Goffin Asteroid Maps

This supplement to Occultation Newsletter contains the occultation predictions by minor planets computed by Edwin Goffin. Goffin first identified most of these events, but some others were found by Scott Donnell, and calculated by Steve Preston (all now have updates by Preston that give more accurate paths than Goffin’s original predictions). Goffin’s explanation appears on pages 3 to 6. Jim Stamm and David Dunham selected from these predictions the better occultations occurring within 0.5 arc seconds of the North American continent as long as they will occur in the dark in populated areas. The events here are the same as those that we selected for, and listed on pages 230 and 231 of, the 2008 RASC Observer’s Handbook except that here, we have eliminated 4 events that are unlikely to be observed.

David P. Werner has annotated the charts, both the 15° charts and the large-scale finder charts, against the True Visual Magnitude Photographic Star Atlas, for equatorial stars, and the Atlas Stellarum for declinations beyond ±30°, and has added faint stars and marginal notations as appropriate. He added the SAO numbers, asteroid classifications (given just after the asteroid’s angular diameter), and spectral types (between the visual and photographic magnitudes) when they were available. If you make copies of these charts, to prevent bleed through of stars on the other side, you should put a black piece of paper behind the page you are copying. If you don't have a black piece of paper handy, make one by making a copy with the copy machine cover open. This problem can be avoided by obtaining the charts from the Web.

Goffin and Preston give only one designation for the star, usually from the new accurate source catalogs such as FK6 (includes Hipparcos data), Hipparcos (HIP), or Tycho-2 (TYC2). But few have the resources to tell, for example, that HIP 23043 = ZC 741 = SAO 094227. D. Dunham and W. Warren wrote programs to cross-reference Goffin’s combined catalog with the PPM catalog to provide other identifications, as well as spectral types and information about duplicity, when available. This has allowed adding this information automatically to the list and manually to the charts. Predictions of the better occultations by major planets are included this year.

Since the chances for actually observing an asteroidal occultation are significantly increased with astrometric updates that are now obtained for most events, your observations will be most effective if you can receive these updates by e-mail; send your address to dunham@starpower.net or better, join the very active IOTAoccultation yahoo group. Updates are placed on Steve Preston’s Web site at http://www.asteroidoccultation.com which is the best source for them.

We are limiting the number of events in this Supplement to 62 (54 after removing past unobserved events) to cut duplication and mailing expenses. Now many observers can obtain the charts from the Web, looking at them there and printing only those charts that they might actually observe based on their schedule, astrometric updates, and the weather forecast a day or two in advance. With the more accurate predictions now possible with the HIP and TYC-2 star catalogs, and also much work in updating asteroid orbits using HIP/TYC-2-relative observations, especially during the weeks before occultations, the predictions for occultations by smaller asteroids can now be effectively improved. So we are considering more events, and this year there are many more because the searches have been more thorough, but we still try to identify just the better events to include here; many more are on Steve Preston’s Web site. This year, the predictions have been divided into two parts. The first part, which will be available on this website, contains predictions of the better asteroidal events judged to be observable by visual observers, events which meet the following criterion: Everything in North America in the RASC Observers' Handbook found by E. Goffin except for 4 events less likely to be observed, and several past events that were not observed. The following other criteria were used in the selection of the RASC Handbook events, primarily by Jim Stamm, but some events satisfying these criteria were not included in the first part: 1. Events which are greater than the following diameter limits while less than the magnitude limits (0.08", 12.0), (0.07", 9.0), (0.06", 8.0), (0.05", 7.0), (0.02", 6.0), (0.00", 5.0). 2. Magnitude drop > 0.5 magnitude. 3. Needs less than 0.5" shift to occur in astronomically populated parts of North America. All North American subscribers are being sent the first group, included here. The second group is no longer available, but charts for them, unannotated versions of the ones here, can be obtained from the ftp site given in Edwin Goffin’s document on the following pages, and path charts and (within a month of the event) detailed finder charts for all of them can be found on Steve Preston’s Web site. In the past, we made these available in printed form, often partially annotated, but requests for this second group of printed charts has declined to zero in recent years so we decided it was no longer effective to produce it, with so much more information readily available on the Web. The event listing description will be included with it when it becomes available, first at the Web site given above.

The International Occultation Timing Association was established to encourage and facilitate the observation of occultations and eclipses. It provides predictions for total and grazing occultations of stars by the Moon and predictions for occultations of stars by asteroids and planets, information on observing equipment and techniques, and reports of observations made. IOTA is a tax exempt organization under section 501(c)(3) and 509(a)(2) of the (USA) Internal Revenue Code, and is incorporated in the State of Texas.

Asteroidal occultation resource master page (Brad Timerson): http://www.asteroidoccultation.com/observations/

Path updates & charts (Steve Preston’s site) : http://www.asteroidoccultation.com

Google maps, station and star pre-point lists, and more (Derek Breit’s site): http://www.poyntsource.com/New/index.htm

These charts: http://www.asteroidoccultation.com/observations/GoffinMaps.html

North American Resource Page: http://www.asteroidoccultation.com/observations/NA

North American 2008 Results Page: http://www.asteroidoccultation.com/Results

Asteroidal satellite occultation predictions (Jerome Berthier): http://www.imcce.fr/en/ephemerides/phenomenes/occult/stellarocc.php?query=predoc

Occult Watcher (Hristo Pavlov): http://www.hristopavlov.net/OccultWatcher/publish.htm

IOTAoccultations Yahoo group (Rob Robinson moderator): http://tech.groups.yahoo.com/group/IOTAoccultations/

IOTA occultation observer’s manual (Richard Nugent): http://www.poyntsource.com/IOTAmanual/Preview.htm

Some notes for 2008 events are given on the charts for the events. I apologize for producing this very late, in early February; information was provided earlier via the internet. David Werner supplied the annotated charts last October, but I misplaced them and didn’t locate them again until late January. D. Dunham

For much more information about asteroidal occultations, visit http://www.asteroidoccultation.com/observations/NA .

The original document cited above can be downloaded here.