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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. GRB060211b: optical observation
  2. GRB060211B: Swift/XRT position
  3. GRB 060210: Optical Observations
  4. GRB060211.7: MASTER_optical_observation under the snow
  5. GRB 060211A: Swift XRT Team Refined Analysis
  6. GRB 060211B: Swift-BAT detection of a burst
  7. GRB060211: Faulkes North observation
  8. GRB 060211: ROTSE-III Optical Limits
  9. GRB 060211: Swift detection of a long burst
  10. GRB 060210: Refined analysis of the Swift-BAT burst
  11. GRB060210: Swift XRT Refined Analysis
  12. GRB060206, optical observations
  13. GRB 060210 : Xinglong and Lulin optical limit
  14. GRB060210: Optical Observations
  15. GRB060210: Gemini absorption spectroscopy
  16. GRB060210: Early Optical Observations
  17. GRB 060210: optical evolution
  18. GRB060210:Faulkes Telescope North Afterglow Confirmation
  19. GRB 060210: candidate afterglow
  20. GRB 060210: Swift detection of a burst
  21. GRB060210: Optical afterglow
  22. GRB 060206: Swift/UVOT Observations
  23. Swift-BAT trigger 180931 is not a GRB
  24. GRB060209: RTT150 optical observations
  25. GRB 060209 : TAROT optical observation
  26. GRB060209A: MASTER optical observation
  27. GRB 060209(?): Swift-BAT detection of a possible burst
  28. GRB 060206: near-infrared observations (JK' imaging)
  29. GRB 060206: WSRT Radio Observations
  30. GRB 060203: Swift/UVOT upper limits
  31. GRB 060206: TTT Observations
  32. GRB 060206: More PROMPT Detections
  33. GRB 060121 : WIDGET Pre-trigger limit
  34. GRB 060206: Tenagra II Observations
  35. GRB 060206: PROMPT Detections
  36. Retraction of orphan GRB afterglow candidate
  37. GRB060204a: Swift XRT Source is not GRB Afterglow
  38. GRB 060206: optical observations at Asiago
  39. Orphan GRB Afterglow candidate
  40. GRB 060204b: pseudo-z from spectral parameters of the prompt emission
  41. GRB 060206: Subaru/FOCAS optical spectroscopy
  42. GRB 060206: IR Detection of the Afterglow
  43. GRB 060206: Lick 3m Spectroscopy
  44. GRB 060204A: ROSAT Pointing
  45. GRB 060206: Super-LOTIS observations
  46. GRB060204A: Swift/UVOT observations
  47. GRB 060206: Swift-BAT refined analysis
  48. GRB 060206 : Lulin optical observations
  49. GRB060206: SDSS Pre-Burst Observations
  50. GRB060206: Swift XRT Refined Analysis
  51. GRB060206: Liverpool Telescope observation
  52. GRB 060206: Spectroscopic Redshift
  53. GRB060206: P60 Optical Observations
  54. GRB 060206: KAIT observations
  55. GRB060206: Swift XRT Position
  56. GRB060206: SARA Detection
  57. GRB 060206: RAPTOR observations of afterglow candidate variability.
  58. GRB 060206: High redshift burst
  59. GRB060204a: Swift XRT Detection of an Afterglow Candidate
  60. GRB060206 - Swift UVOT Confirmation of Optical Afterglow
  61. GRB060206: Optical afterglow
  62. GRB060206: Swift-BAT detection of a burst
  63. GRB 060204C: XRT analysis of Swift J061223.0+701243.9
  64. GRB060203: WHT Z-band observations
  65. BAT GRB 060204C is probably not a GRB
  66. GRB060204C: optical observation
  67. GRB 060204B: BVRi-band detections of optical afterglow
  68. GRB 060204A: Swift XRT upper limit
  69. GRB 060204A: FRAM optical observations
  70. GRB060204B: Swift/UVOT refined analysis
  71. GRB 060204C: optical observations
  72. Swift XRT Observation of GRB 060204C
  73. GRB 060204B: Swift-BAT refined analysis
  74. GRB 060204B: ART early limit
  75. GRB060204B: Swift XRT Team Refined Analysis
  76. GRB 060204C: OSN limits
  77. GRB 060204b: Keck/LRIS Afterglow Confirmation
  78. GRB 060204C: BOOTES-IR optical limits
  79. GRB 060204C: Liverpool Telescopes optical limit
  80. GRB 060204C: ROTSE-III Optical Limits
  81. GRB 060204C: Swift-BAT detection of a burst
  82. GRB 060124: Radio Observations
  83. GRB060204B: Faulkes OT candidate
  84. GRB 060204B: ART optical limit
  85. GRB 060204A: further INTEGRAL results
  86. GRB060204B, optical observation
  87. GRB060204B - SDSS pre-burst observations
  88. GRB 060203: Swift-BAT refined analysis
  89. GRB 060204B: Swift detection of a burst
  90. GRB 060204: a long GRB detected by INTEGRAL
  91. GRB 060202: UKIRT/WFCAM K-band and KeckI/LRIS I-band Observation
  92. GRB 060203: RTT150 optical observations
  93. GRB060203: Swift XRT Team Refined Analysis
  94. GRB060203 - Swift UVOT observation
  95. Swift-BAT trigger is GRB 060203
  96. GRB 060203: IR Counterpart
  97. GRB060203: Observations with SARA
  98. GRB 060203: P60 Confirmation of Optical Afterglow
  99. Possible GRB 060203: candidate optical counterpart
  100. Swift BAT Trigger 180151: Swift XRT source detection

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