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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"

36203 results found.

  1. IPN triangulation of GRB 260121A
  2. GRB 260127A: Swift-BAT refined analysis
  3. GRB 260129B: Fermi GBM Final Localization
  4. GRB 260128B: SVOM detection of a burst through offline search
  5. GRB 260129A: Fermi GBM Final Localization
  6. IPN triangulation of GRB 260127B (short)
  7. GRB 260127B: Swift-XRT observations
  8. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  9. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  10. Fermi GRB 260127A: Global MASTER-Net observations report
  11. GRB 260127A: Fermi GBM Observation
  12. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  13. GRB 260127A: COLIBRÍ optical observations
  14. GRB 260127A: NOT optical observations
  15. GRB 260127B: Swift ToO observations
  16. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  17. GRB 260127A: Swift-XRT refined Analysis
  18. GRB 260127B: GOTO candidate optical counterpart
  19. GRB 260127A: SVOM/C-GFT optical observations
  20. GRB 260127A: Enhanced Swift-XRT position
  21. Fermi GRB 260127B: Global MASTER-Net observations report
  22. GRB 260127B: Fermi GBM Final Real-time Localization
  23. GRB 260127A: Prompt enhanced Swift-XRT position
  24. Swift GRB 260127A: Global MASTER-Net observations report
  25. GRB 260127A: LCO optical afterglow discovery
  26. GRB 260127A: Swift detection of a burst
  27. GRB 260127A: Fermi GBM Final Real-time Localization
  28. GRB 260125A: Swift-XRT observations
  29. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  30. Konus-Wind detection of GRB 260120B
  31. GRB 251222A: SVOM/ECLAIRs refined analysis
  32. GRB 260125A: Swift ToO observations
  33. GRB 260125A: GOTO candidate optical counterpart
  34. Fermi GRB 260125B: Global MASTER-Net observations report
  35. GRB 260125B: Fermi GBM Final Real-time Localization
  36. GRB 260125A: Fermi GBM Final Real-time Localization
  37. GRB 260114A: SVOM/VT optical upper limits
  38. GRB 260120A: AstroSat CZTI detection
  39. GRB 260122B: Swift-BAT refined analysis
  40. GRB 260120B: SVOM/GRM observation
  41. GRB 260120A: GECAM-B observation
  42. GRB 260120B: AstroSat CZTI detection
  43. GRB 260114A: Insight-HXMT/HE detection
  44. GRB 260122B: Swift detection of a burst
  45. EP260119a: Assy AZT-20 optical observations
  46. EP260119a: Mondy and SAO RAS optical upper limits
  47. GRB 260122A: Fermi GBM Final Real-time Localization
  48. Fermi GRB 260120C: Global MASTER-Net observations report
  49. GRB 260120B: Swift-BAT refined analysis
  50. GRB 260120B: Swift-XRT refined Analysis
  51. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  52. GRB 260120B: Fermi GBM Observation
  53. GRB 260120B: Swift/UVOT Detection
  54. GRB 260120B: COLIBRÍ optical upper limits
  55. GRB 260120B: Enhanced Swift-XRT position
  56. GRB 260120B: SVOM/C-GFT optical counterpart detection
  57. GRB 260120C: Fermi GBM Final Real-time Localization
  58. GRB 260101A: 239Alferov CubeSat detection
  59. GRB 260120B: Swift detection of a burst
  60. GRB 260120B: Fermi GBM Final Real-time Localization
  61. EP260119A: Mondy I-Band Observations
  62. GRB 260114A: Swift/UVOT Upper Limits
  63. GRB 251202A: further radio observations with the VLA
  64. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  65. EP260119a: KAIT optical observations
  66. GRB 260120A: Fermi GBM Final Real-time Localization
  67. EP260119a: SAO RAS optical observations
  68. GRB 251208D: SVOM/ECLAIRs refined analysis
  69. GRB 251208D: SVOM/ECLAIRs refined analysis
  70. GRB 260117A: Swift-XRT afterglow detection
  71. GRB 260115A: AstroSat CZTI detection
  72. GRB 260117A: ZTSh optical upper limit
  73. GRB 260110A: SVOM detection of a burst through offline search
  74. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  75. GRB 260117A: SVOM/VT optical candidate
  76. GRB 260117A: SVOM/C-GFT upper limit
  77. GRB 260117A: Swift-XRT observations
  78. GRB 260117A: Swift ToO observations
  79. GRB 260117A: SVOM detection of a long faint burst
  80. GRB 260115A: GECAM-B observation
  81. GRB 260114A: VLT/MUSE spectroscopic observations
  82. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  83. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  84. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  85. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  86. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  87. Fermi GRB 260115A: Global MASTER-Net observations report
  88. GRB 260115A: Fermi GBM Final Real-time Localization
  89. GRB 251222A: radio detection with the VLA
  90. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  91. Konus-Wind detection of GRB 260114A
  92. GRB 260114A: Swift-XRT refined Analysis
  93. GRB 260114A: 6 GHz VLA observations
  94. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  95. GRB 260114A : MITSuME Akeno optical upper limits
  96. GRB 260114A: COLIBRÍ optical upper limits
  97. GRB 260114A: TNG NIR upper limit
  98. GRB 260114A: NOT optical observations
  99. Konus-Wind detection of GRB 251230A / EP251230a
  100. GRB 260114A: SVOM/GRM observation of a short burst

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