CASCADe and HST data

The CASCADe package comes with the functionality to download data from the HST data archive (MAST), and simultaneously generate the correct .ini files and pipeline scripts. files. To make use of this functionality, the user can make use of the build_local_hst_archive.py python script. This script makes use of the WFC_files.pickle database file which can be found in the archive_databases sub-directory of the main CASCADe storage directory as defined by the CASCADE_STORAGE_PATH environment variable. This data base file contains most spectroscopic transit observations made with the HST WFC3 instrument. In this file, for each visit, the data files belonging to that visit are defined, together with the main instrument settings. To get an overview of the main functionality one can execute of the command line the following command:

build_local_hst_archive.py --help

which will print all options available with this python script. To list all planets for which an HST data set is defined in the database file, one can use the following command:

build_local_hst_archive.py -lap

which will print a list of all available planets. One can then pick a planet and download all data from the MAST archive. As an example, for the data of WASP-117b, as published in Carone et al 2021 one can execute the folowing command:

build_local_hst_archive.py -avp WASP-117b

which will download all the spectroscopic data for this planet. In this case the ima data product is downloaded as it is a spatial scanning observation, together with several target acquisition images, for which we use the flt data product. In addition to downloading the data, also the required initialization files are generated, which will be written to the directory specified by the CASCADE_INITIALIZATION_FILE_PATH environment variable. for generating the initialization files, CASCADe makes use of the processing_exceptions.ini file which can be found in the archive_databases sub directory where also the database file is located. This file contains several predefined values for most observations in the database which we found to be optimal, or where derived in published studies. The user has the possibility to overwrite these values by creating a user_processing_exceptions.ini file and define any initialization parameter value in there in a similar manner as is done in the processing_exceptions.ini file. If an observation has no entry in one of these files, standard values are used from one of the exoplanet archives and from the fits headers of the data files.

Finally, also an command line pipeline execution script is generated and stored in the directory defined by the CASCADE_SCRIPTS_PATH environment variable. Executing that script will run the entire CASCADe pipline, extracting the spectral time series from the spectral images or cubes and fit the transit signal to derive the planetary spectrum.