PUNCH data are now available via NASA's Solar Data Analysis Center, or via the PUNCH website at https://punch.space.swri.edu.
PUNCH images of space are now available for download from NASA’s Solar Data Analysis Center (SDAC), in scientific-grade FITS format with relevant pointing and spacecraft-status metadata included. The data are updated twice daily by SDAC from the Science Operation Center (SOC) servers at Southwest Research Institute (SwRI) in Boulder, Colorado – and will continue to update as data arrive from space and are processed by the SOC. The data are also being indexed by the Virtual Solar Observatory. The PUNCH website includes links to documentation for the data and for the mission. Many thanks to Marcus Hughes (PUNCH SOC Lead), Jack Ireland (SDAC Lead), and their teams for opening the taps.
Mission status and data overview: PUNCH is still in commissioning, so full calibration is still in progress as the spacecraft continue to drift toward their final orbital spacing (slated to arrive in late June). Four “calibration levels” of data product will ultimately be produced by the SOC, numbered 0 through 3. Level 0 files are essentially direct from the cameras in space, with included metadata such as the time of acquisition and relevant spacecraft status and configuration. Level 1 files will be photometrically calibrated, in physical radiance units. Level 2 files will be merged into “virtual instrument” mosaics. Level 3 files will have static backgrounds suppressed, to reveal the faint solar wind signal. Two additional levels – Level “Q” (QuickPUNCH) forecast-grade, low-latency scientific images and Level “L” (quickLook) directly-viewable images – are also in progress. The products will be published as soon as each is available from the SOC. Level 2 images are anticipated by June 2025.
Commissioning data: All current PUNCH data are from spacecraft commissioning, so use them at your own risk. If you see something exciting, you are advised to reach out to the PUNCH team to verify.
Data products: PUNCH has many data products, identified by level and by a three-character product code. Level 0 products use a two-letter code plus one digit indicating the spacecraft that created the image. The WFI spacecraft are numbered 1-3; the NFI spacecraft is numbered 4. The most important two-letter codes are: CR (clear/unpolarized images), PM (-60° polarizer), PZ (horizontal polarizer), and PP (+60° polarizer). So, for example, a file labeled PP3 is a WFI-3 image taken with the +60° polarizer angle.
Data organization: The data at SDAC are organized into a file structure by processing level (currently only “0”), data type (three-character code), then year, month, and day of acquisition. Within each daily directory are FITS files with unique names containing that organizing information. The files are being indexed by Virtual Solar Observatory, so you should soon be able to retrieve files that way also.
Level 0 coding and headers: PUNCH level 0 data are often square-root coded. Check the header of each image to see if the “ISSQRT” field is set to a nonzero value. If it is, you must square the value of each pixel, then divide by the SCALE field of the header, to obtain an approximation of the value generated by the camera on-board. This aids compressibility by matching the digital step size to the photon-counting noise level across the entire dynamic range. Level 0 files include World Coordinate System (WCS) information that derives directly from the host spacecraft pointing system, so you can approximately align them using standard WCS tools such as Astropy or JHelioviewer. Level 1 files, when available, will have much more precise pointing information.
How to view and manipulate the data: PUNCH FITS files have been tested to work with standard tools including IDL, Python/Astropy/Sunpy, PDL, JHelioViewer, and the DS9 viewer. So you can manipulate them with your existing toolset. For more information, visit the PUNCH website data access page: https://punch.space.swri.edu/punch_science_getdata.php
Data documentation and source code: The reduction pipeline for PUNCH data is fully open-source, and is available at the PUNCH mission github (linked from the PUNCH data-access page). There is also a user’s guide that describes the data and the steps used to create each data product. The user's guide includes a gallery of example code for how to read and use the images.
Using PUNCH data: PUNCH data are free to use for any purpose. If you do publish PUNCH data, you are requested (not required) to notify the PUNCH team of that use, so we can index and keep track of the mission’s impact on the world. An acknowledgement statement and email link are provided on the PUNCH data access page.
This is PUNCH Nugget #12. PUNCH nuggets are archived at the PUNCH mission website. You can sign up to receive PUNCH nuggets by email. NASA official releases about PUNCH are at the NASA PUNCH blog.
