Pottenger-Dobyns astrological asteroid history

Mark Pottenger


Mom (Zipporah Dobyns) started using asteroids soon after Eleanor Bach published the first low-precision astrological ephemeris of Ceres, Pallas, Juno & Vesta.

My brother Rique spent the summer of 1975 in Pelham, NY using Neil Michelsen’s minicomputer to develop accurate ephemerides for the first four asteroids. He wrote a program to calculate positions by numerical integration, then derived Chebyshev polynomials to get equivalent positions for any date and time in our FORTRAN horoscope program. He added the four asteroids to the 1975 version of the CCRS Horoscope Program, which we ran at a local university computer center where we paid for computer time by the second.

Rique’s work was the basis for our printed ephemeris of Ceres, Pallas, Juno & Vesta. The camera-ready ephemeris pages were printed at Astro in Pelham on 4/3/1977. The introductory text by Zipporah Dobyns was finished and proofread by 6/11/1977.

We produced a quarterly journal called The Mutable Dilemma from Sagittarius 1977 through Sagittarius 1999. Mom wrote most of the articles, Maritha Pottenger (my sister) wrote quite a few, I wrote occasional technical articles, and we had occasional articles from outside the family. Material on asteroids was included frequently. From 1986 on, we produced a newsletter called Asteroid-World between issues of The Mutable Dilemma. After we ceased print publication we posted occasional articles on the http://www.ccrsdodona.org/ web site until Mom’s death. We still plan to have archives of all the paper issues of The Mutable Dilemma on the web site eventually, but it depends on my time and the time of a very busy webmaster. [2019 note: I worked up the archive files using a template supplied by our webmaster Craig Ridgley, finishing in 2007.]

When I translated Rique’s FORTRAN program to BASIC to run on our first home computer, I included the first four asteroids. The CCRS Horoscope Program was first working on a home computer on 12/28/1977. I added Chiron to chart calculations on 7/27/1979.

I started getting the Minor Planet Circulars and annual Soviet ephemeris (EMP) in 1979 and continued for many years until electronic sources made the Soviet ephemeris unnecessary. I still get the Minor Planet Circulars and some related on-line Minor Planet Center data.

I wrote a program (done 8/23/1979) to get zodiacal positions (ecliptic of date) from astronomical positions (1950.0 Right Ascension & declination) in the Soviet ephemeris and other astronomical sources.

Over several years, I developed new integration programs designed to handle any asteroid (Rique’s had been limited to the first four). I implemented the algorithm from Volume 22 of the Astronomical Papers for integrating the outer planets as a step along the way. My generalized numerical integration for asteroids was first working 5/30/1980, tested with the first four asteroids & Chiron 6/1-3/1980. I filled in a critical missing piece in the ability to calculate any asteroid from a single set of starting elements on 9/12/1981 by deriving coefficients the program needed using a special 21-digit math package on our Apple II. I gave a full set of integration programs in MBASIC to both Astrolabe & Matrix (sent 10/13/1982) to encourage them to start using asteroids, though I don’t think they ever used the programs. The integration programs were always so slow in BASIC (days to calculate one ephemeris) that we never did very many asteroids. We finally started using large numbers of asteroids in 1984 when I got the programs going in C on a computer with a math coprocessor where it only took a few hours to calculate one ephemeris (program working right 8/7/1984). For the next several years we calculated ephemerides for whatever asteroids caught our attention or that of our friends.

Batya Stark’s humorous ephemeris of Dudu, Dembowska, Pittsburghia & Frigga was a project we talked about for years. Those four are among the few for which I ever did coordinate conversions from printed ephemerides (back in 1979). I haven’t found any diary entries, but I have found some old printouts which indicate that we created integrated ephemerides for these four November 5-9, 1981. I got the integration program running at Astro (in San Diego by then) in March 1982 (running right 3/21/1982) so that the ephemerides could be typeset for her book. The whole family was suggesting gags & ideas, though Batya did all of the writing. We wish more astrologers had enough humor to appreciate that book.

October of 1981 (another date from printouts rather than diaries) seems to be when I ran integrations of the asteroids being published by Al H. Morrison (CAO) and found the precession problem in those ephemerides. All the early ephemerides in that project have positions that get worse as you move away from 1950 because the conversion from astronomical source material left out precession.

The first version of AstEph, a program to print positions of several asteroids for a date & time (individual chart), was working 9/9/1984 with 41 asteroids.

I first got a program working 1/6/1985 to have the computer check my integrated ephemerides against observations. I checked all ephemerides generated up to that date against observations downloaded from a large computer tape from the Minor Planet Center.

I mailed the first copy of AstEph outside the family 7/28/1986 to Lee Lehman on 28 floppy disks. Once I started selling the ephemerides, I established a “standard” set of asteroid ephemerides: all 453 ephemerides I had calculated up to the time I froze the list. (Like many standards, the basis is pure historical accident.)

Tweaks made 11/23/1987 to the numerical integration program and a 4+ hour calculation in the early hours of 11/24/1987 finally produced an accurate ephemeris for Icarus, which had been a problem for years.

My earliest asteroid ephemeris format only covered the 20th Century, and the process of creating ephemerides involved several manual steps for each ephemeris. In early 1994 I rewrote my integration programs to create ephemerides for the years 1500-2099 and to do all the previously separate steps automatically for a list of asteroids. On 2/5/1994, I finished recalculating ephemerides for the “standard” set of 453. By 2/7/1994 I finished recalculating all previously run ephemerides (a couple thousand). By 2/11/1994 I had calculated ephemerides for all 4,515 named asteroids for which I had starting elements. On 2/25/1994 I got elements I needed to calculate the remainder of all existing named asteroids and finished the ephemeris calculations by 2/26/1994. I have calculated ephemerides for all asteroids named since then as I got the new names, starting with a set on 3/5/1994 that brought the named ephemeris count to 4,617. At the end of 1994, the named ephemeris count was 4,755. The count passed 5,000 in March 1996, 6,000 in August 1998, 7,000 in November 1999, 8,000 in January 2001, 9,000 in January 2002, 10,000 in November 2002, 11,000 in November 2003, and 12,000 in December 2004. The current (early August 2005) named asteroid ephemeris count is 12,449.

The AstSIG bought a copy of my ephemerides & programs in 1993. (Back then I didn’t feel I could donate it given my cost in disks and time to write disks.) Roxana Muise has the AstSIG copy. [2019 note: Dave Campbell now handles it for AstSIG.] The first time I sent files it was 22 disks on 7/31/1993 with 2,392 first-generation ephemerides. I sent 41 disks with 4,650 1994-format ephemerides on 5/10/1994, followed by several updates on floppy disks over the next few years. I first sent complete ephemerides to the AstSIG on a CD-R on 9/4/1997. For the last several years I have always mailed Roxana an updated CD-R after creating ephemerides for newly named asteroids, so the AstSIG is always up to date within a few days of the release of new names. [2019 note: update discs are less frequent now, but I upload the main ephemeris files to DropBox as soon as I finish any set of integrations.]

I made asteroid ephemerides and the programs to use them available on PC, Macintosh and Amiga platforms, using floppy disks for several years and eventually (starting in 1997) switching to CD-Rs. People getting ephemerides for all named asteroids on floppy disks had to be patient when installing. The largest number of disks in a single order that I can find in a quick look through old records is 106 1.4M floppy disks in 1997. I made sure all parts of the CCRS Horoscope Program can use these ephemerides. There was never much demand for the Amiga version. Because the compiler I used on the Macintosh was never updated by the manufacturer, the Macintosh version eventually fell out of use because it could only run on very old models of the Macintosh.

As far as I know, my ephemerides were the only asteroid ephemerides for astrological use available on home computers until the Swiss Ephemeris came along a few years ago.

Asteroid 719 Albert, the last numbered but lost asteroid, was found again in May 2000, closing a small hole in asteroid data.

The named but previously unnumbered asteroid Hermes was rediscovered in fall 2003, appearing in the MPC new name list of 11/9/2003 with the number 69230. As a very close Earth-grazer, Hermes ended up being an even worse calculation challenge than Icarus was many years earlier.

I did another ephemeris redesign in fall-winter 2003-2004. My 1994 file layout could only handle asteroid numbers up to 64K (65535). At the time I created that layout there were only a few thousand numbered asteroids, but that changed drastically in the following decade. New asteroid numbers passed the 64K boundary in mid-2003. Also, my use of 3 two-century files for each asteroid ended up producing very large numbers of files as the asteroid count increased (over 40,000 ephemeris files at last count). I decided to give up the ability to supply custom sets of ephemerides and created a new ephemeris structure that can hold ephemerides for up to 10,000 asteroids in a single file and can handle asteroid numbers up to a billion. Now the ephemerides for all named asteroids are in 10 large files instead of over 37,000 files. I do still keep unnamed unnumbered asteroids in individual files, but I only calculate a few hundred unnumbered ephemerides, mostly Centaurs and Trans-Neptunian Objects. I also derived mean nodes for the asteroids (something requested several times over the years) and included them in the new ephemerides. I include a standalone Windows version of AstEph with the new ephemerides. The new ephemerides for all named asteroids were first complete on 12/29/2003, though I struggled with Hermes experiments for a couple more weeks. Another size milestone was passed on 1/26/2005, when my asteroid ephemeris files got big enough with the addition of the latest new names to need to ship on two CD-Rs instead of one.

The Minor Planet Center is the organization in charge of asteroid names in the astronomical community. They release new names with brief citations describing the origins of the names after the names are accepted by an IAU committee. I have kept track of new names since 1995. Here are counts of names published each year (there have been a few errata over the years, so the total count of named asteroids is slightly less than the sum of counts of names published): 219 in 6 months of 1995, 432 in 9 months of 1996, 396 in 6 months of 1997, 344 in 6 months of 1998, 940 in 6 months of 1999, 871 in 6 months of 2000, 1026 in 10 months of 2001, 1057 in 10 months of 2002, 975 in 9 months of 2003, 1057 in 11 months of 2004, and 384 in 5 months of 2005 so far. Even though many more asteroids are being discovered and numbered, the rate of assigning new names seems to be fairly consistently around 1,000 per year in recent years, so astrologers can look forward to many more named asteroids as long as that continues.

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