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

Advanced

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