Skip to main content
End of Swift Science Operations, CHIME Notices Unavailable During Upgrade. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

43959 results found.

  1. EP250125a: REM optical counterpart detection
  2. GRB 250119C: Fermi GBM Observation
  3. EP250125a: Swift/XRT detection of a fading counterpart
  4. EP250125a: a new X-ray transient detected by Einstein Probe
  5. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  6. The EP-WXT trigger 01709130758 is a false trigger
  7. The EP-WXT trigger 01709130758 is a false trigger
  8. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  9. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  10. IPN triangulation of a bright burst from SGR 1E1841-045
  11. GRB 250121A: CALET Gamma-Ray Burst Monitor detection
  12. EP250108a: AbAO, CMO and Terskol optical upper limits
  13. Konus-Wind detection of GRB 250118B
  14. GRB 250121A: Fermi GBM Observation
  15. IPN triangulation of GRB 250118B
  16. Konus-Wind detection of GRB 250119B
  17. IPN triangulation of GRB 250119B
  18. GRB 250122A: Fermi GBM Final Real-time Localization
  19. Improved IPN triangulation of GRB 250107C
  20. GRB 250114A: Swift-BAT refined analysis
  21. GRB 250121A: INTEGRAL/SPI-ACS detection
  22. GRB 250121A: Fermi-LAT detection
  23. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  24. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  25. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  26. GRB 250121A: Fermi GBM Final Real-time Localization
  27. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  28. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  29. GRB 250119B: Fermi GBM Observation
  30. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  31. Konus-Wind detection of GRB 250117A
  32. IPN triangulation of GRB 250117A (short)
  33. ATCA detection of possible radio counterpart to GRB 250114A
  34. EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
  35. GRB 250119B: INTEGRAL/SPI-ACS detection
  36. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  37. EP 250108A: Late-time optical observation by LCO
  38. GRB 250117A: SVOM/GRM observation of a short burst
  39. LIGO/Virgo/KAGRA S250105bn: 1 counterpart neutrino candidate event from an IceCube neutrino search
  40. LIGO/Virgo/KAGRA S250119cv: Updated NED Galaxies in the Localization Volume
  41. LIGO/Virgo/KAGRA S250119cv: Updated Sky localization and EM Bright Classification
  42. GRB 250119C: Fermi GBM Final Real-time Localization
  43. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  44. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  45. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  46. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  47. LIGO/Virgo/KAGRA S250119ag: Updated Sky localization
  48. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  49. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  50. GRB 250117A: GECAM observation of a short burst
  51. LIGO/Virgo/KAGRA S250118dp: Updated Sky localization
  52. GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)
  53. GRB 250119B: Fermi GBM Final Real-time Localization
  54. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  55. GRB 250119A: Fermi GBM Final Real-time Localization
  56. GRB 250118A: Fermi GBM Final Real-time Localization
  57. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  58. LIGO/Virgo/KAGRA S250118t: Updated Sky localization
  59. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  60. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  61. EP250108a / AT2025kg: VLA radio upper limit
  62. Fermi Gamma-ray Burst Monitor trigger 758829338/250117747 is not a GRB
  63. Konus-Wind detection of GRB 250116A
  64. GRB 250116A: GECAM-B detection of a long burst
  65. GRB 241217A / EP241217B: radio detection with the VLA
  66. GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
  67. Swift Trigger 1282245 is not a GRB
  68. GRB 250116A: Fermi-LAT detection
  69. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  70. GRB 250114B: Swift-XRT afterglow detection
  71. GRB 250114B: SVOM/VT upper limit
  72. Fermi Gamma-ray Burst Monitor trigger 758659047/250115776 is not a GRB
  73. EP250108a: MeerKAT radio upper limit
  74. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  75. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  76. LIGO/Virgo/KAGRA S250114ax: Updated Sky localization
  77. Konus-Wind detection of GRB 250113A
  78. IPN triangulation of GRB 250113A
  79. GRB 250114B: Liverpool Telescope optical upper limit
  80. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  81. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  82. GRB 250114B: Swift-XRT observations
  83. GRB 250114A: LCO optical counterpart detection.
  84. GRB 250114B: OHP/T193 optical upper limit
  85. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  86. GRB 250114A: Swift-XRT refined Analysis
  87. Integral GRB250114.55: Global MASTER-Net observations report
  88. GRB 250114A: LCOGT optical afterglow i-band detection
  89. GRB 250114B : GIT optical upper limit
  90. GRB 250114B: Swift ToO observations
  91. EP250111a: SAO RAS optical upper limit
  92. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  93. GRB 250114B: a short GRB detected with INTEGRAL
  94. EP250108a: correction to GCN 38908
  95. GRB 250114A: Enhanced Swift-XRT position
  96. GRB 250113A: INTEGRAL/SPI-ACS detection
  97. GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
  98. GRB 250114A: REM detection of the optical and NIR counterpart
  99. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  100. Swift GRB250114A: Global MASTER-Net OT detection

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov