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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 121027A: MASTER early prompt optical limit
  2. GRB 121027A: Swift-XRT refined Analysis
  3. GRB 121027A: Brightening IR counterpart
  4. GRB 121028A: Swift-XRT refined Analysis
  5. GRB 121028A: Enhanced Swift-XRT position
  6. GRB 121028A: Swift-BAT refined analysis
  7. GRB 121027A: Enhanced Swift-XRT position
  8. GRB 121028A: MITSuME Okayama Optical upper limits
  9. GRB 121028A: Faulkes Telescope North observations
  10. GRB 121028A: Swift detection of a burst
  11. GRB 121011A: optical observations
  12. GRB 121027A: nIR afterglow candidate with AAT
  13. GRB 121027A: Swift-BAT refined analysis
  14. GRB 121025A: Swift-XRT observation
  15. GRB 121027A: MAXI/GSC detection 40 minutes after the Swift Trigger
  16. GRB 121027A: Swift detection of a burst
  17. Swift Quick-look and HEASARC will be offline for 24 hours this weekend
  18. GRB 121024A: optical observations
  19. GRB 121024A: EVLA Detection
  20. Swift-BAT trigger 536502 is not astrophysical
  21. GRB 121024A: Swift/UVOT Observations
  22. GRB 121024A: CARMA 3mm Detection
  23. GRB 121024A: Swift-BAT refined analysis
  24. GRB 121024A: GMG optical observation
  25. GRB 121024A: MITSuME Ishigakijima upper limits
  26. GRB 121024A: MITSuME Okayama Optical upper limits
  27. GRB 121025A: MAXI/GSC detection
  28. GRB 121024A: Enhanced Swift-XRT position
  29. GRB 121024A: PAIRITEL NIR Detection
  30. GRB 121024A: Swift-XRT refined Analysis
  31. GRB 121024A: GROND Detection of the Optical/NIR Afterglow
  32. GRB 121024A: VLT/X-shooter redshift
  33. Skynet PROMPT/Dolomiti observations of GRB121024A
  34. GRB 121024A: BOOTES-1B optical detection
  35. GRB 121024A: TAROT Calern observatory optical detection of a bright counterpart
  36. GRB 121024A: Swift detection of a burst with an optical counterpart
  37. Swift Trigger 536502 is likely a noise fluctuation in coincidence with SAX J1818.6-1703
  38. GRB 121011A: early optical light curve
  39. GRB 121017A: Swift/UVOT Upper Limits
  40. GRB 121017A: Swift-XRT refined Analysis
  41. GRB 121017A: GROND Observations
  42. GRB 121017A: Swift-BAT refined analysis
  43. GRB 121017A: Enhanced Swift-XRT position
  44. GRB 121017A: 1.23m CAHA R-band observations
  45. GRB 121017A optical observations
  46. GRB 121017A: BOOTES-2/TELMA observations
  47. GRB 121017A: Swift detection of a burst
  48. GRB 121011B: Suzaku WAM observation of the prompt emission
  49. GRB 121011A Suzaku WAM observation of the prompt emission
  50. GRB 121012A: Fermi GBM detection
  51. PdB IRAM observation of GRB 121011A
  52. Konus-Wind observation of GRB 121011B
  53. GRB 121014A: Swift-BAT refined analysis
  54. GRB 121011A: WSRT radio observation
  55. GRB 121014A: Swift detection of a burst
  56. INTEGRAL Alert n.6678: NOT A GRB
  57. GRB 121011A: optical observations
  58. GRB 121011A: Swift/UVOT Detection
  59. IPN Triangulation of short hard GRB 121011B
  60. GRB 121011A: NOT redshift retraction
  61. GRB 121011A: misprint in GCNC 13854
  62. GRB 121011A: Fermi GBM observation
  63. GRB 121011A: Fermi-LAT detection of a burst
  64. Swift-BAT trigger 535733 is not astrophysical
  65. GRB 121011A: Swift-XRT refined Analysis
  66. GRB 121011A: NOT optical observations
  67. GRB 121011A: optical observations
  68. GRB 121011A: MASTER-Net bell light curve
  69. GRB 121011A: TNG optical observations
  70. GRB 121011A, Swift-BAT refined analysis
  71. Swift-BAT refined analysis of the SGR 1806-20 outburst (trigger 535747)
  72. GRB 121011A: Enhanced Swift-XRT position
  73. Planned XMM-Newton and IRAM observation of GRB 121011A
  74. GRB 121011A: MASTER-Net early OT light curve
  75. GRB121011A : Xinglong TNT optical observation
  76. GRB 121011A: MITSuME Okayama Optical Observation
  77. GRB 121011A: Swift detection of a burst with optical afterglow
  78. Trigger 535747: Swift detection of an outburst from SGR1806-20
  79. Trigger 535733: Swift possible detection of SAX J1828.5-1037
  80. GRB 120927A: optical upper limit
  81. GRB 120804A: Late-time Chandra observation
  82. GRB 121001A: GROND Afterglow Confirmation
  83. GRB 121001A: Swift/UVOT Upper Limits
  84. GRB 121001A: Swift-XRT refined Analysis
  85. GRB 121001A: Enhanced Swift-XRT Position
  86. Swift Trigger 535026 is GRB 121001A: Swift-BAT refined analysis
  87. Swift Trigger 535026: Optical decay confirmation with IAC80 and BOOTES-2/TELMA.
  88. GRB 121001A: MASTER optical observations
  89. GRB 121001A: possible optical counterpart
  90. Swift Trigger 535026: ROTSE-III Optical Limits
  91. Swift Trigger 535026: Galactic Transient or possible GRB
  92. GRB 120927A: Swift/UVOT Upper Limits
  93. GRB 120927A, Swift-BAT refined analysis
  94. GRB 120927A: GROND upper limits
  95. GRB 120927A: Swift-XRT refined Analysis
  96. GRB 120923A: Correction to GCN 13823
  97. GRB 120927A: Enhanced Swift-XRT position
  98. GRB 120923A: JHK Observation
  99. GRB 120927A: Swift detection of a burst
  100. Further Swift-XRT observations of the GRB 120919A field.

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