HOP 0416

abstract of observational proposal

Scientific Justification * We organize an observing campaign to build a holistic view of the solar source coronal hole of the high-speed solar wind stream seen by Parker Solar Probe (PSP) at its 8th perihelion on April 29th. This
campaign will address the following questions:

- Where are the individual open magnetic funnels which build the coronal hole rooted?
- How is mass transported from the photosphere to the corona in these funnels?
- How does the outflow velocity and mass flux in the lower corona in coronal holes depend on the properties of the open magnetic funnels in lower atmospheric heights?
- How do the solar wind properties seen by PSP depend on the properties of its source coronal hole?
- How does the associated high-speed solar wind stream evolve from the Sun to 0.9 AU as seen by Solar Orbiter and 1.5 AU as seen by Maven?

The time window around Parker Solar Probe’s (PSPs) 8 th perihelion provides a unique opportunity to address these questions, as the perihelion is observable from Earth view, as it takes place end of April where usually the observing conditions for the ground-based telescopes in Tenerife are good, and as Solar Orbiter and Maven are well aligned with PSP. The observing campaign will be 10 days, i.e., from April 28th to May 7th , with an observing time of roughly 4.5 hours per day.

We received SOLARNET observing time for the ground-based high-resolution spectropolarimetric instruments SST/CHRISP and GREGOR/GRIS. They will probe and create magnetic field maps from the photosphere to the upper chromosphere in 4 heights, which shall allow us to uniquely identify the open magnetic funnels in coronal holes. Here, we request IRIS and Hinode for observations of the transition region and corona to study the plasma outflow velocity, temperature, density, mass flux, and FIP abundances in multiple heights.

The IRIS and Hinode observations during these 10 days shall be performed in two setups, whereby only one setup per observing day will be performed:

・Setup #1: detailed scans over entire coronal holes at multiple days, in order to study the distribution of magnetic funnels and their statistical properties, and their evolution.
・Setup #2: high-cadence scans of subregions of coronal holes, in order to study the short-term evolution and upward propagating waves from the photosphere to the low corona.

In order to maximize the output of this observing campaign, we coordinate this observing campaign with the Whole Heliosphere and Planetary Interaction (WHPI) initiative, and expect that further ground-based optical and radio observatories join the effort. To ease the collaboration, all of the data taken shall be publicly released immediately after the observations. This proposal covers Setup #2 of the campaign.

request to SOT

SOT/SP shall perform the following sequence outside SAAS:
SAA - n1 x 1.5”x164” normal - SSA - n2 x 60”x164” fast - SAA - n3 x 60”x164” fast - SAA.
During the first observing slot outside SAAs, repeat 1.5”x164” SP normal scans as often as possible.

Suitable cadences are
- 1 minute resulting in 0.5 Gbit/hour (e.g., SP 0x232, margin factor 0.95)
- 30 seconds resulting in 0.75 Gbits/hour (e.g., SP 0x231, margin factor 0.75),
- 20 seconds resulting in estimated 1.5 Gbits/hour
Note that SP 0x231 and 0x232 cannot be in the same table (they use the same SEQ and PAR slots).

We will leave it to the discretion of the planner to choose the cadence which best fits to the available telemetry. The 1.5”x164” scans shall be coordinated with EIS and IRIS, to have roughly the same center position. Note that in case of insufficient telemetry, we can skip the SOT observations in this observing slot on some days.

During the observing slots two and three outside SAAs, repeat 60”x164” fast maps as often as possible. The cadence of a single 60”x164” scan is 13min26s. The amount of data is 0.7 Gbit/hour. In case of telemetry issues, these observing slots shall be given priority over the observing slot one (1.5”x164”).

request to EIS

EIS shall perform the following sequence outside SAAs:
SAA - n1 x CH_Funnesl+FIP_sitn - SSA - n2 x CH_Funnesl+FIP_fast - SAA - n3 x CH_Funnesl+FIP_fast - SAA .

During the first observing slot, EIS shall perform repeated sit’n stare scans (CH_Funnesl+FIP_sitn) at the same position as long as the time allows. Note that the sit’n’stare shall be coordinated with SOT and IRIS, to have roughly the same center position.

During the observing slots two and three outside SAAs, EIS shall perform repeated scans using CH_Funnesl+FIP_fast as often as the time allows.

Size: 76-96 MByte, depending on the number of repetitions possible in the slots between SAAs.

Line lists:
Line list: Line(s) Central wavelength (A)
S X 180.53
O VI 184.05
Fe XII 186.75
Fe XI 188.53
Fe X 189.87
S XI 191.27
Ca XVII 192.82
Fe XII 193.54
Fe XII 195.12
S VIII 198.55
Fe XIII 203.40
O V 249.29
He II 256.32
Fe X 257.75
Si X 261.04
S X 264.23
Mg VI 269.05
Mg VI 270.40
Si VII 272.65
Si VII 275.97
Mg VII 278.39
Mg VII 280.15
Fe XV 284.16

other participating instruments

IRIS:
Please run n1 x ObsID 3620340004, followed by n2 x ObsID 3620418060, and then by n3 x ObsID 3620418060. The exact start and end times for these three OBS runs will be provided by the IHOP proposer every day.

The first observing slot is a sit’n’stare, ObsID 3620340004 (Very large sit-and-stare 0.3x175 1s Deep x 15 Spatial x 2, Spectral x1 FUV x2, Data rate 0.41 Mbit/s). The slit shall be roughly aligned with EIS and SOT.

The second and third observing slot runs repeated scans using the ObsID 3620418060 (Very large sparse 64-step raster 63x175 64s, Deep x 8, Spatial x 4, Spectral x1, FUV x2, Data rate: 0.37 Mbit/s).

Additional instrument coordination: GREGOR and SST

remarks

Dates: 10 days of observations, from April 28th to May 7th . The observations shall be coordinated with IRIS, GREGOR and SST. The assigned observing time within the 10 days is shared with the IHOP A holistic view on coronal holes - overview scans, whereby on each day only one of the two IHOPs will be run.

Time window: Shall be arranged with GREGOR and SST, preferable starting at 7:30 am UTC. Three consecutive observing slots outside SAAs are requested.

Target(s) of interest:
Subregion of 60”x175” with a low-latitude coronal hole, or low-latitudinal extension of a polar coronal hole, respectively.

Previous HOPs:
IHOP 400, which was performed on 23rd October, 2020. This IHOP was a test run for the now proposed campaign. We are currently working on the data, which lead to the updated line list and observing program as proposed above.

Additional remarks:
Due the large EIS data amount, we request the limb-mode allocation for Hinode/EIS. Due to the large amount of data, this IHOP can only be run once within one timeline upload window.