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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. Konus-Wind and Konus-A observations of GRB 061121
  2. INTEGRAL results on GRB 061122
  3. Swift-BAT trigger 239987 is not a GRB
  4. GRB 061122A: a long GRB detected by INTEGRAL
  5. GRB 061121: Swift/UVOT Observations
  6. GRB 061121: Swift-XRT Team Refined Analysis
  7. GRB 061121, Swift-BAT refined analysis
  8. GRB061121, optical observation
  9. GRB 061121 : Planned XMM-Newton observation
  10. GRB 061121: Optical observation at the KANATA 1.5m telescope
  11. GRB 061121: Faulkes Telescope North Optical Observation
  12. GRB061121: Spectroscopic Redshift
  13. GRB061121: Keck spectroscopic observations
  14. GRB 061121: ROTSE-III Confirmation of Optical Counterpart
  15. GRB 061121: Swift detection of a bright burst with an optical counterpart
  16. GRB 060605: NIR Observations
  17. GRB 050915B: optical afterglow
  18. GRB 060111B: Swift UVOT Refined Magnitudes
  19. Swift-BAT triggers 238544 and 238546 are not GRBs
  20. GRB061110A: Correction to GCN5817
  21. GRB 061110A: refined R-band analysis
  22. GRB 061110B: NIR Observations
  23. Swift TOO observations of GRB061110A
  24. Swift/UVOT Upper Limits for GRB061110b
  25. Swift/UVOT Upper Limits for GRB061110a
  26. GRB 061110A - VLT tentative redshift
  27. GRB 061110B: Swift XRT refined analysis
  28. GRB 061110B, Swift-BAT refined analysis
  29. GRB 061110B: VLT redshift
  30. GRB061110B: Optical observations at Crni Vrh
  31. GRB 061110B: NOT optical observations
  32. GRB 061110A: Swift XRT refined analysis
  33. GRB 061110B: Swift/XRT position
  34. GRB 061110B : Liverpool Telescope Optical Afterglow Detection
  35. GRB 061110B: Swift-UVOT Initial Observation
  36. GRB 061110A, Swift-BAT refined analysis
  37. GRB 061110B: TAROT Calern observatory optical observations
  38. GRB 061110B: Swift detection of a burst
  39. GRB 061110: NOT observations
  40. GRB 061110: Candidate confirmed
  41. GRB 061110 : Optical afterglow candidate
  42. GRB 061110: ROTSE-III Optical Limits
  43. GRB 061110: Swift detection of a burst
  44. GRB061110A - Optical Non-detection
  45. Swift-BAT Trigger 237821 is a Cosmic Ray Shower event
  46. GRB 061109: optical observation
  47. GRB 061109: TAROT Calern observatory optical observations
  48. GRB 061109: Swift detection of a possible burst
  49. GRB061028: MAGIC telescope GeV observation
  50. GRB 061027: TAROT La Silla observatory optical observations
  51. GRB 061007: Third Epoch ATCA Radio Observations
  52. GRB061019: second epoch CrAO observations
  53. GRB 061028: Swift/XRT Astrometry Correction
  54. GRB 061102: Swift/UVOT Magnitude Upper Limits
  55. GRB 061102, XRT refined analysis
  56. GRB 061004: Further VLT/NTT observations
  57. Swift-BAT Trigger 236481 is a Cosmic Ray Shower event
  58. GRB061102B: Super-LOTIS observations
  59. GRB 061028: Optical R passband observations
  60. GRB 061102B: Swift detection of a possible burst
  61. GRB 061102, Swift-BAT refined analysis
  62. GRB 061102: Swift detection of a burst
  63. GRB 061028: VLA Observation
  64. GRB 061004: Swift/XRT Astrometry Correction
  65. GRB 060801: Swift/XRT Astrometry Correction
  66. GRB 061028: Futher P200 Observations
  67. GRB 061028: MDM Observations
  68. GRB 061028: P200 Observations
  69. GRB 061028: SARA upper limit
  70. GRB 061028: z band imaging
  71. GRB061028: XRT refined analysis
  72. GRB 061028: Swift/UVOT Observations
  73. GRB 061028, Swift-BAT refined analysis
  74. GRB 061028: TAROT Calern observatory late optical observations
  75. GRB 061028: TAROT Calern observatory optical observations
  76. GRB 061028: Swift detection of a burst
  77. GRB 061027, Swift refined analysis of a possible burst
  78. GRB 061027: Swift detection of a possible burst
  79. GRB061025: ROTSE-III Confirmation of Optical Counterpart
  80. GRB061025: Swift XRT refined analysis
  81. GRB061025: Swift/UVOT observations
  82. GRB 061019: MITSuME upper limits
  83. GRB 061025: REM observations
  84. GRB 061025: Gemini-S observations
  85. GRB061025: Swift XRT position
  86. GRB 061025: ROTSE-III Optical Limits
  87. GRB 061025: a long GRB detected by INTEGRAL
  88. Swift XRT boresight update
  89. GRB 061021, Swift-BAT Lag analysis
  90. Konus-Wind observation of GRB 061021
  91. GRB 061021 - VLT spectrum without lines
  92. GRB 061021: Swift-XRT refined analysis
  93. GRB 061021: Swift/UVOT Observation
  94. GRB 061021, Swift-BAT refined analysis
  95. GRB 061021: Swift detection of a burst
  96. GRB 061019: Super-LOTIS upper limit
  97. GRB060904b: optical observations
  98. GRB061019: optical observations
  99. GRB061019: optical observations
  100. GRB 061019: SARA upper limit

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