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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"

27563 results found.

  1. GRB 090529: Mt.Terskol optical observations
  2. XRF 090702: Swift-XRT refined analysis
  3. GRB 090703: Fermi GBM detection
  4. GRB 090702: UVOT upper limits
  5. XRF 090702: VLT imaging
  6. XRF 090702: Swift-XRT afterglow position
  7. GRB 090404: Deep optical imaging and possible host association
  8. GRB 090701: Fermi GBM detection
  9. GRB 090628: Swift XRT refined analysis
  10. GRB 090630: Fermi GBM detection
  11. GRB 090628: Swift/UVOT Upper Limits
  12. GRB080628: SAO RAS optical observations
  13. GRB 090628: GROND upper limits
  14. GRB 090628: Enhanced Swift-XRT position
  15. GRB 090628: 1.23m CAHA optical observations
  16. GRB 090628: Swift/UVOT Finding Chart Observation
  17. GRB 090628: Swift XRT position
  18. GRB 090628: Swift detection of a burst
  19. GRB 090423: Spitzer observations of the z~8.3 burst
  20. GRB 090625B: Swift/UVOT Upper Limits
  21. GRB 090625B: Swift-XRT refined analysis
  22. GRB 090626: Fermi GBM detection
  23. GRB 090625B: GROND upper limits
  24. GRB090618: HCT optical observations
  25. GRB 090618: SARA Second Epoch Observations
  26. GRB 090625B: Faulkes Telescope South observations
  27. GRB 090625B: Swift observation of the INTEGRAL GRB 090625B
  28. GRB 090625: Fermi GBM detection
  29. GRB 090621A: Enhanced Swift-XRT position
  30. GRB 090623: Fermi GBM detection
  31. GRB 090621B: GRT Optical Observation
  32. GRB 090621A: GRT Optical Observation
  33. PAIRITEL observations of GRB 090618
  34. GRB 090621B: Fermi GBM detection
  35. GRB 090621B: I-band observations from 1.23m CAHA
  36. GRB 090621D: Fermi GBM detection
  37. GRB 090621B: Gemini spectrum of afterglow candidate
  38. GRB 090621C: Fermi GBM detection
  39. GRB 090621B: P60 Observations
  40. GRB 090621B: VLA observations
  41. GRB 090621B: Swift/UVOT Upper Limits
  42. GRB 090621B: Swift-XRT refined analysis
  43. GRB 090621B: RTT150 optical observations
  44. GRB 090621B: Optical Observations
  45. GRB 090621B: Swift detection of a short hard burst
  46. GRB 090621: Swift/UVOT Upper Limits
  47. GRB 090621: Swift-XRT Team refined analysis
  48. GRB090618: Spectrum and photometry from 6.0m BTA
  49. GRB 090618: BOAO V-band Observation
  50. GRB 090621: Swift detection of a burst
  51. GRB 090618: ZTSh optical observations
  52. GRB 090618 : WSRT radio detection
  53. GRB090618, underlying supernova search
  54. GRB090618: OAA-OAUV Optical observations
  55. VLA radio detection of GRB 090618
  56. GRB 090618 15GHz radio detection
  57. GRB 090618: SARA observations
  58. GRB090618: Swift-XRT team refined analysis
  59. GRB090618: Swift/UVOT bright afterglow detection
  60. GRB 090618: SDSS host detection
  61. Swift XRT observations of GRB 090531A
  62. GRB 090617: Fermi GBM detection
  63. GRB 090618: LOAO R-band Observation
  64. GRB 090618: Enhanced Swift-XRT position
  65. GRB 090618 Faulkes Telescope North observations
  66. GRB 090618: Lick/KAST Spectroscopy
  67. GRB 090618: ROTSE-III Detection of Optical Counterpart
  68. GRB 090618: KAIT optical afterglow
  69. GRB090618: P60 Optical Afterglow
  70. GRB 090618: Swift detection of a bright burst with optical afterglow
  71. GRB 090616: Fermi GBM detection
  72. GRB 090612: Fermi GBM detection
  73. GRB 090610C: Fermi GBM detection
  74. GRB 090610B: Fermi GBM detection
  75. GRB 090610: Fermi GBM detection
  76. SGR 0418+5729 Fermi/GBM Detection of Pulsations
  77. GRB 090424: WSRT Radio Observations
  78. GRB 090423: WSRT Radio Observations
  79. RXTE Discovery of Pulsations from SGR 0418+5729
  80. GRB 090531B: Fermi GBM detection
  81. GRB 090608: Fermi GBM detection
  82. GRB 090606: Fermi GBM detection
  83. GRB 090607: XRT Team Refined Analysis
  84. GRB 090607: Swift/UVOT Upper Limits
  85. GRB 090607: GRAS001 optical observations
  86. GRB 090607: Faulkes Telescope North observations
  87. GRB 090607: Swift detection of a burst
  88. GRB 090530: Further NOT optical observations
  89. GRB 090530: RTT150 Optical Observation
  90. GRB 090602: Fermi GBM detection
  91. GRB 090529A: RTT150 Optical Observations
  92. GMRT observation of GRB 090424 afterglow
  93. GRB090529: Further NOT optical observations
  94. GRB 090531b, SMARTS optical/IR observations
  95. GRB 090531B: GROND observation
  96. GRB090529B: ROVOR Upper Limits
  97. GRB 090529C: Fermi GBM detection
  98. GRB 090529B: Fermi GBM detection
  99. GRB 090530B: Fermi GBM detection
  100. GRB 090531B: Swift/UVOT Upper Limits

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