Description of a lunar meteor impact imaging run

Home      Lunar Impact page     Lunar Impact telescope setup...


Here's a description of a typical observing run, to record lunar impacts.

Setup   click here for info and pictures of the setup

Setup the mount. Level and polar align mount. Add counterweights; realign mount. Mount telescope, connect focus controller cable, video cable and power for camera. Secure any loose cables. Realign mount to Polaris. Set telescope to home position. Connect power supply to mount and turn on the controller. After initial setup, manually acquire moon, set controller to lunar tracking.

Focus and align image on CCD.

Initially focus the camera and align it so that the illuminated portion of the moon is just at the edge of the top of the FOV and is aligned with the width of the screen as to maximize the moon's darkened portion on the CCD. Focus camera accurately and slew from moon to a star to refine focus as precisely as possible. Reacquire the moon.

Recording the run

Turn on KIWI OSD GPS video time stamp unit; turn on video deck, plug in fire wire cable to laptop. Launch video capture software and once GPS time stamp is running, start recording as 720X480 DV AVI wit no compression. I record to an external 1394 Tera-byte MyBook drive. The drive must be capable of recording without dropping frames. It is also very important to have as accurate a time refreence as possible. Audio WWV is an option or possibly, a very well timed recorder time stamp may suffice.

Alternately, you can record to a digital video recorder and at a later time, record it to a computer.

* My laptop occasionally drops a frame here and there and I therefore always run the KIWI OSD time stamper. However, one can turn off the time stamp after starting to record. The software used to analyze the AVI files will keep accurate time and does not need to have a time stamp.

Chop up the huge AVI files into manageable segments with Virtual Dub

After the run is over, use Virtual Dub to divide the AVI files into manageable sizes. Instructions on how to save these files are in the LunarScan software manual (to download, see link below). This equates to about a third of the duration of the AVI run, for my laptop to preform. However, if your computer really cranks, great! I will soon be using a new laptop and am anticipating an increase in speed.

Download LunarScan 1.3 (784 Kb Zip) Impact detection software by Pete Gural.

Take down the telescope, weights and mount and put it all back in the garage.

Run LunarScan 1.3

After chopping the AVIs into a series of small files, run LunarScan to analyze the files. After LunarScan is done, review the log file for impacts. It will take a few runs to be comfortable with all of these steps working with these monster AVI files.

Review and report!!

Review the log file and extract candidate events from AVI files and use other software to analyze the resulting frames. Cosmic Rays cause impact-like events on the CCD and need to be eliminated. It may take a confirmed impact or two, to be comfortable with being able to identify an event worth reporting. Typically, the light curve for an impact goes to maximum brightness on the first video field (odd or even field extracted from an interlaced video frame). Subsequent video fields should then be dimmer and drop off in brightness. However, there is no guarantee this will be the case with short duration events. Due to atmospheric turbulence, any one star observed using video rapidly fluctuates in brightness. Dim stars sometimes disappear for an individual odd or even video field.

Report impact candidates to      Danielle Moser   danielle.e.moser@nasa.gov
at the Meteoroid Environment Office Marshall Space Flight Center

I also report lunar impact candidates to the the Lunar-Impact group on Yahoo which discusses aspects of lunar impact monitoring, and serves as a place to possibly coordinate suspected impact times:

Group Email Addresses
Post message:     lunar-impact@yahoogroups.com
Subscribe:     lunar-impact-subscribe@yahoogroups.com
Unsubscribe:     lunar-impact-unsubscribe@yahoogroups.com
List owner:     lunar-impact-owner@yahoogroups.com
Subscribe:     lunar-impact-subscribe@yahoogroups.com


Home