Perseus allows you to use the most recent data you can find on the Internet regarding comets and asteroids' visualization. You can download data files directly from sites who give these data, or use the files accessible from this page. These files are the same used by the automatic update program included with Perseus.

Provided data allows you to calculate the positions of asteroids and comets using the osculatory orbital elements. So, if you want to have always precise positions, it's necessary to update your data frequently, no less than once in few months. If you want to get very precise time calculations you should also download the updates to ΔT and leap seconds used to perform he transformations between Terrestrial Time, Universal Time and Local Time. Due to the increasing dimension of the asteroid database, some files are available only compressed in .zip format, in order to reduce download time.

ASTEROIDS updated on 20/01/23 ore 03:01
To use one of these files you have to download it on your hard disk, unzip it (if necessary) using a software like Winzip, the Unzip function of Info-ZIP, or the integrated management of .zip files of Windows XP. After that, in the "Asteroid Database" window of Perseus, section "Create list from a file" press the "Perseus" button and select the downloaded file. Set the selection criteria in the filter window; be aware that Perseus can manage a maximum of 10,000 asteroids simultaneously. A new list will be created.

asteroid.psa, compressed as: asteroid.psa.zip (58687921 byte)
This file contains all asteroids with a determined orbit. Due to the large number of objects, when you create a list starting from this file you'll have to set severe selection criteria. If you need to see all the asteroids in a certain sky zone, use as unique condition the distance from the center of the screen.

bright12.psa, compressed as: bright12.psa.zip (64190 byte)
This file contains the asteroids that may become brighter than magnitude 12.

bright13.psa, compressed as: bright13.psa.zip (126407 byte)
This file contains the asteroids that may become brighter than magnitude 13.

bright14.psa, compressed as: bright14.psa.zip (242547 byte)
This file contains the asteroids that may become brighter than magnitude 14.

bright15.psa, compressed as: bright15.psa.zip (506337 byte)
This file contains the asteroids that may become brighter than magnitude 15.

bright16.psa, compressed as: bright16.psa.zip (1208121 byte)
This file contains the asteroids that may become brighter than magnitude 16.

bright17.psa, compressed as: bright17.psa.zip (3098918 byte)
This file contains the asteroids that may become brighter than magnitude 17.

COMETS updated on 20/01/23 ore 03:00
To use one of these files you have to download it on your hard disk and unzip it if necessary. After that, in the "Comet Database" window of Perseus, section "Create list from a file" press the "Perseus" button and select the downloaded file. Set the selection criteria in the filter window; a new list will be created.

comet.psc, compressed as: comet.psc.zip (75814 byte)
This file contains updated orbits of the comets.

TEMPO updated on 20/01/23 ore 03:01
n order to calculate with extreme precision times, even on future dates, with Perseus you can update data about Universal Cooordinated Time (UTC) and Universal Time (UT1). Copy the following files in the "DATI" folder of Perseus (usually C:\Program Files\Perseus\DATI).

utc.dat, compressed as: utc.dat.zip (528 byte)
This file contains updated parameters for the UTC-TT conversion (leap seconds).

deltat.dat, compressed as: deltat.dat.zip (23459 byte)
This file contains updated parameters for the UT-TT conversion (values of ΔT).

DATA SOURCES
You can download data for asteroids and comets from other sources; Perseus is capable of reading these data directly. Data about asteroids and comets are available from the Minor Planet Center, the ASTORB database (created by Dr.Edward Bowell from the Lowell Observatory) and the JPL site (DASTCOM database). Perseus is capable of reading these data directly. Data on UTC and UT1 variations are available on the U.S. Naval Observatory (USNO) and the International Earth Rotation Service (IERS) sites.

Links:

Minor Planet Center
and the data mirror
http://www.astro.cz/mpcorb/

Asteroid page of the Lowell Observatory

JPL site on the Solar System (DASTCOM database)

IERS site

USNO site