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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. Swift-XRT observations of GRB 081105
  2. GRB 081101B: Fermi GBM detection
  3. Radio observation of GRB 080516 with ATCA
  4. GRB 081105 Swift/BAT and IPN Localization
  5. GRB 081025: Fermi GBM observation
  6. GRB 081104: GROND Detection of the Optical/NIR Afterglow Candidate?
  7. GRB 081104: refined XRT analysis
  8. GRB 081104: Enhanced Swift-XRT position
  9. GRB 081104: Swift-BAT refined analysis
  10. GRB081104: Swift/UVOT Upper Limits
  11. Fermi-GBM detection of a Solar Flare
  12. Fermi Detection of GRB 081102
  13. GRB 081104 : Faulkes Telescope South observations
  14. GRB 081104: Swift-XRT position
  15. GRB 081104: Swift detection of a burst
  16. Radio observation of GRB 080130 with ATCA
  17. GRB 081102: MASTER prompt optical limit
  18. GRB 081102: Swift-XRT refined analysis
  19. GRB 081102: Swift/UVOT refined analysis
  20. GRB 081102: Swift-BAT refined analysis
  21. GRB 081102: Enhanced Swift-XRT position
  22. Radio observation of GRB 080218b with ATCA
  23. Radio observation of GRB 080229a with ATCA
  24. GRB 081102: MASTER VWF promt observation
  25. GRB 081102: OPTIMA-Burst optical upper limit
  26. GRB 081102: Swift detection of a burst
  27. SGR 0501+4516: optical observations in August
  28. GRB 081101 (or SGR 0623-0006 ): Fermi GBM detection
  29. SGR 0623-0006 or GRB 081101: Swift-XRT refined analysis
  30. SGR 0623-0006 or GRB 081101: Swift-BAT/-XRT refined analysis
  31. Swift-BAT triggered on a probable GRB 081101 (trigger=333320)
  32. GRB 081024B: BTA deep optical observations
  33. GRB 081028: CrAO optical observations
  34. GRB 081024B: new Swift-XRT observations
  35. Radio observation of GRB 080229b with ATCA
  36. GRB 081029, SMARTS optical/IR afterglow observations
  37. GRB 081024B: VLA radio observation
  38. GRB 081029: UVOT Detection of the Optical Afterglow
  39. GRB 081029: PROMPT Detections
  40. GRB 081029: Redshift Confirmation from Gemini-South
  41. GRB 081029: Swift-BAT refined analysis
  42. GRB081029: Swift XRT refined analysis
  43. GRB 081025: Suzaku WAM observation of the prompt emission
  44. GRB 081024B: Suzaku WAM observation of the prompt emission
  45. GRB 081029: Enhanced Swift-XRT position
  46. GRB 081028: GROND Confirmation of the Optical/NIR Afterglow
  47. GRB 081029: REM observations
  48. Radio observation of GRB 080303 with ATCA
  49. Radio observation of GRB 080411 with ATCA
  50. GRB 081029: UVES/VLT Absorption Redshift
  51. GRB 081029: GROND Detection of the Optical/NIR Afterglow
  52. GRB 081029: ROTSE-III Detection of Optical Counterpart
  53. GRB 081029: Swift detection of a burst
  54. GRB 081028: Magellan redshift
  55. GRB 081028B: Fermi GBM detection
  56. GRB 081021: Fermi GBM detection
  57. GRB081028: UVOT detection of a brightening afterglow
  58. Swift UVOT observations of GRB081028
  59. GRB 081028: Swift-XRT refined analysis
  60. GRB 081028, Swift-BAT refined analysis
  61. GRB 081028: Enhanced Swift-XRT position
  62. GRB 081028: TAROT Calern observatory optical observations
  63. GRB 081028: optical observations at the NOT
  64. GRB 081028: GROND Detection of the Optical/NIR Afterglow Candidate
  65. Fermi LAT/GBM short-hard GRB 081024B: Possible TLS Afterglow (Corrected)
  66. Fermi LAT/GBM short-hard GRB 081024B: Possible TLS Afterglow
  67. GRB 081028: Swift detection of a burst
  68. GRB 081025: TLS upper limits
  69. GRB 081024: No radio detection with the VLA
  70. GRB081025: RTT150 optical observations
  71. GRB081024B: P200 Observations
  72. GRB 081024B: Swift-XRT further observations
  73. GRB 081025 BAT refined analysis
  74. Swift UVOT observations of GRB081025
  75. Swift UVOT observations of GRB081024B
  76. Konus-Wind observation of GRB 081025
  77. GRB 081025: Swift-XRT position
  78. GRB 081024B: Swift-XRT observations
  79. GRB 081025: Burst detection from Swift-BAT slew data
  80. GRB 081024B: Fermi Gamma-ray Burst Monitor detection
  81. Fermi-LAT observation of GRB 081024B
  82. Swift UVOT observations of GRB 081024
  83. GRB 081024: Swift-XRT refined analysis
  84. GRB 081024, Swift-BAT refined analysis
  85. GRB 081024: Enhanced Swift-XRT position
  86. GRB 081024: Faulkes Telescope North optical observations
  87. GRB 081024: KAIT Optical Limits
  88. GRB 081024: Early Super-LOTIS Observations
  89. GRB 081024A: ROTSE-III Optical Limits
  90. GRB 081024: Swift detection of a burst
  91. GRB 081022, Swift-BAT refined analysis
  92. GRB 081016A: Swift-XRT refined analysis
  93. GRB 081022: Swift detection of a burst
  94. GRB 081012: Swift-XRT Refined Analysis
  95. Swift trigger 332287 is not a GRB
  96. Swift detection of a possible burst (trigger 332287)
  97. GRB 081012 - Enhanced Swift XRT position
  98. GRB 081017, Swift-BAT refined analysis
  99. GRB 081017: REM early observations
  100. GRB 081017: Swift detection of a burst

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