[evlatests] More on Lunar Reflections

[Rick Perley]

I did a bit more on this today.  The results distributed yesterday were 
from the 'decimated' database, with 1 MHz spectral resolution.

The original file has 125 kHz resolution. so I returned to this to get 
better spectral resolution.  Images were made for each of the 128 
channels within SPW08 (432 -- 448 MHz), utilizing all the data over time 
-- 10:04 -- 15:10 IAT on Nov 04.

Reflected circular polarization was seen in most channels, usually at a 
fairly low level, typically at -0.5 Jy or less. (Negative means the 
signal is left circularly polarized -- this is always the case).  But 
some channels have *much* higher levels.  Most notable are the channels 
between 436.5 and 439.0 MHz, where the measured signal varied from -1 to 
-4.7 Jy.

To check on time variability, I selected the 'loudest' channel (437.25 
MHz), and made 14 images, one for each observation scan (9 minutes long 
for each).  This gave quite a spectacular result -- peak 'V' signal 
varied from undetectable (at 13:00 IAT) to a whopping -28.3 Jy/beam at 
14:45.

For the two scans with the highest reflection (14:45 and 15:05, IAT), I 
made full polarization snapshots.  Here is a short table of the peak 
brightness (always at the center of the lunar disk) in each of the 
Stokes parameters: (in Jy/beam).

Time          I                   Q U                    V

---------------------------------------------------------------------------

14:45        37.2            -9.8 9.5                   -28.3

15:05        34.3            -12.3 7.1                   -26.4

----------------------------------------------------------------------------

For reference, the disk brightness at this frequency and resolution is 
typically 1 Jy/beam.  The total disk flux at this frequency is about 70 
Jy.  The synthesize beam width is 220 arcseconds.

Although it might be useful to investigate shorter time intervals (the 
data are originally sampled at 2 seconds) and more frequencies, I have 
many other things to do.  But if anybody wants to poke around some more, 
I can export the data.

Rick
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