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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 121025A: Swift-XRT observation
  2. GRB 121027A: MAXI/GSC detection 40 minutes after the Swift Trigger
  3. GRB 121027A: Swift detection of a burst
  4. Swift Quick-look and HEASARC will be offline for 24 hours this weekend
  5. GRB 121024A: optical observations
  6. GRB 121024A: EVLA Detection
  7. Swift-BAT trigger 536502 is not astrophysical
  8. GRB 121024A: Swift/UVOT Observations
  9. GRB 121024A: CARMA 3mm Detection
  10. GRB 121024A: Swift-BAT refined analysis
  11. GRB 121024A: GMG optical observation
  12. GRB 121024A: MITSuME Ishigakijima upper limits
  13. GRB 121024A: MITSuME Okayama Optical upper limits
  14. GRB 121025A: MAXI/GSC detection
  15. GRB 121024A: Enhanced Swift-XRT position
  16. GRB 121024A: PAIRITEL NIR Detection
  17. GRB 121024A: Swift-XRT refined Analysis
  18. GRB 121024A: GROND Detection of the Optical/NIR Afterglow
  19. GRB 121024A: VLT/X-shooter redshift
  20. Skynet PROMPT/Dolomiti observations of GRB121024A
  21. GRB 121024A: BOOTES-1B optical detection
  22. GRB 121024A: TAROT Calern observatory optical detection of a bright counterpart
  23. GRB 121024A: Swift detection of a burst with an optical counterpart
  24. Swift Trigger 536502 is likely a noise fluctuation in coincidence with SAX J1818.6-1703
  25. GRB 121011A: early optical light curve
  26. GRB 121017A: Swift/UVOT Upper Limits
  27. GRB 121017A: Swift-XRT refined Analysis
  28. GRB 121017A: GROND Observations
  29. GRB 121017A: Swift-BAT refined analysis
  30. GRB 121017A: Enhanced Swift-XRT position
  31. GRB 121017A: 1.23m CAHA R-band observations
  32. GRB 121017A optical observations
  33. GRB 121017A: BOOTES-2/TELMA observations
  34. GRB 121017A: Swift detection of a burst
  35. GRB 121011B: Suzaku WAM observation of the prompt emission
  36. GRB 121011A Suzaku WAM observation of the prompt emission
  37. GRB 121012A: Fermi GBM detection
  38. PdB IRAM observation of GRB 121011A
  39. Konus-Wind observation of GRB 121011B
  40. GRB 121014A: Swift-BAT refined analysis
  41. GRB 121011A: WSRT radio observation
  42. GRB 121014A: Swift detection of a burst
  43. INTEGRAL Alert n.6678: NOT A GRB
  44. GRB 121011A: optical observations
  45. GRB 121011A: Swift/UVOT Detection
  46. IPN Triangulation of short hard GRB 121011B
  47. GRB 121011A: NOT redshift retraction
  48. GRB 121011A: misprint in GCNC 13854
  49. GRB 121011A: Fermi GBM observation
  50. GRB 121011A: Fermi-LAT detection of a burst
  51. Swift-BAT trigger 535733 is not astrophysical
  52. GRB 121011A: Swift-XRT refined Analysis
  53. GRB 121011A: NOT optical observations
  54. GRB 121011A: optical observations
  55. GRB 121011A: MASTER-Net bell light curve
  56. GRB 121011A: TNG optical observations
  57. GRB 121011A, Swift-BAT refined analysis
  58. Swift-BAT refined analysis of the SGR 1806-20 outburst (trigger 535747)
  59. GRB 121011A: Enhanced Swift-XRT position
  60. Planned XMM-Newton and IRAM observation of GRB 121011A
  61. GRB 121011A: MASTER-Net early OT light curve
  62. GRB121011A : Xinglong TNT optical observation
  63. GRB 121011A: MITSuME Okayama Optical Observation
  64. GRB 121011A: Swift detection of a burst with optical afterglow
  65. Trigger 535747: Swift detection of an outburst from SGR1806-20
  66. Trigger 535733: Swift possible detection of SAX J1828.5-1037
  67. GRB 120927A: optical upper limit
  68. GRB 120804A: Late-time Chandra observation
  69. GRB 121001A: GROND Afterglow Confirmation
  70. GRB 121001A: Swift/UVOT Upper Limits
  71. GRB 121001A: Swift-XRT refined Analysis
  72. GRB 121001A: Enhanced Swift-XRT Position
  73. Swift Trigger 535026 is GRB 121001A: Swift-BAT refined analysis
  74. Swift Trigger 535026: Optical decay confirmation with IAC80 and BOOTES-2/TELMA.
  75. GRB 121001A: MASTER optical observations
  76. GRB 121001A: possible optical counterpart
  77. Swift Trigger 535026: ROTSE-III Optical Limits
  78. Swift Trigger 535026: Galactic Transient or possible GRB
  79. GRB 120927A: Swift/UVOT Upper Limits
  80. GRB 120927A, Swift-BAT refined analysis
  81. GRB 120927A: GROND upper limits
  82. GRB 120927A: Swift-XRT refined Analysis
  83. GRB 120923A: Correction to GCN 13823
  84. GRB 120927A: Enhanced Swift-XRT position
  85. GRB 120923A: JHK Observation
  86. GRB 120927A: Swift detection of a burst
  87. Further Swift-XRT observations of the GRB 120919A field.
  88. GRB 120923A: optical upper limit
  89. GRB 120921A: Fermi GBM detection of its 1000th GRB
  90. GRB 120923A: RAPTOR Early Afterglow Limits
  91. GRB 120923A: MITSuME Okayama Optical upper limits
  92. GRB 120916A Suzaku WAM observation of the prompt emission
  93. GRB 120923A: RAPTOR Limits During Gamma-Ray Emitting Interval
  94. GRB 120923A: CARMA Observations
  95. GRB 120923A: EVLA Observations
  96. GRB 120923A: Swift-XRT refined Analysis
  97. GRB 120923A: GROND Upper limits
  98. GRB 120922A: GROND photometric redshift
  99. GRB 120922A: Fermi GBM detection
  100. GRB 120922A: Swift/UVOT Detection

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