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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"

36231 results found.

  1. GRB 260608A: Fermi GBM Final Real-time Localization
  2. GRB 260607A: TRT optical observations
  3. GRB 260604C: GRANDMA further observations
  4. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  5. GRB 260604A: SVOM/GRM detection
  6. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  7. GRB 260607B: Fermi GBM Observation
  8. GRB 260607B: Fermi-LAT detection
  9. GRB 260607B: Fermi GBM Final Localization Correction
  10. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  11. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  12. GRB 260607A: Fermi GBM Final Real-time Localization (duplicate submission)
  13. GRB 260607A: Fermi GBM Final Real-time Localization
  14. GRB 260604C: GECAM-B observation
  15. GRB 260604C: 6 GHz VLA observations
  16. GRB 260604C: SAO RAS optical observations
  17. GRB 260604C: GRANDMA observations
  18. GRB 260604B: SVOM/GRM detection
  19. GRB 260605A: Insight-HXMT/HE detection
  20. GRB260603A: SVOM/ECLAIRs refined analysis
  21. GRB 260604A: Glowbug gamma-ray detection
  22. GRB 260604C: LCO optical upper limit
  23. GRB 260604C: Liverpool Telescope optical detection
  24. GRB 260601B / EP260601a: AstroSat CZTI detection
  25. GRB 260527A/EP260527a: 6 GHz VLA observations
  26. GRB 260604C: GOTO detections of the optical afterglow
  27. GRB 260604C: Correction to GCN 44828
  28. GRB 260604C: Kilonova-Catcher optical afterglow detection
  29. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  30. GRB 260604C: Jinshan optical observations
  31. GRB 260604C: Fermi GBM Observation
  32. GRB 260604C: LAST detection of optical counterpart candidate
  33. GRB 260604C: MASTER OT J145749.59+284903.0 optical counterpart discovery
  34. Fermi GRB 260604C: Global MASTER-Net observations report
  35. Fermi GRB 260604C: Global MASTER-Net observations report
  36. GRB 260604C: SVOM detection of a long burst
  37. GRB 260604C: Fermi GBM Final Real-time Localization
  38. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  39. GRB 260603A: NOT optical observations
  40. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  41. GRB 260604B: Fermi GBM Final Real-time Localization
  42. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  43. GRB 260604A: Fermi GBM Final Real-time Localization
  44. GRB 260603B: Fermi GBM Final Localization
  45. Konus-Wind detection of GRB 260601B/EP260601a
  46. GRB 260603A: EP-FXT follow-up observation
  47. EP260601a/GRB 260601B: EP-FXT follow-up observation
  48. GRB 260601B / EP260601a: Mondy optical upper limit
  49. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  50. GRB 260603A: Kilonova-Catcher optical upper limit
  51. GRB 260603A: SVOM/VT optical observations
  52. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  53. GRB 260601A: SVOM/GRM observation of a short burst
  54. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  55. GRB 260603A: SVOM detection of a burst
  56. GRB 260601B/EP260601a: Insight-HXMT detection
  57. Fermi GRB 260602B: Global MASTER-Net observations report
  58. Fermi GRB 260602B: Global MASTER-Net observations report
  59. GRB 260602B: Fermi GBM Final Localization
  60. GRB 260601A: GECAM-B observation of a short burst
  61. GRB 260601B/EP260601a: J-band upper limit with WINTER
  62. EP260530a/AT 2026nwl: KAIT optical observations
  63. GRB 260602A: Fermi GBM Final Real-time Localization
  64. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  65. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  66. GRB 260601B/EP260601a: SVOM/VT optical observations
  67. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  68. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  69. GRB 260601A: Glowbug gamma-ray detection of a short burst
  70. GRB 260531B: Glowbug gamma-ray detection
  71. GRB 260516D: VLA radio detection
  72. GRB 260601A: Fermi GBM Observation
  73. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  74. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  75. Fermi GRB 260601A: Global MASTER-Net observations report
  76. GRB 260601A: Fermi GBM Final Real-time Localization
  77. GRB 260531B: GECAM-B observation
  78. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  79. GRB 260531C: Fermi GBM Final Localization Correction
  80. Fermi Gamma-ray Burst Monitor trigger 801900520/260531256 is not a GRB
  81. GRB 260531B: Fermi GBM Final Real-time Localization
  82. GRB 260531A: MAXI/GSC detection
  83. AT 2026nuz: COLIBRÍ optical observations
  84. IPN triangulation of GRB 260527A / EP260527a
  85. EP260527a/GRB 260527A: further FTW optical and NIR observations
  86. GRB 260530B: SVOM/GRM detection of a possible bright short GRB
  87. GRB 260530A: Fermi GBM Final Real-time Localization
  88. GRB 260527A / EP260527a: VLA radio detection
  89. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  90. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  91. GRB 260529A: GOTO tentative optical afterglow candidate
  92. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  93. GRB 260527A/EP260527a: Insight-HXMT detection
  94. Fermi GRB 260529A: Global MASTER-Net observations report
  95. GRB 260529A: Fermi GBM Final Real-time Localization
  96. GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
  97. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  98. EP260527a / GRB 260527A: NOT optical observations
  99. GRB 260527A/EP260527a: FTW optical and NIR observations
  100. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE

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