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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 161015A: Swift-XRT observations
  2. GRB 161015A: Fermi GBM detection
  3. GRB 161015A: Tiled Swift observations
  4. GRB 161015A: Fermi-LAT detection
  5. GRB161004A: Further analysis of the burst nature
  6. GRB 161014A: RATIR Optical and NIR Observations
  7. GRB 161014A: Fermi GBM observation
  8. GRB 161014A: Swift-XRT refined Analysis
  9. GRB 161014A: Swift-BAT refined analysis
  10. GRB 161014A: TNG optical observations
  11. GRB 161014A: AROMA-N Optical Observation
  12. GRB 161014A: Continued MITSuME Akeno Optical Observation
  13. GRB 161014A: Swift/UVOT Detection
  14. GRB161014A: NOT optical observations
  15. GRB 161014A: GTC spectroscopy
  16. GRB 161014A: TSHAO optical observations
  17. GRB 161011A: RATIR Optical and NIR Observations
  18. GRB 161014A: Swift-XRT and UVOT afterglow detection
  19. GRB 161014A: Kanata optical observation
  20. GRB 161014A : Xinglong TNT optical observation
  21. GRB161014A: optical afterglow candidate with the LCOGT-FTS
  22. GRB 161014A: MITSuME-Akeno optical observation
  23. GRB 161014A: Swift detection of a burst
  24. GRB 161010A: Swift/UVOT Possible Detection
  25. GRB 161010A: CALET Gamma-Ray Burst Monitor detection
  26. GRB 161011A, Swift-BAT refined analysis
  27. GRB 161011A: Swift burst of interest
  28. GRB 161011A: TSHAO afterglow candidate
  29. GRB 161011A: Swift/UVOT Upper Limits
  30. GRB 161011A: Swift-XRT refined Analysis
  31. Konus-Wind observation of GRB 161010A
  32. GRB 161011A: Enhanced Swift-XRT position
  33. GRB 161010A: Swift-XRT afterglow detection
  34. GRB 161011A: Prompt enhanced Swift-XRT position
  35. GRB 161011A: Swift detection of a burst
  36. GRB 161010A: Swift ToO observations
  37. GRB 161010A: a long GRB detected by INTEGRAL
  38. GRB 161007A: NOT optical observations
  39. GRB 161007A: AbAO optical observations
  40. GRB 161007A: Mondy optical observations
  41. GRB 161007A: Swift-BAT refined analysis
  42. GRB 161007A: Swift/UVOT Upper Limits
  43. GRB 161007A: Swift-XRT refined Analysis
  44. GRB 161007A: GTC observations
  45. GRB 161007A: Enhanced Swift-XRT position
  46. GRB 161004A: Maidanak optical observations
  47. GRB 161004A: refined analysis of TSHAO optical observations
  48. GRB 161007A: Prompt enhanced Swift-XRT position
  49. GRB 161007A: MASTER-net early optical observations
  50. GRB 161007A: Swift detection of a burst
  51. GRB 160821A: Maisoncelles observatory optical observations
  52. GRB 160925A: Kottamia R-band observation
  53. Konus-Wind observation of GRB 161004B
  54. GRB 160927A: GTC observations
  55. GRB 161004B: CALET Gamma-Ray Burst Monitor detection
  56. GRB 160927A: CALET Gamma-Ray Burst Monitor ground detection
  57. GRB 161004A: Swift-BAT refined analysis
  58. GRB 150302A: late-time imaging and optical afterglow confirmation
  59. GRB 161001A: IRSF upper limits
  60. GRB 161004B: Fermi GBM detection
  61. GRB 161004B: Swift/UVOT Upper Limits
  62. GRB161004B: AstroSat CZTI detection
  63. GRB 161004B: Swift-BAT refined analysis
  64. GRB 161004B: Swift-XRT refined Analysis
  65. GRB 161004A: RATIR Optical and NIR Observations
  66. GRB 160917B: Lomonosov BDRG gamma ray discovery
  67. GRB 161004B: Enhanced Swift-XRT position
  68. GRB 160917A: Lomonosov BDRG gamma ray detection
  69. GRB 160915A: Lomonosov BDRG gamma ray detection
  70. GRB 161004B: Prompt enhanced Swift-XRT position
  71. GRB 161004B: Swift detection of a burst
  72. GRB 161004A: SAO RAS optical upper limit
  73. GRB 161004A: Swift-XRT refined Analysis
  74. GRB 161004A: Swift/UVOT Detection
  75. GRB 161004A: Enhanced Swift-XRT position
  76. Swift Trigger 715209 is not an astrophysical event
  77. GRB 161004A: Bassano Bresciano Observatory upper limit
  78. GRB 161004A: TSHAO optical observations
  79. GRB 161004A: Swift detection of a burst with a possible optical counterpart
  80. GRB 160927A: 15 GHz upper limits from AMI
  81. Konus-Wind observation of GRB 161001A (short/hard ?)
  82. GRB 161001A: MASTER-OAFA and MASTER-SAAO early optical observations
  83. GRB 161001A: GROND afterglow candidate
  84. GRB 161001A, Swift-BAT refined analysis (likely a short GRB)
  85. GRB 161001A: Fermi GBM detection
  86. GRB 161001A: Swift-XRT refined Analysis
  87. GRB 161001A: X-shooter spectroscopy, candidate host galaxy and redshift
  88. GRB 161001A: Swift/UVOT Upper Limits
  89. GRB 161001A: Enhanced Swift-XRT position
  90. GRB 161001A: Prompt enhanced Swift-XRT position
  91. GRB 161001A: Swift detection of a burst
  92. Possible radio detection of GRB 160910A with the GMRT
  93. Fermi GBM trigger 496791348/160928900 is not a GRB
  94. GRB 160927A: Magellan imaging
  95. GRB 160927A: Swift/UVOT Upper Limits
  96. GRB 160927A: Bassano Bresciano Observatory optical upper limit
  97. GRB 160927A: Swift-BAT refined analysis
  98. GRB 160927A: NOT optical observations
  99. GRB 160927A: GROND Observations
  100. GRB 160927A: Swift-XRT refined Analysis

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