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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"

36142 results found.

  1. GRB 260129A: Fermi GBM Final Localization
  2. IPN triangulation of GRB 260127B (short)
  3. GRB 260127B: Swift-XRT observations
  4. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  5. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  6. Fermi GRB 260127A: Global MASTER-Net observations report
  7. GRB 260127A: Fermi GBM Observation
  8. GRB 260127A: COLIBRÍ optical observations
  9. GRB 260127A: NOT optical observations
  10. GRB 260127B: Swift ToO observations
  11. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  12. GRB 260127A: Swift-XRT refined Analysis
  13. GRB 260127B: GOTO candidate optical counterpart
  14. GRB 260127A: SVOM/C-GFT optical observations
  15. GRB 260127A: Enhanced Swift-XRT position
  16. Fermi GRB 260127B: Global MASTER-Net observations report
  17. GRB 260127B: Fermi GBM Final Real-time Localization
  18. GRB 260127A: Prompt enhanced Swift-XRT position
  19. Swift GRB 260127A: Global MASTER-Net observations report
  20. GRB 260127A: LCO optical afterglow discovery
  21. GRB 260127A: Swift detection of a burst
  22. GRB 260127A: Fermi GBM Final Real-time Localization
  23. GRB 260125A: Swift-XRT observations
  24. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  25. Konus-Wind detection of GRB 260120B
  26. GRB 251222A: SVOM/ECLAIRs refined analysis
  27. GRB 260125A: Swift ToO observations
  28. GRB 260125A: GOTO candidate optical counterpart
  29. Fermi GRB 260125B: Global MASTER-Net observations report
  30. GRB 260125B: Fermi GBM Final Real-time Localization
  31. GRB 260125A: Fermi GBM Final Real-time Localization
  32. GRB 260114A: SVOM/VT optical upper limits
  33. GRB 260120A: AstroSat CZTI detection
  34. GRB 260122B: Swift-BAT refined analysis
  35. GRB 260120B: SVOM/GRM observation
  36. GRB 260120A: GECAM-B observation
  37. GRB 260120B: AstroSat CZTI detection
  38. GRB 260114A: Insight-HXMT/HE detection
  39. GRB 260122B: Swift detection of a burst
  40. EP260119a: Assy AZT-20 optical observations
  41. EP260119a: Mondy and SAO RAS optical upper limits
  42. GRB 260122A: Fermi GBM Final Real-time Localization
  43. Fermi GRB 260120C: Global MASTER-Net observations report
  44. GRB 260120B: Swift-BAT refined analysis
  45. GRB 260120B: Swift-XRT refined Analysis
  46. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  47. GRB 260120B: Fermi GBM Observation
  48. GRB 260120B: Swift/UVOT Detection
  49. GRB 260120B: COLIBRÍ optical upper limits
  50. GRB 260120B: Enhanced Swift-XRT position
  51. GRB 260120B: SVOM/C-GFT optical counterpart detection
  52. GRB 260120C: Fermi GBM Final Real-time Localization
  53. GRB 260101A: 239Alferov CubeSat detection
  54. GRB 260120B: Swift detection of a burst
  55. GRB 260120B: Fermi GBM Final Real-time Localization
  56. EP260119A: Mondy I-Band Observations
  57. GRB 260114A: Swift/UVOT Upper Limits
  58. GRB 251202A: further radio observations with the VLA
  59. EP260119a: KAIT optical observations
  60. GRB 260120A: Fermi GBM Final Real-time Localization
  61. EP260119a: SAO RAS optical observations
  62. GRB 251208D: SVOM/ECLAIRs refined analysis
  63. GRB 251208D: SVOM/ECLAIRs refined analysis
  64. GRB 260117A: Swift-XRT afterglow detection
  65. GRB 260115A: AstroSat CZTI detection
  66. GRB 260117A: ZTSh optical upper limit
  67. GRB 260110A: SVOM detection of a burst through offline search
  68. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  69. GRB 260117A: SVOM/VT optical candidate
  70. GRB 260117A: SVOM/C-GFT upper limit
  71. GRB 260117A: Swift-XRT observations
  72. GRB 260117A: Swift ToO observations
  73. GRB 260117A: SVOM detection of a long faint burst
  74. GRB 260115A: GECAM-B observation
  75. GRB 260114A: VLT/MUSE spectroscopic observations
  76. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  77. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  78. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  79. Fermi GRB 260115A: Global MASTER-Net observations report
  80. GRB 260115A: Fermi GBM Final Real-time Localization
  81. GRB 251222A: radio detection with the VLA
  82. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  83. Konus-Wind detection of GRB 260114A
  84. GRB 260114A: Swift-XRT refined Analysis
  85. GRB 260114A: 6 GHz VLA observations
  86. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  87. GRB 260114A : MITSuME Akeno optical upper limits
  88. GRB 260114A: COLIBRÍ optical upper limits
  89. GRB 260114A: TNG NIR upper limit
  90. GRB 260114A: NOT optical observations
  91. Konus-Wind detection of GRB 251230A / EP251230a
  92. GRB 260114A: SVOM/GRM observation of a short burst
  93. Swift GRB 260114A: Global MASTER-Net observations report
  94. GRB 260114A: GECAM-B observation of a short burst
  95. GRB 260114A: Mondy optical observations
  96. GRB 260114A: Fermi GBM observation
  97. GRB 260112B: GECAM-B observation
  98. GRB 260114A: GMG Optical Observation
  99. GRB 260114A: Swift detection of a short burst
  100. GRB 260114A: Fermi GBM Final Real-time Localization

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