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"

41981 results found.

  1. GRB 250516A: Swift/UVOT Detection
  2. GRB 250515A: Swift ToO observations
  3. GRB 250516B: GECAM-B detection of a bright long burst
  4. GRB 250516A: Enhanced Swift-XRT position
  5. GRB 250516A: Swift detection of a burst
  6. GRB 250516A: Fermi GBM Final Real-time Localization
  7. GRB 250512B / EP250512a: SVOM/GRM analysis
  8. GRB 250515A: GOTO candidate optical counterpart
  9. MAXI GRB250515.65: Global MASTER-Net observations report
  10. GRB 250515A: Fermi GBM Final Localization
  11. GRB 250424A: COLIBRÍ detection of the associated supernova
  12. Konus-Wind detection of GRB 250512B / EP250512a
  13. GRB 250502A: TESS observations
  14. Fermi trigger No 768922089: Global MASTER-Net observations report
  15. GRB 250511A: GECAM-A detection of a short burst
  16. GRB 250509A: Swift-BAT refined analysis
  17. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  18. Fermi GRB 250512A: Global MASTER-Net observations report
  19. Konus-Wind detection of GRB 250506A
  20. EP250512a/GRB 250512B: REM optical/NIR observations
  21. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  22. GRB 250507B: AstroSat CZTI detection
  23. EP250511a: Gemini optical counterpart observation
  24. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  25. EP250512a/GRB 250512B: FTW optical and NIR observations of the counterpart
  26. EP250512a: Global MASTER-Net observations report
  27. EP250511a: FTW optical and NIR observations
  28. GRB 250512B/EP250512a: SVOM/VT optical fading
  29. GRB 250512B/EP250512a：SVOM/VT bright optical counterpart
  30. EP250511a: Mephisto optical upper limits
  31. GRB 250512B: SVOM detection of a burst
  32. GRB 250507B: SVOM/GRM observation of a burst
  33. EP250512a: Einstein Probe detection of an X-ray transient
  34. GRB 250512A: Fermi GBM Final Real-time Localization
  35. EP250511a: REM optical/NIR observations
  36. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  37. EP250511a: SVOM/VT optical candidate comfirmation
  38. EP250511a: Global MASTER-Net observations report
  39. EP250511a: COLIBRÍ optical counterpart candidate
  40. EP250511a: Einstein Probe detection of an X-ray transient
  41. EP250508a: Gemini NIR upper limits
  42. GRB 250510B: Fermi GBM Observation
  43. Fermi GRB 250510C: Global MASTER-Net observations report
  44. Fermi GRB 250510B: Global MASTER-Net observations report
  45. GRB 250510C: Fermi GBM Final Real-time Localization
  46. GRB 250510A: Swift-XRT observations
  47. GRB 250509A: Fermi GBM Observation
  48. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  49. GRB 250510A: follow-up observation with EP-FXT
  50. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  51. GRB 250510B: Fermi GBM Final Localization
  52. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  53. GRB 250509A: Swift-XRT refined Analysis
  54. GRB 250510A: SVOM possible detection of a burst
  55. GRB 250507A: J-band observations with WINTER (duplicate submission)
  56. GRB 250507A: J-band observations with WINTER
  57. EP250508a: SVOM/VT optical candidate fading
  58. GRB 250509A: Enhanced Swift-XRT position
  59. GRB 250509A: Prompt enhanced Swift-XRT position
  60. Fermi GRB 250509A: Global MASTER-Net observations report
  61. Swift GRB 250509A: Global MASTER-Net observations report
  62. GRB 250509A: Swift detection of a burst
  63. GRB 250509A: Fermi GBM Final Real-time Localization
  64. GRB 250506A: NOT optical upper limits
  65. EP250508a: Liverpool Telescope optical upper limits
  66. EP250508a: follow-up observation with EP-FXT
  67. EP250508a: SVOM/VT optical candidate
  68. GRB 250507A: KAIT optical upper limit
  69. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  70. GRB 250505B: SVOM/GRM observation of a short burst
  71. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  72. GRB 250506A: GECAM detection
  73. EP250508a: REM optical/NIR observations
  74. GRB 250506A: Swift-XRT afterglow detection
  75. EP250508a: Global MASTER-Net observations report
  76. GRB 250506A: SVOM/VT optical upper limit
  77. EP250508a: COLIBRÍ Optical Limit
  78. EP250508a: Einstein Probe detection of an X-ray transient
  79. GRB 250507A: Swift-XRT refined Analysis
  80. IceCube-250506A: Upper limits from a search for additional neutrino events in IceCube
  81. GRB 250506A: Swift/UVOT Upper Limits
  82. GRB 250427B : SVOM detection of a burst through offline search
  83. GRB 250507A: follow-up observation with EP-FXT
  84. GRB 250430A / EP250430a: AstroSat CZTI detection
  85. EP#01709175213/IGR J19566+0326: Swift-XRT detection
  86. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  87. GRB 250507A: refined SVOM/MXT data analysis
  88. GRB 250507A: REM optical/NIR observations
  89. GRB 250507A: SVOM/VT optical upper limit
  90. GRB 250506A: Swift-XRT observations
  91. Fermi-LAT Gamma-ray Observations of IceCube-250506A
  92. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  93. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  94. GRB 250507A: SVOM detection of a long burst
  95. GRB 250506A: Mephisto optical upper limits
  96. GRB 250504A: EIRSAT-1 GMOD Detection
  97. GRB 250506A: Swift ToO observations
  98. GRB 250502A: Bassano Bresciano Observatory upper limit
  99. IceCube-250506A - IceCube observation of a high-energy neutrino candidate track-like event
  100. IceCube Alert 250506.59: Global MASTER-Net observations report

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