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"

36256 results found.

  1. GRB 250129A: NOT optical observations and redshift confirmation
  2. GRB 250129A: GOTO optical observations show brightening afterglow
  3. GRB 250129A: VLT/X-shooter redshift of z = 2.151
  4. Swift GRB 250129A: Global MASTER-Net observations report
  5. GRB 250128B: Enhanced Swift-XRT position
  6. Fermi GRB 250128B: Global MASTER-Net observations report
  7. GRB 250129A: Swift detection of a burst with an optical counterpart
  8. Swift GRB 250129A: Global MASTER-Net OT detection
  9. GRB 250128B: Swift-XRT refined Analysis
  10. GRB 250128B: Fermi GBM Observation
  11. GRB 250128B: GOTO optical upper limit
  12. Swift GRB 250128B: Global MASTER-Net observations report
  13. EP250125a: Upper limits from Swift/BAT-GUANO
  14. GRB 250128B: LCO optical observations
  15. GRB 250128B: Swift detection of a short burst
  16. GRB 250128B: Fermi GBM Final Real-time Localization
  17. GRB 250127A: Swift-XRT observations
  18. GRB 250127B: DDOTI Upper Limit on the Afterglow
  19. GRB 250127A: EP-FXT afterglow detection
  20. Fermi GRB 250128A: Global MASTER-Net observations report
  21. GRB 250128A: Fermi GBM Final Real-time Localization
  22. GRB 250117A: Fermi GBM Observation
  23. Fermi GRB 250127B: Global MASTER-Net observations report
  24. GRB 250127A: SVOM/VT upper limit
  25. GRB 250127B: Fermi GBM Final Real-time Localization
  26. IPN triangulation of GRB 250119C
  27. GRB 250127A: Swift ToO observations
  28. GRB 250127A: LCO optical upper limit
  29. GRB 241223A: cubesat Avion detection
  30. GRB 250127A: SVOM detection of a long burst
  31. GRB 250126A: CALET Gamma-Ray Burst Monitor detection
  32. EP250125A: Non-detection from Fermi-GBM Observations
  33. GRB 250126A: MAXI/GSC detection
  34. GRB 250126A: BALROG localization (Fermi Trigger 759560335 / GRB 250126208)
  35. GRB 250126A: Fermi GBM Final Real-time Localization
  36. GRB 250118A: Fermi GBM Observation
  37. GRB 250119C: Fermi GBM Observation
  38. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  39. GRB 250121A: CALET Gamma-Ray Burst Monitor detection
  40. EP250108a: AbAO, CMO and Terskol optical upper limits
  41. Konus-Wind detection of GRB 250118B
  42. GRB 250121A: Fermi GBM Observation
  43. IPN triangulation of GRB 250118B
  44. Konus-Wind detection of GRB 250119B
  45. IPN triangulation of GRB 250119B
  46. GRB 250122A: Fermi GBM Final Real-time Localization
  47. Improved IPN triangulation of GRB 250107C
  48. GRB 250114A: Swift-BAT refined analysis
  49. GRB 250121A: INTEGRAL/SPI-ACS detection
  50. GRB 250121A: Fermi-LAT detection
  51. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  52. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  53. GRB 250121A: Fermi GBM Final Real-time Localization
  54. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  55. GRB 250119B: Fermi GBM Observation
  56. Konus-Wind detection of GRB 250117A
  57. IPN triangulation of GRB 250117A (short)
  58. ATCA detection of possible radio counterpart to GRB 250114A
  59. GRB 250119B: INTEGRAL/SPI-ACS detection
  60. EP 250108A: Late-time optical observation by LCO
  61. GRB 250117A: SVOM/GRM observation of a short burst
  62. GRB 250119C: Fermi GBM Final Real-time Localization
  63. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  64. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  65. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  66. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  67. GRB 250117A: GECAM observation of a short burst
  68. GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)
  69. GRB 250119B: Fermi GBM Final Real-time Localization
  70. GRB 250119A: Fermi GBM Final Real-time Localization
  71. GRB 250118A: Fermi GBM Final Real-time Localization
  72. EP250108a / AT2025kg: VLA radio upper limit
  73. Fermi Gamma-ray Burst Monitor trigger 758829338/250117747 is not a GRB
  74. Konus-Wind detection of GRB 250116A
  75. GRB 250116A: GECAM-B detection of a long burst
  76. GRB 241217A / EP241217B: radio detection with the VLA
  77. GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
  78. Swift Trigger 1282245 is not a GRB
  79. GRB 250116A: Fermi-LAT detection
  80. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  81. GRB 250114B: Swift-XRT afterglow detection
  82. GRB 250114B: SVOM/VT upper limit
  83. Fermi Gamma-ray Burst Monitor trigger 758659047/250115776 is not a GRB
  84. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  85. Konus-Wind detection of GRB 250113A
  86. IPN triangulation of GRB 250113A
  87. GRB 250114B: Liverpool Telescope optical upper limit
  88. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  89. GRB 250114B: Swift-XRT observations
  90. GRB 250114A: LCO optical counterpart detection.
  91. GRB 250114B: OHP/T193 optical upper limit
  92. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  93. GRB 250114A: Swift-XRT refined Analysis
  94. GRB 250114A: LCOGT optical afterglow i-band detection
  95. GRB 250114B : GIT optical upper limit
  96. GRB 250114B: Swift ToO observations
  97. EP250111a: SAO RAS optical upper limit
  98. GRB 250114B: a short GRB detected with INTEGRAL
  99. GRB 250114A: Enhanced Swift-XRT position
  100. GRB 250113A: INTEGRAL/SPI-ACS 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