Main Objective: We aim to conduct coordinated observations of active regions (AR) that may launch off-limb CMEs. Our goal is to study the changes in the magnetic field and plasma configurations before, during, and after the CME onset. The observations by Hinode (SOT, XRT, EIS) and IRIS will thus form the first "ring" in a unique chain of observations following the entire CME evolution. The second "ring" will be provided by the unprecedented low-corona observations of ASPIICS, followed by the upper-corona observations by, e.g., SOHO/LASCO C2, C3. This chain of observations will allow us to study the trigger mechanisms leading to the onset of CMEs and to investigate the early evolution and acceleration of CMEs. We aim to perform this IHOP several times during its term.
Scientific Justification: ASPIICS coronagraph offers unique capabilities to study the early evolution of (off-limb) CMEs. Thanks to its reach from below 1.1 to 3 solar radii, ASPIICS will fill the gap between the disk imagers (like SDO/AIA) and upper-corona observations by, for example, LASCO C2 (2 - 6 solar radii) and C3 (3.7 - 30 solar radii) coronagraphs. However, even with its reach, ASPIICS will not be able to observe the actual source regions of CMEs (AR or destabilized prominences/filaments) on the solar disk. To provide this missing piece of the puzzle of CME origin, we will conduct coordinated observations during (and prior to) several ASPIICS 6-hour-long observing windows. These coordinated observations will allow us to capture unique sequences of changing magnetic field topology before the CMEs are triggered (SOT) and study the response of the cool plasma (IRIS) and hot plasma (XRT, EIS) during and immediately after the CME onset.
ASPIICS will start nominal observations in Q2 2025. In this nominal period, ASPIICS will provide coronagraphic observations during a 6-hour-long window within an "observing orbit" . ESA will allocate "observing orbits" to the ASPIICS team about 1-2 months ahead, with the average frequency of 2 "observing orbits" out of 7 orbits. Each Proba-3/ASPIICS orbit is nearly 20 hours long. To accommodate this unusual observing schedule, we have designed this IHOP, which can be used for any ASPIICS observing window. To achieve our scientific goals, we would like to request coordinated observations during several ASPIICS observing windows. There is no preference for any particular ASPIICS observing window because the probability of observing a CME is the same (due to the necessity of advanced planning of pointing). Therefore, the coordinated observations could be allocated flexibly, avoiding any conflict with other coordinated observing campaigns. In general, ASPIICS will perform the "CME watch" observing program throughout its first year of observations (until Q2 2026).
The aim of the current IHOP is to maximize the chances of observing as many CMEs as possible, in as great a detail as the current set of instruments allows. With the high CME rate during the period of solar maximum (see, e.g., Wang&Colannino 2014, ApJL 784, L27, or the CDAW catalogue), there is a good probability to observe about 100-200 CMEs within a month. That translates into a good chance of capturing one CME within any of the 6-hour-long ASPIICS observing windows. |
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