Prioritized Flags for Science Cases
As explained in the EUI scietific impact and in the EUI performance sections, the observations are driven by the mission profile in sinergy with the instruments onboard Solar Orbiter. In order to provide a handy toolkit for planning the operations, with the drawback of some unavoidable simplifications, seven main observing modes are foreseen:
- S - Synoptic Observations:
- C - Coronal Hole Observations
- Q - Quiet Sun Observations
- AR - Active Region Observations
- E - Eruptive Events
- G - Global Eruptive events
- I - Instrument calibration
Table 1. Volume of telemetry produced by the most common programs to be compared
to 50.4 Gb allocated for one orbit. Here we assume a 150-day orbit,
compression 50 and 2.5 for programs (S), 15 for the others, an average
20kbps, and 12 bit images. Note that thanks to the adaptive compression
scheme, the required amount of telemetry for program (S) is constant even
though the size of the window changes along the orbit. The science questions
mentioned in the talbe are:
(1) Which physical conditions and processes govern the plasma, fields, and particles in the Sun-Heliosphere system?
(2) What are the origins of the SW structures and the heliospheric magnetic field?
(3) What drives the flow of mass and energy through the magnetically coupled layers of the solar atmosphere and into the heliosphere?
From Table 1 it appears that the continuous synoptic FSI program (S, first line) needs about 1/5th of the allocated TM for one orbit (cycles composed by one low and one high exposure observations using 2048x2048 pixels). A compressed and/or rebinned subset of the data observed by the (S) program can be downloaded in NRT (if the SC is in contact) as beacon data. The FSI images are always 2kx2k. The HRI observations must then trade-off between temporal coverage at lower cadence (program C) versus highest cadence (program A). The latter possibility makes sense only if an event can be identified reliably and autonomously in the HRI FOV. Below, ther are two further examples of high resolutions programs which share the same issue of event identification.
Alternative high resolution programs
|Date||Solar cycle||AU to Sun||Approx max angle||S||C||Q||A||E||G||I|
|PER 11-13||2021 2022||Max||.29||28||20||5||5||25||25||10||10|
|PER 14-16||2022 2023||Max||.34||32||20||5||5||25||25||10||10|
|PER 17-19||2023 2024||Decrease||.37||34||20||10||5||20||25||10||10|
Outline of the scientific mode distribution(S, C, Q, A, E, F, G, I), values are in % of the EUI allocated TM
Telemetry distribution, a template programThe table (on the side) gives a draft scenario of how the EUI TM could be distributed along the first 22 orbits. The numbers in those tables assume a 150 day orbit, an average 20kbps, and 12 bit images. 14-bit images would pertain to the instrumental program (I).
The EUI telescopes are capable of producing two or three orders of magnitude more data than the foreseen telemetry bandwidth. Images can be compressed by factors of 10-50, and perhaps up to 100 or 150, but not much more. Compression alone cannot be expected to resolve the telemetry shortage problem. We therefore foresee onboard prioritization of acquired sequences via simple and robust onboard algorithms. They are applied on the low-resolution version of the original image and histogram characteristics, as explained in the section of the instrument data handling. These algorithms select the image sequences that best correspond to predetermined science priorities, and provide flags for e.g. prioritization, outgoing notification, and feedback on the cadence (the latter TBC). Besides events satisfying EUI selection criteria, we expect to benefit from notifications by other onboard instruments.