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"

22062 results found.

  1. GRB 260610B / AT2026owq: SAO RAS optical observations
  2. EP260610b: GTC likely spectroscopic redshift z = 1.10
  3. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  4. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  5. GRB 260610B / AT2026owq: Early ATLAS observations
  6. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  7. EP260610b: COLIBRÍ optical observations
  8. GRB 260610B: DDOTI optical observations
  9. EP260610b: MAO/AZT-22 optical observations
  10. GRB 260610B: GOTO optical counterpart candidate
  11. EP260610b: SVOM/VT optical confirmation with blue color
  12. GRB 260515A: SOAR optical observations
  13. EP260610b: Gemini North optical counterpart candidate
  14. Konus-Wind detection of GRB 260604C
  15. GRB 260604C: SVOM/ECLAIRs refined analysis
  16. GRB 260608A: SVOM/ECLAIRs refined analysis
  17. Konus-Wind detection of GRB 260607B
  18. GRB 260604C: further SAO RAS optical observations
  19. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  20. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  21. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  22. GRB 260604C: SVOM/C-GFT upper limit
  23. GRB 260607A: TRT optical observations
  24. GRB 260604C: GRANDMA further observations
  25. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  26. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  27. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  28. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  29. GRB 260604C: 6 GHz VLA observations
  30. GRB 260604C: SAO RAS optical observations
  31. GRB 260604C: GRANDMA observations
  32. GRB260603A: SVOM/ECLAIRs refined analysis
  33. GRB 260604C: Liverpool Telescope optical detection
  34. EP260602d: EP-FXT follow-up observation
  35. GRB 260527A/EP260527a: 6 GHz VLA observations
  36. GRB 260604C: GOTO detections of the optical afterglow
  37. GRB 260604C: Kilonova-Catcher optical afterglow detection
  38. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  39. GRB 260604C: Jinshan optical observations
  40. EP260602d: J-band upper limit with WINTER
  41. EP260602b: J-band upper limit with WINTER
  42. GRB 260604C: LAST detection of optical counterpart candidate
  43. GRB 260604C: MASTER OT J145749.59+284903.0 optical counterpart discovery
  44. Fermi GRB 260604C: Global MASTER-Net observations report
  45. Fermi GRB 260604C: Global MASTER-Net observations report
  46. SVOM GRB260604.85: Global MASTER-Net observations report
  47. GRB 260604C: SVOM detection of a long burst
  48. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  49. GRB 260603A: NOT optical observations
  50. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  51. EP260603a: Global MASTER-Net observations report
  52. EP260603a: Einstein Probe detection of a fast X-ray transient
  53. EP260602d: Optical Upper limits with kinder observations
  54. EP260602b: Liverpool Telescope observations
  55. EP260602a: Liverpool Telescope optical upper limits
  56. EP260602b: Liverpool Telescope and LCO observations
  57. EP260602a: GTC and Liverpool Telescope optical observations
  58. GRB 260603A: Kilonova-Catcher optical upper limit
  59. GRB 260603A: SVOM/VT optical observations
  60. EP260602a: NOT NIR J-band observations
  61. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  62. Fermi trigger No 802141998: Global MASTER-Net observations report
  63. EP260602a: SVOM/VT optical magnitudes correction
  64. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  65. EP260602a: COLIBRÍ optical observations
  66. GRB260601B/EP260601a: NOT near-infrared observations
  67. SVOM GRB260603.23: Global MASTER-Net observations report
  68. Fermi GRB 260602B: Global MASTER-Net observations report
  69. Fermi GRB 260602B: Global MASTER-Net observations report
  70. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  71. EP260602a: SVOM/VT optical candidate
  72. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  73. GRB 260601B/EP260601a: J-band upper limit with WINTER
  74. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  75. EP260530a/AT 2026nwl: KAIT optical observations
  76. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  77. EP260602a: Optical upper limits with Kinder observations
  78. GRB 260601B/EP260601a: SVOM/VT optical observations
  79. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  80. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  81. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  82. GRB 260516D: VLA radio detection
  83. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  84. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  85. Fermi GRB 260601A: Global MASTER-Net observations report
  86. AT2026nik: EP-FXT X-ray counterpart
  87. Fermi trigger No 801900520: Global MASTER-Net observations report
  88. AT 2026nuz: COLIBRÍ optical observations
  89. EP260527a/GRB 260527A: further FTW optical and NIR observations
  90. GRB 260530B: SVOM/GRM detection of a possible bright short GRB
  91. GRB 260527A / EP260527a: VLA radio detection
  92. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  93. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  94. GRB 260529A: GOTO tentative optical afterglow candidate
  95. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  96. Fermi GRB 260529A: Global MASTER-Net observations report
  97. EP260526a: SVOM/VT optical upper limits
  98. GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
  99. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  100. EP260527a / GRB 260527A: NOT optical observations

Advanced

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