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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 081228: Swift-XRT Team refined analysis
  2. GRB 081228: detection by GROND
  3. GRB 081228: Enhanced Swift-XRT position
  4. GRB 081228: TAROT Calern observatory optical observations
  5. GRB 081228: Swift detection of a burst
  6. VLA radio observation of GRB 081221
  7. GRB 081226B: Swift XRT and UVOT upper limits
  8. GRB 081224: Suzaku WAM observation of the prompt emission
  9. GRB 081226: Swift-XRT refined analysis
  10. GRB 081226A: Swift UVOT Upper Limits
  11. GRB 081226: Second epoch of Gemini-South imaging
  12. GRB 081226A: Swift-BAT refined analysis
  13. GRB 081226B: a short-hard GRB detected by INTEGRAL
  14. GRB 081226: Gemini-South spectrum of possible afterglow
  15. GRB 081226: Gemini-South imaging
  16. GRB 081226: GROND afterglow candidate
  17. GRB 081226: ROTSE-III Optical Limits
  18. GRB 081226: Swift detection of a possible short-hard burst
  19. GRB 080810: optical observations
  20. GRB 081211B: optical observations
  21. GRB081224: LAT retraction
  22. GRB 081224: Swift-XRT observation
  23. GRB 081222: MITSuME optical observation
  24. GRB 081224: Fermi GBM Detection & LAT Localization
  25. GRB 080810: optical observations
  26. Konus-Wind observation of GRB 081222
  27. GRB 081223: Fermi GBM detection
  28. GRB 081221: GROND observations
  29. GRB 081222: Gemini-N confirmation of redshift z=2.77
  30. GRB 081222:Optical afterglow observation
  31. VLA radio upper limit on GRB 081222
  32. GRB 081222: Fermi GBM observation
  33. Fermi Gamma-ray Burst Monitor trigger 251687595 reclassification
  34. GRB 081222: Gemini-South absorption redshift
  35. GRB081222: Swift/UVOT further observations
  36. GRB 081221: Probable host galaxy in Keck imaging
  37. GRB 081204C: Fermi GBM detection
  38. GRB 081222, Swift-BAT refined analysis
  39. GRB 081221, Swift-BAT refined analysis
  40. GRB081222 optical limit by "Pi of the Sky"
  41. Konus-Wind observation of very bright GRB 081215A
  42. GRB 081222: Swift XRT refined analysis
  43. GRB081221: Fermi GBM observation
  44. Swift/UVOT observations of GRB 081221
  45. IPN triangulation of bright GRB 081215A
  46. GRB 081221: Swift-XRT Refined Analysis
  47. GRB 081221: pseudo-redshift (pz=0.7) from the spectral parameters of the prompt emission
  48. GRB 081222: Faulkes Telescope South observations
  49. GRB 081221: Gemini-N nIR imaging
  50. GRB081222, optical observation
  51. GRB081222: Swift/UVOT detection of an optical afterglow
  52. GRB081203A: BTA observation
  53. Konus-Wind observation of GRB 081221
  54. GRB 081222: GROND Detection of the Optical/NIR Afterglow
  55. GRB081222: REM candidate afterglow
  56. GRB 081222: Swift detection of a burst with a bright optical afterglow
  57. GRB 081221: Enhanced Swift-XRT position
  58. GRB 081221: further NOT observations
  59. GRB 081221: NOT observations
  60. GRB 081221: Swift detection of a burst
  61. GRB 081217: Fermi GBM detection
  62. Modification of Swift/UVOT response to bright GRBs
  63. GRB081215A: Fermi-LAT observations
  64. GRB 081211B: Further Swift-XRT analysis
  65. GRB 081215B: Fermi GBM detection
  66. GRB 081216: Suzaku WAM observation of the prompt emission
  67. GRB 081216 : Fermi GBM observation
  68. GRB 081215A: Fermi GBM detection (correction to event fluence)
  69. GRB 081215A: Fermi GBM detection
  70. IPN localization of short hard GRB 081216
  71. GRB 081211B - possibly a short burst with extended emission
  72. GRB 081118: Zadko observations
  73. Fermi Trig Num 251059717 = SGR 0044+42: MASTER prompt optical observations
  74. GRB 081215A: Gamma Repeater?
  75. GRB 0811215A: MASTER prompt optical observations
  76. GRB 081215A: Andromeda inside Fermi error box: MASTER observations
  77. GRB 0811215A: Andromeda inside Fermi error box: MASTER observations
  78. Possible GRB 081211B: Swift/UVOT Upper Limits
  79. GRB 081213: Fermi GBM detection
  80. GRB 081210: optical observations
  81. Possible GRB 081211B - Swift-XRT analysis
  82. GRB 081207: Fermi GBM detection
  83. GRB 081209: Fermi GBM detection
  84. Fermi Gamma-ray Burst Monitor trigger 250533995 is not a GRB
  85. GRB 081007: Detection of a Supernova
  86. GRB 081211B(?): Possible burst detection from Swift-BAT slew data
  87. GRB 081210: Xinglong TNT R band Upper Limits
  88. GRB 081210, SMARTS optical/IR observations
  89. GRB 081211: Swift-BAT refined analysis
  90. GRB 081211: Swift XRT refined analysis
  91. GRB 081211: Swift/UVOT detection of an optical afterglow
  92. GRB 081211: Enhanced Swift-XRT position
  93. GRB 081210: Swift/UVOT refined analysis
  94. GRB 081211: Swift detection of a burst
  95. GRB 081210: Swift-XRT refined analysis
  96. GRB081203B: optical observations
  97. GRB 081210: Enhanced Swift-XRT position
  98. GRB 081210: Swift-BAT refined analysis
  99. GRB 081210: Swift detection of a burst with optical afterglow
  100. Konus-Wind observation of GRB 081209

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