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

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