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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"

36144 results found.

  1. GRB 260504B: SVOM/MXT refined analysis and potential detection
  2. GRB 260504B: EP-FXT upper limit
  3. GRB 260502A: SVOM/GRM observation of a short GRB
  4. GRB 260503A: SVOM/GRM observation of a GRB
  5. Konus-Wind detection of GRB 260415C
  6. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  7. Konus-Wind detection of GRB 260411C
  8. GRB 260504B: REM optical/NIR observations
  9. IPN triangulation of GRB 260429A
  10. IPN triangulation of GRB 260428A
  11. GRB 260504B: AST3-2 i-band upper limit
  12. GRB 260504B: LCO z-band upper limit
  13. SVOM GRB 260504B: MASTER-OAFA optical observations
  14. GRB 260504B: SVOM detection of a short burst
  15. Fermi GRB 260504A: Global MASTER-Net observations report
  16. GRB 260504A: Fermi GBM Final Real-time Localization
  17. GRB 260503A: Fermi GBM Final Real-time Localization
  18. GRB 260502A: GECAM-B observation of a short burst
  19. GRB 260502A: Fermi GBM Final Localization
  20. GRB 260429B / EP260429a: EP-FXT follow-up observation
  21. GRB 260429B / EP260429a: AstroSat CZTI detection
  22. GRB 260429A: SVOM/GRM observation of a short burst
  23. GRB 260424B: AstroSat CZTI detection
  24. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  25. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  26. GRB 260429A: Fermi GBM Detection
  27. Fermi GRB 260429A: Global MASTER-Net observations report
  28. GRB 260429A: Fermi GBM Final Real-time Localization
  29. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  30. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  31. GRB 260428A: AstroSat CZTI detection
  32. Fermi GRB 260428A: Global MASTER-Net observations report
  33. EP260416a: Mondy and Terskol optical upper limits
  34. GRB 260424B: Glowbug gamma-ray detection of a short burst
  35. GRB 260424B: COLIBRÍ optical upper limit
  36. Konus-Wind detection of GRB 260424B
  37. GRB 260428A: Fermi GBM Final Real-time Localization
  38. GRB 260424C: Fermi GBM Final Localization
  39. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  40. IPN triangulation of GRB 260424B (short)
  41. GRB 260424B: SVOM/GRM detection of a short burst
  42. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  43. GRB 260401A: cubesat Avion detection
  44. GRB 260424A: AstroSat CZTI detection of a long burst
  45. GRB 260421B: Kilonova-Catcher optical afterglow detection
  46. GRB 260421B: Insight-HXMT/HE detection
  47. The EP-WXT trigger 01709258652: Mondy optical observations
  48. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  49. EP260416a: Mondy optical observations
  50. GRB 260421B: SVOM/ECLAIRs refined analysis
  51. GRB 260421B: 3.6m DOT optical observation
  52. EP260416a: ZTSh R band observations
  53. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  54. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  55. GRB 260419A: AstroSat CZTI detection
  56. GRB 260421B: SVOM/GRM observation
  57. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  58. GRB 260421B: EP-FXT follow-up observation
  59. GRB 260421B: J-band upper limit with WINTER
  60. GRB 260421B: LCO optical counterpart detection
  61. GRB 260421B: Fermi GBM Observation
  62. Fermi Gamma-ray Burst Monitor trigger 798482368/260421694 is not a GRB
  63. GRB 260421A: AstroSat CZTI detection
  64. GRB 260412A: SVOM/ECLAIRs refined analysis
  65. GRB 260421B: SVOM/VT optical observations
  66. GRB 260310A: Late-time Chandra X-ray Detection
  67. GRB 260418A: Insight-HXMT/HE detection
  68. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  69. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  70. Fermi GRB 260421C: Global MASTER-Net observations report
  71. GRB 260421C: Fermi GBM Final Real-time Localization
  72. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  73. Fermi GRB 260421B: Global MASTER-Net observations report
  74. GRB 260421B: BOOTES-7 early optical afterglow detection
  75. GRB 260421B: LCO optical afterglow confirmation
  76. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  77. GRB 260421B: TRT optical counterpart detection
  78. GRB 260421B: SVOM detection of a long burst
  79. GRB 260421B: BALROG localization (Fermi Trigger 798437606 / GRB 260421176)
  80. GRB 260421B: Fermi GBM Final Real-time Localization
  81. Fermi GRB 260421A: Global MASTER-Net observations report
  82. GRB 260421A: Fermi GBM Final Real-time Localization
  83. GRB 260412A: LCOGT Optical Upper Limits
  84. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  85. EP-WXT trigger 01709260303: KAIT optical observations
  86. GRB 260417A: SVOM/GRM observation
  87. GRB 260419B: Fermi GBM Final Real-time Localization
  88. GRB 260419A: Fermi GBM Final Real-time Localization
  89. Fermi GRB 260417B: Global MASTER-Net observations report
  90. GRB 260418B: Fermi GBM Final Real-time Localization
  91. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  92. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  93. GRB 260418A: Fermi GBM Final Real-time Localization
  94. Fermi GRB 260417A: Global MASTER-Net observations report
  95. Konus-Wind detection of GRB 260411B
  96. GRB 260417B: Fermi GBM Final Real-time Localization
  97. GRB 260417A: AstroSat CZTI detection
  98. IPN triangulation of GRB 260411B
  99. EP-WXT trigger 01709259586: KAIT optical observations
  100. EP260416a: KAIT optical upper limit

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