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"

28287 results found.

  1. GRB 250520A: DDOTI Optical Upper Limit
  2. GRB 250520A: AstroSat CZTI detection of a short burst
  3. GRB 250520A: Enhanced Swift-XRT position
  4. GRB 250520A: Swift detection of a burst
  5. GRB 250516A: Swift-BAT refined analysis
  6. GRB 250516A: COLIBRÍ optical upper limit
  7. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  8. GRB 250515A: Swift-XRT observations
  9. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  10. GRB 250515A: 1.6m Mephisto optical detection
  11. GRB 250516A: Fermi GBM Observation
  12. GRB 250516A: Swift-XRT refined Analysis
  13. GRB 250516A: Swift/UVOT Detection
  14. GRB 250516B: GECAM-B detection of a bright long burst
  15. GRB 250516A: Enhanced Swift-XRT position
  16. GRB 250516A: Swift detection of a burst
  17. MAXI GRB250515.65: Global MASTER-Net observations report
  18. GRB 250424A: COLIBRÍ detection of the associated supernova
  19. GRB 250502A: TESS observations
  20. GRB 250509A: Swift-BAT refined analysis
  21. Fermi GRB 250512A: Global MASTER-Net observations report
  22. EP250512a/GRB 250512B: REM optical/NIR observations
  23. EP250511a: Koshka Zeiss-1000 Optical Upper Limit
  24. GRB 250507B: AstroSat CZTI detection
  25. EP250511a: Gemini optical counterpart observation
  26. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  27. EP250511a: Mephisto optical upper limits
  28. GRB 250512B: SVOM detection of a burst
  29. EP250512a: Einstein Probe detection of an X-ray transient
  30. EP250511a: REM optical/NIR observations
  31. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  32. EP250511a: COLIBRÍ optical counterpart candidate
  33. EP250511a: BOOTES-5 optical upper limit
  34. EP250511a: Einstein Probe detection of an X-ray transient
  35. EP250508a: Gemini NIR upper limits
  36. GRB 250510B: Fermi GBM Observation
  37. GRB 250510A: Swift-XRT observations
  38. GRB 250509A: Fermi GBM Observation
  39. IceCube-250506A: No Transient Candidates from the Zwicky Transient Facility
  40. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  41. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  42. GRB 250509A: Swift-XRT refined Analysis
  43. GRB 250510A: SVOM possible detection of a burst
  44. GRB 250507A: J-band observations with WINTER
  45. GRB 250509A: Enhanced Swift-XRT position
  46. GRB 250509A: Swift detection of a burst
  47. GRB 250506A: NOT optical upper limits
  48. EP250508a: Liverpool Telescope optical upper limits
  49. EP250508a: KAIT optical upper limit
  50. GRB 250507A: KAIT optical upper limit
  51. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  52. GRB 250505B: SVOM/GRM observation of a short burst
  53. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  54. EP250508a: REM optical/NIR observations
  55. GRB 250506A: Swift-XRT afterglow detection
  56. EP250508a: COLIBRÍ Optical Limit
  57. EP250508a: Einstein Probe detection of an X-ray transient
  58. GRB 250507A: Swift-XRT refined Analysis
  59. IceCube-250506A: Upper limits from a search for additional neutrino events in IceCube
  60. GRB 250506A: Swift/UVOT Upper Limits
  61. GRB 250507A: follow-up observation with EP-FXT
  62. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  63. GRB 250507A: REM optical/NIR observations
  64. GRB 250507A: SVOM/VT optical upper limit
  65. GRB 250506A: Swift-XRT observations
  66. Fermi-LAT Gamma-ray Observations of IceCube-250506A
  67. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  68. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  69. GRB 250507A: SVOM detection of a long burst
  70. GRB 250506A: Mephisto optical upper limits
  71. GRB 250504A: EIRSAT-1 GMOD Detection
  72. GRB 250502A: Bassano Bresciano Observatory upper limit
  73. GRB 250506A: Xinglong 2.16m optical upper limit
  74. SVOM/sb25050601: EP-FXT observations
  75. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  76. GRB 250506A: REM optical/NIR upper limits
  77. GRB 250506A: Fermi GBM Observation
  78. GRB 250506A: Swift XRT observations and possible counterpart detection
  79. GRB 250506A: TRT optical observations
  80. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  81. GRB 250506A: SVOM detection of a burst
  82. GRB 250504A: Swift-BAT refined analysis
  83. GRB 250430A: Swift-BAT refined analysis
  84. GRB 250504A: Swift-XRT refined Analysis
  85. GRB 250504A: VLT/X-shooter upper limits
  86. GRB 250504A: REM optical/NIR observations
  87. GRB 250502A: REM optical/NIR observations
  88. GRB 250504A: MeerLICHT optical afterglow detection
  89. GRB 250504A: Fermi GBM Observation
  90. GRB 250504A: Enhanced Swift-XRT position
  91. Fermi GRB 250504A: Global MASTER-Net observations report
  92. GRB 250504A: Swift detection of a burst
  93. GRB 250502A: Swift/UVOT Follow up
  94. GRB 250502A: Mondy and Tien-Shan Optical Observations
  95. GRB 250502A: KAIT optical observations
  96. GRB 250502A: Montarrenti Observatory optical detection
  97. GRB 250502A: Swift-XRT afterglow detection
  98. GRB 250502A: NOT optical observations
  99. GRB 250502B: AstroSat CZTI detection
  100. GRB 250502A: AKO Optical Afterglow 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