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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 061110B: VLT redshift
  2. GRB061110B: Optical observations at Crni Vrh
  3. GRB 061110B: NOT optical observations
  4. GRB 061110A: Swift XRT refined analysis
  5. GRB 061110B: Swift/XRT position
  6. GRB 061110B : Liverpool Telescope Optical Afterglow Detection
  7. GRB 061110B: Swift-UVOT Initial Observation
  8. GRB 061110A, Swift-BAT refined analysis
  9. GRB 061110B: TAROT Calern observatory optical observations
  10. GRB 061110B: Swift detection of a burst
  11. GRB 061110: NOT observations
  12. GRB 061110: Candidate confirmed
  13. GRB 061110 : Optical afterglow candidate
  14. GRB 061110: ROTSE-III Optical Limits
  15. GRB 061110: Swift detection of a burst
  16. GRB061110A - Optical Non-detection
  17. Swift-BAT Trigger 237821 is a Cosmic Ray Shower event
  18. GRB 061109: optical observation
  19. GRB 061109: TAROT Calern observatory optical observations
  20. GRB 061109: Swift detection of a possible burst
  21. GRB061028: MAGIC telescope GeV observation
  22. GRB 061027: TAROT La Silla observatory optical observations
  23. GRB 061007: Third Epoch ATCA Radio Observations
  24. GRB061019: second epoch CrAO observations
  25. GRB 061028: Swift/XRT Astrometry Correction
  26. GRB 061102: Swift/UVOT Magnitude Upper Limits
  27. GRB 061102, XRT refined analysis
  28. GRB 061004: Further VLT/NTT observations
  29. Swift-BAT Trigger 236481 is a Cosmic Ray Shower event
  30. GRB061102B: Super-LOTIS observations
  31. GRB 061028: Optical R passband observations
  32. GRB 061102B: Swift detection of a possible burst
  33. GRB 061102, Swift-BAT refined analysis
  34. GRB 061102: Swift detection of a burst
  35. GRB 061028: VLA Observation
  36. GRB 061004: Swift/XRT Astrometry Correction
  37. GRB 060801: Swift/XRT Astrometry Correction
  38. GRB 061028: Futher P200 Observations
  39. GRB 061028: MDM Observations
  40. GRB 061028: P200 Observations
  41. GRB 061028: SARA upper limit
  42. GRB 061028: z band imaging
  43. GRB061028: XRT refined analysis
  44. GRB 061028: Swift/UVOT Observations
  45. GRB 061028, Swift-BAT refined analysis
  46. GRB 061028: TAROT Calern observatory late optical observations
  47. GRB 061028: TAROT Calern observatory optical observations
  48. GRB 061028: Swift detection of a burst
  49. GRB 061027, Swift refined analysis of a possible burst
  50. GRB 061027: Swift detection of a possible burst
  51. GRB061025: ROTSE-III Confirmation of Optical Counterpart
  52. GRB061025: Swift XRT refined analysis
  53. GRB061025: Swift/UVOT observations
  54. GRB 061019: MITSuME upper limits
  55. GRB 061025: REM observations
  56. GRB 061025: Gemini-S observations
  57. GRB061025: Swift XRT position
  58. GRB 061025: ROTSE-III Optical Limits
  59. GRB 061025: a long GRB detected by INTEGRAL
  60. Swift XRT boresight update
  61. GRB 061021, Swift-BAT Lag analysis
  62. Konus-Wind observation of GRB 061021
  63. GRB 061021 - VLT spectrum without lines
  64. GRB 061021: Swift-XRT refined analysis
  65. GRB 061021: Swift/UVOT Observation
  66. GRB 061021, Swift-BAT refined analysis
  67. GRB 061021: Swift detection of a burst
  68. GRB 061019: Super-LOTIS upper limit
  69. GRB060904b: optical observations
  70. GRB061019: optical observations
  71. GRB061019: optical observations
  72. GRB 061019: SARA upper limit
  73. GRB 061019: dust-scattered X-ray halo detected in Swift/XRT
  74. GRB 060930: MARGE Optical Limits
  75. GRB 061019: Swift/UVOT upper limit
  76. GRB 061019: SMARTS afterglow confirmation
  77. GRB061019: Swift XRT refined analysis
  78. GRB 061019, Swift-BAT refined analysis
  79. GRB 061019: TAROT La Silla observatory optical observations
  80. GRB 061019: REM K-band candidate afterglow
  81. GRB061019: Swift/XRT position
  82. GRB 061019: Swift-BAT detection of a burst
  83. GRB 060825: GORT Observations
  84. GRB 061007: Second Epoch ATCA Radio Observations
  85. GRB 061007: RHESSI Spectral Fit
  86. GRB 061007: Suzaku/WAM observation of the prompt emission
  87. GRB 061006: astrometry-corrected XRT position
  88. Konus-Wind observation of GRB 061007
  89. GRB 060928: Confirmation of the X-ray afterglow detected by Swift
  90. GRB 061007: ATCA Radio Observations
  91. GRB061007: Swift UVOT followup observations
  92. GRB 061006: optical afterglow
  93. GRB 061006 : Suzaku/WAM observation of the prompt emission
  94. GRB 061007: OA fading and VLT redshift
  95. GRB 061007: Magellan Spectroscopy
  96. GRB 061007: Correction to GCN 5712
  97. GRB 061007: Swift-BAT refined analysis
  98. GRB 061007: Swift XRT refined analysis
  99. GRB 061006: Swift/UVOT optical observations
  100. Konus-Wind observation of the short hard GRB 061006

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