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

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