Contains:  Solar system body or event
Asteroid 420 Vanadis Occults 11th Magnitude Star, 


            Chappel Astro

Asteroid 420 Vanadis Occults 11th Magnitude Star

Acquisition type: Lucky imaging

Acquisition details

Date: March 29, 2021

Time: 03:18

FPS: 66

Focal length: 425

Resolution: 600x510

Locations: Home, Cibolo, Texas, United States

Data source: Backyard


Stellar occultations by asteroids are a thing I have wanted to pursue for years but never got around to doing so. Last week, a local friend made me aware of an upcoming one and invited me to watch the recording of it at a nearby site. Ultimately, that ended up not happening, but I made a spur of the moment decision to catch it from my backyard about an hour and a half before it was to occur.

I had no idea when or where this event would take place in the sky, so I rushed to find it and eventually came across a prediction that 240 Vanadis would occult TYC 0843-01393-1, magnitude 13.5 and 11.2 respectively, at about a quarter past 10 in the evening from my location.

Set up started around 9PM and required digging out my long-neglected HyperStar v3. I used the Cool Edge to quickly acclimate the OTA, then wrapped it with Reflectix for the first time. Supposedly, this can help eliminate internal currents by preventing the aluminum tube from radiating away excess heat as the outside temperature falls over the course of a night. No currents were visible while collimating on Regulus, so more testing will be needed to figure out if this is a good strategy for me.

After collimating the telescope, it was directed at the star and plate solved to make sure it was centered in the sensor about 10 minutes before the occultation. In the moments before the event, I realized a setting needed to be changed before recording and took a few seconds to do so. Once I finished, the star was missing from the image! Realizing what had happened, I quickly hit the ringbuffer button in FireCapture and hoped it saved frames from before the start. Unfortunately, I could not find the video that ringbuffer should have saved, so I only have a recording of the end of the occultation.

Despite the last minute mess-up, I feel this experiment was a success and hope to catch more of these in the future! It turns out the RAM Disk I have automatically created when launching FC was too small, causing ringbuffer to silently fail.