Welcome

You are on the Sudden Ionospheric Disturbances Monitoring Station A118 website. Welcome!

The solar flares release energy that affect the near Earth environment and particularly a part of the atmosphere called ionosphere.

Through monitoring of the propagation of radio communication signals, this station aims at detecting some of the ionospheric effects resulting from solar flares. Those effects are known as Sudden Ionospheric Disturbances, or SIDs.

This station is an amateur observatory located in France. Operational since early 2006, it has received the AAVSO observer code A118 in July 2006 and provides data to a coordinated network of observers around the world.

This website gives you access to real time measurements collected by the station and to a database of SID events observed so far.

I have also include general and basic information related to ionosphere, and to Sudden Ionospheric Disturbances and their detection principle.

This website aims also at providing information for building your own station. The construction of the various parts is described: the VLF antenna, the VLF receiver and the data acquisition and processing software.

I hope you will enjoy this site. Comments and suggestions are more than welcome, so do not hesitate!

The origins...

Early 2005, a Sky & Telescope article mentioned the recording by an amateur astronomer of the effect of a GRB (Gamma Ray Burst) on the Earth ionosphere. This amateur was monitoring radio signals transmitted by VLF (Very Low Frequency) stations hundreds to thousands miles away.

As a child, I used to spend many hours in astronomy books or under the skies. Today, professional constraints impose me to live under light polluted skies and to be less and less available for watching the stars. The monitoring of SID (Sudden Ionospheric Disturbances) appeared to me as a good means to come back to astronomy and gave me the opportunity of discovering a whole new world...
Less than a year after reading the S&T article, after hundreds of hours surfing the web and seeking information, making the VLF receiver and writing software, the SID Monitoring Station was operational.

Latest News

GRBlocator updated to v1.0.0.0
06 Mar 2009 21:25 UTC
Further to a comment (thanks Jean-Jacques!), an option has been added to GRBlocator software to enable or disable the calculation of atmospheric refraction.
Release of GRBlocator v1.0.0.0
01 Mar 2009 22:30 UTC
GRBlocator is a new software that helps determine the visibility of a GRB at the sub-reflective point of the path between an transmitter and a station monitoring VLF signals propagation.
Addition of a page on the signal-to-noise ratio of loop antennas
23 Sep 2008 16:00 UTC
The site has been updated with a page dedicated to loop antenna noise levels at VLF frequencies and calculations of SNR obtained with several antennas configurations.
GOES Primary and Secondary Satellite Change
12 Feb 2008 12:00 UTC
The SWPC (Space Weather Prediction Center) has posted on its website the following information related to GOES X-ray data measurements:

GOES-10 X-ray Data Returns
GOES-11 Xray Data LOST

February 12, 2008 -- GOES-10 data has resumed and GOES-10 has been designed the SWPC primary GOES Satellite for X-ray data.
GOES-11 Xray Data has become unavailable and is not expected to return.
GOES-11 Data Lists ended on Feb 10, 2008.
GOES-11 Data Lists have been discontinued.

The X-ray measurements shown on this site account for this change that took place on February 12, 2008.
Happy New Year 2008
01 Jan 2008 00:00 UTC
I wish you and your loved ones a very Happy New Year!

[View News Archive...]

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