Main Objective: The aim of the HOP is to obtain coordinated observations of the solar north pole between SO/PHI-HRT and Hinode/SP while SO reaches the highest latitude of the orbit.
Scientific Justification: 31 October 2023, co-observations of north pole with Solar Orbiter while Solar Orbiter sees the highest latitude of the pass:
The goal of this HOP is to acquire coordinated observations between the High Resolution Telescope (HRT) of the Polarimetric and Helioseismic Imager of Solar Orbiter (SO/PHI) and the Hinode spectropolarimeter (Hinode/SP), of the solar north pole on October 31 2023, during the Remote Sensing Window (RSW) 12 of the Solar Orbiter (SO) mission. On this day, SO will reach its highest latitude for this orbit. SO/EUI and SO/SPICE will also support the SOOP from the Solar Orbiter side.
Solar Orbiter will be at a solar latitude of 7.98 deg on October 31, 2023, seeing the Sun from the highest latitude during this time, while being at 0.55 AU from the Sun which yields a spatial resolution of 200 km on the Sun. This will allow to study small details of the poles from an angle a little higher than achievable from Earth, and with Hinode support could provide two different points to model polar structures with PHI providing a bit more direct line of sight observation.
The geometrical situation achieved during this time will as well complement the co-ordinated observations to be obtained on the other polar HOP requested for this time, Polar co-latitudinal observations of Solar Orbiter (SO) and Hinode from two different angles, to take place on October 17. At that time, both SO and Hinode will see the Sun from the same latitude of 5.7 deg while being separated by 51.47 deg in longitude. At this time, SO and Earth have diverged in latitude up to a difference of 3.5 deg but come closer in longitude to only 20 deg separation. So the combination of the two situations in a short time, could further improve the knowledge of the polar structure and provide better constraints for modelization of polar field extrapolations.
SO/PHI observations will cover the central period of the polar SOOP RS9_112, from 11:00 to 14:10 UT on October 31, around the time when SO reaches the highest solar latitude for the orbit. The HRT will have two sets of observations, one from 12:25 to 13:05 with mid-cadence of 5 minutes, and the rest of the mentioned time with low cadence observations of 20 minutes.
SO/EUI will support the PHI-HRT observations around the time of highest latitude, running the HRI_EUV and Ly-a channels at cadences of 8 and 300 second, respectively, from 11:20 to 13:20.
Likewise, SO/SPICE will support the SOOP, covering its whole length from 01:15 to 23:49, with a period of higher cadence to perform a raster of 2’ at 11 min cadence around the time of highest latitude, two wider context rasters before and after that, covering a 12.8’ FOV with higher exposure times and two other campaigns to perform polar plumes studies.
The combination of both geometrical situations from the present HOP and the former from the polar SOOP at October 17, provides a great opportunity to study almost the same polar landscape from two different spectroscopic scenarios which will strengthen the achievable results and produce new insights into the structure of the poles and their development towards the heliosphere.
17 October 2023, co-observations with Solar Orbiter while Hinode and Solar Orbiter see the same region of the solar north pole:
The main goal of the HOP is to obtain coordinated observations of the solar north pole on October 17 2023, during the Remote Sensing Window (RSW) 11 of the Solar Orbiter (SO) mission, between the High Resolution Telescope (HRT) of the Polarimetric and Helioseismic Imager on-board the Solar Orbiter mission (SO/PHI) and the Hinode spectropolarimeter (Hinode/SP). On this day, both SO and Earth (and Earth-bond) observatories will be observing the solar pole at the same latitude. SO/EUI and SO/SPICE will also support the SOOP from the Solar Orbiter side and DKIST has planned to join the coobservations from ground for part of the SOOP.
During the RSW 11 on October 17, 2023, SO and Earth will be seeing the north pole of the Sun at the same latitude of 5.71º but from different longitudes, 51.47º apart one from the other. This will provide a unique opportunity of performing co-observations of the polar magnetic field from PHI and Hinode, studying the complex field from two vantage points but with only one different angle, the longitudinal one and not latitude, having one less unknown to match the data. SO will be at 0.37 AU from the Sun at the time, providing a high resolution capability for discerning the smaller polar structures.
This situation will allow to recreate the three-dimensional landscape of the polar field and their structures much better than ever before while the supporting observations from the rest of SO and Hinode instruments provide the connection from the surface field into the upper layers.
SO/PHI observations will cover the whole period of the polar SOOP RS9_111, from 11:30 to 20:30 UT on October 17. Along this period, the HRT will observe all the time with a set of varying cadences: the cadence will change from 20 min at the beginning of the SOOP, to 10 min during most of the SOOP, and entering a high cadence mode of 100 s around the time of exact co-latitude at 15:40 UT.
SO/EUI will support the PHI-HRT observations around the time of co-latitude, running the HRI_EUV channel at a 8 second cadence from 14:30 to 16:30.
SO/SPICE will also co-observe, covering the whole length of the SOOP with a higher cadence polar raster of 2’ at 11 min cadence around the co-latitude time and two wider context rasters before and after that, covering a 12.8’ FOV with higher exposure times.
Given the unique opportunity that arises from this co-latitudinal situation to observe the pole from two different angles differing only in longitude, we request that Hinode/SP observes simultaneously with HRT to obtain these spectroscopic maps and infer the three dimensional polar structure. |
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