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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"

35422 results found.

  1. PAIRITEL observations of GRB 090618
  2. GRB 090621B: Fermi GBM detection
  3. GRB 090621B: I-band observations from 1.23m CAHA
  4. GRB 090621D: Fermi GBM detection
  5. GRB 090621B: Gemini spectrum of afterglow candidate
  6. GRB 090621C: Fermi GBM detection
  7. GRB 090621B: P60 Observations
  8. GRB 090621: Fermi GBM observation
  9. GRB 090621B: VLA observations
  10. GRB 090620: Fermi GBM detecion
  11. Konus-Wind and Konus-RF observations of GRB 090618
  12. GRB 090621B: Swift/UVOT Upper Limits
  13. GRB 090621B: Swift-BAT refined analysis
  14. GRB 090621B: Swift-XRT refined analysis
  15. GRB 090621B: RTT150 optical observations
  16. GRB 090618: RTT150 optical observations
  17. GRB 090621B: Optical Observations
  18. GRB 090621A: Swift-BAT refined analysis
  19. GRB 090621B: Swift detection of a short hard burst
  20. GRB 090621: Swift/UVOT Upper Limits
  21. GRB 090621: Swift-XRT Team refined analysis
  22. GRB 090618: BOAO V-band Observation
  23. GRB 090621: Swift detection of a burst
  24. GRB 090618: ZTSh optical observations
  25. GRB 090618 : WSRT radio detection
  26. GRB090618, underlying supernova search
  27. GRB 090618: Fermi GBM observation
  28. GRB 090618, Swift-BAT refined spectral analysis
  29. VLA radio detection of GRB 090618
  30. GRB 090618 15GHz radio detection
  31. GRB 090618: Swift-BAT refined analysis
  32. GRB 090618: SARA observations
  33. GRB090618: Swift-XRT team refined analysis
  34. GRB090618: Swift/UVOT bright afterglow detection
  35. GRB 090618: SDSS host detection
  36. Swift XRT observations of GRB 090531A
  37. GRB 090618: AGILE observations
  38. GRB 090617: Fermi GBM detection
  39. GRB 090618: LOAO R-band Observation
  40. GRB 090618: Enhanced Swift-XRT position
  41. GRB 090618 Faulkes Telescope North observations
  42. Optical observations of GRB 090618
  43. GRB 090618: Lick/KAST Spectroscopy
  44. GRB 090618: OA behavior from KAIT
  45. GRB 090618: planned XMM-Newton observation
  46. GRB 090618: ROTSE-III Detection of Optical Counterpart
  47. GRB 090618: KAIT 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. GRB 090602: Suzaku WAM observation of the prompt emission
  55. GRB 090424: WSRT Radio Observations
  56. GRB 090423: WSRT Radio Observations
  57. GRB 090531B: Fermi GBM detection
  58. GRB 090608: Fermi GBM detection
  59. GRB 090606: Fermi GBM detection
  60. GRB 090607: XRT Team Refined Analysis
  61. GRB 090607: Swift/UVOT Upper Limits
  62. GRB 090607: Swift-BAT refined analysis of the SHB
  63. GRB 090607: GRAS001 optical observations
  64. GRB 090607: Faulkes Telescope North observations
  65. GRB 090607: Swift detection of a burst
  66. GRB 090530B: Suzaku WAM observation of the prompt emission
  67. GRB 090530: Further NOT optical observations
  68. GRB 090530: RTT150 Optical Observation
  69. GRB 090602: Fermi GBM detection
  70. GRB 090529A: RTT150 Optical Observations
  71. GMRT observation of GRB 090424 afterglow
  72. GRB 090528: Suzaku WAM observation of the prompt emission
  73. GRB090529: Further NOT optical observations
  74. GRB 090531b, SMARTS optical/IR observations
  75. GRB 090531B: GROND observation
  76. GRB 090528B: Suzaku WAM observation of the prompt emission
  77. GRB 090530: Early RAPTOR Optical Observations
  78. GRB090529B: ROVOR Upper Limits
  79. GRB 090531A: SARA upper limit
  80. GRB 090531B: Swift/BAT spectral lag results
  81. GRB 090529C: Fermi GBM detection
  82. GRB 090529B: Fermi GBM detection
  83. GRB 090530B: Fermi GBM detection
  84. Corrections to GRB 090531B Swift/UVOT Upper Limits
  85. GRB 090531B, RIMOTS optical upper limits
  86. GRB 090531B: Swift/UVOT Upper Limits
  87. GRB 090528B: MASTER-II Kourovka optical limit
  88. GRB 090529: MITSuME optical observation
  89. GRB 090530: GRT Optical Observation
  90. GRB 090531B: Swift-BAT refined analysis
  91. Initial Swift/UVOT observations of GRB 090531B
  92. GRB 090531B: Swift-XRT candidate afterglow position
  93. GRB 090531B: ROTSE-III Optical Limits
  94. GRB 090531B: Swift detection of a burst
  95. GRB 090531: Swift-BAT refined analysis
  96. GRB090530: R-band Observation
  97. GRB 090530: break in light curve
  98. GRB 090529: VLT spectroscopic redshift
  99. GRB 090531: GROND upper limits
  100. GRB 090531: P60 Observations

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