Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to https://gcn.nasa.gov.
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

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

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov