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"

37763 results found.

  1. Swift GRB 250828B: Global MASTER-Net observations report
  2. EP-WXT trigger 01709200800 : KAIT optical observations
  3. EP250828a: KAIT optical upper limit
  4. GRB 250828B: Swift detection of a burst
  5. GRB 250828A: Fermi GBM Final Localization
  6. GRID detection of GRB 250824A
  7. Fermi GRB 250827A: Global MASTER-Net observations report
  8. EP250827a: GOTO observation of the optical afterglow
  9. GRB 250826A: SVOM/GRM observation
  10. GRB 250827A: Fermi GBM Final Real-time Localization
  11. EP250827A: An optical rebrightening was detected by LCO.
  12. EP250827a / GRB 250827A: MASTER-OAFA OT observation
  13. Fermi GRB 250826A: Global MASTER-Net observations report
  14. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  15. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz
  16. Fermi trigger No 777883624: Global MASTER-Net observations report
  17. Fermi Gamma-ray Burst Monitor trigger 777883624/250826283 is not a GRB
  18. GRB 250826A: Fermi GBM Final Real-time Localization
  19. Fermi GRB 250824B: Global MASTER-Net observations report
  20. GRB 250823A: Swift-BAT refined analysis
  21. GRB 250821B: AstroSat CZTI detection
  22. GRB 250819A: AstroSat CZTI detection
  23. GRB 250821B: Insight-HXMT detection
  24. GRB 250823A: Swift-XRT refined Analysis
  25. GRB 250824B: Fermi GBM Final Real-time Localization
  26. GRB 250823A: COLIBRÍ optical observations
  27. GRB 250823A: SVOM/VT optical observation
  28. GRB 250824A: Fermi GBM Final Real-time Localization
  29. GRB 250823A: Swift/UVOT Detection
  30. GRB 250823A: NOT optical observations
  31. GRB 250823A: Fermi GBM Observation
  32. GRB 250818B: MeerKAT Detection
  33. GRB 250823A: Enhanced Swift-XRT position
  34. GRB 250823A: LCOGT Optical Detection
  35. GRB 250823A: BOOTES6/DPRT early optical detection
  36. GRB 250823A: Liverpool Telescope optical detection
  37. GRB 250823A: Swift detection of a burst
  38. GRB 250823A: Fermi GBM Final Real-time Localization
  39. Konus-Wind detection of GRB 250821B
  40. GRB 250806A: Gemini observations of host galaxy candidate
  41. IPN triangulation of GRB 250821B (long/bright)
  42. GRB 250821A: Kilonova-Catcher optical upper limits
  43. GRB 250812A: SVOM/ECLAIRs refined analysis
  44. GRB 250821A: Swift-BAT refined analysis
  45. GRB 250821A: VLT/FORS2 Optical Observation
  46. GRB 250821A: GECAM-B detection
  47. GRB 250821B: SVOM/GRM observation
  48. Fermi GRB 250821B: Global MASTER-Net observations report
  49. GRB 250821A: NOT z-band upper limit
  50. GRB 250821C: Fermi GBM Final Real-time Localization
  51. GRB 250821A: KAIT optical upper limit
  52. GRB 250821A: Swift-XRT refined Analysis
  53. Swift GRB 250821A: Global MASTER-Net observations report
  54. GRB 250821B: Fermi GBM Detection
  55. GRB 250821B: BALROG localization (Fermi Trigger / GRB 250821672)
  56. GRB 250821B: Fermi GBM Final Localization of a Bright Burst
  57. GRB 250821A: Enhanced Swift-XRT position
  58. GRB 250821A: Swift/UVOT Upper Limits
  59. GRB 250821A: LCOGT Optical Upper Limits
  60. GRB 250814A: CMO SAI and SAO RAS izJ observations.
  61. GRB 250821A: Prompt enhanced Swift-XRT position
  62. GRB 250821A: Swift detection of a burst
  63. GRB 250819A: SVOM/GRM observation of a possible “long” duration type I burst
  64. GRB 250819A: Insight-HXMT detection
  65. GRB 250818B: 10 GHz VLA detection
  66. GRB 250814A: Swift/UVOT Upper Limits
  67. GRB 250813B: Swift/UVOT Upper Limit
  68. IPN triangulation of GRB 250816A (short)
  69. IPN triangulation of GRB 250814C (short)
  70. IPN triangulation of GRB 250804B (short)
  71. GRB 250818B: FTW optical and NIR observations show reddening of the counterpart
  72. GRB 250818B: Kilonova-Catcher optical afterglow detection
  73. GRB 250818B: Liverpool Telescope optical detections
  74. LIGO/Virgo/KAGRA S250818k: Upper limits from Fermi-GBM Observations
  75. GRB 250818A: AstroSat CZTI detection
  76. GRB 250818B: Swift/UVOT Detection
  77. Fermi Gamma-ray Burst Monitor trigger 777342746/250820022 is not a GRB
  78. GRB 250820A: Fermi GBM Final Real-time Localization
  79. GRB 250818B: optical afterglow detection with Lesedi (GOTO25fzq)
  80. GRB 250818B: TRT Optical Observation
  81. Fermi GRB 250816A: Global MASTER-Net observations report
  82. GRB 250818B: SAO RAS optical observations
  83. Swift GRB 250818A: Global MASTER-Net observations report
  84. GRB 250818B: NOT optical observations
  85. GRB 250818A: Swift-XRT refined Analysis
  86. GRB 250818B: EP-FXT counterpart detection
  87. GRB 250818A: Swift-BAT refined analysis
  88. Fermi Gamma-ray Burst Monitor trigger 777251788/250818970 is not a GRB
  89. GRB 250818C: Fermi GBM Final Real-time Localization
  90. GRB 250818B: Keck redshift of the optical afterglow
  91. Fermi trigger No 776849714: Global MASTER-Net observations report
  92. GRB 250818B: KAIT optical observations
  93. GRB 250818A: Swift/UVOT Upper Limits
  94. GRB 250818A: Enhanced Swift-XRT position
  95. GRB 250813B: SVOM/ECLAIRs refined analysis
  96. GRB 250818A: Fermi GBM Observation
  97. GRB 250818B: SVOM/VT optical observation
  98. GRB 250814A: Further GRAWITA TNG NIR observations
  99. GRB 250818B: Swift-XRT afterglow detection
  100. GRB 250818B: GOTO optical counterpart candidate

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