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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 081109: Swift/UVOT upper limits
  2. GRB 081109A optical upper limit
  3. Swift-BAT Trigger 334129: possible burst
  4. GRB 081109: REM NIR afterglow detection
  5. GRB 081109: Swift detection of a burst
  6. GRB 081028 - PAIRITEL NIR detection
  7. GRB 081024C: Fermi Gamma-ray Burst Monitor detection
  8. SGR 1806-20: Fermi GBM detection
  9. GRB 081102B: Fermi GBM detection
  10. GRB 081105B: Fermi GBM detection
  11. GRB 081107: Fermi GBM detection
  12. GRB 081104: GROND found no Optical/NIR Afterglow
  13. GRB 081105: GROND Upper Limits
  14. Radio observation of GRB 080523 with ATCA
  15. Radio observation of GRB 080520 with ATCA
  16. GRB 081105: Observations from OSN
  17. UVOT/Swift observations of GRB081105
  18. Swift-XRT observations of GRB 081105
  19. GRB 081101B: Fermi GBM detection
  20. Radio observation of GRB 080516 with ATCA
  21. GRB 081105 Swift/BAT and IPN Localization
  22. GRB 081025: Fermi GBM observation
  23. GRB 081104: GROND Detection of the Optical/NIR Afterglow Candidate?
  24. GRB 081104: refined XRT analysis
  25. GRB 081104: Enhanced Swift-XRT position
  26. GRB 081104: Swift-BAT refined analysis
  27. GRB081104: Swift/UVOT Upper Limits
  28. Fermi-GBM detection of a Solar Flare
  29. Fermi Detection of GRB 081102
  30. GRB 081104 : Faulkes Telescope South observations
  31. GRB 081104: Swift-XRT position
  32. GRB 081104: Swift detection of a burst
  33. Radio observation of GRB 080130 with ATCA
  34. GRB 081102: MASTER prompt optical limit
  35. GRB 081102: Swift-XRT refined analysis
  36. GRB 081102: Swift/UVOT refined analysis
  37. GRB 081102: Swift-BAT refined analysis
  38. GRB 081102: Enhanced Swift-XRT position
  39. Radio observation of GRB 080218b with ATCA
  40. Radio observation of GRB 080229a with ATCA
  41. GRB 081102: MASTER VWF promt observation
  42. GRB 081102: OPTIMA-Burst optical upper limit
  43. GRB 081102: Swift detection of a burst
  44. SGR 0501+4516: optical observations in August
  45. GRB 081101 (or SGR 0623-0006 ): Fermi GBM detection
  46. SGR 0623-0006 or GRB 081101: Swift-XRT refined analysis
  47. SGR 0623-0006 or GRB 081101: Swift-BAT/-XRT refined analysis
  48. Swift-BAT triggered on a probable GRB 081101 (trigger=333320)
  49. GRB 081024B: BTA deep optical observations
  50. GRB 081028: CrAO optical observations
  51. GRB 081024B: new Swift-XRT observations
  52. Radio observation of GRB 080229b with ATCA
  53. GRB 081029, SMARTS optical/IR afterglow observations
  54. GRB 081024B: VLA radio observation
  55. GRB 081029: UVOT Detection of the Optical Afterglow
  56. GRB 081029: PROMPT Detections
  57. GRB 081029: Redshift Confirmation from Gemini-South
  58. GRB 081029: Swift-BAT refined analysis
  59. GRB081029: Swift XRT refined analysis
  60. GRB 081025: Suzaku WAM observation of the prompt emission
  61. GRB 081024B: Suzaku WAM observation of the prompt emission
  62. GRB 081029: Enhanced Swift-XRT position
  63. GRB 081028: GROND Confirmation of the Optical/NIR Afterglow
  64. GRB 081029: REM observations
  65. Radio observation of GRB 080303 with ATCA
  66. Radio observation of GRB 080411 with ATCA
  67. GRB 081029: UVES/VLT Absorption Redshift
  68. GRB 081029: GROND Detection of the Optical/NIR Afterglow
  69. GRB 081029: ROTSE-III Detection of Optical Counterpart
  70. GRB 081029: Swift detection of a burst
  71. GRB 081028: Magellan redshift
  72. GRB 081028B: Fermi GBM detection
  73. GRB 081021: Fermi GBM detection
  74. GRB081028: UVOT detection of a brightening afterglow
  75. Swift UVOT observations of GRB081028
  76. GRB 081028: Swift-XRT refined analysis
  77. GRB 081028, Swift-BAT refined analysis
  78. GRB 081028: Enhanced Swift-XRT position
  79. GRB 081028: TAROT Calern observatory optical observations
  80. GRB 081028: optical observations at the NOT
  81. GRB 081028: GROND Detection of the Optical/NIR Afterglow Candidate
  82. Fermi LAT/GBM short-hard GRB 081024B: Possible TLS Afterglow (Corrected)
  83. Fermi LAT/GBM short-hard GRB 081024B: Possible TLS Afterglow
  84. GRB 081028: Swift detection of a burst
  85. GRB 081025: TLS upper limits
  86. GRB 081024: No radio detection with the VLA
  87. GRB081025: RTT150 optical observations
  88. GRB081024B: P200 Observations
  89. GRB 081024B: Swift-XRT further observations
  90. GRB 081025 BAT refined analysis
  91. Swift UVOT observations of GRB081025
  92. Swift UVOT observations of GRB081024B
  93. Konus-Wind observation of GRB 081025
  94. GRB 081025: Swift-XRT position
  95. GRB 081024B: Swift-XRT observations
  96. GRB 081025: Burst detection from Swift-BAT slew data
  97. GRB 081024B: Fermi Gamma-ray Burst Monitor detection
  98. Fermi-LAT observation of GRB 081024B
  99. Swift UVOT observations of GRB 081024
  100. GRB 081024: Swift-XRT refined analysis

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