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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 130427A optical time series
  2. GRB 130427A, Optical Observations
  3. GRB 130427A: Continued iTelescope T21 optical observations
  4. Konus-Wind observation of GRB 130427A
  5. GRB 130427A: Kanata/HOWPol optical imaging polarimetry
  6. GRB 130427A: Swift-XRT refined Analysis
  7. GRB 130427A: SPI-ACS/INTEGRAL observations
  8. GRB 130427A: Continued RATIR Optical and NIR Observations
  9. GRB 130427A: CARMA 85 GHz detection
  10. GRB 130427A: SNUO/SOAO/BOAO Observation
  11. GRB 130427A: VLA 5 GHz detection
  12. GRB 130427B: Swift-XRT refined Analysis
  13. GRB 130427A: NOT optical photometry and redshift
  14. GRB 130427B: MITSuME Okayama upper limits
  15. GRB 130427A: RAPTOR Bright Counterpart Before Swift Trigger
  16. GRB 130427A: T100 observations
  17. GRB 130427A: optical observations in CrAO
  18. GRB 130427A: Fermi GBM observation
  19. GRB130427A: Swift/UVOT followup observations of an Optical Afterglow
  20. GRB 130427A: Fermi-LAT detection of a burst
  21. GRB 130427A: Swift-BAT refined analysis
  22. GRB 130427B: Swift-BAT refined analysis
  23. GRB 130427A: Zadko observatory - Gingin optical observations
  24. GRB 130427B: Enhanced Swift-XRT position
  25. GRB 130427A: GMG optical observation
  26. GRB 130427A: MITSuME Okayama Optical Observation
  27. GRB 130427A: Optical Observations
  28. GRB 130427A: MAXI/GSC detection
  29. GRB 130427B: Faulkes Telescope North afterglow detection
  30. GRB 130427B: Swift detection of a burst with optical counterpart
  31. GRB 130427A: RATIR Optical and NIR Observations
  32. GRB 130427A: Weihai optical observations
  33. GRB 130427A: iTelescope T11 optical observations
  34. GRB 130427A: Continued P60 follow-up of an extremely bright optical afterglow
  35. GRB 130427A: Gemini-North redshift
  36. GRB 130427A: MITSuME Akeno Optical observation(T0+8000s~)
  37. GRB 130427A: PAIRITEL NIR Detections
  38. GRB 130427A: Faulkes Telescope North detection
  39. GRB 130427A: P60 early detection
  40. GRB 130427A: early optical observations
  41. GRB 130427A: P60 early nondetection
  42. GRB 130427A: Swift detection of a very bright burst with a likely bright optical counterpart
  43. Konus-Wind observation of GRB 130425A
  44. IPN Triangulation of GRB 130425A
  45. GRB 130420A: Continued Skynet/GORT Observations/Detections
  46. GRB 130420B: CARMA and VLA radio observations
  47. Trigger 554491: Swift detection of a spike possibly from Sgr A*
  48. GRB 130425A: Fermi GBM detection
  49. GRB 130420A: Continued RATIR Optical and NIR Observations
  50. GRB 130420A: ROTSE-III data analysis
  51. GRB 130420A: Continued RATIR Optical and NIR Observations
  52. GRB 130418A: Continued RATIR Optical and NIR Observations
  53. GRB 130420A: Redshift from 10.4m GTC
  54. GRB 130420A: Early RAPTOR Simultaneous Multi-Color Observations
  55. GRB 130420B: Fermi GBM observation
  56. GRB 130418A: WSRT radio observation
  57. Swift Trigger 554135 is probably not a GRB or transient
  58. GRB 130420B: RATIR Optical and NIR Observations
  59. GRB 130420A: Continued RATIR Optical and NIR Observations
  60. GRB 130420B: Swift-XRT refined Analysis
  61. GRB 130420A: Fermi GBM observation
  62. GRB 130420A: ISON-NM optical observations
  63. Skynet/GORT observations of GRB130420A
  64. GRB 130420B: Weihai optical upper limit
  65. GRB 130420B: Swift/UVOT Upper Limits
  66. GRB 130420A: Swift/UVOT Detection
  67. GRB130420B: GMG optical upper limit
  68. GRB 130420A: Swift-XRT refined Analysis
  69. GRB 130420B: Enhanced Swift-XRT position
  70. GRB 130420B, Swift-BAT refined analysis
  71. GRB 130420A, Swift-BAT refined analysis
  72. GRB 130420A: GMG optical observation
  73. Konus-Wind observation of GRB 130418A
  74. GRB 130420A: Enhanced Swift-XRT position
  75. GRB130420A : Xinglong TNT optical upper limit
  76. GRB 130420B: Faulkes Telescope North observations
  77. GRB 130420A: Weihai Optical Observations
  78. GRB 130420B: MASTER-Net optical observations
  79. GRB 130420B: Swift detection of a burst
  80. GRB 130420A: T21 optical observations
  81. GRB 130420A: RATIR Optical and NIR Observations
  82. GRB 130420A: PAIRITEL NIR detections
  83. GRB 130420A: ROTSE-III Detection of Optical Counterpart
  84. GRB 130420A: Swift detection of a burst with an optical counterpart
  85. GRB 130420A: Faulkes Telescope North candidate
  86. GRB 130418A: Continued RATIR Optical and NIR Observations
  87. GRB 130418A: Swift-XRT refined Analysis
  88. Swift Trigger 553930 is not an astrophysical source
  89. GRB 130418A: SMARTS optical/IR afterglow observations
  90. GRB 130418A: Submm observations from SMA
  91. GRB 130419A, Swift-BAT refined analysis
  92. GRB 130327B: Swift/XRT source is not the afterglow
  93. GRB 130419B (Swift trigger Trigger 553930): MASTER-Net optical observations
  94. Trigger 553930: Swift detection of a possible flare from HR 5110
  95. GRB 130418A: T21 optical observation
  96. GRB 130418A: T18 and T21 optical observations
  97. GRB 130418A: LOAO Observation
  98. GRB 130418A, Swift-BAT refined analysis
  99. GRB 130419A: Swift detection of a burst
  100. GRB130418A: VLT/X-shooter redshift confirmation

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