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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 061126: Faulkes Telescope North Optical Observations
  2. GRB 061126: Swift/UVOT Afterglow Detection
  3. GRB 061126: XRT position
  4. GRB 061126: Swift detection of a burst
  5. GRB 061121: MDM Continued Monitoring
  6. GRB 061122: Confirmation of X-ray/Optical Afterglow
  7. GRB 061121: MDM Continuing Optical Decay
  8. GRB061121: optical observations
  9. GRB 061122: Candidate Optical Afterglow
  10. GRB 061121: Ep,i - Eiso correlation
  11. GRB 061121: MDM Optical Decay
  12. GRB061122: Swift/UVOT Optical Observations
  13. GRB 061121: ART detection in Ic
  14. GRB061121: P60 Observations
  15. Radio detection of GRB 061121
  16. GRB061122: Swift-XRT position
  17. Konus-Wind observation of GRB 061122
  18. GRB 061121: MDM Optical Observations
  19. GRB 061121 declared "Burst of Interest" by Swift team
  20. RHESSI Spectrum of GRB061121
  21. Konus-Wind and Konus-A observations of GRB 061121
  22. INTEGRAL results on GRB 061122
  23. Swift-BAT trigger 239987 is not a GRB
  24. GRB 061122A: a long GRB detected by INTEGRAL
  25. GRB 061121: Swift/UVOT Observations
  26. GRB 061121: Swift-XRT Team Refined Analysis
  27. GRB 061121, Swift-BAT refined analysis
  28. GRB061121, optical observation
  29. GRB 061121 : Planned XMM-Newton observation
  30. GRB 061121: Optical observation at the KANATA 1.5m telescope
  31. GRB 061121: Faulkes Telescope North Optical Observation
  32. GRB061121: Spectroscopic Redshift
  33. GRB061121: Keck spectroscopic observations
  34. GRB 061121: ROTSE-III Confirmation of Optical Counterpart
  35. GRB 061121: Swift detection of a bright burst with an optical counterpart
  36. GRB 060605: NIR Observations
  37. GRB 050915B: optical afterglow
  38. GRB 060111B: Swift UVOT Refined Magnitudes
  39. Swift-BAT triggers 238544 and 238546 are not GRBs
  40. GRB061110A: Correction to GCN5817
  41. GRB 061110A: refined R-band analysis
  42. GRB 061110B: NIR Observations
  43. Swift TOO observations of GRB061110A
  44. Swift/UVOT Upper Limits for GRB061110b
  45. Swift/UVOT Upper Limits for GRB061110a
  46. GRB 061110A - VLT tentative redshift
  47. GRB 061110B: Swift XRT refined analysis
  48. GRB 061110B, Swift-BAT refined analysis
  49. GRB 061110B: VLT redshift
  50. GRB061110B: Optical observations at Crni Vrh
  51. GRB 061110B: NOT optical observations
  52. GRB 061110A: Swift XRT refined analysis
  53. GRB 061110B: Swift/XRT position
  54. GRB 061110B : Liverpool Telescope Optical Afterglow Detection
  55. GRB 061110B: Swift-UVOT Initial Observation
  56. GRB 061110A, Swift-BAT refined analysis
  57. GRB 061110B: TAROT Calern observatory optical observations
  58. GRB 061110B: Swift detection of a burst
  59. GRB 061110: NOT observations
  60. GRB 061110: Candidate confirmed
  61. GRB 061110 : Optical afterglow candidate
  62. GRB 061110: ROTSE-III Optical Limits
  63. GRB 061110: Swift detection of a burst
  64. GRB061110A - Optical Non-detection
  65. Swift-BAT Trigger 237821 is a Cosmic Ray Shower event
  66. GRB 061109: optical observation
  67. GRB 061109: TAROT Calern observatory optical observations
  68. GRB 061109: Swift detection of a possible burst
  69. GRB061028: MAGIC telescope GeV observation
  70. GRB 061027: TAROT La Silla observatory optical observations
  71. GRB 061007: Third Epoch ATCA Radio Observations
  72. GRB061019: second epoch CrAO observations
  73. GRB 061028: Swift/XRT Astrometry Correction
  74. GRB 061102: Swift/UVOT Magnitude Upper Limits
  75. GRB 061102, XRT refined analysis
  76. GRB 061004: Further VLT/NTT observations
  77. Swift-BAT Trigger 236481 is a Cosmic Ray Shower event
  78. GRB061102B: Super-LOTIS observations
  79. GRB 061028: Optical R passband observations
  80. GRB 061102B: Swift detection of a possible burst
  81. GRB 061102, Swift-BAT refined analysis
  82. GRB 061102: Swift detection of a burst
  83. GRB 061028: VLA Observation
  84. GRB 061004: Swift/XRT Astrometry Correction
  85. GRB 060801: Swift/XRT Astrometry Correction
  86. GRB 061028: Futher P200 Observations
  87. GRB 061028: MDM Observations
  88. GRB 061028: P200 Observations
  89. GRB 061028: SARA upper limit
  90. GRB 061028: z band imaging
  91. GRB061028: XRT refined analysis
  92. GRB 061028: Swift/UVOT Observations
  93. GRB 061028, Swift-BAT refined analysis
  94. GRB 061028: TAROT Calern observatory late optical observations
  95. GRB 061028: TAROT Calern observatory optical observations
  96. GRB 061028: Swift detection of a burst
  97. GRB 061027, Swift refined analysis of a possible burst
  98. GRB 061027: Swift detection of a possible burst
  99. GRB061025: ROTSE-III Confirmation of Optical Counterpart
  100. GRB061025: Swift XRT refined analysis

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