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

Advanced

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