HOP 0483

abstract of observational proposal

Main Objective: Coordinate observations with EIS and IRIS for several cross-calibration purposes:
- To compare line radiance using oxygen lines for Quiet Sun and oxygen and magnesium lines for Active Regions.
- To improve the Doppler shift performance of SPICE. This is a follow-up to some of the observations performed in HOP 0454 in March/April 2023.
- To assess the co-alignment that can be achieved using upper chromosphere lines (e.g., He II for EIS and H I, O II and C III for SPICE).

Scientific Justification: Many coordinated science campaigns between SPICE, EIS and IRIS, with the purpose of measuring the solar composition and dynamics, are foreseen. Therefore, these cross-calibration measurements will help to improve the understanding of how to use these instruments together.

This should be run when Solar Orbiter is close to the Sun-Earth line in two instances: on 19 March and 20 March 2024 for a few hours each. This is the best opportunity with a small angle of separation between the spacecraft for the next 2.5 years.

request to EIS

19 Mar 2024 11:00-17:00: Study 404 “Atlas_60”, followed by 2 repeats of a combination of Study 615 “Large_CH_Map_v2” and Study 404 “Atlas_60”.

20 Mar 2024 00:05-03:10: 2 repeats of a combination of Study 571 “ar_vel_fast_scan” and Study 403 “Atlas_30”.

If there is insufficient telemetry, even 1 repeat on each occasion would still be very useful.

Priorities:
-1100-1200 on 19-Mar-24 Atlas_60 in that period.
-Having at least some support on both targets (QS on 19-Mar and AR on 20-Mar) is also better than having full support for one and none for the other.

remarks

Dates: 1. 19/03/2024 - 20/03/2024 as the SOOP will run on those dates.
2. 2 days.
3. The days are fixed as for Solar Orbiter plan.

Time window: 1. 6 hours on 19/03/2024: from 11:00 to 17:00 and 3 hours and 5minutes on 20/03/2024: from 00:05 to 03:10. See EIS requests for details.
2. No.

Target(s) of interest: On 19/03/2024 On-disk as for Solar Orbiter plan.
On 20/03/2024 Active Region as for Solar Orbiter plan.

Previous HOPs: No previous HOP submission.

Additional remarks:
The target on 19 March is Sun centre as seen by Solar Orbiter, while on 20 March is an Active Region.
The precise target coordinates on 19 March will be known well in advance. The target coordinates on 20 March will be chosen by the Solar Orbiter team at a ‘pointing decision’ meeting on 17 March. This will be communicated via the existing route for coordination.