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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 150413A: SAO RAS observations
  2. LOAO B, R Observations of GRB150413A
  3. Swift Trigger 638217 is probably not an astrophysical source
  4. GRB 150416A: Fermi-LAT detection
  5. GRB 150413A: Refined redshift
  6. GRB 150413A: GMG observation
  7. GRB 150413A: AMI 15 GHz detection of possible radio counterpart
  8. GRB 150413A: additional P60 observations
  9. GRB 150413A : Virtual Telescope optical observations
  10. GRB 150413A
  11. GRB 150413A: Bassano Bresciano Observatory optical observations
  12. Konus-Wind observation of a bright burst from SGR 1935+2154
  13. GRB 150413A: T7 and T18 optical observations
  14. GRB 150413A: Swift-BAT refined analysis
  15. GRB150413A, optical observations
  16. IPN Triangulation of a bright burst from SGR 1935+2154
  17. GRB 150413A: optical observations
  18. GRB 150413A: redshift determination with the 2.2m CAHA
  19. GRB 150413A: P60 photometry
  20. GRB 150413A: Khureltogot optical observations
  21. GRB 150413A: Tautenburg observations
  22. GRB 150413A: Nanshan optical and radio follow-ups
  23. GRB 150413A: Khureltogot optical observations
  24. GRB 150413A: MAXI/GSC detection
  25. GRB 150413A: MASTER very bright unusual OT observations
  26. GRB 150413A: MASTER bright OT detection
  27. GRB 150413A: Swift detection of a burst
  28. Swift trigger 637807 is probably not an astrophysical source
  29. Swift detection of SAX J1808.4-3658
  30. Swift GRB150402A: further XRT observations
  31. GRB 150407A: Swift-XRT observations
  32. GRB 150407A: optical observations
  33. GRB 150407A: Swift detection of a possible burst
  34. GRB 150407A: Swift ToO observations
  35. GRB 150403A: MASTER-net optical observation
  36. Swift triggered on a source in Terzan 5 (trigger=637212)
  37. GRB 150404A: Fermi GBM detection
  38. Konus-Wind observation of GRB 150403A
  39. Fermi trigger 449861706: MASTER-SAAO possible candidate to OT of Short GRB
  40. GRB 150403A: Swift-BAT refined analysis
  41. GRB 150403A: Fermi GBM Detection
  42. GRB 150403A: Swift/UVOT Detection
  43. GRB 150403A: VLT/X-shooter redshift
  44. GRB 150323C: CrAO optical observations
  45. GRB 150323C: additional optical observations in Mondy
  46. GRB 150323C: Khureltogot optical observations
  47. GRB 150403A: Swift-XRT refined Analysis
  48. GRB 150403A: Fermi-LAT detection
  49. GRB 150403A: Enhanced Swift-XRT position
  50. GRB 150403A: Swift detection of a burst with an optical counterpart
  51. GRB 150402A: results of Swift observations
  52. GRB 150402A: RATIR Optical Observations
  53. GRB 150402A: Swift ToO observations
  54. GRB 150402A detected in ground analysis of Swift-BAT data
  55. Konus-Wind observation of GRB 150330A
  56. IPN Triangulation of GRB 150330A (long/very intense)
  57. GRB 150330A: Fermi GBM detection
  58. GRB 150323B: Swift-XRT afterglow detection
  59. GRB 141121A: GMG observation
  60. GRB 150323C: possible host galaxy detection
  61. GRB 141212A: GMG observation limit
  62. GRB 141220A: GMG observation limit
  63. GRB 141225A: GMG observation limit
  64. GRB 150120B: GMG observation
  65. GRB 150317A: likely host galaxy detection
  66. GRB 150323B: Khureltogot optical observations
  67. GRB 150323C: Nishi-Harima NIR Observations
  68. GRB 150323A: AAO optical observations
  69. GRB 150323C: MITSuME Akeno Optical observation
  70. GRB 150220A: Optical observations at Kyiv comet station
  71. GRB 150323C; Konkoly optical observations
  72. GRB 150323B; Konkoly optical observations
  73. GRB 150323A; Konkoly optical observations
  74. Konus-Wind observation of GRB 150323B
  75. Konus-Wind observation of GRB 150323A
  76. GRB 150323C: Mondy optical observations
  77. GRB 150323B : Xinglong TNT upper limit
  78. GRB 150323C, Swift-BAT refined analysis
  79. GRB 150323C: RATIR Optical Afterglow Observations - Errata
  80. GRB 150323C: Swift/UVOT Upper Limits
  81. GRB 150323B: Swift-XRT observations
  82. GRB 150323C: Enhanced Swift-XRT position
  83. GRB 150323C: RATIR Optical Afterglow Observations
  84. GRB 150323C : Xinglong TNT optical observation
  85. GRB 150323C: Swift-XRT refined Analysis
  86. GRB 150323C: Xingming upper limit
  87. GRB 150323A, Swift-BAT refined analysis
  88. GRB150323C: Fermi GBM detection
  89. GRB 150323A: KAIT Optical Observations
  90. GRB 150323C: Nanshan optical afterglow detection
  91. GRB 150323C: Prompt enhanced Swift-XRT position
  92. GRB 150323B: Fermi GBM observation
  93. GRB 150323C: MASTER-net optical observation
  94. GRB 150323C: Swift detection of a burst
  95. GRB 150323B: Swift ToO observations
  96. GRB 150323B detected in ground analysis of Swift-BAT data
  97. GRB 150323A: Swift-XRT refined Analysis
  98. GRB150323A: Swift-UVOT detection of the afterglow
  99. GRB 150323A: Keck redshift
  100. GRB 150323A: Enhanced Swift-XRT position

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Download all Circulars as a .tar.gz archive (updated once a day):
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