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"

37523 results found.

  1. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  2. Konus-Wind detection of GRB 260120B
  3. GRB 251222A: SVOM/ECLAIRs refined analysis
  4. GRB 260125A: Swift ToO observations
  5. GRB 260125A: GOTO candidate optical counterpart
  6. Fermi GRB 260125B: Global MASTER-Net observations report
  7. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  8. GRB 260125B: Fermi GBM Final Real-time Localization
  9. GRB 260125A: Fermi GBM Final Real-time Localization
  10. GRB 260114A: SVOM/VT optical upper limits
  11. GRB 260120A: AstroSat CZTI detection
  12. GRB 260122B: Swift-BAT refined analysis
  13. GRB 260120B: SVOM/GRM observation
  14. GRB 260120A: GECAM-B observation
  15. GRB 260120B: AstroSat CZTI detection
  16. GRB 260114A: Insight-HXMT/HE detection
  17. GRB 260122B: Swift detection of a burst
  18. EP260119a: Assy AZT-20 optical observations
  19. EP260119a: Mondy and SAO RAS optical upper limits
  20. GRB 260122A: Fermi GBM Final Real-time Localization
  21. Fermi GRB 260120C: Global MASTER-Net observations report
  22. GRB 260120B: Swift-BAT refined analysis
  23. GRB 260120B: Swift-XRT refined Analysis
  24. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  25. GRB 260120B: Fermi GBM Observation
  26. GRB 260120B: Swift/UVOT Detection
  27. GRB 260120B: COLIBRÍ optical upper limits
  28. GRB 260120B: Enhanced Swift-XRT position
  29. GRB 260120B: SVOM/C-GFT optical counterpart detection
  30. GRB 260120C: Fermi GBM Final Real-time Localization
  31. GRB 260101A: 239Alferov CubeSat detection
  32. GRB 260120B: Swift detection of a burst
  33. GRB 260120B: Fermi GBM Final Real-time Localization
  34. EP260119A: Mondy I-Band Observations
  35. Fermi trigger No 790601190: Global MASTER-Net observations report
  36. Fermi trigger No 790570272: Global MASTER-Net observations report
  37. GRB 260114A: Swift/UVOT Upper Limits
  38. GRB 251202A: further radio observations with the VLA
  39. EP260119a: KAIT optical observations
  40. GRB 260120A: Fermi GBM Final Real-time Localization
  41. EP260119a: SAO RAS optical observations
  42. GRB 251208D: SVOM/ECLAIRs refined analysis
  43. GRB 251208D: SVOM/ECLAIRs refined analysis
  44. GRB 260117A: Swift-XRT afterglow detection
  45. GRB 260115A: AstroSat CZTI detection
  46. GRB 260117A: ZTSh optical upper limit
  47. GRB 260110A: SVOM detection of a burst through offline search
  48. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  49. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  50. GRB 260117A: SVOM/VT optical candidate
  51. GRB 260117A: SVOM/C-GFT upper limit
  52. GRB 260117A: Swift-XRT observations
  53. GRB 260117A: Swift ToO observations
  54. GRB 260117A: SVOM detection of a long faint burst
  55. GRB 260115A: GECAM-B observation
  56. GRB 260114A: VLT/MUSE spectroscopic observations
  57. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  58. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  59. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  60. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  61. Fermi GRB 260115A: Global MASTER-Net observations report
  62. GRB 260115A: Fermi GBM Final Real-time Localization
  63. GRB260114A: STEP/T80S optical limits
  64. GRB 251222A: radio detection with the VLA
  65. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  66. Konus-Wind detection of GRB 260114A
  67. GRB 260114A: Swift-XRT refined Analysis
  68. GRB 260114A: 6 GHz VLA observations
  69. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  70. GRB 260114A : MITSuME Akeno optical upper limits
  71. GRB 260114A: COLIBRÍ optical upper limits
  72. GRB 260114A: TNG NIR upper limit
  73. GRB 260114A: NOT optical observations
  74. Konus-Wind detection of GRB 251230A / EP251230a
  75. GRB 260114A: SVOM/GRM observation of a short burst
  76. Swift GRB 260114A: Global MASTER-Net observations report
  77. GRB 260114A: GECAM-B observation of a short burst
  78. GRB 260114A: Mondy optical observations
  79. GRB 260114A: Fermi GBM observation
  80. GRB 260112B: GECAM-B observation
  81. GRB 260114A: GMG Optical Observation
  82. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  83. GRB 260114A: Swift detection of a short burst
  84. GRB 260114A: Fermi GBM Final Real-time Localization
  85. Konus-Wind detection of GRB 260101A
  86. GRB 260111A: Swift-XRT observations
  87. Swift Trigger 1439093: is probably not GRB 260113A
  88. GRB 260111A: COLIBRÍ optical afterglow candidate
  89. GRB 260111A: GECAM-B observation of a burst
  90. GRB 260111A: Fermi GBM Observation
  91. Swift Trigger 1434591 is not a GRB
  92. GRB 260111A: GOTO optical upper limits
  93. GRB 260112B: Fermi GBM Final Real-time Localization
  94. GRB 260111A: Swift ToO observations
  95. GRB 251230A: Mondy Optical Observations
  96. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  97. GRB 260112A: Fermi GBM Final Real-time Localization
  98. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  99. Fermi GRB 260111A: Global MASTER-Net observations report
  100. GRB 260111A: Fermi GBM Final Real-time Localization

Advanced

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