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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 090102: Swift-BAT refined analysis
  2. GRB 090102: Swift burst of interest
  3. GRB 090102: Swift XRT refined analysis
  4. GRB 090102: NOT redshift
  5. GRB 090102: Enhanced Swift-XRT position
  6. GRB 090102: TAROT Calern observatory optical light curve
  7. GRB 090102: REM observations of a bright afterglow
  8. GRB 090102: Swift detection of a burst with an optical counterpart
  9. GRB 090102: TAROT Calern observatory optical observations
  10. GRB 081230: GROND confirmation of the afterglow
  11. GRB 081230, Swift-BAT refined analysis
  12. GRB081230: Swift-XRT refined analysis
  13. GRB 081230 Swift/UVOT Observations
  14. GRB 081230: Enhanced Swift-XRT position
  15. GRB 081230: Swift/UVOT Detection of an Optical Afterglow
  16. GRB 081230: ROTSE-III Detection of Optical Counterpart
  17. GRB 081230: Swift detection of a burst
  18. GRB 081228: GROND confirmation of the optical/NIR afterglow
  19. GRB 081226B: Fermi GBM observation
  20. GRB 081226C: Fermi GBM detection
  21. GRB 081228, Swift-BAT refined analysis
  22. VLA radio detection of GRB 081221
  23. GRB 081228: Swift/UVOT Upper Limits
  24. GRB 081228: Swift-XRT Team refined analysis
  25. GRB 081228: detection by GROND
  26. GRB 081228: Enhanced Swift-XRT position
  27. GRB 081228: TAROT Calern observatory optical observations
  28. GRB 081228: Swift detection of a burst
  29. VLA radio observation of GRB 081221
  30. GRB 081226B: Swift XRT and UVOT upper limits
  31. GRB 081224: Suzaku WAM observation of the prompt emission
  32. GRB 081226: Swift-XRT refined analysis
  33. GRB 081226A: Swift UVOT Upper Limits
  34. GRB 081226: Second epoch of Gemini-South imaging
  35. GRB 081226A: Swift-BAT refined analysis
  36. GRB 081226B: a short-hard GRB detected by INTEGRAL
  37. GRB 081226: Gemini-South spectrum of possible afterglow
  38. GRB 081226: Gemini-South imaging
  39. GRB 081226: GROND afterglow candidate
  40. GRB 081226: ROTSE-III Optical Limits
  41. GRB 081226: Swift detection of a possible short-hard burst
  42. GRB 080810: optical observations
  43. GRB 081211B: optical observations
  44. GRB081224: LAT retraction
  45. GRB 081224: Swift-XRT observation
  46. GRB 081222: MITSuME optical observation
  47. GRB 081224: Fermi GBM Detection & LAT Localization
  48. GRB 080810: optical observations
  49. Konus-Wind observation of GRB 081222
  50. GRB 081223: Fermi GBM detection
  51. GRB 081221: GROND observations
  52. GRB 081222: Gemini-N confirmation of redshift z=2.77
  53. GRB 081222:Optical afterglow observation
  54. VLA radio upper limit on GRB 081222
  55. GRB 081222: Fermi GBM observation
  56. Fermi Gamma-ray Burst Monitor trigger 251687595 reclassification
  57. GRB 081222: Gemini-South absorption redshift
  58. GRB081222: Swift/UVOT further observations
  59. GRB 081221: Probable host galaxy in Keck imaging
  60. GRB 081204C: Fermi GBM detection
  61. GRB 081222, Swift-BAT refined analysis
  62. GRB 081221, Swift-BAT refined analysis
  63. GRB081222 optical limit by "Pi of the Sky"
  64. Konus-Wind observation of very bright GRB 081215A
  65. GRB 081222: Swift XRT refined analysis
  66. GRB081221: Fermi GBM observation
  67. Swift/UVOT observations of GRB 081221
  68. IPN triangulation of bright GRB 081215A
  69. GRB 081221: Swift-XRT Refined Analysis
  70. GRB 081221: pseudo-redshift (pz=0.7) from the spectral parameters of the prompt emission
  71. GRB 081222: Faulkes Telescope South observations
  72. GRB 081221: Gemini-N nIR imaging
  73. GRB081222, optical observation
  74. GRB081222: Swift/UVOT detection of an optical afterglow
  75. GRB081203A: BTA observation
  76. Konus-Wind observation of GRB 081221
  77. GRB 081222: GROND Detection of the Optical/NIR Afterglow
  78. GRB081222: REM candidate afterglow
  79. GRB 081222: Swift detection of a burst with a bright optical afterglow
  80. GRB 081221: Enhanced Swift-XRT position
  81. GRB 081221: further NOT observations
  82. GRB 081221: NOT observations
  83. GRB 081221: Swift detection of a burst
  84. GRB 081217: Fermi GBM detection
  85. Modification of Swift/UVOT response to bright GRBs
  86. GRB081215A: Fermi-LAT observations
  87. GRB 081211B: Further Swift-XRT analysis
  88. GRB 081215B: Fermi GBM detection
  89. GRB 081216: Suzaku WAM observation of the prompt emission
  90. GRB 081216 : Fermi GBM observation
  91. GRB 081215A: Fermi GBM detection (correction to event fluence)
  92. GRB 081215A: Fermi GBM detection
  93. IPN localization of short hard GRB 081216
  94. GRB 081211B - possibly a short burst with extended emission
  95. GRB 081118: Zadko observations
  96. Fermi Trig Num 251059717 = SGR 0044+42: MASTER prompt optical observations
  97. GRB 081215A: Gamma Repeater?
  98. GRB 0811215A: MASTER prompt optical observations
  99. GRB 081215A: Andromeda inside Fermi error box: MASTER observations
  100. GRB 0811215A: Andromeda inside Fermi error box: MASTER observations

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