HOP 0522

abstract of observational proposal

Main Objective: Conduct coordinated observations of equatorial coronal holes to characterize the sources of fast solar wind and compare their properties at the Sun with in situ measurements, focusing on the relationship between switchbacks and jets.

Scientific Justification: We aim to conduct coordinated observations of equatorial coronal holes to characterize the sources of fast solar wind and compare their properties at the Sun with in situ measurements. Our focus is on the relationship between switchbacks and jets, using simultaneous imaging and spectroscopic observations from EIS, XRT, and IRIS. We will measure variations in temperature, electron density, emission measure, and velocities before, during, and after jet evolution. This will help determine the physical parameters in coronal holes and find quantitative relations between coronal-hole parameters and solar-wind parameters. These observations are crucial for understanding the mechanisms behind fast solar wind formation and will be conducted in conjunction with Solar Orbiter and Parker Solar Probe encounters. The first set of observations should be run right before and simultaneous to the first instance of the SOOP and a second set of observations before the second instance of the SOOP.

request to XRT

For on-disk coronal hole, run the following XRT study.
Filters: Al-poly 4s fixed exposure, Be-thin 16s fixed exposure
Field of view: 512" X 512"
Cadence: 30 sec (or even higher cadence depending the telemetry)
Priority Days: February 14th to 25th.
Priority timings:
February 14th from 12:19 to 13:20
February 20th from 22:30 to 23:30
February 25th from 22:24 to 23:25

request to EIS

Details: Coordinate exact details with the chief planner.
Pointing: Disk observation of a coronal hole.
Alternate between the two studies listed below.

Observation Schedule:

Dates: February 14th, 20th and 25th, plus March 5th, 6th and 9th (the March period is low priority as targets may not be visible from EARTH)
Priority Days: February 14th to 25th (EUI high-res campaign)

Study 1: Coronal Hole Observation
Study ID: 618
Acronym: HOP81_new_study_v2
Title: New coronal hole study for polar monitoring campaign, increased exposure Timing: February 14th - February 25th
Run once a day or twice if telemetry permits. If possible, observations should be coordinated with times when SPICE is running its composition observations.
Timing of SPICE composition rasters:
February 14th from 10:20 to 14:38
February 20th from 21:25 to February 21st at 06:00
February 25th from 20:00 to February 26th at 00:18

Study 2: Coronal Hole Jet Observation
Study ID: 512
Acronym: Cor_Hole_Jet_v1
Title: Small, fast raster for studying coronal hole jets.
Timing: February 14th - February 25th
Run as many repeats as telemetry allows during each of these time windows
Pointing: A bright point inside a coronal hole region, during EUI high-resolution observations.
Timing of EUI high-res bursts:
February 14th from 12:19 to 13:20
February 20th from 22:30 to 23:30
February 25th from 22:24 to 23:25
Time outside the Fast Wind SOOP of Feb. 14th to Mar. 9th, please run one of each study per day pointing at the CH connected to SolO at that time. As telemetry allows.

For second period (March 5th to 9th), please run one of each study per day pointing at the predicted source regions, as telemetry allows. Highest priority to March 5th.

EIS studies have the highest priority. Willing to sacrifice XRT (first) and SOT (second) observations if additional telemetry is available for EIS studies.

other participating instruments

IRIS requests:
Request sent to IRIS team awaiting response IRIS requests: For on-disk/polar coronal hole, run the following IRIS study. IRIS spectrograph: OBS ID : 3620109459 | Large sparse 64-step raster 63x120 64s Si IV Mg II h/k Deep x 8 Spa | 588.93 |253.62 | 0.3 | 9.2+-0.1 | 589+-0 | 0.0+-0.0 | 18.4+-0.0 | 18.4+-0.0 | 0.0+-0.0
IRIS Slit-Jaw Imager:
Field of view: 120" X 120"
SJI window: Si IV and Mg II
Exposure time: 4 sec
SJI cadence: 18.4 sec

Additional instrument coordination: SOOP: L_SMALL_HRES_HCAD_Fast-Wind https://issues.cosmos.esa.int/solarorbiterwiki/display/SOSP/Solar+Orbiter+Planning+-+for+coordination+with+external+parties

remarks

Dates: 2026/02/10-2026/03/09 The Fast Wind SOOP will run on six dates, February 14th, 20th and 25th, plus March 5th, 6th and 9th (the March period is low priority as targets may not be visible from EARTH)

Time window:
Target(s) of interest: Solar Wind Source Regions: Equatorial Coronal Hole or Polar Extension

Previous HOPs:
HOP 0502 - Last year's Fast Wind SOOP yielded the richest fast wind connection science dataset to date. Myself and Natalia are currently working on an overview of this SOOP and the coordinated observations with Hinode and IRIS. We are also supervising a group of early career researchers working this dataset. The combined datasets from these Fast Wind SOOPs will be used by the community for years to come.

Additional remarks:
Note that target information requires using models to map the Solar Orbiter connectivity foot point location back to the solar surface. Solar Orbiter target coordinates are provided (https://issues.cosmos.esa.int/solarorbiterwiki/display/SOSP/Solar+Orbiter+Planning+-+for+coordination+with+external+parties) and we can assist with pointing decisions outside of these times.