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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 061121: MDM Continued Monitoring
  2. GRB 061122: Confirmation of X-ray/Optical Afterglow
  3. GRB 061121: MDM Continuing Optical Decay
  4. GRB061121: optical observations
  5. GRB 061122: Candidate Optical Afterglow
  6. GRB 061121: Ep,i - Eiso correlation
  7. GRB 061121: MDM Optical Decay
  8. GRB061122: Swift/UVOT Optical Observations
  9. GRB 061121: ART detection in Ic
  10. GRB061121: P60 Observations
  11. Radio detection of GRB 061121
  12. GRB061122: Swift-XRT position
  13. Konus-Wind observation of GRB 061122
  14. GRB 061121: MDM Optical Observations
  15. GRB 061121 declared "Burst of Interest" by Swift team
  16. RHESSI Spectrum of GRB061121
  17. Konus-Wind and Konus-A observations of GRB 061121
  18. INTEGRAL results on GRB 061122
  19. Swift-BAT trigger 239987 is not a GRB
  20. GRB 061122A: a long GRB detected by INTEGRAL
  21. GRB 061121: Swift/UVOT Observations
  22. GRB 061121: Swift-XRT Team Refined Analysis
  23. GRB 061121, Swift-BAT refined analysis
  24. GRB061121, optical observation
  25. GRB 061121 : Planned XMM-Newton observation
  26. GRB 061121: Optical observation at the KANATA 1.5m telescope
  27. GRB 061121: Faulkes Telescope North Optical Observation
  28. GRB061121: Spectroscopic Redshift
  29. GRB061121: Keck spectroscopic observations
  30. GRB 061121: ROTSE-III Confirmation of Optical Counterpart
  31. GRB 061121: Swift detection of a bright burst with an optical counterpart
  32. GRB 060605: NIR Observations
  33. GRB 050915B: optical afterglow
  34. GRB 060111B: Swift UVOT Refined Magnitudes
  35. Swift-BAT triggers 238544 and 238546 are not GRBs
  36. GRB061110A: Correction to GCN5817
  37. GRB 061110A: refined R-band analysis
  38. GRB 061110B: NIR Observations
  39. Swift TOO observations of GRB061110A
  40. Swift/UVOT Upper Limits for GRB061110b
  41. Swift/UVOT Upper Limits for GRB061110a
  42. GRB 061110A - VLT tentative redshift
  43. GRB 061110B: Swift XRT refined analysis
  44. GRB 061110B, Swift-BAT refined analysis
  45. GRB 061110B: VLT redshift
  46. GRB061110B: Optical observations at Crni Vrh
  47. GRB 061110B: NOT optical observations
  48. GRB 061110A: Swift XRT refined analysis
  49. GRB 061110B: Swift/XRT position
  50. GRB 061110B : Liverpool Telescope Optical Afterglow Detection
  51. GRB 061110B: Swift-UVOT Initial Observation
  52. GRB 061110A, Swift-BAT refined analysis
  53. GRB 061110B: TAROT Calern observatory optical observations
  54. GRB 061110B: Swift detection of a burst
  55. GRB 061110: NOT observations
  56. GRB 061110: Candidate confirmed
  57. GRB 061110 : Optical afterglow candidate
  58. GRB 061110: ROTSE-III Optical Limits
  59. GRB 061110: Swift detection of a burst
  60. GRB061110A - Optical Non-detection
  61. Swift-BAT Trigger 237821 is a Cosmic Ray Shower event
  62. GRB 061109: optical observation
  63. GRB 061109: TAROT Calern observatory optical observations
  64. GRB 061109: Swift detection of a possible burst
  65. GRB061028: MAGIC telescope GeV observation
  66. GRB 061027: TAROT La Silla observatory optical observations
  67. GRB 061007: Third Epoch ATCA Radio Observations
  68. GRB061019: second epoch CrAO observations
  69. GRB 061028: Swift/XRT Astrometry Correction
  70. GRB 061102: Swift/UVOT Magnitude Upper Limits
  71. GRB 061102, XRT refined analysis
  72. GRB 061004: Further VLT/NTT observations
  73. Swift-BAT Trigger 236481 is a Cosmic Ray Shower event
  74. GRB061102B: Super-LOTIS observations
  75. GRB 061028: Optical R passband observations
  76. GRB 061102B: Swift detection of a possible burst
  77. GRB 061102, Swift-BAT refined analysis
  78. GRB 061102: Swift detection of a burst
  79. GRB 061028: VLA Observation
  80. GRB 061004: Swift/XRT Astrometry Correction
  81. GRB 060801: Swift/XRT Astrometry Correction
  82. GRB 061028: Futher P200 Observations
  83. GRB 061028: MDM Observations
  84. GRB 061028: P200 Observations
  85. GRB 061028: SARA upper limit
  86. GRB 061028: z band imaging
  87. GRB061028: XRT refined analysis
  88. GRB 061028: Swift/UVOT Observations
  89. GRB 061028, Swift-BAT refined analysis
  90. GRB 061028: TAROT Calern observatory late optical observations
  91. GRB 061028: TAROT Calern observatory optical observations
  92. GRB 061028: Swift detection of a burst
  93. GRB 061027, Swift refined analysis of a possible burst
  94. GRB 061027: Swift detection of a possible burst
  95. GRB061025: ROTSE-III Confirmation of Optical Counterpart
  96. GRB061025: Swift XRT refined analysis
  97. GRB061025: Swift/UVOT observations
  98. GRB 061019: MITSuME upper limits
  99. GRB 061025: REM observations
  100. GRB 061025: Gemini-S observations

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