Scriptable Components

Fast Scriptable Access to MPCORB Orbital Elements Database V5.1 (Aug 2018)
Download Tools for making and scripting a fast MS Access database that contains orbital elements from the MPCORB.DAT catalog from the Minor Planet Center. 32-bit applications only. MS ACCESS/OFFICE IS NOT REQUIRED ON YOUR SYSTEM!. Three small tools that were made with Notepad create the database, provide scripts with object-oriented access to it, and test & demonstrate the scripted object use. The downloaded file is a self-installer. Installed to C:\Program Files (x86)\Common Files\ASCOM\MPCORB\. Read the readme.txt file there!
Fast Scriptable Access to MPC Comet Elements Database CometEls.txt V1.3 (Sept 2021)
Download Tools for making and scripting a fast MS Access database that contains orbital elements from the Visible Comet catalog from the Minor Planet Center (soft00cmt.txt). 32-bit applications only. MS ACCESS/OFFICE IS NOT REQUIRED ON YOUR SYSTEM!. Three small tools that were made with Notepad create the database, provide scripts with object-oriented access to it, and test & demonstrate the scripted object use. The downloaded file is a self-installer. Installed to C:\Program Files (x86)\Common Files\ASCOM\MPCCOMET\. Read the readme.txt file there! Thanks to Jörg Hanisch for this! Update 1.3 supports the CometEls.txt records with no discoverer name (e.g. A/2021 E4).
MiniSAC 1.3 Deep Sky Object Database (~950KB)

Download Lightweight server for the Saguaro Astronomy Club (SAC) 7.9 catalog, the Third Catalog of Bright Galaxies (RC3) which contains, among many others, the entire PGC catalog, the Sharpless second catalog, the Arp Peculiar Galaxies, and a number of Henden and Landolt standard photometry fields. The latter four sets of objects, along with corrected coordinates for M 67, were provided thanks to Dick Berg.

MiniSAC contains only the J2000 equatorial coordinates for over 70,000 listings (some refer to the same object). Intended to be used for automated observing, this component gives you a lightweight and fast way to get coordinates given the catalog name. 1.2 contains the recently updated SAC (version 7.9) catalog and many more mojects from the RC3/PGC catalog, and has corrections to object names, separating the catalog name from the ID. For tools to add your own objects and catalogs, see the MiniSAC Catalog Maintenance Kit below.

NOVAS-COM Vector Astrometry Engine V2.2 (~293KB)
Download This is the USNO NOVAS Vector Astrometry Library wrapped in a COM object. This component provides many scriptable tools for positional astronomy including conversion from J2000 to local topocentric coordinates. NOVAS-COM uses the most rigorous and precise algorithms available, NOVAS, as developed and tested by the Astronomical Applications Dept. of the US Naval Observatory for their use. Note that the Kepler Orbit Engine (also available here) is designed to "plug into" NOVAS-COM. The combination provides a robust and accurate ephemeris system with local topo outputs. Included is a sample script that shows how to use NOVAS and Kepler together. The downloaded file is a self-installer. V2.2 (Sep 2018) extends the Delta-T tables through 2018 using actual and predicted values from USNO.
Kepler Orbit Engine V1.0.1 (~300KB)
Download Ephemeris generator designed to be used separately or as a as a plug-in to NOVAS-COM V2.0 for planetary reductions. Very closely approximates the accuracy of JPL DE-404 and produces heliocentric position and velocity of major planets, and with input of MPC orbital elements, minor planets and comets. The downloaded file is a self-installer.
FITS Access Object (external link)
Download The FITS driver can be used from scripts or other clients to read and write astronomical FITS images. It provides access to many of the keywords of the FITS header via properties. It is written in C++ and makes use of the cfitsio library. Matthias Busch's page says this is beta, but users' experience is that it works well.
MiniSAC Catalog Maintenance Kit 1.3 (~1 MB)
DownloadTools for adding objects and catalogs to the MiniSAC 1.3 Deep Sky Object Database. With this kit, you can add your own objects to the database and make corrections to data already in the database.