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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. GRB081230: Swift-XRT refined analysis
  2. GRB 081230 Swift/UVOT Observations
  3. GRB 081230: Enhanced Swift-XRT position
  4. GRB 081230: Swift/UVOT Detection of an Optical Afterglow
  5. GRB 081230: ROTSE-III Detection of Optical Counterpart
  6. GRB 081230: Swift detection of a burst
  7. GRB 081228: GROND confirmation of the optical/NIR afterglow
  8. GRB 081226B: Fermi GBM observation
  9. GRB 081226C: Fermi GBM detection
  10. GRB 081228, Swift-BAT refined analysis
  11. VLA radio detection of GRB 081221
  12. GRB 081228: Swift/UVOT Upper Limits
  13. GRB 081228: Swift-XRT Team refined analysis
  14. GRB 081228: detection by GROND
  15. GRB 081228: Enhanced Swift-XRT position
  16. GRB 081228: TAROT Calern observatory optical observations
  17. GRB 081228: Swift detection of a burst
  18. VLA radio observation of GRB 081221
  19. GRB 081226B: Swift XRT and UVOT upper limits
  20. GRB 081224: Suzaku WAM observation of the prompt emission
  21. GRB 081226: Swift-XRT refined analysis
  22. GRB 081226A: Swift UVOT Upper Limits
  23. GRB 081226: Second epoch of Gemini-South imaging
  24. GRB 081226A: Swift-BAT refined analysis
  25. GRB 081226B: a short-hard GRB detected by INTEGRAL
  26. GRB 081226: Gemini-South spectrum of possible afterglow
  27. GRB 081226: Gemini-South imaging
  28. GRB 081226: GROND afterglow candidate
  29. GRB 081226: ROTSE-III Optical Limits
  30. GRB 081226: Swift detection of a possible short-hard burst
  31. GRB 080810: optical observations
  32. GRB 081211B: optical observations
  33. GRB081224: LAT retraction
  34. GRB 081224: Swift-XRT observation
  35. GRB 081222: MITSuME optical observation
  36. GRB 081224: Fermi GBM Detection & LAT Localization
  37. GRB 080810: optical observations
  38. Konus-Wind observation of GRB 081222
  39. GRB 081223: Fermi GBM detection
  40. GRB 081221: GROND observations
  41. GRB 081222: Gemini-N confirmation of redshift z=2.77
  42. GRB 081222:Optical afterglow observation
  43. VLA radio upper limit on GRB 081222
  44. GRB 081222: Fermi GBM observation
  45. Fermi Gamma-ray Burst Monitor trigger 251687595 reclassification
  46. GRB 081222: Gemini-South absorption redshift
  47. GRB081222: Swift/UVOT further observations
  48. GRB 081221: Probable host galaxy in Keck imaging
  49. GRB 081204C: Fermi GBM detection
  50. GRB 081222, Swift-BAT refined analysis
  51. GRB 081221, Swift-BAT refined analysis
  52. GRB081222 optical limit by "Pi of the Sky"
  53. Konus-Wind observation of very bright GRB 081215A
  54. GRB 081222: Swift XRT refined analysis
  55. GRB081221: Fermi GBM observation
  56. Swift/UVOT observations of GRB 081221
  57. IPN triangulation of bright GRB 081215A
  58. GRB 081221: Swift-XRT Refined Analysis
  59. GRB 081221: pseudo-redshift (pz=0.7) from the spectral parameters of the prompt emission
  60. GRB 081222: Faulkes Telescope South observations
  61. GRB 081221: Gemini-N nIR imaging
  62. GRB081222, optical observation
  63. GRB081222: Swift/UVOT detection of an optical afterglow
  64. GRB081203A: BTA observation
  65. Konus-Wind observation of GRB 081221
  66. GRB 081222: GROND Detection of the Optical/NIR Afterglow
  67. GRB081222: REM candidate afterglow
  68. GRB 081222: Swift detection of a burst with a bright optical afterglow
  69. GRB 081221: Enhanced Swift-XRT position
  70. GRB 081221: further NOT observations
  71. GRB 081221: NOT observations
  72. GRB 081221: Swift detection of a burst
  73. GRB 081217: Fermi GBM detection
  74. Modification of Swift/UVOT response to bright GRBs
  75. GRB081215A: Fermi-LAT observations
  76. GRB 081211B: Further Swift-XRT analysis
  77. GRB 081215B: Fermi GBM detection
  78. GRB 081216: Suzaku WAM observation of the prompt emission
  79. GRB 081216 : Fermi GBM observation
  80. GRB 081215A: Fermi GBM detection (correction to event fluence)
  81. GRB 081215A: Fermi GBM detection
  82. IPN localization of short hard GRB 081216
  83. GRB 081211B - possibly a short burst with extended emission
  84. GRB 081118: Zadko observations
  85. Fermi Trig Num 251059717 = SGR 0044+42: MASTER prompt optical observations
  86. GRB 081215A: Gamma Repeater?
  87. GRB 0811215A: MASTER prompt optical observations
  88. GRB 081215A: Andromeda inside Fermi error box: MASTER observations
  89. GRB 0811215A: Andromeda inside Fermi error box: MASTER observations
  90. Possible GRB 081211B: Swift/UVOT Upper Limits
  91. GRB 081213: Fermi GBM detection
  92. GRB 081210: optical observations
  93. Possible GRB 081211B - Swift-XRT analysis
  94. GRB 081207: Fermi GBM detection
  95. GRB 081209: Fermi GBM detection
  96. Fermi Gamma-ray Burst Monitor trigger 250533995 is not a GRB
  97. GRB 081007: Detection of a Supernova
  98. GRB 081211B(?): Possible burst detection from Swift-BAT slew data
  99. GRB 081210: Xinglong TNT R band Upper Limits
  100. GRB 081210, SMARTS optical/IR observations

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