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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"

36310 results found.

  1. GRB 260504B: GECAM-B detection
  2. GRB 260504C: SVOM/GRM observation of short GRB
  3. GRB 260504B: SVOM/GRM spectral analysis
  4. GRB 260430B: AstroSat CZTI detection of a long burst
  5. GRB 260504B: SVOM/MXT refined analysis and potential detection
  6. GRB 260504B: EP-FXT upper limit
  7. GRB 260502A: SVOM/GRM observation of a short GRB
  8. GRB 260503A: SVOM/GRM observation of a GRB
  9. IceCube-260504A - IceCube observation of a high-energy neutrino candidate track-like event
  10. Konus-Wind detection of GRB 260415C
  11. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  12. Konus-Wind detection of GRB 260411C
  13. GRB 260504B: REM optical/NIR observations
  14. IPN triangulation of GRB 260429A
  15. IPN triangulation of GRB 260428A
  16. GRB 260504B: AST3-2 i-band upper limit
  17. GRB 260504B: LCO z-band upper limit
  18. SVOM GRB 260504B: MASTER-OAFA optical observations
  19. GRB 260504B: SVOM detection of a short burst
  20. Fermi GRB 260504A: Global MASTER-Net observations report
  21. GRB 260504A: Fermi GBM Final Real-time Localization
  22. GRB 260503A: Fermi GBM Final Real-time Localization
  23. GRB 260502A: GECAM-B observation of a short burst
  24. IPN triangulation of a bright burst from SGR 1E1841-045
  25. GRB 260502A: Fermi GBM Final Localization
  26. GRB 260429B / EP260429a: EP-FXT follow-up observation
  27. GRB 260429B / EP260429a: AstroSat CZTI detection
  28. GRB 260429A: SVOM/GRM observation of a short burst
  29. GRB 260424B: AstroSat CZTI detection
  30. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  31. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  32. GRB 260429A: Fermi GBM Detection
  33. Fermi GRB 260429A: Global MASTER-Net observations report
  34. GRB 260429A: Fermi GBM Final Real-time Localization
  35. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  36. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  37. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  38. GRB 260428A: AstroSat CZTI detection
  39. Fermi GRB 260428A: Global MASTER-Net observations report
  40. EP260416a: Mondy and Terskol optical upper limits
  41. GRB 260424B: Glowbug gamma-ray detection of a short burst
  42. GRB 260424B: COLIBRÍ optical upper limit
  43. Konus-Wind detection of GRB 260424B
  44. GRB 260428A: Fermi GBM Final Real-time Localization
  45. GRB 260424C: Fermi GBM Final Localization
  46. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  47. IPN triangulation of GRB 260424B (short)
  48. GRB 260424B: SVOM/GRM detection of a short burst
  49. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  50. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  51. GRB 260401A: cubesat Avion detection
  52. GRB 260424A: AstroSat CZTI detection of a long burst
  53. GRB 260421B: Kilonova-Catcher optical afterglow detection
  54. GRB 260421B: Insight-HXMT/HE detection
  55. The EP-WXT trigger 01709258652: Mondy optical observations
  56. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  57. EP260416a: Mondy optical observations
  58. GRB 260421B: SVOM/ECLAIRs refined analysis
  59. GRB 260421B: 3.6m DOT optical observation
  60. EP260416a: ZTSh R band observations
  61. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  62. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  63. GRB 260419A: AstroSat CZTI detection
  64. GRB 260421B: SVOM/GRM observation
  65. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  66. GRB 260421B: EP-FXT follow-up observation
  67. GRB 260421B: J-band upper limit with WINTER
  68. GRB 260421B: LCO optical counterpart detection
  69. GRB 260421B: Fermi GBM Observation
  70. Fermi Gamma-ray Burst Monitor trigger 798482368/260421694 is not a GRB
  71. GRB 260421A: AstroSat CZTI detection
  72. GRB 260412A: SVOM/ECLAIRs refined analysis
  73. GRB 260421B: SVOM/VT optical observations
  74. GRB 260310A: Late-time Chandra X-ray Detection
  75. GRB 260418A: Insight-HXMT/HE detection
  76. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  77. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  78. Fermi GRB 260421C: Global MASTER-Net observations report
  79. GRB 260421C: Fermi GBM Final Real-time Localization
  80. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  81. Fermi GRB 260421B: Global MASTER-Net observations report
  82. GRB 260421B: BOOTES-7 early optical afterglow detection
  83. GRB 260421B: LCO optical afterglow confirmation
  84. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  85. GRB 260421B: TRT optical counterpart detection
  86. GRB 260421B: SVOM detection of a long burst
  87. GRB 260421B: BALROG localization (Fermi Trigger 798437606 / GRB 260421176)
  88. GRB 260421B: Fermi GBM Final Real-time Localization
  89. Fermi GRB 260421A: Global MASTER-Net observations report
  90. GRB 260421A: Fermi GBM Final Real-time Localization
  91. GRB 260412A: LCOGT Optical Upper Limits
  92. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  93. EP-WXT trigger 01709260303: KAIT optical observations
  94. GRB 260417A: SVOM/GRM observation
  95. GRB 260419B: Fermi GBM Final Real-time Localization
  96. GRB 260419A: Fermi GBM Final Real-time Localization
  97. Fermi GRB 260417B: Global MASTER-Net observations report
  98. GRB 260418B: Fermi GBM Final Real-time Localization
  99. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  100. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations

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