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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 090621B: Gemini spectrum of afterglow candidate
  2. GRB 090621C: Fermi GBM detection
  3. GRB 090621B: P60 Observations
  4. GRB 090621: Fermi GBM observation
  5. GRB 090621B: VLA observations
  6. GRB 090620: Fermi GBM detecion
  7. Konus-Wind and Konus-RF observations of GRB 090618
  8. GRB 090621B: Swift/UVOT Upper Limits
  9. GRB 090621B: Swift-BAT refined analysis
  10. GRB 090621B: Swift-XRT refined analysis
  11. GRB 090621B: RTT150 optical observations
  12. GRB 090618: RTT150 optical observations
  13. GRB 090621B: Optical Observations
  14. GRB 090621A: Swift-BAT refined analysis
  15. GRB 090621B: Swift detection of a short hard burst
  16. GRB 090621: Swift/UVOT Upper Limits
  17. GRB 090621: Swift-XRT Team refined analysis
  18. GRB090618: Spectrum and photometry from 6.0m BTA
  19. GRB 090618: BOAO V-band Observation
  20. GRB 090621: Swift detection of a burst
  21. GRB 090618: ZTSh optical observations
  22. GRB 090618 : WSRT radio detection
  23. GRB090618, underlying supernova search
  24. GRB090618: OAA-OAUV Optical observations
  25. GRB 090618: Fermi GBM observation
  26. GRB 090618, Swift-BAT refined spectral analysis
  27. VLA radio detection of GRB 090618
  28. GRB 090618 15GHz radio detection
  29. GRB090618 - Continued optical monitoring and light curve break
  30. GRB 090618: Swift-BAT refined analysis
  31. GRB 090618: SARA observations
  32. GRB090618: Swift-XRT team refined analysis
  33. GRB090618: Swift/UVOT bright afterglow detection
  34. GRB 090618: SDSS host detection
  35. Swift XRT observations of GRB 090531A
  36. GRB 090618: AGILE observations
  37. GRB 090617: Fermi GBM detection
  38. GRB 090618: LOAO R-band Observation
  39. GRB 090618: Enhanced Swift-XRT position
  40. GRB 090618 Faulkes Telescope North observations
  41. Optical observations of GRB 090618
  42. GRB 090618: Lick/KAST Spectroscopy
  43. GRB 090618: OA behavior from KAIT
  44. GRB 090618: planned XMM-Newton observation
  45. GRB 090618: ROTSE-III Detection of Optical Counterpart
  46. GRB 090618: KAIT optical afterglow
  47. GRB090618: P60 Optical Afterglow
  48. GRB 090618: Swift detection of a bright burst with optical afterglow
  49. GRB 090616: Fermi GBM detection
  50. GRB 090612: Fermi GBM detection
  51. GRB 090610C: Fermi GBM detection
  52. GRB 090610B: Fermi GBM detection
  53. GRB 090610: Fermi GBM detection
  54. SGR 0418+5729 Fermi/GBM Detection of Pulsations
  55. GRB 090602: Suzaku WAM observation of the prompt emission
  56. GRB 090424: WSRT Radio Observations
  57. GRB 090423: WSRT Radio Observations
  58. RXTE Discovery of Pulsations from SGR 0418+5729
  59. GRB 090531B: Fermi GBM detection
  60. Konus-RF observation of SGR burst 090605A
  61. Discovery of a new soft gamma repeater source, SGR 0418+5729
  62. GRB 090608: Fermi GBM detection
  63. GRB 090606: Fermi GBM detection
  64. GRB 090607: XRT Team Refined Analysis
  65. GRB 090607: Swift/UVOT Upper Limits
  66. GRB 090607: Swift-BAT refined analysis of the SHB
  67. GRB 090607: GRAS001 optical observations
  68. GRB 090607: Faulkes Telescope North observations
  69. GRB 090607: Swift detection of a burst
  70. Ignore GCN/Swift-BAT Lightcurve Notices for trigger 353567
  71. GRB 090530B: Suzaku WAM observation of the prompt emission
  72. GRB 090530: Further NOT optical observations
  73. GRB 090530: RTT150 Optical Observation
  74. GRB 090602: Fermi GBM detection
  75. GRB 090529A: RTT150 Optical Observations
  76. GMRT observation of GRB 090424 afterglow
  77. GRB 090528: Suzaku WAM observation of the prompt emission
  78. GRB090529: Further NOT optical observations
  79. GRB 090531b, SMARTS optical/IR observations
  80. GRB 090531B: GROND observation
  81. GRB 090528B: Suzaku WAM observation of the prompt emission
  82. GRB 090530: Early RAPTOR Optical Observations
  83. GRB090529B: ROVOR Upper Limits
  84. GRB 090531A: SARA upper limit
  85. GRB 090531B: Swift/BAT spectral lag results
  86. GRB 090529C: Fermi GBM detection
  87. GRB 090529B: Fermi GBM detection
  88. GRB 090530B: Fermi GBM detection
  89. Corrections to GRB 090531B Swift/UVOT Upper Limits
  90. GRB 090531B, RIMOTS optical upper limits
  91. GRB 090531B: Swift/UVOT Upper Limits
  92. GRB 090528B: MASTER-II Kourovka optical limit
  93. GRB 090529: MITSuME optical observation
  94. GRB 090530: GRT Optical Observation
  95. GRB 090531B: Swift-BAT refined analysis
  96. Initial Swift/UVOT observations of GRB 090531B
  97. GRB 090531B: Swift-XRT candidate afterglow position
  98. GRB 090531B: ROTSE-III Optical Limits
  99. GRB 090531B: Swift detection of a burst
  100. GRB 090531: Swift-BAT refined analysis

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