source: Science Performance Document Iss 4.0 (CDR version - March 2016) & Metis User Manual Iss3 (May 2016) - table 4.1.3.2


Specific instrument observing modes have been defined in order to address the scientific objectives of the METIS investigation. In general, METIS observations consist of global maps of the coronal emission in UV H I Ly-α and VL (580-640 nm range), obtained with different spatial resolution and detector exposure time, depending on the science goal and the instantaneous field of view (FoV).

The special observing modes defined for METIS are: 

 

FLUCTS and TBF – Brightness fluctuations spectra (best near perihelion) - acquisition sequence details below

High spatial resolution and cadence time series of VL coronal brightness over a range of distances covering from 1.6 R! out to 5 R!, to constrain the amplitude of the density fluctuations spectrum.
High frequency: TCAD=1 s (FLUCTS), =20 s (TBF).
The typical duration of this program is approximately 1 hour 

CMEOBS – CME propagation, related driven shocks and filamentary structures, SEP accelerated by CMEs Measurement of the electron density and outward expansion velocity gradient at high spatial resolution and temporal cadence. This mode is activated by a proper CME event flag.
Such measurements can be used to identify the path of the shock front where particles can be accelerated in the outer solar corona. Moreover, combined with radio observations, they can help to distinguish flare- accelerated SEPs from those associated with CMEs.

COMET – Mapping the emission of Sungrazing comets
These measurements are used to monitor the evolution of the cometary emission along its trajectory close to the Sun.

PROBE – Coordinated observations with Solar Probe Plus (SPP)
Characterising the properties of the coronal regions crossed by the SPP spacecraft, during its transit close to the Sun. 


FLUCTS + TBF mode: Coronal brightness fluctuations at high frequence: acquisition details

Source: Science Performance Report 4.0

 

The program relevant to the study of the high frequency brightness fluctuations spectra (observing modes FLUCTS and TBF, see Table 12) will be carried out in about 1 hr, as shown in Fig. 2:

The program relevant to the study of the high frequency brightness fluctuations spectra (observing modes FLUCTS and TBF, see Table 12) will be carried out in about 1 hr, as shown in Fig. 2:
- Run mode FLUCTS twice as follows:

  • step 1: acquisition of ~60 consecutive raw VL images with DIT=1 s, NPOL=1, temporarily stored in the instrument memory

  • step 2: wait for on-board processing (masking, binning, compression, see Sect. 5.1.1) of the raw images (TW ~10 s per image, in total ~600 s) and transfer of the reduced size images to the S/C SSMM (280.2 Mb) to empty the instrument memory

 

- Change from mode FLUCTS to mode TBF

 - Run mode TBF:

  • acquisition of ~120 VL images with DIT=20 s, NPOL=2, changing the polarization angle by 90° after 10 s during each acquisition; on-board processing of image i and transfer to the S/C SSMM is performed contemporarily to the acquisition of image i+1 (data volume: 560.4 Mb)

The expected data volume produced by the instrument in 1 hr is equal to 1120.8 Mb. 

 


Corresponding EPS observations:

METIS_FLUCTS with parameters:

MET_DATARATE = 311333 [bits/sec] 

 

METIS_CMEOBS with parameters:

CADENCE = 60 [s] \
VL_COMPR = 12.7 \
UV_COMPR = 3.2 \
=> MET_DATARATE = 384700 [bits/sec]

 

METIS_COMET with parameters:

CADENCE = 600 [s] \
VL_COMPR = 12.7 \
UV_COMPR = 3.2 \
=> MET_DATARATE = 38470 [bits/sec]

 

METIS_PROBE with parameters:

 

CADENCE = 900 [s] \
VL_COMPR = 12.7 \
UV_COMPR = 12.7 \
=> MET_DATARATE = 21834 [bits/sec]

 
 
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