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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 160310A: Swift-XRT observations
  2. GRB 160310A: Fermi GBM observation
  3. GRB 160303A: GTC imaging of possible host galaxy
  4. GRB 160310A: Swift ToO observations
  5. GRB 160310A: Fermi-LAT detection
  6. Swift Trigger 678197 is a noise fluctuation
  7. LIGO/Virgo G211117: HAWC follow-up of northern sky
  8. Trigger 677981: Swift detection of IGRJ17091-3624
  9. GRB 160303A: X-shooter spectroscopy
  10. Swift trigger 677890 is noise
  11. GRB 160303A: Continued optical monitoring from NOT
  12. GRB 160303A: JCMT SCUBA-2 sub-mm observation
  13. GRB160303A: further GROND observations
  14. GRB 160303A: 9.8 GHz VLA upper limit
  15. GRB 160303A, Swift-BAT refined analysis
  16. GRB 160303A: MMT Optical Detection
  17. GRB 160303A: Continued RATIR Optical and NIR Observations
  18. LIGO/Virgo G211117: GRAWITA LBT follow-up of PS15dpn
  19. GRB 160303A: GROND Optical Detection
  20. GRB 160303A: Observations from T150 OSN
  21. GRB 160303A: VLT/FORS2 afterglow obervations
  22. GRB 160303A: BOAO R-band Detection
  23. GRB 160303A: McDonald 2.1m CQUEAN Detection
  24. GRB 160303A SMA observation
  25. GRB 160303A iTelescope observation
  26. GRB 160303A: Swift-XRT refined Analysis
  27. GRB 160303A: Optical observations from the NOT
  28. Swift possibly triggered on IGR17091-3624
  29. GRB 160303A: Swift/UVOT Detection
  30. GRB 160303A: RAPTOR Observations During Gamma-Ray Emitting Interval
  31. GRB 160303A: Enhanced Swift-XRT position
  32. GRB 160303A: RATIR Optical and NIR Afterglow Detection
  33. GRB 160303A: MITSuME Akeno optical upper limits
  34. GRB 160303A: LCOGT-FTN optical observations
  35. GRB 160303A: MITSuME Okayama upper limits
  36. GRB 160303A: ISON-NM early optical early limits
  37. GRB 160303A: Swift detection of a burst, possibly short
  38. GRB 160227A: LOAO 1.0m optical detection
  39. GRB 160227A: McDonald 0.8m Detection
  40. GRB 160228A: Swift/UVOT Upper Limits
  41. GRB 160227A: Swift/UVOT Detection
  42. GRB160228A: Further analyses on spectral lag and extended emission
  43. GRB 160228A: Mondy optcial observations
  44. GRB 160228A: RATIR Optical and NIR Observations
  45. GRB 160228A: MASTER-Amur prompt observations
  46. GRB 160228A: Swift-XRT refined Analysis
  47. GRB 160227A: MASTER prompt OT Detection and LC
  48. GRB 160227A: AROMA-N Optical Observation
  49. GRB 160228A: GROND Afterglow Candidate
  50. GRB 160228A: Swift-BAT refined analysis
  51. GRB 160228A: optical observations
  52. GRB 160227B: Fermi GBM detection
  53. GRB 160228A: Enhanced Swift-XRT position
  54. GRB 160227A: NOT redshift
  55. GRB 160228A: Prompt enhanced Swift-XRT position
  56. GRB 160228A: Swift detection of a burst
  57. GRB 160227A, Swift-BAT refined analysis
  58. GRB 160227A: Swift-XRT refined Analysis
  59. GRB 160227A: Enhanced Swift-XRT position
  60. GRB 160227A: MAXI/GSC detection
  61. GRB 160225A: TSHAO optical afterglow detection
  62. GRB 160227A: ISON-Kislovodsk optical observation
  63. GRB 160227A: Mt. Terskol observatory optical observation
  64. GRB 160227A: MASTER OT Detection
  65. GRB 160227A: Swift detection of a burst with an optical counterpart
  66. GRB 160225A: LOAO optical upper limit
  67. GRB 160225B: Fermi GBM detection
  68. IPN Triangulation of GRB 160225B
  69. GRB 160225.81/FERMI Trigg 478121069: MASTER OT J095503.19-355149.4 follow up observations
  70. GRB 160225A: Continued RATIR Optical and NIR Observations
  71. GRB 160225.81/FERMI Trigg 478121069: MASTER OT J095503.19-355149.4 detection
  72. GRB 160225A: Swift-BAT refined analysis
  73. Fermi GBM trigger 478156376/16022621 is not a GRB
  74. GRB 160225A: MASTER-Amur observations
  75. GRB 160225A: RATIR Optical and NIR Observations
  76. GRB 160225A: Swift/UVOT Upper Limits
  77. GRB 160225A: Xinglong TNT optical observation
  78. GRB 160223B: CALET Gamma-Ray Burst Monitor detection
  79. GRB 160225A: Swift-XRT refined Analysis
  80. GRB 160225A: NOT optical observations
  81. GRB 160225A: WHT LIRIS observations
  82. GRB 160225A: MITSuME Okayama Optical Observation
  83. GRB 160225A: MITSuME Akeno Optical Observation
  84. GRB 160223A: RATIR Optical and NIR Observations
  85. GRB 160225A: TSHAO optical upper limit
  86. GRB 160225A: Enhanced Swift-XRT position
  87. GRB 160225A: MASTER-Amur early observations
  88. GRB 160225A: Swift detection of a burst
  89. GRB 160223A: Swift-XRT afterglow detection
  90. GRB 160221A: Swift-XRT afterglow detection
  91. GRB 160223A: AbAO optical observations
  92. Swift trigger 675784 is probably not an astrophysical source
  93. Konus-Wind observation of GRB 160219A
  94. GRB 160223B: MASTER-Amur early observations
  95. Fermi GBM trigger 477460274/160218161 is not a GRB
  96. Fermi GBM trigger 477985003/160224234 is not a GRB
  97. GRB 160223A: Swift-BAT refined analysis
  98. GRB 160223B: Khureltogot optical observations
  99. GRB 160223A: Fermi GBM observation
  100. GRB 160223B: Swift-XRT observations

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