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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"

23417 results found.

  1. PAIRITEL observations of GRB 090618
  2. GRB 090621B: I-band observations from 1.23m CAHA
  3. GRB 090621D: Fermi GBM detection
  4. GRB 090621C: Fermi GBM detection
  5. GRB 090621B: P60 Observations
  6. GRB 090621B: VLA observations
  7. GRB 090620: Fermi GBM detecion
  8. GRB 090621B: Swift/UVOT Upper Limits
  9. GRB 090621B: RTT150 optical observations
  10. GRB 090621B: Swift detection of a short hard burst
  11. GRB 090621: Swift/UVOT Upper Limits
  12. GRB090618: Spectrum and photometry from 6.0m BTA
  13. GRB 090621: Swift detection of a burst
  14. GRB090618: OAA-OAUV Optical observations
  15. VLA radio detection of GRB 090618
  16. GRB 090618 15GHz radio detection
  17. GRB090618 - Continued optical monitoring and light curve break
  18. GRB 090618: SARA observations
  19. GRB090618: Swift/UVOT bright afterglow detection
  20. GRB 090618: SDSS host detection
  21. Swift XRT observations of GRB 090531A
  22. GRB 090618: AGILE observations
  23. GRB 090617: Fermi GBM detection
  24. GRB 090618: Enhanced Swift-XRT position
  25. GRB 090618 Faulkes Telescope North observations
  26. GRB 090618: Lick/KAST Spectroscopy
  27. GRB090618: P60 Optical Afterglow
  28. GRB 090618: Swift detection of a bright burst with optical afterglow
  29. GRB 090616: Fermi GBM detection
  30. GRB 090612: Fermi GBM detection
  31. GRB 090610C: Fermi GBM detection
  32. GRB 090610B: Fermi GBM detection
  33. GRB 090610: Fermi GBM detection
  34. SGR 0418+5729 Fermi/GBM Detection of Pulsations
  35. RXTE Discovery of Pulsations from SGR 0418+5729
  36. Discovery of a new soft gamma repeater source, SGR 0418+5729
  37. GRB 090608: Fermi GBM detection
  38. GRB 090606: Fermi GBM detection
  39. GRB 090607: Swift/UVOT Upper Limits
  40. GRB 090607: GRAS001 optical observations
  41. GRB 090607: Faulkes Telescope North observations
  42. GRB 090607: Swift detection of a burst
  43. GRB 090530: Further NOT optical observations
  44. GRB 090530: RTT150 Optical Observation
  45. GRB 090602: Fermi GBM detection
  46. GRB 090529A: RTT150 Optical Observations
  47. GMRT observation of GRB 090424 afterglow
  48. GRB090529: Further NOT optical observations
  49. GRB 090531B: GROND observation
  50. GRB 090530: Early RAPTOR Optical Observations
  51. GRB090529B: ROVOR Upper Limits
  52. GRB 090531A: SARA upper limit
  53. GRB 090531B: Swift/BAT spectral lag results
  54. GRB 090529C: Fermi GBM detection
  55. GRB 090529B: Fermi GBM detection
  56. GRB 090530B: Fermi GBM detection
  57. Corrections to GRB 090531B Swift/UVOT Upper Limits
  58. GRB 090531B, RIMOTS optical upper limits
  59. GRB 090531B: Swift/UVOT Upper Limits
  60. GRB 090529: MITSuME optical observation
  61. GRB 090530: GRT Optical Observation
  62. Initial Swift/UVOT observations of GRB 090531B
  63. GRB 090531B: Swift-XRT candidate afterglow position
  64. GRB 090531B: ROTSE-III Optical Limits
  65. GRB 090531B: Swift detection of a burst
  66. GRB090530: R-band Observation
  67. GRB 090530: break in light curve
  68. GRB 090531: GROND upper limits
  69. GRB 090531: P60 Observations
  70. GRB 090531: Swift detection of a burst
  71. GRB 090529: NOT optical observations
  72. GRB 090530: NOT optical observations
  73. GRB090530: Swift/UVOT afterglow detection
  74. GRB 090529: Swift-XRT refined analysis
  75. GRB 090528B: Fermi GBM detection
  76. GRB 090528: Fermi GBM detection
  77. GRB 090530: Enhanced Swift-XRT position
  78. GRB 090530: Swift-BAT refined analysis
  79. GRB 090530: GRAS002 refined OA analysis
  80. GRB 090530: GRAS002 optical observations
  81. GRB 090530: PAIRITEL NIR Detections
  82. GRB 090530: Swift detection of a burst with an optical counterpart
  83. GRB 090529: TLS Afterglow Observations
  84. GRB090529: UVOT/Swift detection of a brightening optical afterglow
  85. GRB 090529: Swift-BAT refined analysis
  86. GRB 090529: Enhanced Swift-XRT position
  87. GRB 090529: Preliminary Swift/UVOT Upper Limit
  88. GRB 090529: Swift detection of a burst
  89. GRB 090520D: Fermi GBM detection
  90. GRB 090520C: Fermi GBM detection
  91. GRB 090520B: Fermi GBM detection
  92. GRB 090522 : Fermi GBM detection
  93. GRB 090524: Fermi GBM detection
  94. GRB 090518 - NOT upper limit
  95. GRB 090516A: Konus-Wind and Swift/BAT joint spectral analysis
  96. GRB 090513B: Fermi GBM detection
  97. GRB 090520: GROND upper limits
  98. GRB 090516C: Fermi GBM detection
  99. GRB 090520 Swift-BAT detection of a burst in ground analysis
  100. GRB 090516B: Fermi GBM detection

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