(meteorobs) IR Signature of Meteors in the near IR

Swift, Wesley R. (MSFC-EV44)[Raytheon - Jacobs] wesley.swift at nasa.gov
Thu May 28 11:32:48 EDT 2009


The most practical way to keep the sun from spoiling all sky images is to use a shadow band.  Shadow band pyranometers and photometers have been used for decades to measure solar and sky radiance.  There are two types, static and rotating shadow band instruments. The static shadow bands need to be manually adjusted for solar declination as seasons change while the rotating shadow band is computer controlled. The fraction of the sky obstructed by either is actually quite small.

http://www.eppleylab.com/PrdShadingDevices.htm
http://www.novalynx.com/240-152.html  http://www.yesinc.com/products/data/mfr7/index.html  

Wes


-----Original Message-----
From: meteorobs-bounces at meteorobs.org [mailto:meteorobs-bounces at meteorobs.org] On Behalf Of Ed Majden
Sent: Wednesday, May 27, 2009 4:39 PM
To: Global Meteor Observing Forum; bob71741
Cc: borovic at asu.cas.cz
Subject: Re: (meteorobs) IR Signature of Meteors in the near IR

Hello Bob:
	I saw your original post, but isn't recording meteorite impacts on  
the dark side of the Moon at night a different kettle of fish?   Has  
one ever been recorded on the sunlit side, I don't think so!  The big  
problem with our all-sky cameras is the Sun scatters light on the ccd  
frame blotting out around 1/4 of the frame.  The auto iris in the  
security type camera used, also reduces the sensitivity of the camera  
so the ccd is not damaged by the strong sunlight.  Possibly, using a  
mask that would blot out the Sun may help improving the situation a  
bit.  Filtering out transmission to a specific region of the  
spectrum, i.e. near IR region, will also reduce overall sensitivity.   
I'm not sure if low velocity fireballs, the type that may drop a  
meteorite would have strong emissions in the near IR region.  I could  
be wrong about this but I think this is correct.  See: Astron.  
Astrophys. 279, 627-645 (1993) A fireball Spectrum Analysis by Jiri  
Borovicka.  Too bad these Lunar impacts are so faint as I would love  
to get a spectrum of such an impact! ;-)
Ed


On 27-May-09, at 2:12 PM, bob71741 wrote:

> Ed - I posted a link for the usage of a Wratten 87 filter and CCD  
> video camera used to record meteor impacts on the moon. I realize  
> that this is not exactly what Thomas wants to do since he is  
> interested in imaging the meteor trail, but if you can image the  
> impact,in IR, on the moon, then imaging meteor trails in the  
> atmosphere during daylight may be realizable too.
>
> Below is a copy of the Allan Kimble dialog. Please note that Allan  
> is a scientist, not an amateur, so I would have to place some value  
> to his experiences. Also note that he wants to capture  
> spectroscopic images of the impact as well.
>
> Thanks for the opportunity to write. I began filming meteor impacts  
> on the moon in 1997 using CCD cameras and long-pass near-infrared  
> filters. I was successful during the Leonids of 1997 in capturing  
> several images of the impacts on video -- some simultaneous. For a  
> while, I had posted them on a website, but they drew no great  
> attention. Since then, I have developed several smaller camera  
> systems for imaging in the NIR portion of the spectrum between  
> 850nm and about 1100nm. What I have found is that electronic noise  
> lasts, at most, 2 video frames. I have been able to see impact  
> flashes lasting between 30 and 45 video frames by using the NIR  
> portion of the spectrum. I published a couple of articles in the  
> Northeast Florida Astronomical Society newsletter (Skywatch)  
> regarding my findings and the methods of constructing NIR CCD  
> systems. The advantage is that I can make observations in daylight  
> without much interference from the sun. The original video was  
> obtained using a 1! 50mm f/13 r
> My eventual goal is to be able to spectroscopically image the  
> impacts to see if there is a correlation between the spectral light  
> emissions and the compositions of the meteor and the soil where it  
> impacts -- a kind of remote lunar geology.
>
> Allan Kimble
> Sr. Scientist
> Microscopy & Spectroscopy Laboratory
> Vistakon, Johnson & Johnson Vision Care
> Jacksonville, FL
> Tel. (904) 443-3020
> Fax (904) 443-3433
>
> Regards
> Bob
>
>
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