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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 081216 : Fermi GBM observation
  2. GRB 081215A: Fermi GBM detection (correction to event fluence)
  3. GRB 081215A: Fermi GBM detection
  4. IPN localization of short hard GRB 081216
  5. GRB 081211B - possibly a short burst with extended emission
  6. GRB 081118: Zadko observations
  7. Fermi Trig Num 251059717 = SGR 0044+42: MASTER prompt optical observations
  8. GRB 081215A: Gamma Repeater?
  9. GRB 0811215A: MASTER prompt optical observations
  10. GRB 081215A: Andromeda inside Fermi error box: MASTER observations
  11. GRB 0811215A: Andromeda inside Fermi error box: MASTER observations
  12. Possible GRB 081211B: Swift/UVOT Upper Limits
  13. GRB 081213: Fermi GBM detection
  14. GRB 081210: optical observations
  15. Possible GRB 081211B - Swift-XRT analysis
  16. GRB 081207: Fermi GBM detection
  17. GRB 081209: Fermi GBM detection
  18. Fermi Gamma-ray Burst Monitor trigger 250533995 is not a GRB
  19. GRB 081007: Detection of a Supernova
  20. GRB 081211B(?): Possible burst detection from Swift-BAT slew data
  21. GRB 081210: Xinglong TNT R band Upper Limits
  22. GRB 081210, SMARTS optical/IR observations
  23. GRB 081211: Swift-BAT refined analysis
  24. GRB 081211: Swift XRT refined analysis
  25. GRB 081211: Swift/UVOT detection of an optical afterglow
  26. GRB 081211: Enhanced Swift-XRT position
  27. GRB 081210: Swift/UVOT refined analysis
  28. GRB 081211: Swift detection of a burst
  29. GRB 081210: Swift-XRT refined analysis
  30. GRB081203B: optical observations
  31. GRB 081210: Enhanced Swift-XRT position
  32. GRB 081210: Swift-BAT refined analysis
  33. GRB 081210: Swift detection of a burst with optical afterglow
  34. Konus-Wind observation of GRB 081209
  35. IPN triangulation of short hard GRB 081209
  36. GRB 081203A: optical observations
  37. GRB 081206C: Fermi GBM detection
  38. Radio observation of GRB 081121 with ATCA
  39. Radio observation of GRB 081118 with ATCA
  40. GRB 081206B: Fermi GBM detection
  41. GRB 081206: Fermi GBM detection
  42. GRB 081128: afterglow observations
  43. GRB 081203B: Suzaku WAM observation of the prompt emission
  44. GRB 081203B: Additional Gemini imaging
  45. Radio observation of GRB 081109 with ATCA
  46. Radio observation of GRB 081104 with ATCA
  47. Radio observation of GRB 081029 with ATCA
  48. Radio observation of GRB 081008 with ATCA
  49. GRB081203A: Ashra-1 observation of early optical and VHE-neutrino emission
  50. GRB 081203B: Gemini observations
  51. GRB 081128: optical observation in CrAO
  52. GRB081203A: Optical observations at Ishigaki
  53. GRB 081128: Optical afterglow observations
  54. GRB 081204: GROND Observations
  55. GRB081203B: optical observations
  56. Radio detection of GRB 081203B with the VLA
  57. GRB 081204: Magellan observations
  58. GRB081203A: Radio upper limit at 15 GHz
  59. GRB 081204B: Fermi GBM detection
  60. GRB 081204: Swift/UVOT Upper Limits
  61. GRB 081204: Swift XRT afterglow confirmation
  62. GRB081203A: MITSuME optical observation
  63. GRB 081203A: Optical observations of Xinglong TNT telescope
  64. GRB 081203A: Skynet/GORT Detections
  65. GRB 081204: Swift XRT afterglow candidate
  66. GRB081203A: optical observation
  67. GRB 081204 : a long GRB localized by INTEGRAL
  68. VLA Radio upper limit on GRB 081203A
  69. Swift-XRT observations of GRB 081203B
  70. Konus-Wind observation of GRB 081203A
  71. Konus-Wind observation of GRB 081203B
  72. GRB081203A: Swift-XRT refined analysis
  73. GRB 081203B: optical observations
  74. GRB 081203B: SDSS upper limits at the position of the optical afterglow
  75. Swift/UVOT detection of GRB081203B
  76. GRB 081203B: Swift-XRT candidate afterglow.
  77. GRB 081203A: optical observations
  78. Swift UVOT observations of GRB 081203A
  79. GRB 081203B: Naming correction for burst detected in Swift-BAT slew data
  80. GRB081203A: Swift/UVOT grism redshift
  81. GRB 081203A: Burst detection from Swift-BAT slew data
  82. GRB 081203A: Swift-BAT refined analysis
  83. GRB 081203: Enhanced Swift-XRT position
  84. GRB 081130B: MASTER prompt optical observations
  85. GRB081203: optical observation
  86. GRB 081203: Swift detection of a burst with a bright optical counterpart
  87. GRB 081128: optical observation
  88. GRB 081130B: Fermi GBM detection
  89. GRB 081130: Fermi GBM detection
  90. Swift Trigger 335971: Swift/UVOT Observations
  91. GRB 081126: afterglow photometry
  92. GRB 081126: Fermi GBM detection
  93. Fermi Gamma-ray Burst Monitor trigger 249166723 reclassification
  94. VLA Radio upper limit on GRB 081126
  95. GRB 081129: Fermi GBM detection
  96. GRB 081130: MASTER VWF prompt optical observations Fermi GRB
  97. GRB 081128A: optical observations
  98. Swift Trigger 335971 is probably not a real source
  99. Trigger 335971: Swift possible detection of a burst
  100. GRB081128: Swift/UVOT Upper Limits

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