omicron_virgo.md

@@ -91,6 +91,31 @@ For a complete documentation to run omicron, see [the omicron documentation](htt
 <a href="https://git.ligo.org/virgo/virgoapp/Omicron/-/raw/master/doc/images/gw170817_spectro.png"><img src="https://git.ligo.org/virgo/virgoapp/Omicron/-/raw/master/doc/images/gw170817_spectro.png"></a>
  The most basic plot produced by a scan is a SNR spectrogram. Omicron offers additional plots: amplitude spectrogram, raw time series, time series after whitening, PSD, ASD...
  
+## Online production of Omicron triggers
+
+Currently, around 400 channels are automatically processed when the Virgo interferometer is in `LOW_NOISE_3` Metatron state (triggering on the flag `DQ_META_NOMINAL_LOCK`), through a series of processes running in the `OnlineDataQuality` package and on `olservers` machines. We included the possibility to send the rate of omicron triggers in the DAQ with channels of the type `V1:OMICRON_RATE_SNR_#_ADC_ChannelName`.
+
+Example of channels:
+```
+V1:OMICRON_RATE_SNR_20_ADC_LSC_DARM
+V1:OMICRON_RATE_SNR_5_ADC_LSC_DARM
+V1:OMICRON_RATE_SNR_8_ADC_LSC_DARM 
+```
+Channel values:
+```
+-10: Omicron has been reset (too many triggers)
+-2: synchronization problem (should never happen…)
+-1: State vector down
+0: rate is null (likely Omicron triggers are not computed for the state in which the interferometer is)
+>0: rate -- unit: Hz
+``` 
+
+## Offline production of Omicron triggers
+
+Periodically during a Virgo science run (~every month), omicron triggers are reprocessed at the IN2P3 computing center (Lyon). All channels in the raw data with a sampling rate larger than 500 Hz are processed. Omicron is configured with a low SNR threshold (5) and a fairly high resolution (tile mismatch=20%).
+
+To access Omicron triggers at the CCIN2P3, see [Omicron at CCIN2P3](omicron_ccin2p3).
+
 ## Other applications
 
 - [Omicron conda package](https://anaconda.org/conda-forge/omicron)