Instrument Calibration of the Interface Region Imaging Spectrograph (IRIS) Mission

Wülser, J. P.; Jaeggli, Sarah A.; Pontieu, Bart De; Tarbell, T. D.; Boerner, P.; Freeland, S.; Liu, W.; Timmons, R.; Brannon, Sean; Kankelborg, C. C.; Madsen, C. A.; McKillop, S.; Prchlik, J.; Saar, Steven H.; Schanche, N.; Testa, Paola; Bryans, P.; Wiesmann, M.

doi:10.1007/s11207-018-1364-8

Cited by 47 publications

(43 citation statements)

References 15 publications

(15 reference statements)

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“…The IRIS data consist of dense (0.349 ) 16-step rasters with a pixel size of 0.167 along the slit, scanning a field of view (FoV) of 5.3 × 66.7 initially centered at the edge of the plage at [x, y] ∼ [−265 , 269 ] where the x and y axes are the helioprojective longitude and latitude, respectively. The exposure time per step was 0.5 s and the raster cadence was 25 s. The data have been flat-fielded, dark-subtracted, corrected for geometrical distortions, and calibrated in wavelength as described in Wülser et al (2018). The radiometric calibration was performed using version four of the calibration files obtained using the iris_get_response routine in SolarSoft (SSW, Freeland & Handy 1998) with a flux calibration uncertainty of 15%.…”

Section: Data Reduction and Alignmentmentioning

confidence: 99%

The multi-thermal chromosphere

Santos

Rodríguez

Leenaarts

et al. 2020

A&A

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Context. Numerical simulations of the solar chromosphere predict a diverse thermal structure with both hot and cool regions. Observations of plage regions in particular typically feature broader and brighter chromospheric lines, which suggests that they are formed in hotter and denser conditions than in the quiet Sun, but also implies a nonthermal component whose source is unclear. Aims. We revisit the problem of the stratification of temperature and microturbulence in plage and the quiet Sun, now adding millimeter (mm) continuum observations provided by the Atacama Large Millimiter Array (ALMA) to inversions of near-ultraviolet Interface Region Imaging Spectrograph (IRIS) spectra as a powerful new diagnostic to disentangle the two parameters. We fit cool chromospheric holes and track the fast evolution of compact mm brightenings in the plage region. Methods. We use the STiC nonlocal thermodynamic equilibrium (NLTE) inversion code to simultaneously fit real ultraviolet and mm spectra in order to infer the thermodynamic parameters of the plasma. Results. We confirm the anticipated constraining potential of ALMA in NLTE inversions of the solar chromosphere. We find significant differences between the inversion results of IRIS data alone compared to the results of a combination with the mm data: the IRIS+ALMA inversions have increased contrast and temperature range, and tend to favor lower values of microturbulence (∼3−6 km s−1 in plage compared to ∼4−7 km s−1 from IRIS alone) in the chromosphere. The average brightness temperature of the plage region at 1.25 mm is 8500 K, but the ALMA maps also show much cooler (∼3000 K) and hotter (∼11 000 K) evolving features partially seen in other diagnostics. To explain the former, the inversions require the existence of localized low-temperature regions in the chromosphere where molecules such as CO could form. The hot features could sustain such high temperatures due to non-equilibrium hydrogen ionization effects in a shocked chromosphere – a scenario that is supported by low-frequency shock wave patterns found in the Mg II lines probed by IRIS.

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Section: Data Reduction and Alignmentmentioning

confidence: 99%

The multi-thermal chromosphere

Santos

Rodríguez

Leenaarts

et al. 2020

A&A

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“…In our research we used IRIS level 2 data, which are corrected for i.a. dark current, flat-field, geometric distortion and scattered light [25]. In the upper panel of Figure 7 we marked also moments, for which SDO/AIA maps were obtained (green vertical dotted lines).…”

Section: Observationsmentioning

confidence: 92%

Type III Radio Bursts Observations on 20th August 2017 and 9th September 2017 with LOFAR Bałdy Telescope

et al. 2021

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We present the observations of two type III solar radio events performed with LOFAR (LOw-Frequency ARray) station in Bałdy (PL612), Poland in single mode. The first event occurred on 20th August 2017 and the second one on 9th September 2017. Solar dynamic spectra were recorded in the 10 MHz up to 90 MHz frequency band. Together with the wide frequency bandwidth LOFAR telescope (with single station used) provides also high frequency and high sensitivity observations. Additionally to LOFAR observations, the data recorded by instruments on boards of the Interface Region Imaging Spectrograph (IRIS) and Solar Dynamics Observatory (SDO) in the UV spectral range complement observations in the radio field. Unfortunately, only the radio event from 9th September 2017 was observed by both satellites. Our study shows that the LOFAR single station observations, in combination with observations at other wavelengths can be very useful for better understanding of the environment in which the type III radio events occur.

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“…We used the IRIS slit jaw images to get the temporal evolution of the granulation at λ = 2832Å with a time step of 20.8 seconds [Wülser et al, 2018]. By temporal interpolation, we removed the images of the slit on each frame allowing a perfect 2D field.…”

Section: Themis Iris Hmi Hinode and Simulation Datamentioning

confidence: 99%

Evolution of exploding granules from coordinated observations by THEMIS, IRIS, SDO/HMI, and HINODE, and a simulation

Roudier

Malherbe

Gelly³

et al. 2020

A&A

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Exploding granules constitute the strongest horizontal flows on the quiet Sun and contribute to the structure of the surface horizontal velocity fields which build the large-scale organization of the discrete magnetic field. In this work we explore exploding granule expansion through the observations of the ground-based THEMIS telescope, IRIS, SDO, and the Hinode space-borne instruments, and finally with the magnetohydrodynamics simulation. We evaluate the detection and the expansion of exploding granules at several wavelengths and at various spatial and temporal resolutions. To analyze the different temporal sequences, two methods of image segmentation are applied to select the granules. The first allows us to follow individually the exploding granules observed simultaneously by THEMIS, IRIS, and SDO. The second uses long time independent sequences from THEMIS, IRIS, SDO, Hinode, and a simulation. In the first method (called manual) the segmentation isolates the cell of the granules (bright granules and intergranular parts), while in the second method (called statistical) only the bright part of the granules are isolated. The results obtained with simultaneous or distinct temporal observations using the two methods of segmentation are in good agreement. The granule area evolves linearly with an expansion velocity that decreases with the radius. A rapid decrease in the velocity expansion in the first two minutes is observed. The detection and measurement of the dynamics of the explosive granules can be performed from ground- and space-based instruments. Our work reveals the usefulness of SDO data, with low spatial resolution, to study the dynamics of the exploding granules all over the solar surface.

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Instrument Calibration of the Interface Region Imaging Spectrograph (IRIS) Mission

Cited by 47 publications

References 15 publications

The multi-thermal chromosphere

The multi-thermal chromosphere

Type III Radio Bursts Observations on 20th August 2017 and 9th September 2017 with LOFAR Bałdy Telescope

Evolution of exploding granules from coordinated observations by THEMIS, IRIS, SDO/HMI, and HINODE, and a simulation

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