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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: VDP authorized test (self-spoof, please disregard) [20260706T063208Z]
  2. GRB 260704A: VDP reachability check [20260706T063208Z]
  3. GRB 260704A: VDP authorized test (self-spoof, please disregard) [20260706T062346Z]
  4. GRB 260704A: VDP reachability check [20260706T062346Z]
  5. GRB test: this is a test
  6. [TEST] Super-Kamiokande finds a supernova in the Milky Way Galaxy
  7. GW test test test
  8. GW test test test
  9. GW Test GCN circular submission still works
  10. GRB test
  11. GRB 250115: A GRB during the coffee break at AAS
  12. GRB test from AAS
  13. GRB test
  14. GRB 000000A Testing - Have a good day!
  15. GRB 123456Z courey testing
  16. GRB Test
  17. GRB testing
  18. GRB iOS chrome again
  19. grb123: iOS Chrome testing
  20. GRB testing iOS
  21. GRB test from Chrome iOS
  22. GRB testing
  23. GRB Testing for Kafka
  24. GRB Testing
  25. GRB foobar
  26. GRB foobar test
  27. GRB testing 3
  28. GRB testing 2
  29. GRB testing
  30. GRB test 4
  31. GRB test 3
  32. GRB test 2
  33. GRB test
  34. GRB foobar
  35. GRB foobar
  36. LIGO/Virgo/KAGRA S230627c: Zwicky Transient Facility observations and candidates
  37. LIGO/Virgo/KAGRA S230627c: Zwicky Transient Facility observations and candidates
  38. GRB foobar
  39. GRB foobar
  40. PKS2326-505, millimeter wavelength flare, transient
  41. GRB foo 3
  42. GRB foo 2
  43. GRB foo
  44. GRB foo
  45. GRB foo
  46. GRB foo
  47. GRB test
  48. GRB foo
  49. GRB foobar
  50. GRB foobar
  51. GRB foobar
  52. GRB foobar
  53. GRB foobar
  54. GRB test
  55. MAGIC test
  56. GRB test
  57. GRB foo
  58. Test GCN GW submission
  59. GRB test 2
  60. GRB test
  61. GRB test
  62. Test GW GCN hermes submission 2
  63. Test GW GCN hermes submission
  64. Test GW GCN hermes submission
  65. A GRB test
  66. TEST GW GCN hermes submission
  67. GRB 170817A: an awesome GCN Circular
  68. VIRT optical transient detection
  69. GRB 230414B: 3.6m DOT Optical observations, slow decay at early epochs
  70. GRB 230307A: iTelescope optical upper limit (likely)
  71. GRB 230414B: Montarrenti Observatory late time optical afterglow detection
  72. IceCube-230416A: IceCube observation of a high-energy neutrino candidate
  73. Fermi trigger No 703284533: Global MASTER-Net observations report
  74. GRB 230414B: Lulin 40cm-SLT optical limit
  75. GRB 230414B: Bassano Bresciano Observatory optical observations
  76. GRB 230414B: Redshift from OSIRIS/GTC
  77. GRB 230414B: AbAO optical observations
  78. GRB 230409B: 3.6m DOT near-infrared detection, afterglow confirmation
  79. GRB 230414B: Swift-XRT refined Analysis
  80. GRB 230414B: Dabancheng/GHOST optical observations
  81. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230414A
  82. GRB 230414B: slow optical light curve decay
  83. GRB 230414B: SAO RAS optical observations
  84. GRB 230414B: Enhanced Swift-XRT position
  85. GRB 230414B: 1.3m DFOT Optical observations
  86. Fermi GRB 230414A: Global MASTER-Net observations report
  87. GRB 230414B: GROWTH India Telescope afterglow confirmation
  88. GRB 230414B (correction GRB name in the GCN 33615): Mondy optical afterglow candidate
  89. GRB 230414B: Nanshan/HMT optical afterglow detection
  90. GRB 230414A: Mondy optical afterglow candidate
  91. Swift GRB 230414B: Global MASTER-Net observations report
  92. GRB 230414B: Prompt enhanced Swift-XRT position
  93. GRB 230414B: Swift detection of a burst
  94. IceCube-230405A: BOOTES-4/MET Optical Upper Limits
  95. GRB 230414A: Fermi GBM Final Real-time Localization
  96. GRB 230328B: redshift lower limit estimating
  97. GRB 230409B: Mondy optical upper limit
  98. GRB 230409B: OHP/T193 optical upper limit
  99. GRB 230410B: VZLUSAT-2 detection
  100. GRB 230409D: VZLUSAT-2 detection

Advanced

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