Main Objective: Perform coordinated observations with the Solar Orbiter instruments and Hinode during the 9th Remote Sensing Window (RSW) of the SO nominal mission phase that will take place between April 20 and April 24, 2023. The main goal of this HOP is to acquire co-temporal high resolution data with the Polarimetric and Helioseismic Imager (SO/PHI) and Hinodefs spectropolarimeter (Hinode/SP) where SO/PHI observes the North Pole while Hinode/SP observes the South Pole. In addition, the SO/PHI observations will be supported by SO/EUI and SO/SPICE.
Scientific Justification: Solar Orbiter (SO) was successfully launched on Feb. 10th, 2020, and since January 1st, 2022 is in nominal mission phase. Detailed scientific observations are acquired during the so-called remote sensing windows (RSWs).
SO/PHI provides maps of the vector magnetic field and line-of-sight velocities with two telescopes, the High Resolution Telescope (HRT) and the Full Disk Telescope (FDT).
A polar joint observation programme with Hinode and PHI provides a unique opportunity to obtain co-temporal observations of both poles. This will produce the first true high resolution snapshot of the Sunfs poles, which will help to simultaneously study the fine structure of the polar landscape. Such data will be beneficial to improve pole-filling routines and models of the polar magnetic field (Mikic et al. 2018) that are commonly used to substitute seasonally obstructed polar latitudes in synoptic maps. Current methods are limited to polar observations from periods when the Sun reaches a maximum tilt angle in early September and March which introduces a 6 months gap between observations (Sun et al. 2011).
The SO/PHI observations that will be used for the North Pole observation on April 24th 2023, when SO is at a distance of 0.426 au from the Sun, and with 135.2 degree longitudinal separation with respect to Earth and a latitude of 7.064 degrees, and therefore SO will have a view of the North Pole. At those times, the pixel scale is about 155 km for HRT.
During the 1 hour of observations HRT will be observing on a 100 second cadence with an accumulation scheme that maximises the polarimetric sensitivity, to produce 36 scans. However to save telemetry, the 36 scans will be averaged onboard to produce 12 scans with a 5 minute cadence. As such, the exact HRT pointing decision will be decided by the SOOP coordinators about three days in advance.
SO/EUI will co-observe and run the HRI_EUV and Lyman-alpha channels at a 30 second cadence from 23:00 to 00:00. SO/SPICE will also co-observe at 23:00-00:00 with an exposure time of 20 seconds, with a 2.1f FOV. From 21:00-23:00 SO/SPICE will observe with a larger 8.5f FOV and longer exposure time (60 seconds).
Since Hinode will have a similar view, but of the South Pole instead, we request that Hinode/SP observes simultaneously with HRT observations to create a dataset that captures both poles at the same time. |
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