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"

18513 results found.

  1. EP250421a: REM optical upper limit
  2. EP250421A: COLIBRÍ Optical Upper Limit
  3. GRB 250419A: Mondy Continued Optical Observations
  4. Fermi GRB 250421A: Global MASTER-Net observations report
  5. EP250421a: Einstein Probe detection of an X-ray transient
  6. EP250421a: Mephisto optical counterpart confirmation
  7. EP250421a: JinShan likely optical counterpart
  8. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  9. GRB 250419A: LCO optical observation
  10. GRB 250419A: JinShan optical observations
  11. GRB 250419A: SVOM/C-GFT optical observations
  12. GRB 250419A: Swift/UVOT Follow up
  13. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  14. GRB 250419A: LCO optical afterglow multi-band observations
  15. GRB 250419A: Mondy and AbAO Optical Observations
  16. GRB 250419A: AKO Optical Afterglow Detection
  17. GRB 250419A: KAIT optical afterglow observations
  18. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  19. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  20. GRB 250419A: SVOM detection of a soft burst
  21. EP250416a: refined EP-WXT and EP-FXT analysis
  22. EP20250416a: Swift/XRT counterpart detection
  23. IceCube-250416A: DDOTI Optical Observations
  24. EP250416a: Gemini South-GMOS optical counterpart
  25. SVOM/sb25041603 is not a GRB
  26. EP250416a: Einstein Probe detection of an X-ray transient
  27. IceCube-250416A: Global MASTER-Net observations report
  28. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  29. IceCube 250414.324: DDOTI Optical Observations
  30. EP250304a: ATCA radio observations
  31. EP250404a: Nanshan 0.43m Telescope optical observatios
  32. GRB 250411A: DDOTI Optical Observations
  33. GRB 250314A: e-MERLIN observations
  34. GRB 250407A: Mondy and AbAO Optical Observations
  35. EP250227a: Further NOT optical observations
  36. IceCube-250406A: Swift-XRT observations
  37. GRB 250407A: LCO detection of a fading optical counterpart
  38. GRB 250407A: SVOM/GRM observation of a bright long burst
  39. GRB 250407A: EP-WXT afterglow detection
  40. EP250407a: EP-WXT detection of a fast X-ray transient
  41. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  42. GRB 250407A: KAIT Optical Afterglow Candidate
  43. IceCube-250406A: No candidates from the Zwicky Transient Facility
  44. GRB 250407A: Swift-XRT afterglow detection
  45. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  46. IPN triangulation of GRB 250406B (short/hard)
  47. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  48. IceCube 250406.951: DDOTI Optical Observations
  49. IceCube Alert 250406.95: Global MASTER-Net observations report
  50. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  51. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  52. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  53. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  54. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  55. Konus-Wind detection of GRB 250404A / EP250404a
  56. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  57. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  58. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  59. EP250402a: Optical upper limit with PD 1.3m observations
  60. GRB 250404A / EP250404a: NOT optical observations
  61. GRB 250331D: Swift-XRT afterglow detection
  62. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  63. EP250404a: REM optical/NIR observations
  64. EP250404a: Seimei/TriCCS optical counterpart detection
  65. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  66. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  67. EP250404a: LCO optical counterpart detection
  68. EP250404a: Xinglong decaying optical counterpart
  69. GRB 250403A: Montarrenti Observatory optical detection
  70. GRB 250403A: KAIT optical observations
  71. EP250404a: AKO Optical Afterglow Detection
  72. EP250404a: LAST detection of optical counterpart
  73. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  74. GRB 250327B: VIRT Optical Upper Limit
  75. EP250404a: Mephisto multi-band optical detection
  76. EP250321A: J band upper limit by SYSU 80cm telescope
  77. EP250404a: Nanshan/HMT optical counterpart detection
  78. EP250404a: Einstein Probe detection of an X-ray transient
  79. GRB 250403A: Swift/UVOT Detection
  80. GRB 250402A: Swift/UVOT Upper Limits
  81. EP250402a: Optical upper limit with Kinder observations
  82. GRB 250403A: REM NIR afterglow detection
  83. GRB 250403A: LCO optical counterpart detection
  84. GRB 250403A: JinShan optical observations
  85. GRB 250402A: EP-FXT afterglow detection
  86. GRB 250403A: Optical counterpart detection by LCO.
  87. EP250402a: EP-FXT follow-up observations
  88. GRB 250403A: GMG Optical Observation
  89. GRB 250403A: 1.6m Mephisto multi-band optical detection
  90. GRB 250403A: SVOM/C-GFT optical observations
  91. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  92. GRB 250402A: REM optical/NIR upper limits
  93. GRB 250402A: LCO optical counterpart detection
  94. The EP-WXT trigger 01709133862 is a flaring star
  95. EP250402a: Einstein Probe detection of a fast X-ray transient
  96. GRB 250402A: SVOM/VT optical counterpart
  97. GRB 250402A: SVOM detection of a burst
  98. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  99. GRB 250329B: Swift/UVOT Upper Limit
  100. GRB 250329A: Swift/UVOT Upper Limit

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