Use of Registax and LiMovie for the Reduction of Marginal Occultations. Tony George Umatilla, Oregon. Low light video cameras such as the Supercircuits PC164C and Watec WAT 902H series cameras allow observers to record occultations at the very limit of detectability.
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Low light video cameras such as the Supercircuits PC164C Occultationsand Watec WAT 902H series camerasallow observers to recordoccultations at the very limit of detectability
The problem comes when we try to reduce the data from these very low brightness events, sometimes the target star is not visible on the video monitor and sometimes in LiMovie we cannot see the target star to affix an aperture to measure the brightness
WAT 120N and Astrovid Stellacam very low brightness events, sometimes the target star is not visible on the video monitor and sometimes in LiMovie we cannot see the target star to affix an aperture to measure the brightness
SBIG STVTo avoid this problem, some observers use integrating cameras such as:
One solution to this problem is to use the non-integrating CCD video camera and then integrate the video after recording. This allows you to extract just enough of the signal to detect the event (or confirm a negative event), but no more than is necessary to avoid unnecessary loss of time resolution
Videos can be easily and quickly integrated with Registax without any loss of video integrity and only the minimum required for time resolution
Is there an occultation in this raw data?
This was done with a 5-frame integration from raw data
This was done with an 11-frame integration from raw data
Do not ‘Optimize’
Press Save to create a ‘Registered’ file
In the ‘registered’ file, LiMovie tracks the faint star, even right next to the bright star – and we have data on both stars. If the faint star was the one occulted, we would now have good data.
Detailed procedures for using Registax for preprocessing videos for subsequent analysis by LiMovie are contained here:http://www.asteroidoccultation.com/observations/Forms/RegistaxAlignment.htm
LiMovie, coupled with Registax can prove to be a very powerful combination – one that can greatly extend the events we can detect and report