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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"
  1. GRB 081221: Swift detection of a burst
  2. GRB 081217: Fermi GBM detection
  3. Modification of Swift/UVOT response to bright GRBs
  4. GRB081215A: Fermi-LAT observations
  5. GRB 081211B: Further Swift-XRT analysis
  6. GRB 081215B: Fermi GBM detection
  7. GRB 081216: Suzaku WAM observation of the prompt emission
  8. GRB 081216 : Fermi GBM observation
  9. GRB 081215A: Fermi GBM detection (correction to event fluence)
  10. GRB 081215A: Fermi GBM detection
  11. IPN localization of short hard GRB 081216
  12. GRB 081211B - possibly a short burst with extended emission
  13. GRB 081118: Zadko observations
  14. Fermi Trig Num 251059717 = SGR 0044+42: MASTER prompt optical observations
  15. GRB 081215A: Gamma Repeater?
  16. GRB 0811215A: MASTER prompt optical observations
  17. GRB 081215A: Andromeda inside Fermi error box: MASTER observations
  18. GRB 0811215A: Andromeda inside Fermi error box: MASTER observations
  19. Possible GRB 081211B: Swift/UVOT Upper Limits
  20. GRB 081213: Fermi GBM detection
  21. GRB 081210: optical observations
  22. Possible GRB 081211B - Swift-XRT analysis
  23. GRB 081207: Fermi GBM detection
  24. GRB 081209: Fermi GBM detection
  25. Fermi Gamma-ray Burst Monitor trigger 250533995 is not a GRB
  26. GRB 081007: Detection of a Supernova
  27. GRB 081211B(?): Possible burst detection from Swift-BAT slew data
  28. GRB 081210: Xinglong TNT R band Upper Limits
  29. GRB 081210, SMARTS optical/IR observations
  30. GRB 081211: Swift-BAT refined analysis
  31. GRB 081211: Swift XRT refined analysis
  32. GRB 081211: Swift/UVOT detection of an optical afterglow
  33. GRB 081211: Enhanced Swift-XRT position
  34. GRB 081210: Swift/UVOT refined analysis
  35. GRB 081211: Swift detection of a burst
  36. GRB 081210: Swift-XRT refined analysis
  37. GRB081203B: optical observations
  38. GRB 081210: Enhanced Swift-XRT position
  39. GRB 081210: Swift-BAT refined analysis
  40. GRB 081210: Swift detection of a burst with optical afterglow
  41. Konus-Wind observation of GRB 081209
  42. IPN triangulation of short hard GRB 081209
  43. GRB 081203A: optical observations
  44. GRB 081206C: Fermi GBM detection
  45. Radio observation of GRB 081121 with ATCA
  46. Radio observation of GRB 081118 with ATCA
  47. GRB 081206B: Fermi GBM detection
  48. GRB 081206: Fermi GBM detection
  49. GRB 081128: afterglow observations
  50. GRB 081203B: Suzaku WAM observation of the prompt emission
  51. GRB 081203B: Additional Gemini imaging
  52. Radio observation of GRB 081109 with ATCA
  53. Radio observation of GRB 081104 with ATCA
  54. Radio observation of GRB 081029 with ATCA
  55. Radio observation of GRB 081008 with ATCA
  56. GRB081203A: Ashra-1 observation of early optical and VHE-neutrino emission
  57. GRB 081203B: Gemini observations
  58. GRB 081128: optical observation in CrAO
  59. GRB081203A: Optical observations at Ishigaki
  60. GRB 081128: Optical afterglow observations
  61. GRB 081204: GROND Observations
  62. GRB081203B: optical observations
  63. Radio detection of GRB 081203B with the VLA
  64. GRB 081204: Magellan observations
  65. GRB081203A: Radio upper limit at 15 GHz
  66. GRB 081204B: Fermi GBM detection
  67. GRB 081204: Swift/UVOT Upper Limits
  68. GRB 081204: Swift XRT afterglow confirmation
  69. GRB081203A: MITSuME optical observation
  70. GRB 081203A: Optical observations of Xinglong TNT telescope
  71. GRB 081203A: Skynet/GORT Detections
  72. GRB 081204: Swift XRT afterglow candidate
  73. GRB081203A: optical observation
  74. GRB 081204 : a long GRB localized by INTEGRAL
  75. VLA Radio upper limit on GRB 081203A
  76. Swift-XRT observations of GRB 081203B
  77. Konus-Wind observation of GRB 081203A
  78. Konus-Wind observation of GRB 081203B
  79. GRB081203A: Swift-XRT refined analysis
  80. GRB 081203B: optical observations
  81. GRB 081203B: SDSS upper limits at the position of the optical afterglow
  82. Swift/UVOT detection of GRB081203B
  83. GRB 081203B: Swift-XRT candidate afterglow.
  84. GRB 081203A: optical observations
  85. Swift UVOT observations of GRB 081203A
  86. GRB 081203B: Naming correction for burst detected in Swift-BAT slew data
  87. GRB081203A: Swift/UVOT grism redshift
  88. GRB 081203A: Burst detection from Swift-BAT slew data
  89. GRB 081203A: Swift-BAT refined analysis
  90. GRB 081203: Enhanced Swift-XRT position
  91. GRB 081130B: MASTER prompt optical observations
  92. GRB081203: optical observation
  93. GRB 081203: Swift detection of a burst with a bright optical counterpart
  94. GRB 081128: optical observation
  95. GRB 081130B: Fermi GBM detection
  96. GRB 081130: Fermi GBM detection
  97. Swift Trigger 335971: Swift/UVOT Observations
  98. GRB 081126: afterglow photometry
  99. GRB 081126: Fermi GBM detection
  100. Fermi Gamma-ray Burst Monitor trigger 249166723 reclassification

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