April 21, 2005 UT: No data on occultation by asteroid (204) Kallisto

Michael Richmond

April 21, 2005

On the morning of April 21, 2005, the asteroid (204) Kallisto was predicted to occult the star TYC 5770-00924-1 for observers in the northeast US.

Map courtesy of Steve Preston -- see the Asteroid Occultation Update page for upcoming events.

I woke up around 3 AM to set up for the event. The plan was was:

• Meade LX200 12-inch telescope
• no focal reducer, so working at f/10
• SuperCircuits PC164C video camera (mount this so that lettering on the side is upright and legible)
• Kiwi OSD time insertion unit
• a new VCR to record video for later analysis

RIT physics major Tom Schwarting kindly provided a new VCR to replace the one which did not work during last week's occultation by Stobbe. This one DOES work -- thanks, Tom!

During last week's event, we discovered that the KIWI OSD time insertion unit built by RIT physics major Matt Montanaro had a loose connector. Matt took the unit home over the weekend and fixed it. Indeed, as soon as I connected it to the VCR this morning, I saw stars and the GPS time on the display; no problems. Thanks, Matt!

Alas, although all the equipment worked just fine, I could not detect the target star (or the much fainter asteroid) in the video images. I am pretty sure that I was in the right place, as I sync'ed the telescope on several stars within a few degrees of the target. My explanation for failing to detect the star with our 12-inch telescope plus PC-164C has several components:

• a faint target star, with mags B=11.5, R=11.0, I=10.8 from the USNO B1.0.
• observing low in the sky, at airmass 2.55, leading to extinction of roughly 0.4 mag more that at the zenith
• observing just before dawn, with the Sun only 12.7 degrees below horizon, and in the same general direction as target (to the SE)

My guess is that we could probably detect this star as a faint source above the noise under ideal conditions, but this morning was far from ideal.

So, there's nothing for me to report. I hope other people had better luck, either in detecting the star, or in staying in bed.