The Near-Earth Object Wide-field Infrared Survey Explorer Reactivation Mission (NEOWISE; Mainzer et al. 2014, ApJ, 792, 30) is a NASA Planetary Science Division space-based survey to detect, track and characterize asteroids and comets, and to learn more about the population of near-Earth objects that could pose an impact hazard to the Earth. NEOWISE systematically images the sky at 3.4 and 4.6 μm, obtaining multiple independent observations on each location that enable detection of previously known and new solar system small bodies by virtue of their motion. Because it is an infrared survey, NEOWISE detects asteroid thermal emission and is equally sensitive to high and low albedo objects. Over the course of its mission, NEOWISE's thermal infrared flux measurements will enable diameters and albedos to be radiometrically determined for thousands of main belt and near-Earth asteroids (e.g., Nugent et al. 2015 ApJ, 814, 117, Nugent et al. 2016, AJ, 152, 63, Masiero et al. 2017, AJ, 154, 168, Masiero et al. 2018, AJ, 156, 60, and Masiero et al. 2020, PSJ, 1, 5).
NEOWISE utilizes the Wide-Field Infrared Explorer (WISE; Wright et al. 2010, AJ, 140, 1868) spacecraft that surveyed the entire sky in 2010 with a cryogenically cooled 40 cm telescope and four 1kx1k mid-infrared array detectors operating at 3.4, 4.6, 12 and 22 μm (W1, W2, W3, W4). After the exhaustion of its solid hydrogen cryogen in September 2010, WISE continued to survey for four months using its two short wavelength bands. WISE was placed into hibernation in February 2011 after completing a survey of the inner main asteroid belt and a second coverage of the sky.
The WISE spacecraft was brought out of hibernation in September 2013 and renamed NEOWISE for its new mission. The spacecraft was returned to zenith pointing which enabled the telescope and focal plane to passively cool down to approximately 73 K. Survey operations were resumed on December 13, 2013 UTC with the W1 and W2 detectors operating at sensitivities near those of the original cryogenic survey. The first solar system moving object tracklet candidates were reported to the IAU Minor Planet Center on December 26, 2013. Tracklet deliveries have been made three times per week since that time, and in the first ten years of operations NEOWISE made over 1.3 million confirmed infrared measurements of over 42,000 solar system small bodies (Figure 1). These numbers continue to increase as the survey progresses; NEOWISE has acquired approximately 1,500,000 thermal infrared measurements of over 44,000 different solar system objects as of March 2024.
NEOWISE follows the same survey strategy that was used during the original WISE mission. The full sky is surveyed every six months, during which time 12 or more independent Single-exposures are made on each point on the sky. Solar system objects are typically observed at least 15-16 times during each sky pass because their motion often follows the progression of the survey. Consequently, the NEOWISE images and source measurements are time-domain resources for extracting positions and thermal fluxes and light curves for moving solar system objects, and for precovery of objects discovered after the NEOWISE observations. Because the great majority of objects detected by NEOWISE are background galactic and extragalactic sources, the NEOWISE archive is also a powerful resource for studying the proper motion of nearby stars and brown dwarfs, as well as flux variability for all classes of object.
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| Figure 1 - Top-down view of the Solar System showing the position on December 22, 2023 of all asteroids and comets detected by NEOWISE during the first ten years of the Reactivation Mission. The blue circles and points indicate the orbits and locations of Mercury, Venus and Mars. The Earth and its orbit are shown in cyan. Filled gray circles are Main Belt asteroids, filled green circles are Near Earth asteroids and the filled yellow squares are comets. The white points indicate the objects NEOWISE detected during the last week of the tenth year of surveying. The tick marks on the x and y axes are in increments of 1 AU. This animation shows how solar system object detections accumulated over the first ten years of the survey. The white points show the new detections from each successive run of the WISE Moving Object Pipeline System, and illustrate how the NEOWISE scan longitudes progress around the sky. |
NEOWISE data releases began with the first delivery of moving object tracklet candidates to the MPC on December 26, 2013, approximately two weeks following the start of the Reactivation Mission survey. Tracklet deliveries to the MPC continue to be made three times per week since that time. The number of NEOWISE confirmed detections continues to increase with each new delivery.
Annual releases of the Single-exposure images, the database of source detections made on those images, and ancillary information from the previous year's observations began in 2015. Each subsequent year's image, extracted source and meta-data are combined into a single archive so that all data may be queried easily at one time. A summary of the data products in the annual Single-exposure Data Releases is given in I.3.
NEOWISE observations and data products represent new infrared measurements of the sky that are distinct from those carried out by the original WISE mission. However, NEOWISE data complement those from the original mission that are available in the AllWISE, WISE All-Sky, 3-Band Cryo, and NEOWISE Post-Cryo data releases. Taken together with the original WISE mission data, NEOWISE greatly extends the time baseline and number of independent measurements available for both solar system and more distant objects, and hold the prospect of enabling considerably deeper source detection if all the data are combined.
The first annual release of NEOWISE Single-exposure data contains all observations from the first year of survey operations, 13 December 2013 to 13 December 2014 UTC. NEOWISE scanned the sky nearly two complete times during this period, accumulating 24 or more independent exposures on each point on the sky.
The 2015 release includes 2,497,867 Single-exposure images, 18,468,575,596 detections extracted from those images, and approximately 137,000 detections of 10,200 different small bodies confirmed by the MPC.
The second annual release of NEOWISE Single exposure data adds to the public archive all observations from the second year of survey operations, 13 December 2014 to 13 December 2015 UTC. NEOWISE scanned the sky two more complete times during this period, bringing the total number of NEOWISE sky coverage epochs to four and approximately 48 or more independent exposures on each point on the sky.
The 2016 release adds to the archive an additional 2,557,865 calibrated images, 19,691,230,571 detections extracted from the images, and approximately 157,000 detections of 11,600 different small bodies that are confirmed by the MPC.
The third annual release of NEOWISE Single exposure data adds to the public archive all observations from the third year of survey operations, 13 December 2015 to 13 December 2016 UTC. NEOWISE scanned the sky two more complete times during this period, bringing the total number of NEOWISE sky coverage epochs to six and approximately 72 or more independent exposures on each point on the sky.
The 2017 release adds to the archive an additional 2,599,344 calibrated images, 19,631,135,692 detections extracted from the images, and approximately 158,000 detections of 12,000 different small bodies that are confirmed by the MPC.
The fourth annual release of NEOWISE Single exposure data adds to the public archive all observations from the fourth year of survey operations, 13 December 2016 to 13 December 2017 UTC. NEOWISE scanned the sky two more complete times during this period, bringing the total number of NEOWISE sky coverage epochs to eight and approximately 96 or more independent exposures on each point on the sky.
The 2018 release adds to the archive an additional 2,565,705 calibrated images, 19,098,199,664 detections extracted from the images, and approximately 156,000 detections of 11,700 different small bodies that are confirmed by the MPC.
The fifth annual release of NEOWISE Single exposure data adds to the public archive all observations from the fifth year of survey operations, 13 December 2017 to 13 December 2018 UTC. NEOWISE scanned the sky two more complete times during this period, bringing the total number of NEOWISE sky coverage epochs to ten and approximately 120 or more independent exposures on each point on the sky.
The 2019 release adds to the archive an additional 2,524,881 calibrated images, 18,795,708,783 detections extracted from the images, and approximately 153,000 detections of 11,900 different small bodies that are confirmed by the MPC.
The sixth annual release of NEOWISE Single exposure data adds to the public archive all observations from the sixth year of survey operations, 13 December 2018 to 13 December 2019 UTC. NEOWISE scanned the sky two more complete times during this period, bringing the total number of NEOWISE sky coverage epochs to twelve and approximately 144 or more independent exposures on each point on the sky.
The 2020 release adds to the archive an additional 2,512,443 calibrated images, 18,717,323,537 detections extracted from the images, and approximately 151,000 detections of 11,700 different small bodies that are confirmed by the MPC.
The seventh annual release of NEOWISE Single exposure data adds to the public archive all observations from the seventh year of survey operations, 13 December 2019 to 13 December 2020 UTC. NEOWISE scanned the sky two more complete times during this period, bringing the total number of NEOWISE sky coverage epochs to fourteen and approximately 168 or more independent exposures on each point on the sky.
The 2021 release adds to the archive an additional 2,522,253 calibrated images, 18,784,693,939 detections extracted from the images, and approximately 153,000 detections of 11,900 different small bodies that are confirmed by the MPC.
The eighth annual release of NEOWISE Single exposure data adds to the public archive all observations from the eighth year of survey operations, 13 December 2020 to 13 December 2021 UTC. NEOWISE scanned the sky two more complete times during this period, bringing the total number of NEOWISE sky coverage epochs to sixteen and approximately 200 or more independent exposures on each point on the sky.
The 2022 release adds to the archive an additional 2,506,333 calibrated images, 18,668,416,994 detections extracted from the images, and approximately 150,000 detections of 11,600 different small bodies that are confirmed by the MPC.
The ninth annual release of NEOWISE Single exposure data adds to the public archive all observations from the ninth year of survey operations, 13 December 2021 to 13 December 2022 UTC. NEOWISE scanned the sky two more times during this period, bringing the total number of NEOWISE sky coverage epochs to eighteen and approximately 230 or more independent exposures on each point on the sky.
The 2023 release adds to the archive an additional 2,507,530 calibrated images, 18,650,186,132 detections extracted from the images, and approximately 154,000 detections of 11,800 different small bodies that are confirmed by the MPC.
The tenth annual release of NEOWISE Single exposure data adds to the public archive all observations from the tenth year of survey operations, 13 December 2022 to 13 December 2023 UTC. NEOWISE scanned the sky two more times during this period, bringing the total number of NEOWISE sky coverage epochs to twenty and approximately 260 or more independent exposures on each point on the sky.
The 2024 release adds to the archive an additional 2,488,285 calibrated images, 18,371,369,954 detections extracted from the images, and approximately 153,500 detections of 11,800 different small bodies that are confirmed by the MPC.
The NEOWISE Explanatory Supplement provides a description of the content, format and properties of the NEOWISE data products, along with their acquisition and data reduction processing. High-level descriptions of the NEOWISE flight system and survey strategy are provided in section I.2. Frequent links are provided back to the WISE All-Sky Data Release Explanatory Supplement which contains more detailed descriptions.
An executive summary of the NEOWISE data products is available in section I.3. Comprehensive descriptions of the Single-exposure Source Database and Single-exposure Images are given in sections II and III, respectively. Included are descriptions of content and formats, their key features, cautionary notes and advice on how best to use these products in your research. An overview of NEOWISE data processing is given in section IV, with emphasis on changes that were made specifically to handle the actual characteristics of the NEOWISE data. Again, many links are provided back to the Explanatory Supplements to the WISE All-Sky Data Release and the AllWISE Data Release which contain more complete descriptions of the WISE Science Data System.
This Explanatory Supplement is a living document that will be updated frequently to provide the most current information for users of the NEOWISE data products. Please see the Document Change History for a record of the latest significant updates.
The NEOWISE Reactivation Mission is funded by the NASA Science Mission Directorate Planetary Science Division as part of the Planetary Defense Coordination Office. Dr. Amanda Mainzer of the University of Arizona is the NEOWISE Principal Investigator. NEOWISE is managed and operated by JPL. Data processing, archiving, and distribution for NEOWISE is carried out by IPAC, California Institute of Technology. Operations of the NEOWISE spacecraft and payload are supported by Ball Aerospace and Technology Corp. and the Space Dynamics Laboratory, Utah State University.
NEOWISE gratefully acknowledges the services contributed by the IAU Minor Planet Center, operated by the Harvard-Smithsonian Center for Astrophysics.
NEOWISE makes use of data from the WISE, AllWISE and original NEOWISE projects that were funded by the NASA Astrophysics and Planetary Science Divisions.
Last Updated: 19 March 2024