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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"

37580 results found.

  1. GRB 260504B: SVOM/ECLAIRs refined analysis
  2. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  3. GRB 260506B: Fermi GBM Final Real-time Localization
  4. Fermi GRB 260506A: Global MASTER-Net observations report
  5. GRB 260506A: Fermi GBM Final Real-time Localization
  6. GRB 260503A: GECAM-B observation of a burst
  7. GRB 260430B: Glowbug gamma-ray detection
  8. GRB 260504B: SVOM/VT optical upper limits
  9. GRB 260421B: radio observation with the VLA
  10. Konus-Wind detection of GRB 260504B (short/hard)
  11. GRB 260504B: GECAM-B detection
  12. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  13. GRB 260504C: SVOM/GRM observation of short GRB
  14. GRB 260504B: SVOM/GRM spectral analysis
  15. GRB 260430B: AstroSat CZTI detection of a long burst
  16. GRB 260504B: SVOM/MXT refined analysis and potential detection
  17. GRB 260504B: EP-FXT upper limit
  18. GRB 260502A: SVOM/GRM observation of a short GRB
  19. GRB 260503A: SVOM/GRM observation of a GRB
  20. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  21. Konus-Wind detection of GRB 260415C
  22. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  23. Konus-Wind detection of GRB 260411C
  24. GRB 260504B: REM optical/NIR observations
  25. IPN triangulation of GRB 260429A
  26. IPN triangulation of GRB 260428A
  27. GRB 260504B: AST3-2 i-band upper limit
  28. GRB 260504B: LCO z-band upper limit
  29. SVOM GRB 260504B: MASTER-OAFA optical observations
  30. GRB 260504B: SVOM detection of a short burst
  31. Fermi GRB 260504A: Global MASTER-Net observations report
  32. GRB 260504A: Fermi GBM Final Real-time Localization
  33. GRB 260503A: Fermi GBM Final Real-time Localization
  34. GRB 260502A: GECAM-B observation of a short burst
  35. GRB 260502A: Fermi GBM Final Localization
  36. GRB 260429B / EP260429a: EP-FXT follow-up observation
  37. GRB 260429B / EP260429a: AstroSat CZTI detection
  38. GRB 260429A: SVOM/GRM observation of a short burst
  39. GRB 260424B: AstroSat CZTI detection
  40. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  41. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  42. GRB 260429A: Fermi GBM Detection
  43. Fermi GRB 260429A: Global MASTER-Net observations report
  44. GRB 260429A: Fermi GBM Final Real-time Localization
  45. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  46. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  47. GRB 260428A: AstroSat CZTI detection
  48. Fermi GRB 260428A: Global MASTER-Net observations report
  49. EP260416a: Mondy and Terskol optical upper limits
  50. GRB 260424B: Glowbug gamma-ray detection of a short burst
  51. GRB 260424B: COLIBRÍ optical upper limit
  52. Konus-Wind detection of GRB 260424B
  53. GRB 260428A: Fermi GBM Final Real-time Localization
  54. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  55. GRB 260424C: Fermi GBM Final Localization
  56. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  57. IPN triangulation of GRB 260424B (short)
  58. GRB 260424B: SVOM/GRM detection of a short burst
  59. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  60. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  61. Fermi trigger No 798737427: Global MASTER-Net observations report
  62. GRB 260401A: cubesat Avion detection
  63. GRB 260424A: AstroSat CZTI detection of a long burst
  64. GRB 260421B: Kilonova-Catcher optical afterglow detection
  65. GRB 260421B: Insight-HXMT/HE detection
  66. The EP-WXT trigger 01709258652: Mondy optical observations
  67. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  68. EP260416a: Mondy optical observations
  69. GRB 260421B: SVOM/ECLAIRs refined analysis
  70. GRB 260421B: 3.6m DOT optical observation
  71. EP260416a: ZTSh R band observations
  72. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  73. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  74. GRB 260419A: AstroSat CZTI detection
  75. GRB 260421B: SVOM/GRM observation
  76. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  77. GRB 260421B: EP-FXT follow-up observation
  78. GRB 260421B: J-band upper limit with WINTER
  79. GRB 260421B: LCO optical counterpart detection
  80. GRB 260421B: Fermi GBM Observation
  81. Fermi Gamma-ray Burst Monitor trigger 798482368/260421694 is not a GRB
  82. GRB 260421A: AstroSat CZTI detection
  83. GRB 260412A: SVOM/ECLAIRs refined analysis
  84. GRB 260421B: SVOM/VT optical observations
  85. GRB 260310A: Late-time Chandra X-ray Detection
  86. GRB 260418A: Insight-HXMT/HE detection
  87. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  88. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  89. Fermi GRB 260421C: Global MASTER-Net observations report
  90. GRB 260421C: Fermi GBM Final Real-time Localization
  91. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  92. Fermi GRB 260421B: Global MASTER-Net observations report
  93. GRB 260421B: BOOTES-7 early optical afterglow detection
  94. GRB 260421B: LCO optical afterglow confirmation
  95. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  96. GRB 260421B: TRT optical counterpart detection
  97. GRB 260421B: SVOM detection of a long burst
  98. GRB 260421B: BALROG localization (Fermi Trigger 798437606 / GRB 260421176)
  99. GRB 260421B: Fermi GBM Final Real-time Localization
  100. Fermi GRB 260421A: Global MASTER-Net observations report

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