J.; Gajdos, S.; Toth, J.; Griesser, M.; Pravec, P.; Busch, M.; Kresken, R.; Balam, D. D.; Sheridan, E.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Viggh, H.; Klinglesmith, D. A., III; Wentworth, J.; Robinson, L.; Ikari, Y.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-O15, 2000 OG

Kusnirak, P.; Wolf, M.; Sarounova, L.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-N29, 2000 NF11

Gajdos, S.; Kornos, L.; Dawson, M.; Kusnirak, P.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-N28, 2000 NL10

Tichy, M.; Moravec, Z.; Kornos, L.; Gajdos, S.; Pravec, P.; Kusnirak, P.; Busch, M.; Stoss, R.; Balam, D. D.; Rogers, J. E.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Sikes, L.; Segal, B.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-L03, 2000 KW43

 

Pauwels, T.; Tichy, M.; Moravec, Z.; Otuki, N.; Sugie, A.; Broughton, J.; Pravec, P.; Kusnirak, P.; Busch, M.; Stoss, R.; Balam, D. D.; Rogers, J. E.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Manguso, L.; Stuart, J.; Sayer, R.; Evans, J. B.; Klinglesmith, D. A., III; Hug, G.; Robinson, L.; Elliott, R.; Zoltowski, F. B.; Holvorcem, P. R.; Camargo, J.; Yoshimi, M.; Gomez, J. J.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-K40, 2000 KE41

Kim, S.-L.; Park, Y.-H.; Pravec, P.; Kusnirak, P.; Balam, D. D.; Martinez, R.; Hicks, M. D.; Gleason, A. E.; Skiff, B. A.; Koehn, B. W.; Hug, G.; Zoltowski, F. B.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-K39, 2000 KD41

Ticha, J.; Tichy, M.; Moravec, Z.; Mikuz, H.; Skvarc, J.; Kandler, J.; Galad, A.; Koleny, P.; Gajdos, S.; Toth, J.; Sugie, A.; Garradd, G. J.; Meyer, E.; Obermair, E.; Sarounova, L.; Kusnirak, P.; Lombardi, G.; Pettarin, E.; Stoss, R.; Busch, M.; Hormuth, F.; Kluegl, S.; Kresken, R.; Seib, A.; Kirk, M.; Alburty, J.; Granger, Ja.; Young, D.; Rycraft, R.; Trentman, D.; Balam, D. D.; Rogers, J. E.; Deaver, D.; Hicks, M.; Skiff, B. A.; Koehn, B. W.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Stuart, J.; Viggh, H.; Sayer, R.; Evans, J. B.; Robinson, L.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-J56, 2000 HD74

Tichy, M.; Moravec, Z.; Galad, A.; Koleny, P.; Toth, J.; Sugie, A.; Meyer, E.; Obermair, E.; Sarounova, L.; Kusnirak, P.; Busch, M.; Stoss, R.; Balam, D. D.; Deaver, D.; Hicks, M.; Van Ness, M. E.; Koehn, B. W.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-J54, 2000 JT66

Ticha, J.; Tichy, M.; Moravec, Z.; Galad, A.; Koleny, P.; Nakamura, A.; Garradd, G. J.; Sarounova, L.; Kusnirak, P.; Babiakova, U.; Testa, A.; Cavagna, M.; Busch, M.; Stoss, R.; Kluegl, S.; Busch, B.; Balam, D. D.; Hicks, M.; Martinez, R.; Deaver, D.; Wasserman, L. H.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Stuart, J.; Viggh, H.; Sayer, R.; Evans, J. B.; Hug, G.; Bell, G. E.; McGaha, J. E.; Zoltowski, F. B.; Marsden, B. G., 2000, Minor Planet Electronic Circ., 2000-J02, COMET C/2000 J2 (LINEAR)

 

Ticha, J.; Tichy, M.; Moravec, Z.; Galad, A.; Kornos, L.; Koleny, P.; Toth, J.; Sugie, A.; Sarneczky, K.; Kiss, L.; Sziladi, K.; Meyer, E.; Obermair, E.; Kusnirak, P.; Babiakova, U.; Manca, F.; Stoss, R.; Balam, D. D.; Rogers, J. E.; Hicks, M.; Deaver, D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Stuart, J.; Viggh, H.; Sayer, R.; Evans, J. B.; Hug, G.; Holvorcem, P. R.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-H38, 2000 GV147

Ticha, J.; Tichy, M.; Moravec, Z.; Sarounova, L.; Kusnirak, P.; Balam, D. D.; Ferris, W. D.; Koehn, B. W.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-H27, 2000 GG147

Ticha, J.; Tichy, M.; Moravec, Z.; Balam, D. D.; Montani, J. L.; Gleason, A. E.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-G10, 2000 FP10

Ticha, J.; Tichy, M.; Griesser, M.; Broughton, J.; Kusnirak, P.; Balam, D. D.; Rogers, J. E.; Hergenrother, C. W.; Koff, R. A.; Elliott, R.; Holvorcem, P. R.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-G06, 2000 FL10

Ticha, J.; Tichy, M.; Kusnirak, P.; McGaha, J. E.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Stuart, J.; Viggh, H.; Sayer, R.; Evans, J. B.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-G05, 2000 FK10

Tichy, M.; Moravec, Z.; Kornos, L.; Koleny, P.; Toth, J.; Dawson, M.; Sugie, A.; Sarounova, L.; Lombardi, G.; Toso, A.; Pettarin, E.; Balam, D. D.; Spahr, T. B.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Stuart, J.; Viggh, H.; Sayer, R.; Evans, J. B.; Durig, D. T.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-F29, 2000 EB107

Ticha, J.; Tichy, M.; Moravec, Z.; Tesi, L.; Boattini, A.; Tombelli, M.; Forti, G.; Skvarc, J.; Galad, A.; Kornos, L.; Koleny, P.; Moon, H.-K.; Park, Y.-H.; Chun, M.-Y.; Sugie, A.; McNaught, R. H.; Garradd, G. J.; Sarounova, L.; Lombardi, G.; Pettarin, E.; McGaha, J. E.; Balam, D. D.; Rogers, J. E.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Stuart, J.; Viggh, H.; Sayer, R.; Evans, J. B.; Durig, D. T.; Wilson, J. L.; Zoltowski, F. B.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-E12, 2000 DM8

Ticha, J.; Tichy, M.; Kornos, L.; Koleny, P.; McNaught, R. H.; Sarounova, L.; McGaha, J. E.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Stuart, J.; Viggh, H.; Sayer, R.; Evans, J. B.; Hug, G.; Zoltowski, F. B.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-E11, 2000 DL8

Ticha, J.; Tichy, M.; Galad, A.; Kornos, L.; Koleny, P.; Sugie, A.; Sarounova, L.; Vasta, L.; McGaha, J. E.; Balam, D. D.; Hergenrother, C. W.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Stuart, J.; Viggh, H.; Sayer, R.; Evans, J. B.; Zoltowski, F. B.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-E07, 2000 DG8

Ticha, J.; Tichy, M.; Sugie, A.; McNaught, R. H.; Griffin, I. P.; Brady, N.; Sarounova, L.; Vasta, L.; Stoss, R.; Kluegl, S.; Mueller, F.; McGaha, J. E.; Balam, D. D.; Rogers, J. E.; Spahr, T. B.; Hill, R. E.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Stuart, J.; Viggh, H.; Sayer, R.; Evans, J. B.; Hug, G.; Bell, G.; Zoltowski, F. B.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-E06, 2000 DF8

Ticha, J.; Tichy, M.; Moravec, Z.; Galad, A.; Kornos, L.; Koleny, P.; Sarounova, L.; Stoss, R.; Busch, M.; McGaha, J. E.; Balam, D. D.; Hergenrother, C. W.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Stuart, J.; Viggh, H.; Sayer, R.; Evans, J. B.; Zoltowski, F. B.; Marsden, B. G., 2000, Minor Planet Electronic Circ., 2000-E04, COMET C/2000 D2 (LINEAR)

Ticha, J.; Tichy, M.; Griesser, M.; McNaught, R. H.; Garradd, G. J.; Busch, M.; Balam, D. D.; Spahr, T. B.; Hill, R. E.; Elliott, R.; Zoltowski, F. B.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-D35, 2000 DO1

Ticha, J.; Tichy, M.; Tesi, L.; Boattini, A.; Tombelli, M.; Forti, G.; Kornos, L.; Gajdos, S.; Sugie, A.; Pravec, P.; Sarounova, L.; Kusnirak, P.; McGaha, J. E.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Stuart, J.; Viggh, H.; Sayer, R.; Evans, J. B.; Ries, J. G.; Zoltowski, F. B.; Marsden, B. G., 2000, Minor Planet Electronic Circ., 2000-D09, COMET C/2000 B4 (LINEAR)

Ticha, J.; Tichy, M.; Garradd, G. J.; Lombardi, G.; Pettarin, E.; McGaha, J. E.; Balam, D. D.; Scotti, J. V.; Read, M. T.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-D07, 2000 CR101

Ticha, J.; Tichy, M.; Tesi, L.; Boattini, A.; Tombelli, M.; Forti, G.; Lombardi, G.; Pettarin, E.; Toso, A.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Stuart, J.; Viggh, H.; Sayer, R.; Evans, J. B.; Zoltowski, F. B.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-D06, 2000 CQ101

Ticha, J.; Tichy, M.; Kim, S.-L.; Chun, M.-Y.; Garradd, G. J.; Lombardi, G.; Pettarin, E.; Busch, M.; Stoss, R.; McGaha, J. E.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Stuart, J.; Viggh, H.; Sayer, R.; Evans, J. B.; Ries, J. G.; Zoltowski, F. B.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-D04, 2000 CO101

Ticha, J.; Tichy, M.; Tesi, L.; Boattini, A.; Tombelli, M.; Forti, G.; Kornos, L.; Gajdos, S.; Garradd, G. J.; Lombardi, G.; Pettarin, E.; Stoss, R.; McGaha, J. E.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Stuart, J.; Viggh, H.; Sayer, R.; Evans, J. B.; Shelus, P. J.; Ries, J. G.; Zoltowski, F. B.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-D03, 2000 CN101

Kornos, L.; Toth, J.; Garradd, G. J.; Sarounova, L.; McGaha, J. E.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Stuart, J.; Viggh, H.; Sayer, R.; Evans, J. B.; Ries, J. G.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-C41, 2000 CH59

Pauwels, T.; Tichy, M.; Galad, A.; Kornos, L.; Koleny, P.; Sugie, A.; Sarneczky, K.; Kiss, L.; Sziladi, K.; Sarounova, L.; Kusnirak, P.; Manca, F.; Sicoli, P.; Balam, D. D.; Blythe, M.; Shelly, F.; Bezpalko, M.; Elowitz, M.; Huber, R.; Stuart, J.; Viggh, H.; Sayer, R.; Evans, J. B.; Zoltowski, F. B.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-C09, 2000 BD19

Whiteley, R. J.; Tholen, D. J.; Fernandez, Y.; Balam, D. D.; Williams, G. V., 2000, Minor Planet Electronic Circ., 2000-C08, 2000 AB246

Kusnirak, P.; Balam, D., 2000, IAU Circ., 7368, Comet C/2000 B4 (LINEAR)