HOP 0433

abstract of observational proposal

Main Objective: Coordinated observations with the Solar Orbiter (SO) Polarimetric and Helioseismic Imager (PHI) High-Resolution Telescope (HRT) of a tracked active region (AR) for the identification of sources of slow wind,
which will take place in March 2022.
Scientific Justification:

SO was successfully launched on Feb. 10, 2020. All its onboard instruments are performing nominally and were commissioned during the early phase of the mission. Among them, SO/PHI provides maps of the vector magnetic field and line-of-sight velocities with two telescopes (Full Disk Telescope, FDT, and HRT).
The proposed HOP will take place when SO is at 0.35AU, equivalent to a HRT spatial resolution of 260 km, while being at an angle varying from 31 to 45deg latitude (over the four days of co-observation) with Earth, ideal for stereoscopy.
The proposed HOP has two goals, namely a cross-calibration goal and a scientific one. The cross-calibration goal is to compare high-resolution SO/PHI-HRT maps with fast maps from SP, when the angular separation between the two spacecraft is relevant for stereoscopic observations. This requires an AR target to fully explore the range of field values, taken at the same time from both telescopes. In conjunction with other dedicated HOPs that request for normal maps (IHOP_Submission_139 and 140 by the same team), this HOP will complement the full cross-calibration by providing comparison with SP-fast maps.
The second goal is scientific in nature, namely to support the investigation of sources of slow wind from AR boundaries. The requested SP maps will complement the SO/PHI-HRT ones in providing stereoscopic information for a more accurate determination of the AR magnetic field (e.g., for stereoscopic disambiguation). Details about this specific science SOOP are public and can be found in:
https://issues.cosmos.esa.int/solarorbiterwiki/display/SOSP/L_SMALL_HRES_HCAD_Slow-Wind-Connection
This HOP is requested by the PHI team as support for the calibration HOPs (IHOP_Submission 139 and 140 from the same team).

request to SOT

Science support for the HRT high-resolution campaign.
We request one fast map, 320”x164”, for each of the four days of co-observation, namely
March 18th, from 9:50
March 19th, from 10:16
March 20th, from 11:07
March 21st, from 11:16
The above are intended as starting times of SP observations. Notice that, in the above, we considered one-hour duration for the SP scan of 320” width, and that the AR will be at the center of the FoV, resulting in SP starting to observe 20 minutes earlier than the corresponding PHI observation of the same day.
Adjustments might be necessary. The important point is that the AR is contained within the FoV and the time of SP scans overlap with the corresponding time of PHI-HRT observations given in “Target of Interest”.
Pointing: Active region. Ponting coordinates will be provided 3 days in advance of the start of the co-observing time, at the latest.
Telemetry requirement is expected to be 600 Mbits for each map, i.e. 2400 Mbits in total for the whole HOP. In the case of telemetry conflict with other HOPs, we would

1) Accept a reduced width of the field of view, as long as the AR is contained within the FoV and the time of SP scans overlap with the corresponding time of PHI-HRT observations given in “Target of Interest”

2) Prioritise later dates over earlier ones.

remarks

Dates: We request support for calibration and scientific activities during the HRT high-resolution observations on 18 to 21 March 2022 : HRT will perform 20 minutes of high-resolution observations at one-minute cadence in each of the four days.

Time window: The SO/PHI-HRT observations will take place on (year is 2022, time is UT)
March 18th, from 10:10 to 10:30
March 19th, from 10:36 to 10:56
March 20th, from 11:27 to 11:47
March 21st, from 11:36 to 11:56
It is important to take into account that the specific times (UT) above may be subject to slight changes, and are still to be confirmed. Exact times will be fixed around two weeks (worst case) prior observation starts.

Target(s) of interest: HRT will point at an AR, which will be identified, at the latest, three days in advance of the first observation on March 18th. The same AR is expected to be tracked during the 4 days
of required co-observation.
SO position on the relevant days is (Ecliptic longitude and latitude distance from Earth)
March 18th, at 10:10, 31.558 degrees, 1.762 degrees
March 19th, at 10:36, 35.936 degrees, 1.525 degrees
March 20th, at 11:27, 40.672 degrees, 1.256 degrees
March 21st, at 11:36, 45.537 degrees, 0.970 degrees

Additional remarks:
We do not include here any request for other Hinode instruments in order to maximize the telemetry available for the requested SOT/SP maps.
Pointing requires special coordination between SO/PHI and Hinode teams. The exact pointing coordinates (AR) will be provided about three days in advance of the requested Hinode/SP observation.