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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"

11649 results found.

  1. Fermi trigger No 766173972: Global MASTER-Net observations report
  2. GRB 250411A: DDOTI Optical Observations
  3. Fermi GRB 250411A: Global MASTER-Net observations report
  4. GRB 250411A: Fermi GBM Final Real-time Localization
  5. GRB 250407A: Mondy and AbAO Optical Observations
  6. GRB 250320B: cubesat Avion detection
  7. IPN triangulation of GRB 250407A
  8. GRB 250407A: LCO detection of a fading optical counterpart
  9. Fermi-LAT gamma-ray observations of IceCube-250406A
  10. Konus-Wind detection of GRB 250407A
  11. GRB 250407A: SVOM/GRM observation of a bright long burst
  12. GRB 250407A: EP-WXT afterglow detection
  13. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  14. GRB 250407A: KAIT Optical Afterglow Candidate
  15. GRB 250407A: Fermi GBM Detection
  16. GRB 250407A: Swift-XRT afterglow detection
  17. Fermi GRB 250407A: Global MASTER-Net observations report
  18. GRB 250407A: Swift ToO observations
  19. GRB 250407A: SRG/ART-XC afterglow detection
  20. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  21. GRB 250407A: Fermi GBM Final Real-time Localization
  22. GRB 250406A: AstroSat CZTI detection
  23. Fermi trigger No 765663719: Global MASTER-Net observations report
  24. Fermi GRB 250406A: Global MASTER-Net observations report
  25. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  26. GRB 250406A: Fermi GBM Final Real-time Localization
  27. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  28. Fermi trigger No 765619921: Global MASTER-Net observations report
  29. Fermi Gamma-ray Burst Monitor trigger 765619921/250406342 is not a GRB
  30. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  31. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  32. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  33. Konus-Wind detection of GRB 250404A / EP250404a
  34. GRB 250404A / EP250404a: Mondy optical observations
  35. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  36. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  37. GRB 250404A / EP250404a: NOT optical observations
  38. GRB 250403A: AstroSat CZTI detection
  39. EP250404a: REM optical/NIR observations
  40. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  41. EP250404a: LCO optical counterpart detection
  42. Fermi GRB 250404A: Global MASTER-Net observations report
  43. GRB 250403A: Montarrenti Observatory optical detection
  44. GRB 250404A: Fermi GBM Detection
  45. GRB 250403A: KAIT optical observations
  46. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  47. EP250404a: Xinglong-2.16m spectroscopic redshift
  48. GRB 250403A: Fermi GBM observations
  49. EP250404a: Mephisto multi-band optical detection
  50. EP250404a: Nanshan/HMT optical counterpart detection
  51. EP250404a: Einstein Probe detection of an X-ray transient
  52. GRB 250404A: Fermi GBM Final Real-time Localization
  53. GRB 250403A: Swift/UVOT Detection
  54. GRB 250403A: SVOM/VT optical observation
  55. GRB 250403A: REM NIR afterglow detection
  56. GRB 250403A: LCO optical counterpart detection
  57. GRB 250403A: JinShan optical observations
  58. GRB 250403A: Optical counterpart detection by LCO.
  59. GRB 250403A: Swift-XRT observations
  60. Fermi GRB 250403A: Global MASTER-Net observations report
  61. GRB 250403A: GOTO optical counterpart follow-up observations
  62. GRB 250403A: GMG Optical Observation
  63. GRB 250403A: 1.6m Mephisto multi-band optical detection
  64. GRB 250402A: Fermi GBM Observation
  65. GRB 250403A: SVOM/C-GFT optical observations
  66. GRB 250403A: GOTO detection of the optical afterglow
  67. GRB 250403A : SVOM detection of a burst
  68. GRB 250403A: Fermi GBM Final Real-time Localization
  69. GRB 250331E: SVOM/GRM observation
  70. GRB250331D: AbAO optical observations
  71. GRB 250331D: Fermi GBM observation
  72. GRB 250330B: SVOM/GRM observation of a short burst
  73. Fermi GRB 250331E: Global MASTER-Net observations report
  74. Fermi GRB 250331D: Global MASTER-Net observations report
  75. GRB 250330B: EIRSAT-1 GMOD Detection
  76. GRB 250331E: Fermi GBM Final Real-time Localization
  77. Fermi trigger No 765078057: Global MASTER-Net observations report
  78. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  79. Fermi-LAT gamma-ray observations of IceCube-250330A
  80. GRB 250330A: Fermi GBM Observation
  81. GRB 250331D: Fermi GBM Final Real-time Localization
  82. Fermi GRB 250330B: Global MASTER-Net observations report
  83. GRB 250330B: Fermi GBM Final Real-time Localization
  84. Fermi GRB 250330A: Global MASTER-Net observations report
  85. GRB 250330A: BOOTES-7 early optical upper limit
  86. GRB 250330A: Fermi GBM Final Localization
  87. IceCube-250330A - IceCube observation of a high-energy neutrino candidate track-like event
  88. GRB 250330A: Swift detection of a burst
  89. GRB 250327B: CrAO and SAO RAS Optical Observations
  90. GRB 250327A: SVOM/VT upper limits on the XRT position
  91. GRB 250327A: J-band observations with WINTER
  92. GRB 250327A: SVOM/VT optical candidate
  93. GRB 250327A: Fermi GBM observation
  94. Fermi GRB 250327A: Global MASTER-Net observations report
  95. GRB 250327A: DDOTI Optical Observations
  96. GRB 250327A: COLIBRÍ optical upper limit
  97. GRB 250327A: Fermi GBM Final Real-time Localization
  98. Fermi trigger No 764700395: Global MASTER-Net observations report
  99. GRB 250225B: GECAM-A detection
  100. GRB 250320B: NuSTAR detection of the prompt emission from two broad bursts and preliminary analysis

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