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"

28057 results found.

  1. GRB 260212A: SVOM/GRM observation of a long burst
  2. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  3. GRB 260211A: EP-FXT follow-up observation
  4. GRB 260211A: SVOM/VT optical observation
  5. GRB 260212A: Glowbug gamma-ray detection
  6. Fermi GRB 260212A: Global MASTER-Net observations report
  7. GRB 260211A: LAST optical upper limit
  8. GRB 260210A: SVOM/GRM observation
  9. Fermi GBM Sub-Threshold Detection of GRB 260211A
  10. GRID detection of GRB 260207B
  11. GRB 260211A: LCO optical upper limits
  12. GRB260131A/B: 3.6m DOT Optical Observations
  13. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  14. Fermi trigger No 792537871: Global MASTER-Net observations report
  15. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  16. EP260209a: COLIBRÍ optical upper limit
  17. Fermi GRB 260210C: Global MASTER-Net observations report
  18. EP260209a: LCO optical upper limits
  19. EP260210a: Global MASTER-Net observations report
  20. EP260210a: refined analysis of the EP-FXT observation
  21. EP260209a: Global MASTER-Net observations report
  22. GRB 260208A: LCO detection of the optical counterpart
  23. EP260209a: Einstein Probe detection of a fast X-ray transient
  24. EP260210a: Optical upper limits with Kinder observations
  25. GRB 260210A: Glowbug gamma-ray detection
  26. GRB 260208C: AstroSat CZTI detection
  27. EP260210a: COLIBRÍ optical upper limit
  28. EP260210a: SVOM/C-GFT upper limit
  29. EP260210a: Einstein Probe detection of an X-ray transient
  30. GRB 260207B: AstroSat CZTI detection
  31. GRB 260208C: SVOM/GRM observation
  32. GRB 260204A: Swift-XRT afterglow detection
  33. GRB 260208B: AstroSat CZTI detection of a bright long burst
  34. GRB260208A: Liverpool Telescope optical follow-up observations
  35. GRB 260208A: Glowbug gamma-ray detection
  36. GRB 260208A: NuSTAR detection of prompt emission
  37. GRB 260208A: Fermi GBM Observation
  38. Fermi GRB 260209A: Global MASTER-Net observations report
  39. GRB 260208B: Swift-XRT observations
  40. GRB 260131A/B: continued Mondy optical observations
  41. GRB 260204A: Swift/UVOT Upper Limits
  42. GRB 260208B: COLIBRÍ optical observations
  43. GRB 260208A: Mondy optical observations
  44. GRB 260208A: 1.3m DFOT optical detection
  45. GRB 260208A: COLIBRÍ optical observations
  46. GRB 260208B: EP-FXT observation
  47. Fermi GRB 260208C: Global MASTER-Net observations report
  48. GRB 260208B: SVOM/VT optical candidate
  49. GRB 260208A: GECAM-B observation of a bright burst
  50. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  51. GRB 260208A: SVOM/VT optical observation
  52. Fermi GRB 260208D: Global MASTER-Net observations report
  53. GRB 260208A: Swift-XRT observations
  54. GRB 260208B: SVOM/GRM observation of a bright burst
  55. GRB 260208B: Fermi GBM Detection
  56. LAT GRB 260208B: Global MASTER-Net observations report
  57. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  58. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  59. Fermi GRB 260208A: Global MASTER-Net observations report
  60. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  61. GRB 260131A/B: Mondy and Terskol optical observations
  62. Fermi GRB 260207B: Global MASTER-Net observations report
  63. GRB 260206A: Swift-XRT observations
  64. Fermi trigger No 792135758: Global MASTER-Net observations report
  65. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  66. GRB 260204A: Swift-XRT observations
  67. GRB 260204A: SVOM/VT optical candidate
  68. GRB 260204A : MASTER Global robotic net optical observations
  69. Fermi GBM Sub-Threshold Detection of GRB 260204A
  70. GRB 260204A: LCO optical upper limits
  71. EP260110a: Late GTC/EMIR near-infrared observations
  72. GRB 260121A: 239Alferov CubeSat detection
  73. GRB 260131A: KAIT optical observations
  74. GRB 251230A: MeerLICHT afterglow detection
  75. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  76. GRB 260130A: Insight-HXMT/HE detection
  77. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  78. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  79. GRB 260127A: GECAM-B observation
  80. EP260131a: Liverpool Telescope optical upper limits
  81. EP260131a: COLIBRÍ further observations
  82. EP260131a: SVOM/VT optical observation
  83. EP260131a: Xinglong optical upper limit
  84. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  85. GRB 260131A/B: Fermi GBM Observation
  86. EP260131a: COLIBRÍ observations of slow optical fading
  87. EP260131a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  88. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  89. GRB 260131B: MAXI/GSC detection
  90. EP260131a: COLIBRÍ optical observations of the counterpart
  91. EP260131a: Las Cumbres detection of an optical counterpart
  92. GRB 260127B: AstroSat CZTI detection
  93. GRB 260130A: Fermi GBM Detection
  94. EP260131a: Einstein Probe detection of an X-ray transient
  95. GRB 260127B: Fermi GBM Detection
  96. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  97. Fermi GRB 260130A: Global MASTER-Net observations report
  98. Fermi GRB 260129A: Global MASTER-Net observations report
  99. GRB 260128B: LCO optical upper limits
  100. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits

Advanced

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