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"

19535 results found.

  1. NuSTAR 260828: a 1100s hard X-ray transient
  2. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  3. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  4. AT2026nik: EP-FXT X-ray counterpart
  5. SVOM GRB 260515A: Global MASTER-Net observations report
  6. EP260321a: Chandra X-ray Non-detection
  7. Swift BAT trigger 1500295: A solar flare
  8. Swift BAT trigger 1500287: A solar flare
  9. Swift BAT trigger 1500148: A solar flare
  10. Retraction of GCN 43965: GRB is actually solar flare
  11. GRB 260312A: Swift detection of a burst
  12. GRB 260208A: radio detection with the VLA
  13. IPN triangulation of GRB 260212A
  14. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  15. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  16. GRB 260208A: Swift UVOT detection
  17. GRB 260208A: LCO detection of the optical counterpart
  18. GRB 260208B: refined analysis of the EP-FXT observation
  19. GRB 260204A: Swift-XRT afterglow detection
  20. GRB 260208A: Fermi GBM Observation
  21. GRB 260208B: Swift-XRT observations
  22. GRB 260204A: Swift/UVOT Upper Limits
  23. GRB 260208B: EP-FXT observation
  24. GRB 260208B: SVOM/VT optical candidate
  25. GRB 260208A: SVOM/VT optical observation
  26. GRB 260208A: Swift-XRT observations
  27. GRB 260208B: Swift ToO observations
  28. GRB 260208B: Fermi-LAT detection
  29. GRB 260208A: Fermi-LAT detection
  30. GRB 260208A: Swift ToO observations
  31. GRB 260206A: Swift-XRT observations
  32. GRB 260206A: Tiled Swift observations
  33. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  34. GRB 260204A: Swift-XRT observations
  35. GRB 260204A: SVOM/VT optical candidate
  36. GRB 251230A: MeerLICHT afterglow detection
  37. GRB 260127A: GECAM-B observation
  38. GRB 260127B: AstroSat CZTI detection
  39. IPN triangulation of GRB 260121A
  40. GRB 260127A: Swift-BAT refined analysis
  41. GRB 260127B: Swift-XRT observations
  42. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  43. GRB 260127A: Fermi GBM Observation
  44. GRB 260127A: COLIBRÍ optical observations
  45. GRB 260127B: Swift ToO observations
  46. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  47. GRB 260127A: Swift-XRT refined Analysis
  48. GRB 260127A: SVOM/C-GFT optical observations
  49. GRB 260127A: Enhanced Swift-XRT position
  50. GRB 260127A: Prompt enhanced Swift-XRT position
  51. Swift GRB 260127A: Global MASTER-Net observations report
  52. GRB 260127A: Swift detection of a burst
  53. GRB 260125A: Swift-XRT observations
  54. Konus-Wind detection of GRB 260120B
  55. GRB 260125A: Swift ToO observations
  56. GRB 260114A: SVOM/VT optical upper limits
  57. GRB 260122B: Swift-BAT refined analysis
  58. GRB 260120B: SVOM/GRM observation
  59. GRB 260120B: AstroSat CZTI detection
  60. GRB 260114A: Insight-HXMT/HE detection
  61. GRB 260122B: Swift detection of a burst
  62. Swift GRB260122.97: Global MASTER-Net observations report
  63. GRB 260120B: Swift-BAT refined analysis
  64. GRB 260120B: Swift-XRT refined Analysis
  65. GRB 260120B: Fermi GBM Observation
  66. GRB 260120B: Swift/UVOT Detection
  67. GRB 260120B: COLIBRÍ optical upper limits
  68. GRB 260120B: Enhanced Swift-XRT position
  69. GRB 260120B: SVOM/C-GFT optical counterpart detection
  70. GRB 260101A: 239Alferov CubeSat detection
  71. GRB 260120B: Swift detection of a burst
  72. Swift GRB260120B: Global MASTER-Net observations report
  73. GRB 260114A: Swift/UVOT Upper Limits
  74. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  75. GRB 260117A: Swift-XRT afterglow detection
  76. GRB 260117A: ZTSh optical upper limit
  77. Swift GRB260118.48: Global MASTER-Net observations report
  78. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  79. Swift trigger on the HMXB 1A 1118-61
  80. GRB 260117A: SVOM/VT optical candidate
  81. GRB 260117A: SVOM/C-GFT upper limit
  82. GRB 260117A: Swift-XRT observations
  83. GRB 260117A: Swift ToO observations
  84. Swift triggered on the HMXB 1A 1118-61
  85. GRB 260114A: VLT/MUSE spectroscopic observations
  86. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  87. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  88. GRB260114A: STEP/T80S optical limits
  89. GRB 251222A: radio detection with the VLA
  90. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  91. Konus-Wind detection of GRB 260114A
  92. GRB 260114A: Swift-XRT refined Analysis
  93. GRB 260114A: 6 GHz VLA observations
  94. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  95. GRB 260114A : MITSuME Akeno optical upper limits
  96. GRB 260114A: COLIBRÍ optical upper limits
  97. GRB 260114A: TNG NIR upper limit
  98. GRB 260114A: NOT optical observations
  99. Konus-Wind detection of GRB 251230A / EP251230a
  100. GRB 260114A: SVOM/GRM observation of a short burst

Advanced

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