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Kilonova and Host Galaxy

Bright galaxies and other light sources in various sizes, shapes, and colors are scattered across a black swath of space. Toward the center right is a blue-white spiral galaxy seen face-on that is larger than the other light sources in the image. The galaxy is labeled “former home galaxy.” Toward the upper left is a small red point, which has a white circle around it and is labeled “GRB 230307A kilonova.”

A team of scientists has used NASA’s James Webb Space Telescope to observe an exceptionally bright gamma-ray burst, GRB 230307A, and its associated kilonova. Kilonovas—an explosion produced by a neutron star merging with either a black hole or with another neutron star—are extremely rare, making it difficult to observe these events. The highly sensitive infrared capabilities of Webb helped scientists identify the home address of the two neutron stars that created the kilonova.

This image from Webb’s NIRCam (Near-Infrared Camera) instrument highlights GRB 230307A’s kilonova and its former home galaxy among their local environment of other galaxies and foreground stars. The neutron stars were kicked out of their home galaxy and traveled the distance of about 120,000 light-years, approximately the diameter of the Milky Way galaxy, before finally merging several hundred million years later.

About the Object

  • R.A. Position
    R.A. PositionRight ascension – analogous to longitude – is one component of an object's position.
    04:03:26.01
  • Dec. Position
    Dec. PositionDeclination – analogous to latitude – is one component of an object's position.
    -75:22:42.78
  • Constellation
    ConstellationOne of 88 recognized regions of the celestial sphere in which the object appears.
    Mensa
  • Dimensions
    DimensionsThe physical size of the object or the apparent angle it subtends on the sky.
    Image is approximately 1.3 arcminutes across

About the Data

  • Data Description
    Data DescriptionProposal: A description of the observations, their scientific justification, and the links to the data available in the science archive.
    Science Team: The astronomers who planned the observations and analyzed the data. "PI" refers to the Principal Investigator.

    The Webb observations include those from program: 4434 (A. Levan) 

  • Instrument
    InstrumentThe science instrument used to produce the data.
    NIRCam
  • Exposure Dates
    Exposure DatesThe date(s) that the telescope made its observations and the total exposure time.
    05 April 2023, 08 May 2023
  • Filters
    FiltersThe camera filters that were used in the science observations.
    F115W, F150W, F277W, F356W, F444W
  • Object Name
    Object NameA name or catalog number that astronomers use to identify an astronomical object.
    GRB 230307A
  • Object Description
    Object DescriptionThe type of astronomical object.
    Gamma ray burst from two colliding neutron stars
  • Release Date
    October 25, 2023
  • Science Release
    NASA’s Webb Makes First Detection of Heavy Element from Star Merger
    Read the release
  • Credit
    Image: NASA, ESA, CSA, STScI, Andrew Levan (IMAPP, Warw)

Downloads

  • Main, Full Res (For Print), 2525 × 1561
    tif (4.9 MB)
  • Main, Full Res (For Display), 2525 × 1561
    png (4.05 MB)
  • Crop Main, 2000 × 1236
    png (2.57 MB)
  • Wide, Full Res (For Print), 4316 × 2826
    tif (15.31 MB)
  • Wide, Full Res (For Display), 4316 × 2826
    png (12.5 MB)
  • Wide, 2000 × 1310
    png (3.01 MB)
Bright galaxies and other light sources in various sizes, shapes, and colors are scattered across a black swath of space. Toward the center right is a blue-white spiral galaxy seen face-on that is larger than the other light sources in the image. The galaxy is labeled “former home galaxy.” Toward the upper left is a small red point, which has a white circle around it and is labeled “GRB 230307A kilonova.”
Color Info
Color InfoA brief description of the methods used to convert telescope data into the color image being presented.

This image is a composite of separate exposures acquired by the James Webb Space Telescope using the NIRCam instrument. Several filters were used to sample wide wavelength ranges. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are:  Blue: F115W + F150W Green: F277W Red: F356W + F444W

Compass and Scale
Compass and ScaleAn astronomical image with a scale that shows how large an object is on the sky, a compass that shows how the object is oriented on the sky, and the filters with which the image was made.

Related Images & Videos

Graph titled “GRB 230307A Kilonova Emission Spectrum,” which compares the spectral data of GRB 230307A’s kilonova as observed by the James Webb Space Telescope and a kilonova model.

Kilonova Emission Spectrum

This graphic presentation compares the spectral data of GRB 230307A’s kilonova as observed by the James Webb Space Telescope and a kilonova model. Both show a distinct peak in the region of the spectrum associated with tellurium, with the area shaded in red. The detection of...

Bright galaxies and other light sources in various sizes, shapes, and colors are scattered across a black swath of space. Toward the center right is a blue-white spiral galaxy seen face-on that is larger than the other light sources in the image. The galaxy is labeled “former home galaxy.” Toward the upper left is a small red point, which has a white circle around it and is labeled “GRB 230307A kilonova.” At the bottom left are compass arrows indicating the orientation of the image on the sky. The north arrow points in the 12 o’clock direction. The east arrow points toward 9 o’clock. At the lower right is a scale bar labeled 10 arcseconds. Below the image is a color key showing which NIRCam filters were used to create the image and which visible-light color is assigned to each filter.

Kilonova and Host Galaxy (Compass Image)

An image of the GRB 230307A kilonova and the former home galaxy of the neutron stars captured by Webb's NIRCam (Near-Infrared Camera), with compass arrows, a scale bar, and color key for reference. The north and east compass arrows show the orientation of the image on the sky....

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Details

Last Updated
Aug 28, 2025
Contact
Media

Laura Betz
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
laura.e.betz@nasa.gov

Image Credit

NASA, ESA, CSA, STScI, Andrew Levan (IMAPP, Warw)

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