Transcript Use of Registax and LiMovie for the Reduction of Marginal

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
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
To avoid this problem, some observers
use integrating cameras such as:
• WAT 120N and
Astrovid Stellacam
• Lumenera SKYnyx2-0
• SBIG STV
These are great cameras but there
are a couple of problems
• At the maximum frame rate, they may not
be as sensitive as the non-integrating
cameras
• If you select an integration rate that is too
long, you lose time resolution in your data
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
So how do you do this?
Registax to the rescue…
Videos can be easily and quickly integrated with Registax without any
loss of video integrity and only the minimum required for time resolution
Integration can be done in four
simple steps
We can take LiMovie data that
looks like this….
Is there an occultation in this raw
data?
And turn it into data that looks like this
This was done with a 5-frame integration from raw data
This was done with an 11-frame integration from raw data
We can extract data from videos
where wind vibration is excessive…
Do not
‘Optimize’
Press Save to create a ‘Registered’ file
If there is a bright star in the field, a preregistration can be done in six simple steps
Here is a raw shaky image…
LiMovie cannot reliably track the faint star in the
raw data…it is hard to tell what is happening to
the faint star
Pre-registering so the target star is steady and
can be analyzed with LiMovie…
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