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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"

36195 results found.

  1. IPN triangulation of GRB 260428A
  2. GRB 260504B: AST3-2 i-band upper limit
  3. GRB 260504B: LCO z-band upper limit
  4. SVOM GRB 260504B: MASTER-OAFA optical observations
  5. GRB 260504B: SVOM detection of a short burst
  6. Fermi GRB 260504A: Global MASTER-Net observations report
  7. GRB 260504A: Fermi GBM Final Real-time Localization
  8. GRB 260503A: Fermi GBM Final Real-time Localization
  9. GRB 260502A: GECAM-B observation of a short burst
  10. IPN triangulation of a bright burst from SGR 1E1841-045
  11. GRB 260502A: Fermi GBM Final Localization
  12. GRB 260429B / EP260429a: EP-FXT follow-up observation
  13. GRB 260429B / EP260429a: AstroSat CZTI detection
  14. GRB 260429A: SVOM/GRM observation of a short burst
  15. GRB 260424B: AstroSat CZTI detection
  16. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  17. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  18. GRB 260429A: Fermi GBM Detection
  19. Fermi GRB 260429A: Global MASTER-Net observations report
  20. GRB 260429A: Fermi GBM Final Real-time Localization
  21. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  22. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  23. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  24. GRB 260428A: AstroSat CZTI detection
  25. Fermi GRB 260428A: Global MASTER-Net observations report
  26. EP260416a: Mondy and Terskol optical upper limits
  27. GRB 260424B: Glowbug gamma-ray detection of a short burst
  28. GRB 260424B: COLIBRÍ optical upper limit
  29. Konus-Wind detection of GRB 260424B
  30. GRB 260428A: Fermi GBM Final Real-time Localization
  31. GRB 260424C: Fermi GBM Final Localization
  32. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  33. IPN triangulation of GRB 260424B (short)
  34. GRB 260424B: SVOM/GRM detection of a short burst
  35. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  36. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  37. GRB 260401A: cubesat Avion detection
  38. GRB 260424A: AstroSat CZTI detection of a long burst
  39. GRB 260421B: Kilonova-Catcher optical afterglow detection
  40. GRB 260421B: Insight-HXMT/HE detection
  41. The EP-WXT trigger 01709258652: Mondy optical observations
  42. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  43. EP260416a: Mondy optical observations
  44. GRB 260421B: SVOM/ECLAIRs refined analysis
  45. GRB 260421B: 3.6m DOT optical observation
  46. EP260416a: ZTSh R band observations
  47. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  48. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  49. GRB 260419A: AstroSat CZTI detection
  50. GRB 260421B: SVOM/GRM observation
  51. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  52. GRB 260421B: EP-FXT follow-up observation
  53. GRB 260421B: J-band upper limit with WINTER
  54. GRB 260421B: LCO optical counterpart detection
  55. GRB 260421B: Fermi GBM Observation
  56. Fermi Gamma-ray Burst Monitor trigger 798482368/260421694 is not a GRB
  57. GRB 260421A: AstroSat CZTI detection
  58. GRB 260412A: SVOM/ECLAIRs refined analysis
  59. GRB 260421B: SVOM/VT optical observations
  60. GRB 260310A: Late-time Chandra X-ray Detection
  61. GRB 260418A: Insight-HXMT/HE detection
  62. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  63. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  64. Fermi GRB 260421C: Global MASTER-Net observations report
  65. GRB 260421C: Fermi GBM Final Real-time Localization
  66. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  67. Fermi GRB 260421B: Global MASTER-Net observations report
  68. GRB 260421B: BOOTES-7 early optical afterglow detection
  69. GRB 260421B: LCO optical afterglow confirmation
  70. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  71. GRB 260421B: TRT optical counterpart detection
  72. GRB 260421B: SVOM detection of a long burst
  73. GRB 260421B: BALROG localization (Fermi Trigger 798437606 / GRB 260421176)
  74. GRB 260421B: Fermi GBM Final Real-time Localization
  75. Fermi GRB 260421A: Global MASTER-Net observations report
  76. GRB 260421A: Fermi GBM Final Real-time Localization
  77. GRB 260412A: LCOGT Optical Upper Limits
  78. GOTO26djh/AT2026jpw: CrAO and Mondy optical observations of the transient
  79. EP-WXT trigger 01709260303: KAIT optical observations
  80. GRB 260417A: SVOM/GRM observation
  81. GRB 260419B: Fermi GBM Final Real-time Localization
  82. GRB 260419A: Fermi GBM Final Real-time Localization
  83. Fermi GRB 260417B: Global MASTER-Net observations report
  84. GRB 260418B: Fermi GBM Final Real-time Localization
  85. EP260416a: VLT/FORS2 spectroscopic redshift confirmation
  86. EP260417a/GRB 260417A: refined analysis of the EP-WXT and follow-up EP-FXT observations
  87. GRB 260418A: Fermi GBM Final Real-time Localization
  88. Fermi GRB 260417A: Global MASTER-Net observations report
  89. Konus-Wind detection of GRB 260411B
  90. GRB 260417B: Fermi GBM Final Real-time Localization
  91. GRB 260417A: AstroSat CZTI detection
  92. IPN triangulation of GRB 260411B
  93. EP-WXT trigger 01709259586: KAIT optical observations
  94. EP260416a: KAIT optical upper limit
  95. GRB 260414A: Insight-HXMT/HE detection
  96. GRB 260417A: Fermi GBM Final Real-time Localization
  97. GOTO26djh/AT2026jpw: ZTSh R,I bands observations of the transient
  98. GRB 260415B: Glowbug gamma-ray detection
  99. GRB 260411B: Glowbug gamma-ray detection
  100. GRB 260415A: Insight-HXMT/HE detection

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