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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 060926: OPTIMA-Burst -- further observations
  2. GRB 060926: Swift XRT refined analysis
  3. GRB 060926, Swift-BAT refined analysis
  4. GRB 060923A: Radio Observations
  5. GRB 060926: MASTER OT alert observation
  6. GRB 060926: RTT150, UVOT afterglow candidate confirmation
  7. GRB 060912A: Redshift of probable host galaxy
  8. GRB 060926: BOOTES-IR observations
  9. GRB 060926: Watcher observations
  10. GRB060926 OPTIMA-Burst optical observation
  11. GRB 060926: MASTER optical observation
  12. GRB 060926: Swift detection of a burst
  13. GRB 060923C, Swift-BAT refined analysis
  14. GRB 060923C: VLA Observation
  15. GRB 060923C: NIR afterglow confirmed
  16. GRB060923C: AROMA optical obsevation
  17. GRB 060923C: Gemini Observations and Afterglow Candidate
  18. GRB 060923C, optical observation
  19. GRB 060923A: Gemini Second Epoch and Afterglow Confirmation
  20. GRB 060923C: VLT J-band observations
  21. GRB060923B: Swift/UVOT upper limits
  22. GRB 060923B: Swift XRT Refined Analysis
  23. GRB 060923C: Swift XRT refined analysis
  24. GRB 060923C, Swift-BAT partial refined analysis
  25. GRB 060923A: Swift XRT refined analysis
  26. GRB 060923C: Keck Observations
  27. GRB 060923A: Keck and Gemini Observations
  28. GRB 060923C: Xinglong TNT optical observations
  29. GRB 060923B, Swift-BAT refined analysis
  30. GRB060923C : Faulkes Telescope South optical limits
  31. GRB060923C: Faulkes Telescope North optical observations
  32. GRB 060923C: optical observation
  33. GRB 060923C: Swift detection of a burst
  34. GRB 060923B: Swift detection of a burst
  35. GRB 060923, Swift-BAT refined analysis
  36. GRB 060923: Early Super-LOTIS Observations
  37. GRB 060923: UKIRT nIR observations - candidate afterglow
  38. GRB060923: Faulkes Telescope North optical observations
  39. GRB060923 - SDSS Pre-Burst Observations
  40. GRB 060923: KAIT observations
  41. GRB 060923: Swift detection of a burst
  42. Swift detection of IGR J17497-2821 (trigger 230504)
  43. Swift detects a hard X-ray burst from AXP CXOU J164710.2-455216
  44. GRB060919: Swift/UVOT optical observations
  45. GRB 060919 : Faulkes South Telescope Observations
  46. GRB 060919, Swift-BAT refined analysis
  47. GRB060919: XRT refined analysis
  48. GRB 060919: TAROT optical observations
  49. GRB 060919: Swift detection of a burst
  50. GRB 060912A: VLA Observation
  51. GRB 060912A: Probable Host Galaxy
  52. IBAS Alert n.3470: not a GRB
  53. GRB060825: MAGIC telescope GeV observation
  54. Konus-Wind observation of GRB 060912
  55. IBAS Alert No.3468: not a GRB
  56. GRB 060912: Redshift of nearby 2MASS galaxy
  57. GRB060912: optical observations
  58. GRB 060912B: Watcher observations
  59. GRB060912: Swift/UVOT Observations
  60. GRB060912: OPTIMA-Burst optical observations
  61. GRB 060912B: a long GRB detected with INTEGRAL
  62. GRB 060912: Swift XRT Team Refined Analysis
  63. GRB 060912, Swift-BAT refined analysis
  64. GRB 060912: Correction to GCN 5559
  65. GRB 060912: Xinglong TNT optical observations
  66. GRB 060912: Swift detection of a burst with an optical afterglow
  67. GRB060906: Danish/DFOSC optical observations
  68. VLA observations of GRB 060908
  69. GRB 060908: redshift
  70. GRB 060908, Swift/XRT refined analysis
  71. GRB 060908: Swift/UVOT Observations
  72. GRB 060908: Danish/DFOSC optical observations
  73. GRB 060908, Swift-BAT refined analysis
  74. GRB 060908 - SDSS Pre-burst Observations
  75. GRB 060904B : CFHT/WIRCam NIR afterglow observations
  76. GRB 060904B: Kiso Optical observation
  77. GRB 060904A : Optical limit
  78. GRB 060908: REM optical prompt observation
  79. GRB 060908: PROMPT Detection of a Bright Counterpart
  80. GRB 060908: Swift detection of a burst with a bright optical counterpart
  81. GRB 060904A: Suzaku/WAM observation of the prompt emission
  82. GRB060906 , optical observation
  83. GRB060904b optical detections (delayed report due to internet outage)
  84. GRB 060906: optical observation
  85. GRB 060906: Early RAPTOR optical limits
  86. GRB 060906, Swift-BAT refined spectral analysis
  87. GRB 060906: Swift/XRT Refined Analysis
  88. GRB 060906: Swift-UVOT observations
  89. VLT redshift of GRB 060906
  90. GRB 060906, Swift-BAT refined analysis
  91. GRB 060906: FRAM observations - flash determination (airplane)
  92. GRB 060906: KAIT observations
  93. GRB 060906: Confirmation of P60 Optical Afterglow
  94. GRB 060906: observations with FRAM
  95. GRB 060906 (?): P60 Optical Afterglow Candidate
  96. GRB 060906: Swift detection of a probable burst
  97. GRB 060904A Milagro GeV/TeV Observations
  98. GRB060904b, optical observations
  99. GRB 060904b: SMARTS optical/IR afterglow observations
  100. GRB 060904B: RTT150 optical observations

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