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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 081222: Gemini-N confirmation of redshift z=2.77
  2. GRB 081222:Optical afterglow observation
  3. VLA radio upper limit on GRB 081222
  4. GRB 081222: Fermi GBM observation
  5. Fermi Gamma-ray Burst Monitor trigger 251687595 reclassification
  6. GRB 081222: Gemini-South absorption redshift
  7. GRB081222: Swift/UVOT further observations
  8. GRB 081221: Probable host galaxy in Keck imaging
  9. GRB 081204C: Fermi GBM detection
  10. GRB 081222, Swift-BAT refined analysis
  11. GRB 081221, Swift-BAT refined analysis
  12. GRB081222 optical limit by "Pi of the Sky"
  13. Konus-Wind observation of very bright GRB 081215A
  14. GRB 081222: Swift XRT refined analysis
  15. GRB081221: Fermi GBM observation
  16. Swift/UVOT observations of GRB 081221
  17. IPN triangulation of bright GRB 081215A
  18. GRB 081221: Swift-XRT Refined Analysis
  19. GRB 081221: pseudo-redshift (pz=0.7) from the spectral parameters of the prompt emission
  20. GRB 081222: Faulkes Telescope South observations
  21. GRB 081221: Gemini-N nIR imaging
  22. GRB081222, optical observation
  23. GRB081222: Swift/UVOT detection of an optical afterglow
  24. GRB081203A: BTA observation
  25. Konus-Wind observation of GRB 081221
  26. GRB 081222: GROND Detection of the Optical/NIR Afterglow
  27. GRB081222: REM candidate afterglow
  28. GRB 081222: Swift detection of a burst with a bright optical afterglow
  29. GRB 081221: Enhanced Swift-XRT position
  30. GRB 081221: further NOT observations
  31. GRB 081221: NOT observations
  32. GRB 081221: Swift detection of a burst
  33. GRB 081217: Fermi GBM detection
  34. Modification of Swift/UVOT response to bright GRBs
  35. GRB081215A: Fermi-LAT observations
  36. GRB 081211B: Further Swift-XRT analysis
  37. GRB 081215B: Fermi GBM detection
  38. GRB 081216: Suzaku WAM observation of the prompt emission
  39. GRB 081216 : Fermi GBM observation
  40. GRB 081215A: Fermi GBM detection (correction to event fluence)
  41. GRB 081215A: Fermi GBM detection
  42. IPN localization of short hard GRB 081216
  43. GRB 081211B - possibly a short burst with extended emission
  44. GRB 081118: Zadko observations
  45. Fermi Trig Num 251059717 = SGR 0044+42: MASTER prompt optical observations
  46. GRB 081215A: Gamma Repeater?
  47. GRB 0811215A: MASTER prompt optical observations
  48. GRB 081215A: Andromeda inside Fermi error box: MASTER observations
  49. GRB 0811215A: Andromeda inside Fermi error box: MASTER observations
  50. Possible GRB 081211B: Swift/UVOT Upper Limits
  51. GRB 081213: Fermi GBM detection
  52. GRB 081210: optical observations
  53. Possible GRB 081211B - Swift-XRT analysis
  54. GRB 081207: Fermi GBM detection
  55. GRB 081209: Fermi GBM detection
  56. Fermi Gamma-ray Burst Monitor trigger 250533995 is not a GRB
  57. GRB 081007: Detection of a Supernova
  58. GRB 081211B(?): Possible burst detection from Swift-BAT slew data
  59. GRB 081210: Xinglong TNT R band Upper Limits
  60. GRB 081210, SMARTS optical/IR observations
  61. GRB 081211: Swift-BAT refined analysis
  62. GRB 081211: Swift XRT refined analysis
  63. GRB 081211: Swift/UVOT detection of an optical afterglow
  64. GRB 081211: Enhanced Swift-XRT position
  65. GRB 081210: Swift/UVOT refined analysis
  66. GRB 081211: Swift detection of a burst
  67. GRB 081210: Swift-XRT refined analysis
  68. GRB081203B: optical observations
  69. GRB 081210: Enhanced Swift-XRT position
  70. GRB 081210: Swift-BAT refined analysis
  71. GRB 081210: Swift detection of a burst with optical afterglow
  72. Konus-Wind observation of GRB 081209
  73. IPN triangulation of short hard GRB 081209
  74. GRB 081203A: optical observations
  75. GRB 081206C: Fermi GBM detection
  76. Radio observation of GRB 081121 with ATCA
  77. Radio observation of GRB 081118 with ATCA
  78. GRB 081206B: Fermi GBM detection
  79. GRB 081206: Fermi GBM detection
  80. GRB 081128: afterglow observations
  81. GRB 081203B: Suzaku WAM observation of the prompt emission
  82. GRB 081203B: Additional Gemini imaging
  83. Radio observation of GRB 081109 with ATCA
  84. Radio observation of GRB 081104 with ATCA
  85. Radio observation of GRB 081029 with ATCA
  86. Radio observation of GRB 081008 with ATCA
  87. GRB081203A: Ashra-1 observation of early optical and VHE-neutrino emission
  88. GRB 081203B: Gemini observations
  89. GRB 081128: optical observation in CrAO
  90. GRB081203A: Optical observations at Ishigaki
  91. GRB 081128: Optical afterglow observations
  92. GRB 081204: GROND Observations
  93. GRB081203B: optical observations
  94. Radio detection of GRB 081203B with the VLA
  95. GRB 081204: Magellan observations
  96. GRB081203A: Radio upper limit at 15 GHz
  97. GRB 081204B: Fermi GBM detection
  98. GRB 081204: Swift/UVOT Upper Limits
  99. GRB 081204: Swift XRT afterglow confirmation
  100. GRB081203A: MITSuME optical observation

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