Asteroid (790) Pretoria passes in front of a star in Pegasus

History making expedition with LIVE broadcast from centerline


Saturday evening / Sunday morning July 18/19, 2009

Broadcast begins Saturday at 6PM CDT (23h UT)




o    170 km diameter asteroid (790) Pretoria occults target star =  TYC 2255-01354-1

o    Pretoria’s shadow will travel across entire USA from south to north at almost 11km/s (410mph)!

o    Maximum predicted duration of occultation =  ~ 16 seconds

o    Magnitude of target star in Pegasus:   10.0 visual,   9.3 red magnitude (red is where our cameras are most sensitive)

o    Approximate time of the occultation event at broadcast site near Bowling Green, KY:  between 01:05:30 – 01:06:00 AM CDT Sunday July 19, 2009

o    Path at a glance:

20090719 (790) Pretoria Google path map.png

The green line represents the center of the predicted path of the shadow of (790) Pretoria. The blue lines represented the predicted edges of the shadow, so theoretically if you are standing between the blue lines you will see the light of the target star disappear for up to 16 seconds or less. The red lines represent the 1 sigma statistical error in the predictions. Path shifts of up to 1.5 sigma are not uncommon, so if you are between the red lines you still have a chance of seeing Pretoria’s shadow.

Interactive Google map to find your location can be found on Derek Breit’s website:


o    Star charts and additional information at Derek Breit’s and Steve Preton’s websites (click on names)




o    6PM CDT Saturday: broadcast will begin and a brief “show and tell” of my equipment for deployment will be given.

o    Shortly after the introduction I will begin the approximate 2 hour drive to Cadiz, Ky.

o    Around 8:15 PM CDT Saturday I will refuel and regroup at Cadiz while I am waiting for twilight to darken

o    Between 8:25 to 8:45 PM CDT I will deploy my first station and prepoint to the area of sky where the target will drift through four and a half hours later

o    Every 10 to 15 minutes after that I will be deploying another station at a new location between 5 to 10km further east. When I am able I will orient my camera so you can watch the deployment. At some point I will even attempt to wear a helmet cam so that you can see EXACTLY what I see while deploying! You will simply have to stay tuned to see which site I do that at (or watch the recording that will be re-aired after the broadcast)

o    Between 00:45 to 01:00 AM CDT Sunday I will arrive at my final site at centerline where I will once again show the equipment and prepare to broadcast the actual occultation

o    between 01:05:30 – 01:06:00 AM CDT Sunday July 19, 2009 you and I should witness the light of the target star blink out as the shadow of (790) Pretoria pass over and darkens our world for up to 16 seconds! Knowing the event outcome in real time will indicated whether the path shifted or not. If I get a near 16 second event at centerline that indicates the predictions were correct.

o    In the days after the event the actual shadow profile will be assemble based on all 20 of my planned stations and the more than a dozen other observers spread out across the path. This profile can be viewed at our IOTAAsteroid Occultation Results for North America




It wasn’t until 1961 that a prediction of an asteroid passing in front of a star was successfully confirmed by observation ((2) Pallas recorded photoelectrically at Naini Tal Observatory in India). Since then improvements in both the known position of the stars and asteroids have made it practical for people to not only plan for observing an occultation at an ideally placed fixed location, but also travel remotely to the path of the shadow to place observing equipment directly in its path. Prior to 2001 these asteroidal occultation expeditions involved a person setting up at a single site to monitor the target star. On September 7th, 2001 David Dunham made history when got a positive chord from two different stations he deployed. Along with David, sporadic attempts were made after that by a lot of early pioneers of multi-station deployments, notably Roger Venable, Steve Preston, and Dave Gault.

After almost a 10 year hiatus with my work with the International Occultation Timing Association I returned in 2007 to try my hand at asteroidal occultations. Prior to this I had mainly timed lunar occultations of stars and planets. My early astrovideography pioneering days left me with quite the scrap heap of optics and cameras. Newer cameras such as the Supercircuits PC164C were now available that were many times more sensitive than the ones I used in the early 1990s. When combining these newer cameras with my fast lenses I soon developed a new observing method that would allow a single person to deploy more than a dozen to almost 2 dozen stations by his or her self! You can read more about my “Galileo reincarnated” efforts in a book entitled Small Telescope and Astronomical Research comes out in 2009 by Collins Foundation Press. I have posted on my website an unedited version of my chapter with permission of Collins Foundation Press. There you will find additional graphs that could fit in the edited chapter of the book, as well as instructions on how to construct my Mighty Mini observing system at And make sure to visit the new website for the Mighty Mini, Mighty Midi, and Mighty Maxi observing systems (site still under construction!) at

The new observing method has given rise to unprecedented coverage of asteroidal occultation events and is leading to very high resolution measurements of these asteroid bodies. Here is a sample graph showing dates of the introduction of the different observing systems and the resulting sharp increase in multi-station deployments by individual observers:


Figure10 Extra stations plotV3.jpg



        On September 12, 2008 my first deployment of the Mighty Mini system was for the asteroid (9) Metis occultation and resulted in a successful deployment of 11 stations by me alone, of which 9 succeeded in collecting data (2 of them were prepointed to the wrong time and place). All 9 missed the path of the shadow and were too far north. David Dunham set up 3 Minis and succeeded in being the first person to get positive occultation data from an asteroid occultation at all 3 of his Mini stations! The resulting profile is here:


9 Metis 2008  9 12 all misses.jpg

(Reduction by permission from B. Timerson, IOTA 2008)


        This new miss record would soon be shattered even worse (unfortunately!). Only about a week and a half after the Metis event David Dunham and I traveled to the remote regions of Fort Nelson, British Columbia to try to capture the shadow of (216) Kleopatra. I traveled with 21 observing stations and Dunham brought almost a dozen as well. I succeeded in deploying 14 stations that collected good data and Dunham had 5 stations that collected data. Again, all 14 of my stations recorded solid misses, setting a new miss record by a single person!! There was an almost 8 sigma path shift south, but thank goodness 2 of Dunham’s sites snagged the shadow at least showing us where it shifted.


20080926_KleopatraProfile all misses.jpg


        Finally on December 11, 2008 I would set the opposite record, the most number of positive observations by a single person at 14. I actually deployed 15 stations for the (135) Hertha event, but one got stolen, so I would actually have had 15 positive events, but I was only able to report 14 measurements (for obvious reasons!). the results of that reduction showed the incredible information capable of being achieved with such high resolution deployment efforts:


20081211_HerthaProfile V6 final.jpg


20081211 (135) Hertha invert compare ppt.png


        In May of 2009 I attempted my first true 20 station deployment that would have succeeded for the (547) Praxedis asteroidal occultation of 20090520. I deployed near Area 51 and along the Extraterrestrial Highway in the Nevada Desert (very apropos I thought!). Clouds prevented me from getting a good start during the first hour after sunset. This would cost me the time to reach my last 4 stations. So I only succeeded in reaching 16 stations, but 3 of those suffered failures (2 due to clouds and 1 due to the programmable remote failing to activate the recorder). The results…. Alien spacecraft nudged the body of asteroid (547) Praxedis northward causing all 13 of my stations to record misses…. That’s my story and I’m stickin’ to it!!! A large several sigma shift north gave me a large amount of misses again. But it was my first time using programmable remote controls to activate each recording device unattended, thus allowing me time to spread further and deploy more stations.


20090520PraxedisProfile prelim.jpg


        So now comes the shadow of (790) Pretoria on July 19, 2009! If weather and interruptions (including Alien spacecraft) do not interfere I will deploy and acquire data from a record number of stations, TWENTY! If the shadow travels as predicted I will also have a new record of 20 positive observations by a single person (a record I might add that will not be broken anytime soon …). Join me for the broadcast at event time to see in real time if history is indeed made, and if (790) Pretoria had her mug shot captured!


Scotty (“Galileo on steroids,” according to Russ Genet!)



Scotty Degenhardt

Columbia, TN  USA
888-687-5444 toll free to my cell


ADDITIONAL INFORMATION: Derek Breit’s prediction site Steve Preston’s North American Asteroid Occultation Page  Chasing the Shadow’ (Copyright © 2007 Richard Nugent, International Occultation Timing Association, ISBN 978-0-615-29124-6) Asteroid Results page See the universe as viewed from Scotty’s Sky!




A new science of measuring asteroids by interferometery has been developed by the French VLT-MIDI team. Asteroid (234) Barbara has been measured by this new technology to be binary. Amateur astronomers have a chance to be at the front of verifying this new observing method through an occultation measurement of (234) Barbara!