Re: Video: Pro & Con

Bart De Pontieu (BDP@MPEPL)
Tue, 25 Jun 1996 23:08:12 +0100 (CET)

RB Minton writes:

> dk058@cleveland.Freenet.Edu

No need to CC: messages to all these people, RB, they're all subscribed to
SeeSat-L. I think it's a good idea to have this discussion on SeeSat-L,
as opposed to private messages, we might all learn something from the others
on your CC-list.

>I've been told that our server is acting-up and since its been over 24 hours
>since I posted my last message (with no response); I'll do it again but with
>a slant on group participation - and addressed to Seesat-l.

Your last message was message 2760, from 10:22 (-6 time zone) Monday.
Ii'm not sure whether you're referring to local problems or not. In any case,
to my knowledge, SeeSat-L has been functioning well in the latest 24 hours.
>1 to 5 seconds.  Bart says that 0.5 sec. accuracy is required, so we are now
>thinking of ways to reduce video observations into precise times of maxima.

The accuracy needed actually depends on various factors: length of pass,
number of flashes, amount of variation of synodic effect, etc...
0.5 sec is a good rough number. But I've used measurements with only 0.8 sec
accuracy to determine very good estimates of the direction of the rotation 
axis of one satellite. It just happened to have shown an extreme case of 
synodic effect.

>1.  Build a 2-channel photometer to slide-around on the face of a TV screen so
>that the satellite is under 1 and the sky is under the other.  The satellite
>signal would be A-B.  The output would go to a chart recorder and times of 

Would it be easy to digitize the output of the chart recorder (short of 
scanning in the print-out?). No need to throw away good data (the whole
lightcurve as opposed to just times of maxima) if it's available.

>2.  Digitize the TV images and do a bona-fide photometric reduction.  I have a
>CCD and reduction software (MIPS) suitable for this; but I believe this is too
>time-consuming and labor-intensive for routine contributions.  Does anyone else
>have another slant on digitizing, but with faster reductions?
I will ask my colleague who regularly digitizes video images of northern
lights on the method he uses. More tomorrow.
I didn't get the impression it would be time-consuming, and it seems to be
highly automated here at MPE.
>3.  View the TV with a stopwatch and record the times just like most other 
>Seesat-l members.

Which is probably OK for satellites with sharp, distinct flashes.
Paul Maley (in a private messages) confirmed to me that using video 
can compress the amplitude of the flashes enormously.

>I invite discussion on this topic, especially since video recording is men-
>tioned in the announcements of topics for Eurosom 2; and the general trend 

I also hope all video-observers will join this discussion. 

>I was fortunate to spend 3 nights atop Mt. Haleakala observing how 
>the Air Force studies satellites.  (Yes Mr. John Pike - this is why I am so
>familiar with AMOS - the Air Force Maui Optical Tracking Station).

Thanks for writing your introduction. Any chance you'll write an article
for Flash about your experiences with AMOS ? Or is that information 
classified ?