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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"

28048 results found.

  1. GRB 090623: Fermi GBM detection
  2. GRB 090621B: GRT Optical Observation
  3. GRB 090621A: GRT Optical Observation
  4. GRB 090621B: I-band observations from 1.23m CAHA
  5. GRB 090621D: Fermi GBM detection
  6. GRB 090621C: Fermi GBM detection
  7. GRB 090621B: P60 Observations
  8. GRB 090621B: VLA observations
  9. GRB 090620: Fermi GBM detecion
  10. GRB 090621B: Swift/UVOT Upper Limits
  11. GRB 090621B: Swift-BAT refined analysis
  12. GRB 090621B: Swift-XRT refined analysis
  13. GRB 090621B: RTT150 optical observations
  14. GRB 090621B: Swift detection of a short hard burst
  15. GRB 090621: Swift/UVOT Upper Limits
  16. GRB 090621: Swift-XRT Team refined analysis
  17. GRB090618: Spectrum and photometry from 6.0m BTA
  18. GRB 090621: Swift detection of a burst
  19. GRB090618, underlying supernova search
  20. GRB090618: OAA-OAUV Optical observations
  21. GRB 090618: Fermi GBM observation
  22. GRB 090618, Swift-BAT refined spectral analysis
  23. VLA radio detection of GRB 090618
  24. GRB 090618 15GHz radio detection
  25. GRB090618 - Continued optical monitoring and light curve break
  26. GRB 090618: Swift-BAT refined analysis
  27. GRB 090618: SARA observations
  28. GRB090618: Swift-XRT team refined analysis
  29. GRB090618: Swift/UVOT bright afterglow detection
  30. GRB 090618: SDSS host detection
  31. Swift XRT observations of GRB 090531A
  32. GRB 090618: AGILE observations
  33. GRB 090617: Fermi GBM detection
  34. GRB 090618: Enhanced Swift-XRT position
  35. GRB 090618 Faulkes Telescope North observations
  36. GRB 090618: ROTSE-III Detection of Optical Counterpart
  37. GRB090618: P60 Optical Afterglow
  38. GRB 090618: Swift detection of a bright burst with optical afterglow
  39. GRB 090616: Fermi GBM detection
  40. GRB 090612: Fermi GBM detection
  41. GRB 090610C: Fermi GBM detection
  42. GRB 090610B: Fermi GBM detection
  43. GRB 090610: Fermi GBM detection
  44. SGR 0418+5729 Fermi/GBM Detection of Pulsations
  45. GRB 090602: Suzaku WAM observation of the prompt emission
  46. RXTE Discovery of Pulsations from SGR 0418+5729
  47. GRB 090531B: Fermi GBM detection
  48. Konus-RF observation of SGR burst 090605A
  49. Discovery of a new soft gamma repeater source, SGR 0418+5729
  50. GRB 090608: Fermi GBM detection
  51. GRB 090606: Fermi GBM detection
  52. GRB 090607: XRT Team Refined Analysis
  53. GRB 090607: Swift/UVOT Upper Limits
  54. GRB 090607: Swift-BAT refined analysis of the SHB
  55. GRB 090607: GRAS001 optical observations
  56. GRB 090607: Faulkes Telescope North observations
  57. GRB 090607: Swift detection of a burst
  58. GRB 090530B: Suzaku WAM observation of the prompt emission
  59. GRB 090530: Further NOT optical observations
  60. GRB 090530: RTT150 Optical Observation
  61. GRB 090602: Fermi GBM detection
  62. GRB 090529A: RTT150 Optical Observations
  63. GMRT observation of GRB 090424 afterglow
  64. GRB 090528: Suzaku WAM observation of the prompt emission
  65. GRB090529: Further NOT optical observations
  66. GRB 090531B: GROND observation
  67. GRB 090528B: Suzaku WAM observation of the prompt emission
  68. GRB 090530: Early RAPTOR Optical Observations
  69. GRB090529B: ROVOR Upper Limits
  70. GRB 090531A: SARA upper limit
  71. GRB 090531B: Swift/BAT spectral lag results
  72. GRB 090529C: Fermi GBM detection
  73. GRB 090529B: Fermi GBM detection
  74. GRB 090530B: Fermi GBM detection
  75. Corrections to GRB 090531B Swift/UVOT Upper Limits
  76. GRB 090531B, RIMOTS optical upper limits
  77. GRB 090531B: Swift/UVOT Upper Limits
  78. GRB 090528B: MASTER-II Kourovka optical limit
  79. GRB 090529: MITSuME optical observation
  80. GRB 090530: GRT Optical Observation
  81. GRB 090531B: Swift-BAT refined analysis
  82. GRB 090531B: Swift-XRT candidate afterglow position
  83. GRB 090531B: ROTSE-III Optical Limits
  84. GRB 090531: Swift-BAT refined analysis
  85. GRB090530: R-band Observation
  86. GRB 090530: break in light curve
  87. GRB 090531: GROND upper limits
  88. GRB 090531: P60 Observations
  89. GRB 090529: NOT optical observations
  90. GRB 090530: NOT optical observations
  91. GRB090530: Swift XRT refined analysis
  92. GRB090530: Swift/UVOT afterglow detection
  93. GRB 090529: Swift-XRT refined analysis
  94. GRB 090528B: Fermi GBM detection
  95. GRB 090528: Fermi GBM detection
  96. GRB 090530: Enhanced Swift-XRT position
  97. Strong radio emission from SN 2007bg one year after the explosion - detection of spreading, off-axis GRB jet?
  98. GRB 090530: Swift-BAT refined analysis
  99. GRB 090530: GRAS002 refined OA analysis
  100. GRB 090530: GRAS002 optical observations

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