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HINODE Operation Plan (HOP)

accepted on

23-feb-2023


 HOP No.

 HOP title

HOP 0450

EIS observations in support of total eclipse ground observations

plan term

2023/04/20-2023/04/20

@ @

proposer

 name : Landi @  e-mail : elandi[at]umich.edu

contact person in HINODE team

 name : Matthews, Culhane @  e-mail : sarah.matthews[at]ucl.ac.uk, j.culhane[at]ucl.ac.uk

 abstract of observational proposal
Main Objective: Carry out large FOV observations at the solar limb during totality including strong diagnostic lines

Scientific Justification: Solar eclipses provide unique opportunities to study the solar corona from the ground at a time when the impact of the solar atmosphere is minimized. During eclipses, coronal radiation in the visible wavelength range can be observed for much larger distances than with space-borne EUV and X-ray instrumentation, opening a window on the physical properties of the solar atmosphere at heights not easily reached with other instrumentation. In particular, the measurement of spectral line profiles allows for the measurement of physical properties (ion temperatures and non-thermal velocities), and Doppler shifts which are key to understand coronal heating in the magnetically closed corona, as well as solar wind heating and acceleration in the magnetically open corona (Landi et al. 2016, Boe et al. 2022). In coronal holes, visible line intensities also allow us to study the evolution of the solar wind ionization status and determine the freeze in height of the ions being observed (Boe et al. 2018). The overall coronal magnetic field topology can also be inferred during eclipses (Boe et al. 2020).

The combination of ground-based eclipse totality spectral observations in the visible with EIS EUV spectral scans can extend the reach of diagnostic results obtained with EUV spectral lines to distances usually unavailable, providing context and most importantly information on how these properties depend on height, in regions of critical importance for the acceleration and heating of the solar wind, the solar corona and coronal mass ejections.

In the past few eclipses, we have developed a high resolution spectrometer capable of observing select portions of the visible wavelength range and of measuring the profile of key coronal lines such as Fe X, Fe XI, and Fe XIV across half of the solar corona during the few minutes of totality, along with spectral lines from lower ionization species part of coronal mass ejections (Ding & Habbal 2017); narrow band filters have allowed the measurement of individual spectral line intensities for the entire corona up to 2 solar radii and beyond to study plasma thermal structure, solar wind source regions, and coronal mass ejections (Habbal et al. 2010, 2014, 2021, Alzate et al. 2017).

Here we propose to combine large field of view EIS observations of the off-limb corona with spectrally resolved scans and narrow band images of the entire solar corona in key coronal lines in the visible range during the total eclipse of 20 April 2023 in order carry out measurements of plasma temperature, density, line of sight speed, ion temperatures, non-thermal velocities, elemental abundances and ionization status evolution in large portions of the solar corona.

 request to SOT
None

 request to XRT
Standard Full-disk synoptic observation sequence (suitable for making a standard good-quality composite full-disk image.

 request to EIS
Run dhb_polar_scan starting before the eclipse, in order to include totality during the EIS scan.
Try to avoid SAA if at all possible (it might not be possible) or at least minimize their impact.
Use JPEG90 compression to decrease memory usage.

Study ID: 261
Study acronym: dhb_polar_scan
FOV: 360 x 512
Slit: 2"
Step size: 2"
Exposure time: 70s
Duration: 3h46m46s
Data usage (JPEG90): 382970 kBits
Pointing: depends on what is available, contact Enrico Landi prior to plannning (elandi@umich.edu)
Observation needs to be off-limb on the E hemisphere.
Target priority:
1st: coronal hole
2nd: quiet Sun/streamers
3rd: active regions
Remarks: Run including the 4:00-5:00UT period on 20 April 2023 (eclipse totality)

 other participating instruments
IRIS requests: Not at the moment

 remarks
Dates: 20 April 2023

Time window: 4:00-5:00UT

Target(s) of interest: In order of priority: Coronal holes, Quiet Sun, Active regions

Additional instrument coordination: None

Previous HOPs: No prior submission

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