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(meteorobs) Performance of PC164C

I received my PC164C camera last week and have had poor skies, but Monday I
did get some good images. The moon was near full, so these images are
representative of performance during the upcoming Leonids. I used a 9mm f1.4
lens. The total cost of the setup ran to USD170.00.

My conclusions are as follows: the PC164C is exceptionally strong at the red
end of the spectrum; star fields don't match the maps. The camera
under-represents blue stars and exaggerates red stars. Overall, the camera
seems capable of recording down to magnitude 4.2 -- averaging blue stars
with red stars. Thus, it easily saw some red stars of magnitude 4.5, but one
magnitude 3.8 blue star was barely visible. There is also, of course, the
fact that its response from frame to frame is quite variable. This can be
averaged out with stars, but not with meteors. The field of view is 32
degrees by 24 degrees.

So, is the PC164C cost-competitive with a system using an image intensifier?
I don't know, because I don't have solid specs on such systems. Moreover, a
proper cost comparison requires full system comparison. With that in mind, I
shall present two preliminary sets of numbers, both highly speculative.
Moreover, I have slapped together a figure of merit based on the assumption
that the number of meteors recorded is directly proportional to the light
sensitivity of the camera. Thus, a camera that can record one magnitude
fainter will see 2.54 times more meteors. I'm sure that someone will correct
that assumption.

I assume that other members of this list will correct these numbers:

PC164C System:
   PC164C       $139
   Lens          $50
   Power Supply  $15
   Computer    $1000

Total Cost:    $1204
Coverage:       768 square degrees to magnitude 4
Figure of Merit: $1.57 per square degree - meteor


Image Intensifier system:
   Intensifier $1000
   Lens          $50
   Camera       $100
   camera lens   $50
   Computer    $1000

Total cost:    $2200
Coverage:       1000 square degrees to magnitude 7
Figure of Merit: $0.13 per square degree - meteor

Again, I remind everybody that I am pulling these numbers out of thin air; I
hope that they are so wrong that somebody will be motivated to post better
numbers.

The primary cost of the PC164C system is the computer. I assume a computer
that can take regular video in and process it -- that's fairly expensive. It
seems to me that there are two interesting possibilities here. First, what
if the video output of the PC164C were recorded using a regular video camera
(not a digital one), and the tapes were fed into the computer? This would
require more busywork, but it would also greatly reduce the cost of a large
system.

The second possibility would be to build special hardware to process the
data. If we could get our hands on the data stream coming out of the CCD,
before it goes into the video converter, then we would have direct digital
video ready for fast processing. I don't think that's possible, as Sony has
designed their chipset to function in an integrated fashion; it's not likely
that we could get our hands on the raw data stream.

I confess that I am not competent to handle true video processing. I can put
together some simple digital systems, but this might be over my head --
unless somebody knows about some handy-dandy chip out there that would make
this task much simpler. It seems to me that the most time-consuming
processing is very simple: just moving brightness bytes around, taking
averages. It might be possible to do this at the board level, which would
allow us to use much cheaper data-recording computers.

Chris Crawford


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