DOI: 10.5281/zenodo.11442266
title: Test dataset of VLT/SPHERE/IRDIS H2 observation Injected with simulated disks.

description: Test data sets used in Juillard et. al. (2023) and , Juillard et. al. (2024), used to compare three different algorithms for processing data sets using ADI alone and to compare the three different strategies: RDI, ADI, and ARDI.

This test pipeline consists of a total of 60 test data sets composed of five different disk morphologies, injected at three different contrast levels ($10^{-3}$, $10^{-4}$, and $10^{-5}$), into four different observing ADI sequences of stars without any known circumstellar signal, reflecting different observing conditions. 

CONTENT 

 

You will find in this folder the battery of test dataset in the compressed folder "test_cubes_sphere.zip". It contains 60 folders, one for each test dataset, with two files in each: "angle.fits" and "cube.fits"

 

Additionaly there folders containg the empty cubes, injected disks, star flux, mask that reprensent the location of the apperture where the flux of the disk was integrated to compute contrast. The Jupyter notebook "asses_quality_of_disk_estimate.ipynb" shows how to compare a disk estimate. We also provided an example disk estimate (file 'X_3_2_0.fits') to try out the notebook.

 

Finally, a folder named "Ref_lib_sphere" containes the different set of references frames library used in the publication Juillard et. al. (2024). In this folder, "ref_lib_X" corresponds to the optimal references for testing using empty cube X, "randref" corresponds to "shuffled" (same for every cube), and "randref_nooverlap_X" corresponds to "excluded." 

In the “Optimal” case, we used the most correlated frames, which is the same selection used in the first series, where we compare ADI, RDI, and ARDI. In the “Shuffled” case, we randomly selected a sample from the reference libraries dedicated to each of our four ADI test cubessequences into one common reference library. In this test, the random selection contains 25% of frames from the “Optimal” reference library. In the “Excluded” case, we selected for each ADI cube a sample only from references dedicated to the three other ADI cubes, creating a selection that excludes optimal references. The PCC computed for each of the three selections of references is presented in Fig. 5 of Juillard et. al. (2024).

 

ABOUT THE DATA

The data sets, obtained through the High-Contrast Data Center (HCDC), were acquired using the Infrared Dual-Band Imager and Spectrograph (IRDIS, Dohlen et al. 2008; Vigan et al. 2010) camera of the Spectro-Polarimetric High-contrast Exoplanet Research coronagraphic system on the Very Large Telescope  (VLT/SPHERE, Beuzit et al. 2019). The test data sets all consist of the $H$2 channel from the dual-band $H$23 set. They were chosen to exhibit a diverse range of characteristics, including low Strehl ratio with a 26\degr\ rotation (ID #1), wind-driven halo (ID #2), an unstable speckle field (ID #3), and good Strehl ratio with an 80\degr\ field rotation (ID #4). The raw data processed with the data handling software  (Pavlov et al. 2008) of the HCDC (Delorme et al. 2017), which performs dark, flat, and bad pixel correction on a coronagraphic sequence. For future reference, we computed the mean and standard deviation of the Pearson correlation coefficients (PCC) between each unique pair of frames in the ADI cube. The mean PCC are as follows: Cube #1: $\mu = 0.99$; Cube #2: $\mu = 0.97$; Cube #3: $\mu = 0.93$; Cube #4: $\mu = 0.96$, with standard deviations below $0.001$ for all the cubes.

The injected disks represent a range of scenarios for both debris and protoplanetary disks. As detailed in Juillard et.al 2023, this selection consists of two 75\degr\ inclined disks with varying sharpness levels (A and B), a 45\degr\ inclined disk with two concentric rings (C), a nearly face-on disk with azimuthal flux variation (D), and a hydrodynamical simulation of a disk with embedded spiral structures and a companion (E). The contrast of the injected disks is determined by measuring the integrated flux within a full width at half-maximum (FWHM)-sized aperture, centered at the peak intensity of the disk, and then dividing this value by the integrated flux within an FWHM-sized aperture of the stellar point spread function. However, we made an exception for the synthetic disk E, where we measured the flux at the companion location.

The reference frames were selected from a set of archival IRDIS observations taken with the same filter, coronagraph, and exposure time as the test data sets. These reference targets were observed between 2014 December 11 and 2021 June 1, and the raw data were calibrated through the same process as the test data sets. For each test data set, the PCC was calculated between the frames of the data set and the reference targets, excluding any observations of the data set star taken at different epochs. The PCC was calculated within a circular annulus between 0\farcs31 and 0\farcs67, which captures both the dominant speckle region and position of the waffle pattern, used for precise star centering of a coronagraphic sequence (Zurlo et al. 2014), if it was included in the observation. For each frame in the data set, the 300 best correlated reference frames were identified, and those that appeared in this selection for more than 30\% of the data set frames were selected for the final reference library.