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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. [DRILL] Super-Kamiokande test
  2. GRB 260704A: test
  3. GRB 260704A: test
  4. GRB 260704A: VDP reachability check [20260706T063208Z]
  5. GRB foo
  6. GRB foo
  7. GRB 260704A: VDP authorized test (self-spoof, please disregard) [20260706T063208Z]
  8. GRB 260704A: VDP reachability check [20260706T063208Z]
  9. GRB 260704A: VDP authorized test (self-spoof, please disregard) [20260706T062346Z]
  10. GRB 260704A: VDP reachability check [20260706T062346Z]
  11. GRB test: this is a test
  12. [TEST] Super-Kamiokande finds a supernova in the Milky Way Galaxy
  13. GW test test test
  14. GW test test test
  15. GW Test GCN circular submission still works
  16. GRB test
  17. GRB 250115: A GRB during the coffee break at AAS
  18. GRB test from AAS
  19. GRB test
  20. GRB 000000A Testing - Have a good day!
  21. GRB 123456Z courey testing
  22. GRB Test
  23. GRB testing
  24. GRB iOS chrome again
  25. grb123: iOS Chrome testing
  26. GRB testing iOS
  27. GRB test from Chrome iOS
  28. GRB testing
  29. GRB Testing for Kafka
  30. GRB Testing
  31. GRB foobar
  32. GRB foobar test
  33. GRB testing 3
  34. GRB testing 2
  35. GRB testing
  36. GRB test 4
  37. GRB test 3
  38. GRB test 2
  39. GRB test
  40. GRB foobar
  41. GRB foobar
  42. LIGO/Virgo/KAGRA S230627c: Zwicky Transient Facility observations and candidates
  43. LIGO/Virgo/KAGRA S230627c: Zwicky Transient Facility observations and candidates
  44. GRB foobar
  45. GRB foobar
  46. PKS2326-505, millimeter wavelength flare, transient
  47. GRB foo 3
  48. GRB foo 2
  49. GRB foo
  50. GRB foo
  51. GRB foo
  52. GRB foo
  53. GRB test
  54. GRB foo
  55. GRB foobar
  56. GRB foobar
  57. GRB foobar
  58. GRB foobar
  59. GRB foobar
  60. GRB test
  61. MAGIC test
  62. GRB test
  63. GRB foo
  64. Test GCN GW submission
  65. GRB test 2
  66. GRB test
  67. GRB test
  68. Test GW GCN hermes submission 2
  69. Test GW GCN hermes submission
  70. Test GW GCN hermes submission
  71. A GRB test
  72. TEST GW GCN hermes submission
  73. GRB 170817A: an awesome GCN Circular
  74. VIRT optical transient detection
  75. GRB 230414B: 3.6m DOT Optical observations, slow decay at early epochs
  76. GRB 230307A: iTelescope optical upper limit (likely)
  77. GRB 230414B: Montarrenti Observatory late time optical afterglow detection
  78. IceCube-230416A: IceCube observation of a high-energy neutrino candidate
  79. Fermi trigger No 703284533: Global MASTER-Net observations report
  80. GRB 230414B: Lulin 40cm-SLT optical limit
  81. GRB 230414B: Bassano Bresciano Observatory optical observations
  82. GRB 230414B: Redshift from OSIRIS/GTC
  83. GRB 230414B: AbAO optical observations
  84. GRB 230409B: 3.6m DOT near-infrared detection, afterglow confirmation
  85. GRB 230414B: Swift-XRT refined Analysis
  86. GRB 230414B: Dabancheng/GHOST optical observations
  87. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230414A
  88. GRB 230414B: slow optical light curve decay
  89. GRB 230414B: SAO RAS optical observations
  90. GRB 230414B: Enhanced Swift-XRT position
  91. GRB 230414B: 1.3m DFOT Optical observations
  92. Fermi GRB 230414A: Global MASTER-Net observations report
  93. GRB 230414B: GROWTH India Telescope afterglow confirmation
  94. GRB 230414B (correction GRB name in the GCN 33615): Mondy optical afterglow candidate
  95. GRB 230414B: Nanshan/HMT optical afterglow detection
  96. GRB 230414A: Mondy optical afterglow candidate
  97. Swift GRB 230414B: Global MASTER-Net observations report
  98. GRB 230414B: Prompt enhanced Swift-XRT position
  99. GRB 230414B: Swift detection of a burst
  100. IceCube-230405A: BOOTES-4/MET Optical Upper Limits

Advanced

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