Asteroid (240) Vanadis passes in front of a bright star in Libra

LIVE broadcast from centerline


Wednesday evening August 19, 2009

Broadcast begins Wednesday at about 5PM EDT




o    104 km diameter asteroid (240) Vanadis occults target star =  HIP 75848

o    The shadow of asteroid Vanadis will travel across entire USA from east to west at almost 16km/s (580mph)!

o    Maximum predicted duration of occultation =  6.7 seconds

o    Magnitude of target star in Libra:   6.8 visual,   6.6 red magnitude (red is where our cameras are most sensitive)

o    Approximate time of the occultation event at broadcast site near Orlando, FL:  between 9:46 and 9:47 PM EDT Wednesday August 19, 2009

o   Many highly populated areas will be able to view the shadow of (240) Vanadis with only a pair of binoculars!

o   The (240) Vanadis shadow path covers virtually the same ground in Florida as the upcoming and very scientifically significant (234) Barbara occultation on November 20, 2009. So the Vanadis event is a practice run for Florida for the November Barbara event.

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 (240) Vanadis. 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 Vanadis’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 Preston’s websites (click on names)




o    5PM CDT Wednesday: broadcast will begin and a brief “show and tell” of my equipment will be given.

o    Shortly after the introduction I will begin the short drive from Orlando to survey sites for this event and potential sites for the November 20, 2009 (234) Barbara occultation.

o    Around 8PM EDT I will arrive at the first of several sites that I intend to set up for the Vanadis occultation. I will be waiting for twilight to darken. Estimated end of Civil Twilight = 8:24 PM EDT, at which time I hope to acquire the star Spica in the sky where my first station will be prepointed to.

o    Between 8:15 to 8:35 PM EDT I will deploy my first station and prepoint to the area of sky where the target will drift through exactly centered at event time.

o    Every 10 to 15 minutes after that I will be deploying another station at a new location about 5km further south. When I am able I will orient my camera so you can watch the deployment.

o    Around 9:15 PM EDT 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 9:46 and 9:47 PM EDT you and I should witness the light of the target star blink out as the shadow of (240) Vanadis pass over and darkens our world for up to 7 seconds! Knowing the event outcome in real time will indicated whether the path shifted or not. If I get a near 7 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 more than a dozen other observers spread out across the path. This profile can be viewed at our IOTAAsteroid Occultation Results for North America

o    IMPORTANT NOTES: Central Florida is well known for pop up thundershowers that start mid afternoon, but usually dissipate in the evening at sunset. If clouds linger persistently you may get to watch me sit and stare at the sky, and worse, I may not get to point a single camera to see the event live. Also, the part of Florida I will be deploying in has known dead zones for wireless reception. I will periodically lose signal resulting in a black out of the broadcast. Just stay logged on and once I am back in signal range the broadcast will automatically resume. I intend to discover an area with a good signal to do the actual event broadcast for Vanadis so that I know that I can successfully broadcast the November (234) Barbara occultation from that very same site.



Scotty Degenhardt

Columbia, TN  USA

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!





· - The attempt to deploy a record 20 stations by me alone for the (19) Pretoria occultation was completely dashed by persistent clouds. But 7 of us succeeded in getting a total of 21 chords of measurement around (19) Pretoria and making a new discovery that the target star was a previously unknown double star! Go to the RESULTS page to see the light curves and profiles showing the two shadows plotted from the two different stars:


Equipment tour:

Live at centerline blunder (for some reason I completely lost audio, and I failed to locate the target star until 40 seconds AFTER the event!):



· - (488) Kreusa occultation was my first attempt to show a deployment live from beginning to end. I broadcast for 10 hours straight, but I had numerous signal interruptions, as I was traveling through Amish country through Arkansas and Missouri where there was sparse cell coverage. I only succeeded in deploying 3 stations, and the signal completely dropped out at centerline when I went to broadcast the actual occultation event. But that was of little significance, as there was a major shift in the path and all 3 of my stations (including the one I would have broadcast live) completely missed the shadow! You can visit the RESULTS page to see the final profile. I do have a few archived videos from that deployment from Scotty’s Sky.


Introduction of expedition:


This was the first time I field deployed my 120mm short tube refractor (now dubbed by David Dunham as the Mighty Maxi, as it has a 13th magnitude limit!). In the video I managed to record the deployment, with prepointing starting about 4:22 minutes into it, and completed by 8:20 minutes. This took me 4 minutes to prepoint using a might mini as a finderscope. I then patch in the video from the telescope at the very end of the video... and then my signal dropped out!

The signal came back for another minute and here is a view through the scope:

Here was the best I could do with deployment at my Station 2B:

But these are the things I hoped to learn from this trip: How to show it better.