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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 081105B: Fermi GBM detection
  2. GRB 081107: Fermi GBM detection
  3. GRB 081104: GROND found no Optical/NIR Afterglow
  4. GRB 081105: GROND Upper Limits
  5. Radio observation of GRB 080523 with ATCA
  6. Radio observation of GRB 080520 with ATCA
  7. GRB 081105: Observations from OSN
  8. UVOT/Swift observations of GRB081105
  9. Swift-XRT observations of GRB 081105
  10. GRB 081101B: Fermi GBM detection
  11. Radio observation of GRB 080516 with ATCA
  12. GRB 081105 Swift/BAT and IPN Localization
  13. GRB 081025: Fermi GBM observation
  14. GRB 081104: GROND Detection of the Optical/NIR Afterglow Candidate?
  15. GRB 081104: refined XRT analysis
  16. GRB 081104: Enhanced Swift-XRT position
  17. GRB 081104: Swift-BAT refined analysis
  18. GRB081104: Swift/UVOT Upper Limits
  19. Fermi-GBM detection of a Solar Flare
  20. Fermi Detection of GRB 081102
  21. GRB 081104 : Faulkes Telescope South observations
  22. GRB 081104: Swift-XRT position
  23. GRB 081104: Swift detection of a burst
  24. Radio observation of GRB 080130 with ATCA
  25. GRB 081102: MASTER prompt optical limit
  26. GRB 081102: Swift-XRT refined analysis
  27. GRB 081102: Swift/UVOT refined analysis
  28. GRB 081102: Swift-BAT refined analysis
  29. GRB 081102: Enhanced Swift-XRT position
  30. Radio observation of GRB 080218b with ATCA
  31. Radio observation of GRB 080229a with ATCA
  32. GRB 081102: MASTER VWF promt observation
  33. GRB 081102: OPTIMA-Burst optical upper limit
  34. GRB 081102: Swift detection of a burst
  35. SGR 0501+4516: optical observations in August
  36. GRB 081101 (or SGR 0623-0006 ): Fermi GBM detection
  37. SGR 0623-0006 or GRB 081101: Swift-XRT refined analysis
  38. SGR 0623-0006 or GRB 081101: Swift-BAT/-XRT refined analysis
  39. Swift-BAT triggered on a probable GRB 081101 (trigger=333320)
  40. GRB 081024B: BTA deep optical observations
  41. GRB 081028: CrAO optical observations
  42. GRB 081024B: new Swift-XRT observations
  43. Radio observation of GRB 080229b with ATCA
  44. GRB 081029, SMARTS optical/IR afterglow observations
  45. GRB 081024B: VLA radio observation
  46. GRB 081029: UVOT Detection of the Optical Afterglow
  47. GRB 081029: PROMPT Detections
  48. GRB 081029: Redshift Confirmation from Gemini-South
  49. GRB 081029: Swift-BAT refined analysis
  50. GRB081029: Swift XRT refined analysis
  51. GRB 081025: Suzaku WAM observation of the prompt emission
  52. GRB 081024B: Suzaku WAM observation of the prompt emission
  53. GRB 081029: Enhanced Swift-XRT position
  54. GRB 081028: GROND Confirmation of the Optical/NIR Afterglow
  55. GRB 081029: REM observations
  56. Radio observation of GRB 080303 with ATCA
  57. Radio observation of GRB 080411 with ATCA
  58. GRB 081029: UVES/VLT Absorption Redshift
  59. GRB 081029: GROND Detection of the Optical/NIR Afterglow
  60. GRB 081029: ROTSE-III Detection of Optical Counterpart
  61. GRB 081029: Swift detection of a burst
  62. GRB 081028: Magellan redshift
  63. GRB 081028B: Fermi GBM detection
  64. GRB 081021: Fermi GBM detection
  65. GRB081028: UVOT detection of a brightening afterglow
  66. Swift UVOT observations of GRB081028
  67. GRB 081028: Swift-XRT refined analysis
  68. GRB 081028, Swift-BAT refined analysis
  69. GRB 081028: Enhanced Swift-XRT position
  70. GRB 081028: TAROT Calern observatory optical observations
  71. GRB 081028: optical observations at the NOT
  72. GRB 081028: GROND Detection of the Optical/NIR Afterglow Candidate
  73. Fermi LAT/GBM short-hard GRB 081024B: Possible TLS Afterglow (Corrected)
  74. Fermi LAT/GBM short-hard GRB 081024B: Possible TLS Afterglow
  75. GRB 081028: Swift detection of a burst
  76. GRB 081025: TLS upper limits
  77. GRB 081024: No radio detection with the VLA
  78. GRB081025: RTT150 optical observations
  79. GRB081024B: P200 Observations
  80. GRB 081024B: Swift-XRT further observations
  81. GRB 081025 BAT refined analysis
  82. Swift UVOT observations of GRB081025
  83. Swift UVOT observations of GRB081024B
  84. Konus-Wind observation of GRB 081025
  85. GRB 081025: Swift-XRT position
  86. GRB 081024B: Swift-XRT observations
  87. GRB 081025: Burst detection from Swift-BAT slew data
  88. GRB 081024B: Fermi Gamma-ray Burst Monitor detection
  89. Fermi-LAT observation of GRB 081024B
  90. Swift UVOT observations of GRB 081024
  91. GRB 081024: Swift-XRT refined analysis
  92. GRB 081024, Swift-BAT refined analysis
  93. GRB 081024: Enhanced Swift-XRT position
  94. GRB 081024: Faulkes Telescope North optical observations
  95. GRB 081024: KAIT Optical Limits
  96. GRB 081024: Early Super-LOTIS Observations
  97. GRB 081024A: ROTSE-III Optical Limits
  98. GRB 081024: Swift detection of a burst
  99. GRB 081022, Swift-BAT refined analysis
  100. GRB 081016A: Swift-XRT refined analysis

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