Skip to main content
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"

28034 results found.

  1. GRB 260619A: Kilonova-Catcher optical upper limit
  2. EP260618a: LCO optical counterpart confirmation
  3. EP260618a: COLIBRÍ optical counterpart candidate
  4. GRB 260616A: NuSTAR detection of prompt emission
  5. GRB 260614B: NuSTAR detection of prompt emission
  6. GRB 260619A: SVOM possible detection of a faint burst
  7. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  8. EP260618a: EP-WXT detection of an X-ray transient
  9. GRB 260610B: AbAO optical observations
  10. GRB 260506B: cubesat Avion detection
  11. GRB 260617A: Fermi GBM Detection
  12. GRB 260616A: Fermi GBM Observation
  13. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  14. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  15. GRB 260429A: cubesat Avion detection
  16. GRB260616C: MAXI/GSC detection
  17. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  18. EP260616a: EP-WXT detection of a fast X-ray transient
  19. GRB 260616B: Fermi GBM Detection
  20. GRB 260616B: BALROG localization (Fermi Trigger 803286321 / GRB 260616295)
  21. GRB 260616A: BALROG localization (Fermi Trigger 803272919 / GRB 260616140)
  22. GRB 260610B: Terskol optical observations
  23. GRB 260610B: SVOM/GRM observation
  24. GRB 260614B: Fermi GBM Observation
  25. GRB 260614B: SVOM/VT optical candidate from VHF data
  26. GRB 260614B: SVOM detection of a burst
  27. GRB 260611B: SVOM/GRM detection
  28. The EP-WXT trigger 01709269488 is likely a flaring star
  29. GRB 260610B: further Liverpool Telescope optical observations
  30. GRB 260610B: Fermi GBM Observation
  31. GRB 260610B / AT2026owq: GRANDMA optical observations
  32. GRB 260610B / AT2026owq: further SAO RAS optical observations
  33. EP260605a: COLIBRÍ optical upper limits
  34. GRB 260610b: Liverpool Telescope optical observations
  35. EP260610b: Liverpool Telescope optical upper limits
  36. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  37. GRB 260610B / AT2026owq: SAO RAS optical observations
  38. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  39. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  40. GRB 260610B / AT2026owq: Early ATLAS observations
  41. GRB 260610B: TRT optical observation
  42. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  43. EP260610b: COLIBRÍ optical observations
  44. GRB 260610B: DDOTI optical observations
  45. EP260610b: MAO/AZT-22 optical observations
  46. EP260610b: NOT optical observation
  47. EP260610b: SVOM/VT optical confirmation with blue color
  48. GRB 260515A: SOAR optical observations
  49. EP260610a: SVOM/VT optical upper limits
  50. EP260610b: Einstein Probe detection of an X-ray transient
  51. EP260610a: COLIBRÍ optical upper limits
  52. EP260610a: Einstein Probe detection of a fast X-ray transient
  53. GRB 260608A: Fermi GRB Observation
  54. GRB 260604C: further SAO RAS optical observations
  55. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  56. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  57. GRB 260604C: SVOM/C-GFT upper limit
  58. EP260605a: EP-FXT follow-up observation
  59. GRB 260607A: TRT optical observations
  60. GRB 260604A: SVOM/GRM detection
  61. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  62. GRB 260607B: Fermi GBM Observation
  63. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  64. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  65. GRB 260604C: 6 GHz VLA observations
  66. GRB 260604C: SAO RAS optical observations
  67. GRB 260604B: SVOM/GRM detection
  68. EP260605a: Einstein Probe detection of a fast X-ray transient
  69. EP260603a: COLIBRÍ optical upper limit
  70. GRB 260604A: Glowbug gamma-ray detection
  71. GRB 260604C: LCO optical upper limit
  72. EP260602d: EP-FXT follow-up observation
  73. EP260602c: EP-FXT follow-up observation
  74. GRB 260601B / EP260601a: AstroSat CZTI detection
  75. GRB 260527A/EP260527a: 6 GHz VLA observations
  76. GRB 260604C: Kilonova-Catcher optical afterglow detection
  77. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  78. GRB 260604C: Jinshan optical observations
  79. GRB 260604C: Fermi GBM Observation
  80. EP260602d: J-band upper limit with WINTER
  81. EP260602b: J-band upper limit with WINTER
  82. GRB 260604C: LAST detection of optical counterpart candidate
  83. Fermi GRB 260604C: Global MASTER-Net observations report
  84. Fermi GRB 260604C: Global MASTER-Net observations report
  85. SVOM GRB260604.85: Global MASTER-Net observations report
  86. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  87. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  88. EP260602a: EP-FXT follow-up observation
  89. EP260603a: Global MASTER-Net observations report
  90. EP260603a: Einstein Probe detection of a fast X-ray transient
  91. EP260602d: Optical Upper limits with kinder observations
  92. EP260602b: Liverpool Telescope observations
  93. EP260602a: Liverpool Telescope optical upper limits
  94. EP260602b: Liverpool Telescope and LCO observations
  95. EP260602a: GTC and Liverpool Telescope optical observations
  96. EP260601a/GRB 260601B: EP-FXT follow-up observation
  97. GRB 260601B / EP260601a: Mondy optical upper limit
  98. EP260602b: EP-FXT follow-up observation
  99. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  100. GRB 260603A: Kilonova-Catcher optical upper limit

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov