Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. 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"

27938 results found.

  1. EP250610A: Swift/UVOT Upper limits
  2. EP250610a: Liverpool Telescope optical upper limits
  3. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  4. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  5. GRB 250610B: Swift-XRT counterpart detection
  6. GRB 250610B: SVOM/VT optical counterpart
  7. GRB 250610B: LT detection of the optical counterpart
  8. GRB 250610C: Fermi GBM Final Real-time Localization
  9. GRB 250610B: SVOM detection of a long burst
  10. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  11. GRB 250610A: Fermi GBM Final Real-time Localization
  12. GRB 250605A: Swift-BAT refined analysis
  13. EP250610a: SVOM/VT optical upper limit
  14. EP250610a: REM optical/NIR observations
  15. GRB 250609A: Fermi GBM Observation
  16. EP250610a: Swift-XRT counterpart detection
  17. EP250610a: Einstein Probe detection of an X-ray transient
  18. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  19. GRB 250605A: Swift/UVOT Upper Limits
  20. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  21. GRB 250527C: CrAO Optical Upper Limit
  22. GRB 250609A: Fermi GBM Final Real-time Localization
  23. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  24. GRB 250607A: Fermi GBM Final Localization
  25. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  26. GRB 250605A: SVOM/VT optical upper limit
  27. GRB 250605A: Swift-XRT refined Analysis
  28. GRB 250605A: Enhanced Swift-XRT position
  29. GRB 250606A: Fermi GBM Final Real-time Localization
  30. GRB 250602A: GECAM detection
  31. GRB 250605A: LT optical observations
  32. GRB 250605A: Swift detection of a burst
  33. Swift GRB250605.79: Global MASTER-Net observations report
  34. Konus-Wind detection of GRB 250601A
  35. IPN triangulation of GRB 250404B
  36. IPN triangulation of GRB 250529A
  37. GRB 250601A: PRIME H band upper limit.
  38. GRB 250601A: PRIME J band upper limit.
  39. GRB 250601A: VLT/FORS2 Optical Observation
  40. GRB 250601A: Fermi GBM Observation
  41. GRB 250603A: Swift/UVOT Upper Limits
  42. GRB 250603A: Swift-XRT refined Analysis
  43. GRB 250603A: Enhanced Swift-XRT position
  44. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  45. Swift GRB250603.05: Global MASTER-Net observations report
  46. GRB 250603A: Swift detection of a burst or new Galactic transient Swift J0839.7-3916
  47. GRB 250602A: Fermi-LAT detection
  48. GRB 250530C: Swift-BAT refined analysis
  49. GRB 250601A: EP-FXT follow-up observation and afterglow candidates
  50. GRB 250601A: Swift/XRT candidate afterglow
  51. GRB 250601A: Swift-XRT observations
  52. GRB 250602A: Fermi GBM Final Real-time Localization
  53. GRB 250601A: Swift/BAT-GUANO arcminute localization of a likely short burst
  54. GRB 250601A: Swift ToO observations
  55. GRB 250601A: Fermi GBM Final Real-time Localization
  56. EP#01709177494: SVOM/VT optical observations
  57. GRB 250531A: Fermi GBM Final Real-time Localization
  58. EP#01709177494: Swift-XRT counterpart detection of known source
  59. GRB 250530C: BOOTES-7 optical upper limit
  60. GRB 250530C: Swift-XRT refined Analysis
  61. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  62. Swift GRB 250530C: Global MASTER-Net observations report
  63. GRB 250530C: Enhanced Swift-XRT position
  64. GRB 250530C: Swift detection of a burst
  65. GRB 250530A: EP-FXT counterpart detection
  66. GRB 250530A: SVOM/VT optical upper limit
  67. GRB 250530B: Fermi GBM Final Real-time Localization
  68. GRB 250530A: Swift-XRT counterpart detection
  69. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  70. GRB 250530A: SVOM detection of a burst
  71. GRB 250527D: CALET Gamma-Ray Burst Monitor detection
  72. GRB 250527C: Swift/UVOT Upper Limits
  73. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  74. EP J1350.0-8622: EP-FXT follow-up observation
  75. GRB 250529B: Fermi GBM Final Real-time Localization
  76. GRB 250527B: Swift-XRT observations
  77. EP-WXT trigger 01709177124: confirmation of a stellar flare by BOOTES-6
  78. GRB 250529A: Fermi GBM Final Real-time Localization
  79. GRB 250521C (short): Zwicky Transient Facility identification of a possible fast optical transient counterpart
  80. GRB 250520A: Swift-BAT refined analysis
  81. GRB 250527C: Swift ToO observations
  82. GRB 250527C: Swift/BAT-GUANO arcminute localization of a burst
  83. GRB 250527B: Tiled Swift observations
  84. GRB 250520A: Gemini-South optical afterglow detection
  85. GRB 250527B / MAXI J1450-527 : MAXI/GSC detection
  86. GRB 250527A: Fermi GBM Final Localization
  87. EP250526a: Einstein Probe detection of a fast X-ray transient
  88. EP J1350.0-8622: BOOTES-6/DPRT optical upper limit
  89. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  90. GRB 250520A: 3 GHz MeerKAT Detection
  91. GRB 250521A: GRBAlpha detection
  92. GRB 250520A: GRBAlpha detection
  93. GRB 250523A: Fermi GBM Final Real-time Localization
  94. GRB 250521B: SVOM/VT optical upper limit
  95. The EP-WXT trigger 01709176612: refined analysis of the EP-FXT observation
  96. GRB 250521B: EP-FXT follow-up observation and afterglow candidates
  97. GRB 250522B: Fermi GBM Final Localization
  98. GRB 250522A: Fermi GBM Final Real-time Localization
  99. EP#01709176612: Swift-XRT counterpart detection of flaring star
  100. GRB 250521D: GOTO detects LAST counterpart candidate prior to the GRB

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