[SQM] Little changing in SQM-network data collection

Massimo Alessandria massimo at bresciaraduno.it
Mon Jul 23 11:22:57 UTC 2012


I Chris,
sorry for the delay, but this is not our work (would be nice!).
I've verified in many nights that the "noise" of SQM is consistent only 
in a range of mag fron 15-16, and there's no many skies with this 
natural brightness ... so this noise is not important for readings 
because it wasn't taked in astronomical darkness. So we haven't noise in 
readings from 18 and 22 (you can verify it from yourself simply leafing 
many graph on uor website)
We take misure every minutes for all the station connected (more than 
30), and if you see on the graph in clear nights you will see anything 
that seems "noise".

In the next days i will take a read on the standard you're proposing for 
IL data format, and i hope to have enough time to write you my opinion 
and any suggest.

Regards, and thank you for your work!

Massimo Alessandria
Light Pollution monitoring Network
www.sqm-network.com

Il 13/07/2012 14:00, sqm-request at unihedron.com ha scritto:
>     1. Re: Little changing in SQM-network data collection
>        (Christopher Kyba)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 12 Jul 2012 15:48:31 +0200
> From: Christopher Kyba <christopher.kyba at wew.fu-berlin.de>
> Subject: Re: [SQM] Little changing in SQM-network data collection
> To: massimo at bresciaraduno.it
> Cc: sqm at unihedron.com
> Message-ID:
> 	<CADECMXsf+3YVK+qiHGcmarJhLRkwK228RspT+4jK6AjCVaqTyQ at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Hi Massimo,
>
> The variability that you get from -ux rather than -rx is just "noise".
>   Specifically, it looks like the SQM sometimes picks up an external EM
> field and this causes the readings to jump around.  The point at which
> the jumps start and the size of the jumps are not consistent from SQM
> to SQM, and I think it is non-existent for the SQM-LU.
>
> I very strongly recommend that you do not take measurements with -ux!
> It will simply make your light pollution data worse by adding
> non-Gaussian "jitter".  It must surely be much better to modify your
> cloudy/clear detection algorithm to work with noise-removed data than
> to add a bunch of noise into the data collection.
>
> I have been hoping to hear back from you regarding the skyglow data
> format that Dorien Lolkema and I proposed, which has now been modified
> and altered based on feedback from the community.  You can find the
> most recent version of the format here:
> http://tech.groups.yahoo.com/group/LPResearch/message/60
>
> I hope you will get back to me about the format, because we would
> really appreciate your input based on your experience running the
> network.  I also hope that you'll adopt the format for GECO when it is
> finalized this fall.  You can always write out two files in order to
> not break your current scripts.
>
> Best wishes,
>
> Chris
>


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