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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 060923A: Keck and Gemini Observations
  2. GRB 060923C: Xinglong TNT optical observations
  3. GRB 060923B, Swift-BAT refined analysis
  4. GRB060923C : Faulkes Telescope South optical limits
  5. GRB060923C: Faulkes Telescope North optical observations
  6. GRB 060923C: optical observation
  7. GRB 060923C: Swift detection of a burst
  8. GRB 060923B: Swift detection of a burst
  9. GRB 060923, Swift-BAT refined analysis
  10. GRB 060923: Early Super-LOTIS Observations
  11. GRB 060923: UKIRT nIR observations - candidate afterglow
  12. GRB060923: Faulkes Telescope North optical observations
  13. GRB060923 - SDSS Pre-Burst Observations
  14. GRB 060923: KAIT observations
  15. GRB 060923: Swift detection of a burst
  16. Swift detection of IGR J17497-2821 (trigger 230504)
  17. Swift detects a hard X-ray burst from AXP CXOU J164710.2-455216
  18. GRB060919: Swift/UVOT optical observations
  19. GRB 060919 : Faulkes South Telescope Observations
  20. GRB 060919, Swift-BAT refined analysis
  21. GRB060919: XRT refined analysis
  22. GRB 060919: TAROT optical observations
  23. GRB 060919: Swift detection of a burst
  24. GRB 060912A: VLA Observation
  25. GRB 060912A: Probable Host Galaxy
  26. IBAS Alert n.3470: not a GRB
  27. GRB060825: MAGIC telescope GeV observation
  28. Konus-Wind observation of GRB 060912
  29. IBAS Alert No.3468: not a GRB
  30. GRB 060912: Redshift of nearby 2MASS galaxy
  31. GRB060912: optical observations
  32. GRB 060912B: Watcher observations
  33. GRB060912: Swift/UVOT Observations
  34. GRB060912: OPTIMA-Burst optical observations
  35. GRB 060912B: a long GRB detected with INTEGRAL
  36. GRB 060912: Swift XRT Team Refined Analysis
  37. GRB 060912, Swift-BAT refined analysis
  38. GRB 060912: Correction to GCN 5559
  39. GRB 060912: Xinglong TNT optical observations
  40. GRB 060912: Swift detection of a burst with an optical afterglow
  41. GRB060906: Danish/DFOSC optical observations
  42. VLA observations of GRB 060908
  43. GRB 060908: redshift
  44. GRB 060908, Swift/XRT refined analysis
  45. GRB 060908: Swift/UVOT Observations
  46. GRB 060908: Danish/DFOSC optical observations
  47. GRB 060908, Swift-BAT refined analysis
  48. GRB 060908 - SDSS Pre-burst Observations
  49. GRB 060904B : CFHT/WIRCam NIR afterglow observations
  50. GRB 060904B: Kiso Optical observation
  51. GRB 060904A : Optical limit
  52. GRB 060908: REM optical prompt observation
  53. GRB 060908: PROMPT Detection of a Bright Counterpart
  54. GRB 060908: Swift detection of a burst with a bright optical counterpart
  55. GRB 060904A: Suzaku/WAM observation of the prompt emission
  56. GRB060906 , optical observation
  57. GRB060904b optical detections (delayed report due to internet outage)
  58. GRB 060906: optical observation
  59. GRB 060906: Early RAPTOR optical limits
  60. GRB 060906, Swift-BAT refined spectral analysis
  61. GRB 060906: Swift/XRT Refined Analysis
  62. GRB 060906: Swift-UVOT observations
  63. VLT redshift of GRB 060906
  64. GRB 060906, Swift-BAT refined analysis
  65. GRB 060906: FRAM observations - flash determination (airplane)
  66. GRB 060906: KAIT observations
  67. GRB 060906: Confirmation of P60 Optical Afterglow
  68. GRB 060906: observations with FRAM
  69. GRB 060906 (?): P60 Optical Afterglow Candidate
  70. GRB 060906: Swift detection of a probable burst
  71. GRB 060904A Milagro GeV/TeV Observations
  72. GRB060904b, optical observations
  73. GRB 060904b: SMARTS optical/IR afterglow observations
  74. GRB 060904B: RTT150 optical observations
  75. GRB060904A: Swift/UVOT optical observations
  76. GRB 060904A: Subaru NIR observation
  77. GRB 060904A: pseudo-z from spectral parameters of the prompt emission
  78. GRB 060904B: Swift-BAT refined analysis
  79. GRB060904b: Optical observations with Swift/UVOT
  80. Konus-Wind observation of GRB 060904A
  81. GRB 060904B: Swift-XRT refined analysis
  82. GRB 060904A: Refined analysis of the Swift-BAT burst
  83. GRB 060904A: Swift-XRT refined analysis
  84. GRB 060904A: Suzaku-XIS and -HXD observation plan
  85. GRB 060904B: VLT redshift
  86. GRB 060904A: P60 Observations
  87. GRB 060904B: Optical observations at Crni Vrh
  88. GRB060904B: Watcher observations
  89. GRB 060904B BOOTES-IR and 1.5m OSN observations
  90. GRB 060904B: TAROT optical counterpart observations
  91. GRB060904B - SDSS Pre-Burst Observations
  92. GRB 060904: TAROT optical observations
  93. GRB 060904B: Swift detection of a burst with optical counterpart
  94. GRB 060904B: ROTSE-III Detection of Optical Counterpart
  95. GRB060904 - SDSS Pre-Burst Observations
  96. GRB 060904: Swift detection of a bright burst
  97. GRB060901: Optical observations
  98. 060901: Swift UVOT followup observations
  99. GRB 060901: pseudo-z from spectral parameters of the prompt
  100. Konus-Wind observation of GRB 060901

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