IV. NEOWISE Data Processing

IV.2. Scan/Frame Pipeline Updates

IV.2.e. Known Solar System Object Search Updates

Asteroids, comets, planets and planetary satellites that are known at the time of NEOWISE data processing and that are predicted to be within the field of view of the individual Single-exposures at the time of the NEOWISE observations are identified during the Scan/Frame processing. The list of objects found to be within the Single-exposure footprints, along with their predicted positions and selected orbital parameters are summarized in the Known Solar System Object Possible Association List (KSSOPAL). If the predicted position of a known solar system object is in close proximity to Single-exposure detection in the appropriate image, the associated detection is also provided. However, the KSSOPAL entries with Single-exposure detection associations are not confirmed solar system object detections. Please refer to the Moving Object Tracklets for a vetted list of NEOWISE solar system object detections.

The algorithms used to predict the positions of the objects during each Single-exposure are described in section IV.4.e of the WISE All-Sky Release Explanatory Supplement. The format and content of the columns in the KSSOPAL are given in IV.2.e.i.

IV.2.e.i. Known Solar System Object Possible Association List (KSSOPAL) Format and Column Descriptions

IV.2.e.ii. Known Solar System Object Search Updates for NEOWISE

Two updates were made to the Solar System object search module of the Scan/Frame pipeline for NEOWISE data processing:

• Updated lists of osculating orbital elements were generated to predict object positions at the time of the NEOWISE observations. The lists are updated every 100 days with the latest list of objects and orbital element information from the IAU Minor Planet Center. During the first ten years of NEOWISE observations, the osculation epochs were MJD=56650, 56750, 56850, 56950, 57050, 57150, 57250, 57350, 57450, 57550, 57650, 57750, 57850, 57950, 58050, 58150, 58250, 58350, 58450, 58550, 58650, 58750, 58850, 58950, 59050, 59150, 59250, 59350, 59450, 59550, 59650, 59750, 59850, 59950, 60050, 60150, and 60250. Processing for a given Single-exposure uses the list that is closest in time to the observation epoch. The elements continue to be updated as the NEOWISE survey progresses.

  N.B. - Solar system objects that were discovered after the epoch of the orbital elements file used in NEOWISE data processing but that were within the field of view of a particular NEOWISE Single-exposure will not be listed in the KSSOPAL. This will include the first observation epochs for NEOWISE discoveries. It is possible to search for observations that covered the position of such objects, or to perform general precovery searches using the Moving (or Solar System) Object search capabilities in the NASA/IPAC Infrared Science Archive Catalog Query Engine or WISE/NEOWISE Image Service.



• For solar system objects that have an associated NEOWISE Single-exposure source detection, the number of different solar system objects to which that detection was associated is computed and given by the parameter m. These confused associations can occur when a solar system object falls in a region of very high background source density, and when a particular solar system object appears more than once under different names in the orbital elements list. There are 92,517 entries in the KSSOPAL for the first ten years of NEOWISE observations that have m>1.

Last update: 9 February 2024