Re: Observing Satelite based LIDAR

From: John A. Dormer 2 via Seesat-l <seesat-l_at_satobs.org>
Date: Mon, 6 Mar 2023 10:18:42 -0600
Conjecturing a bit, it's possible that the Daqi-1/AEMS system was not in 
its nominal mode based on Eubanks' information. Perhaps its operators 
were trying out a different duty cycle for some unknown-to-us reason.

In regular RADAR systems, long pulse-lengths lead to range-folding 
issues where the detector is still receiving reflections from the 
previous pulse when the next transmission begins. The photos I saw of 
the Daqi-1 system imply a long transmit time. Without knowing how far 
away the light-fan was from the camera which took the picture, it may be 
difficult to tell just how long the "on" phase was. We do have ways to 
calculate the angular rate of Daqi-1, at least.

However, that may still not explain all of why a relatively simple 
camera was able to capture the light-fan.

     John

On 3/4/2023 10:14, Marshall Eubanks via Seesat-l wrote:
> On 2023-03-03 14:53, Jim Blackhurst via Seesat-l wrote:
>> I was reading again today about the sighting of green laser beams, as
>> recorded by a webcam at the Subaru Telescope in Hawaii. It's now widely
>> acknowledged that this was caused by the ACDL (LIDAR) instrument of the
>> Chinese satellite Daqi-1/AEMS.
>>
>> Sightings of the lasers used in satellite-based Lidar are amazingly 
>> rare,
> ...
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Received on Mon Mar 06 2023 - 10:20:03 UTC

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