Encounter 26 Summary

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Encounter 26 (2025-12-08 - 2025-12-21)

 

This animation shows all L3 WISPR full-field observations from the twenty-sixth PSP Mission Encounter (2025-12-08 - 2025-12-21). We have superimposed a grid showing helioprojective longitude and latitude, and a scale representation of the size and location of the Sun in the observations using the SDO/HMI Carrington map for this time period. The velocity and distance metrics displayed on the movies correspond respectively to the spacecraft's heliocentric velocity in kilometers per second, and its distance from the Sun's center in units of solar radii (where 1 solar radius = 695,700km). The "FOV Range" label provides the plane-of-sky distance limits of the inner and outermost edges of the fields of view, in units of solar radii. The horizontal blue line indicates the orbital plane of PSP. The timespan of this composite movie covers only the nominal science window when the spacecraft was within 0.25 au; a limited amount of data outside of this range may be available at the below links.
You can download this movie directly as an 79 MB mp4 file. This sequence is also available as data processed via the LW Algorithm developed by Dr. Guillermo Stenborg (JHUAPL) and detailed in Appendix A of Howard et al. 2022 (ApJ, 936, id.43. DOI 10.3847/1538-4357/ac7ff5). Please contact the team for access to this data, which will be posted here one year after the acquisition of those observations. Team contact information can be found in Section 1.2 of the WISPR User's Guide [PDF link].

[Credit: NASA/NRL/JHUAPL. Movie processed/compiled by Guillermo Stenborg (JHUAPL) and Karl Battams (NRL). SDO inset courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.]

 

Solar Features

TBD

Comets and planets

A few Kreutz sungrazers are visible. Their exact identities still to be determined.

Planets as follows:

  • TBD

Operations summary

A low gain bias image was mistakenly commanded for December 12 at 20:29 UT in the outer telescope, even though the images themselves were taken in high gain. This removed an excess bias from the images in the outer telescope taken between 20:32 UT on the 12th and 18:27 UT on the 13th, leaving a noticeable column to column artifact in the L1 images and diminishing the overall intensities compared to the rest of the encounter. To correct this problem, the last image before the erroneous bias, and the first image impacted by this issue, were run through the L2 WISPR_PREP pipeline WITHOUT the calibration factor, vignetting function and straylight correction applied. For the ‘bad’ image, the biasoffset and bias corrections were also turned off. Taking a difference of these two images and calculating the median in each detector column, the missing bias pattern was determined. This single row was copied into a 960x1024 array to be used as a ‘bias image’ in the L2 pipeline, adding the missing signal into the impacted images to replace the external bias. Fortunately, it does not seem as though the extra bias removed was larger than the total signal in the any part of the images, so this process appears to have fully corrected the images and allowed for all products of level 2 and higher to be created in a consistent matter throughout the encounter. The impacted filenames (as Level 0) have been saved in an IDL save file named ‘e26_bias_files.sav’ and the bias image used is in a fits file named ‘e26_outer_bias.fits’. Both of these files have been added to the calibration directory in the WISPR SSW folder and released publicly.

Miscellaneous notes

None.

Encounter 26 Data Products

Released data for all encounters can be obtained from our WISPR Data Page. Descriptions of other encounters can be found on the Encounter Summaries Page.

N/A