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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 081118: Enhanced Swift-XRT position
  2. GRB 081118: Swift detection of a burst
  3. GRB 081109A: confirmation of possible detection host galaxy
  4. Further Swift-XRT observations of the probable GRB 081105.
  5. GRB 081113: Fermi GBM detection
  6. GRB 081102: RTT150 Optical observations
  7. GRB 081110: Fermi GBM detection
  8. GRB 081110: MASTER: first optical observations Fermi GRB
  9. GRB 081109: TAROT La Silla observatory optical observations
  10. GRB 081102: MASTER refind and final results
  11. GRB 081109: GROND redshift limit and host extinction
  12. GRB 081025: Swift-XRT further analysis
  13. GRB 081024B: Swift-XRT late-time observations
  14. Swift-BAT refined analysis of trigger 334129
  15. GRB 081109B: Swift/UVOT refined analysis
  16. GRB 081109: GROND Detection of the Optical/NIR Afterglow Candidate
  17. GRB 081109A: Possible Swift-UVOT detection
  18. GRB 081109A: Faulkes Telescope South observations
  19. GRB 081109A, Swift-BAT refined analysis
  20. GRB 081109A: Swift-XRT refined analysis
  21. GRB 081109: Fermi GBM detection
  22. GRB 081109: Swift/UVOT upper limits
  23. GRB 081109A optical upper limit
  24. Swift-BAT Trigger 334129: possible burst
  25. GRB 081109: REM NIR afterglow detection
  26. GRB 081109: Swift detection of a burst
  27. GRB 081028 - PAIRITEL NIR detection
  28. GRB 081024C: Fermi Gamma-ray Burst Monitor detection
  29. SGR 1806-20: Fermi GBM detection
  30. GRB 081102B: Fermi GBM detection
  31. GRB 081105B: Fermi GBM detection
  32. GRB 081107: Fermi GBM detection
  33. GRB 081104: GROND found no Optical/NIR Afterglow
  34. GRB 081105: GROND Upper Limits
  35. Radio observation of GRB 080523 with ATCA
  36. Radio observation of GRB 080520 with ATCA
  37. GRB 081105: Observations from OSN
  38. UVOT/Swift observations of GRB081105
  39. Swift-XRT observations of GRB 081105
  40. GRB 081101B: Fermi GBM detection
  41. Radio observation of GRB 080516 with ATCA
  42. GRB 081105 Swift/BAT and IPN Localization
  43. GRB 081025: Fermi GBM observation
  44. GRB 081104: GROND Detection of the Optical/NIR Afterglow Candidate?
  45. GRB 081104: refined XRT analysis
  46. GRB 081104: Enhanced Swift-XRT position
  47. GRB 081104: Swift-BAT refined analysis
  48. GRB081104: Swift/UVOT Upper Limits
  49. Fermi-GBM detection of a Solar Flare
  50. Fermi Detection of GRB 081102
  51. GRB 081104 : Faulkes Telescope South observations
  52. GRB 081104: Swift-XRT position
  53. GRB 081104: Swift detection of a burst
  54. Radio observation of GRB 080130 with ATCA
  55. GRB 081102: MASTER prompt optical limit
  56. GRB 081102: Swift-XRT refined analysis
  57. GRB 081102: Swift/UVOT refined analysis
  58. GRB 081102: Swift-BAT refined analysis
  59. GRB 081102: Enhanced Swift-XRT position
  60. Radio observation of GRB 080218b with ATCA
  61. Radio observation of GRB 080229a with ATCA
  62. GRB 081102: MASTER VWF promt observation
  63. GRB 081102: OPTIMA-Burst optical upper limit
  64. GRB 081102: Swift detection of a burst
  65. SGR 0501+4516: optical observations in August
  66. GRB 081101 (or SGR 0623-0006 ): Fermi GBM detection
  67. SGR 0623-0006 or GRB 081101: Swift-XRT refined analysis
  68. SGR 0623-0006 or GRB 081101: Swift-BAT/-XRT refined analysis
  69. Swift-BAT triggered on a probable GRB 081101 (trigger=333320)
  70. GRB 081024B: BTA deep optical observations
  71. GRB 081028: CrAO optical observations
  72. GRB 081024B: new Swift-XRT observations
  73. Radio observation of GRB 080229b with ATCA
  74. GRB 081029, SMARTS optical/IR afterglow observations
  75. GRB 081024B: VLA radio observation
  76. GRB 081029: UVOT Detection of the Optical Afterglow
  77. GRB 081029: PROMPT Detections
  78. GRB 081029: Redshift Confirmation from Gemini-South
  79. GRB 081029: Swift-BAT refined analysis
  80. GRB081029: Swift XRT refined analysis
  81. GRB 081025: Suzaku WAM observation of the prompt emission
  82. GRB 081024B: Suzaku WAM observation of the prompt emission
  83. GRB 081029: Enhanced Swift-XRT position
  84. GRB 081028: GROND Confirmation of the Optical/NIR Afterglow
  85. GRB 081029: REM observations
  86. Radio observation of GRB 080303 with ATCA
  87. Radio observation of GRB 080411 with ATCA
  88. GRB 081029: UVES/VLT Absorption Redshift
  89. GRB 081029: GROND Detection of the Optical/NIR Afterglow
  90. GRB 081029: ROTSE-III Detection of Optical Counterpart
  91. GRB 081029: Swift detection of a burst
  92. GRB 081028: Magellan redshift
  93. GRB 081028B: Fermi GBM detection
  94. GRB 081021: Fermi GBM detection
  95. GRB081028: UVOT detection of a brightening afterglow
  96. Swift UVOT observations of GRB081028
  97. GRB 081028: Swift-XRT refined analysis
  98. GRB 081028, Swift-BAT refined analysis
  99. GRB 081028: Enhanced Swift-XRT position
  100. GRB 081028: TAROT Calern observatory optical observations

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