Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

37512 results found.

  1. GRB 250402A: NUTTelA-TAO Early Optical Limits
  2. GRB 250403A: GMG Optical Observation
  3. GRB 250403A: 1.6m Mephisto multi-band optical detection
  4. GRB 250402A: Fermi GBM Observation
  5. GRB 250403A: SVOM/C-GFT optical observations
  6. GRB 250403A: GOTO detection of the optical afterglow
  7. GRB 250402A: Swift-XRT observations
  8. GRB 250403A : SVOM detection of a burst
  9. GRB 250403A: Fermi GBM Final Real-time Localization
  10. GRB 250225B: VLT host galaxy redshift z = 0.950
  11. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  12. GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
  13. GRB 250402A: REM optical/NIR upper limits
  14. GRB 250402A: LCO optical counterpart detection
  15. GRB 250402A: refined SVOM/MXT data analysis
  16. GRB 250402B: AstroSat CZTI detection of a short burst
  17. GRB 250402A: SVOM/VT optical counterpart
  18. GRB 250402A: SVOM detection of a burst
  19. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  20. GRB 250314A: ALMA detection
  21. GRB 250329B: Swift/UVOT Upper Limit
  22. GRB 250329A: Swift/UVOT Upper Limit
  23. GRB 250327B: Swift/UVOT Detection
  24. GRB 250327A: Swift/UVOT Upper Limits
  25. GRB 250331E: SVOM/GRM observation
  26. GRB 250327B: Kilonova-Catcher Observations
  27. GRB250331D: AbAO optical observations
  28. GRB 250331D: Fermi GBM observation
  29. GRB 250331C: Swift/UVOT Upper Limits
  30. GRB 250331B: Swift/UVOT Upper Limits
  31. GRB 250328A: AbAO AS-32 Optical Observations
  32. GRB 250219A: NOT candidate host galaxy detection
  33. GRB 250322B: GRBAlpha detection
  34. GRB 250331D: Swift-XRT observations
  35. GRB 250331C: Swift-XRT refined Analysis
  36. GRB 250331B: Swift-XRT refined Analysis
  37. GRB 250331B: Swift-XRT refined Analysis
  38. GRB 250322B possible detection by the AstroSat Satellite
  39. GRB 250330B: SVOM/GRM observation of a short burst
  40. Fermi GRB 250331E: Global MASTER-Net observations report
  41. Fermi GRB 250331D: Global MASTER-Net observations report
  42. GRB 250330B: EIRSAT-1 GMOD Detection
  43. GRB 250331E: Fermi GBM Final Real-time Localization
  44. GRB 250327A Swift-BAT refined analysis
  45. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  46. Fermi trigger No 765078057: Global MASTER-Net observations report
  47. GRB 250329B: CAHA 2.2m telescope optical limit
  48. GRB 250331D: Swift ToO observations
  49. Swift GRB 250331C: Global MASTER-Net observations report
  50. Swift GRB 250331B: Global MASTER-Net observations report
  51. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  52. Konus-Wind detection of GRB 250327B
  53. GRB 250331C: Enhanced Swift-XRT position
  54. GRB 250331B: Enhanced Swift-XRT position
  55. GRB 250320C : SVOM detection of a burst through offline search
  56. GRB 250329B: Swift-XRT confirmation of fading
  57. GRB 250330A: VLT/FORS2 Afterglow Detection
  58. GRB20250327B: 45th Parallel Observatory upper limit
  59. GRB 250328A: Swift/UVOT Detection
  60. GRB 250328A: Swift-XRT refined Analysis
  61. Fermi-LAT gamma-ray observations of IceCube-250330A
  62. GRB 250330A: Fermi GBM Observation
  63. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  64. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  65. GRB 250331D: Fermi GBM Final Real-time Localization
  66. GRB 250331C: Prompt enhanced Swift-XRT position
  67. GRB 250331C: Swift detection of a burst
  68. GRB 250331B: Swift detection of a burst
  69. GRB 250330A: SVOM/VT optical upper limit
  70. GRB 250331A: MAXI/GSC detection
  71. GRB 250314A: VLA detection
  72. Fermi GRB 250330B: Global MASTER-Net observations report
  73. GRB 250330B: Fermi GBM Final Real-time Localization
  74. Fermi GRB 250330A: Global MASTER-Net observations report
  75. GRB 250330A: BOOTES-7 early optical upper limit
  76. GRB 250330A: Swift/UVOT Upper Limits
  77. GRB 250330A: Swift-XRT afterglow detection
  78. GRB 250328A: 1.6m Mephisto optical observations
  79. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  80. GRB 250330A: Fermi GBM Final Localization
  81. IceCube-250330A - IceCube observation of a high-energy neutrino candidate track-like event
  82. GRB 250330A: VLT/FORS2 Optical Observations
  83. GRB 250330A: Prompt Swift-XRT position
  84. GRB 250329B: Swift-XRT afterglow detection
  85. GRB 250330A: Swift detection of a burst
  86. GRB 250328A: A fading optical afterglow confirmed by SVOM/VT
  87. GRB 250329B: SVOM/C-GFT optical upper limit
  88. GRB 250327B: ALMA detection
  89. GRB 250327B: VLA detection
  90. GRB 250329B: SVOM/VT optical upper limit
  91. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  92. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  93. GRB 250329B: GWAC-F50A optical upper limit
  94. GRB 250329B: SVOM detection of a faint transient
  95. GRB 250329A: Swift-XRT afterglow detection
  96. GRB 250328A: SVOM/VT optical observation
  97. GRB 250329A: Fading optical counterpart detection by LCO.
  98. GRB 250328A: SVOM/C-GFT optical upper limit
  99. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  100. GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov