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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 071013: TNT optical data refined analysis
  2. GRB 071010B: Keck/DEIMOS emission-line redshift
  3. GRB 071017: a SHORT GRB detected by INTEGRAL
  4. GRB 071013: TLS 2nd epoch - Kornienko candidate constant
  5. GRB071013: optical observations
  6. GRB 071010B: Optical observations of EST
  7. GRB 071010B: TLS 3rd Epoch - finally a break??
  8. GRB 071011: MITSuME Optical Observations
  9. GRB 070920A: deep optical observations at the NOT
  10. GRB 071010B: Photometry after 1.6 days
  11. GRB 071010B: Keck/LRIS Photometry
  12. GRB 071010B: TLS 2nd Epoch, refined analysis
  13. GRB 071013: TLS Upper Limit
  14. Correction to GCN circular no. # 6915 for GRB 071010B
  15. VLA detection of radio afterglow of GRB 071010B
  16. VLA non-detection of GRB 071011
  17. GRB 071013: Optical observations
  18. GRB 071013: optical observations at NOT
  19. GRB 071013, Swift-BAT refined analysis
  20. GRB071013: optical limit
  21. GRB071010B, BVRcIc field calibration
  22. GRB 20071013: Xinglong TNT optical Upper Limit
  23. GRB 071013: Swift detection of a burst
  24. GRB 071010C Swift-BAT detection of a burst
  25. GRB 071011: Optical Limit after 13.95hrs
  26. GRB 071011: Xinglong TNT Optical afterglow observations
  27. GRB 071010B correction to GCN 6892 optical observations
  28. GRB 071011: Swift-XRT refined analysis
  29. VLA non-detection of GRB 071010A
  30. GRB 071011: NAYUTA Optical Observation, correction to GCN6886
  31. GRB 071011, Optical afterglow
  32. GRB 071011: Confirmation of P60 optical afterglow
  33. GRB 071010B: Optical Detection
  34. GRB 071011: Kanazawa Optical limits
  35. GRB 071011: P60 Optical Afterglow Candidate
  36. GRB 071011: MARGE Optical Limits
  37. GRB 071010B: Super-LOTIS upper limit
  38. GRB 071010B optical photometry
  39. GRB 071011: XRT afterglow detection
  40. GRB 071010B: Keck/LRIS Spectroscopy
  41. GRB 071011, Swift-BAT refined analysis
  42. GRB 071010B: Gemini Spectroscopic Observations
  43. GRB 071011: Early Super-LOTIS Observations
  44. GRB 071011: NAYUTA Optical Observation
  45. GRB 071010A: Continued Keck Imaging
  46. GRB 071010B: Bright OT confirmed with TLS
  47. GRB 071011: Optical afterglow candidate
  48. GRB 071011: Swift detection of a burst
  49. Optical Observation: GRB 071010
  50. Optical observations: GRB 071010A
  51. Konus-Wind observation of GRB 071010B
  52. GRB071010B: Swift/XRT detection
  53. GRB 071010B, Swift-BAT refined analysis
  54. GRB 071010A: bright NIR afterglow
  55. GRB 071006, Swift-BAT refined analysis
  56. GRB071008: optical observations
  57. GRB 071010B possible optical transient
  58. GRB 071010A: Keck/LRIS Photometry
  59. GRB 071010B: Swift detection of a burst
  60. GRB 071010: Swift-XRT observation
  61. GRB 071008, Swift-BAT refined analysis
  62. GRB 071010, Swift-BAT refined analysis
  63. Konus-Wind observation of GRB 071006
  64. GRB071008: Swift-XRT observation
  65. GRB 071010 REM NIR observations
  66. GRB 071010: Keck/LRIS Spectroscopy
  67. GRB 071010: TAROT La Silla observatory photometry of the afterglow
  68. GRB 071010: Rapid PROMPT Detections
  69. GRB 071010: Keck Observations of the Afterglow
  70. GRB 071010: TAROT La Silla observatory detection of the afterglow
  71. GRB 071010: Swift detection of a burst
  72. GRB 071006 Swift-BAT detection of a burst
  73. GRB071008: IAC80 observation
  74. GRB 071008: Swift detection of a burst
  75. GRB 071003: XRT refined analysis
  76. GRB070920A: MAGIC telescope GeV observation
  77. Radio detection of GRB 071003 with the VLA
  78. GRB 070810B: further XRT analysis
  79. GRB 071003: VLT spectroscopy
  80. GRB 071003: Keck spectroscopy
  81. Konus-Wind observation of GRB 071003
  82. GRB071003: Faulkes Telescope North observations
  83. GRB 071003: Possible rebrightening
  84. GRB 071003 : Lulin R-band observations
  85. GRB 071003: Swift XRT position
  86. GRB 071003: OA power-law decay indices from KAIT
  87. GRB 071003: Keck HIRES spectroscopy
  88. GRB 071003, Swift-BAT refined analysis
  89. GRB 071003: MARGE Observations
  90. GRB 071003 Optical observations
  91. GRB 071003: P60 Confirmation of Optical Afterglow
  92. GRB 071003: KAIT optical afterglow observations
  93. GRB 071003: Swift detection of a bright burst
  94. GRB 070714B: host galaxy spectroscopic redshift
  95. GRB 071001: Swift-XRT Team refined analysis
  96. GRB 071001, Swift-BAT refined analysis
  97. Faulkes Telescope South observations of GRB 071001
  98. GRB 071001: Swift detection of a burst
  99. VLA observation of GRB 070923
  100. Disregard the Swift-XRT Notices today

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