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"

20364 results found.

  1. EP260213a: refined analysis of the EP-FXT observation
  2. EP260213a: Einstein Probe detection of a fast X-ray transient
  3. EP/WXT 01709258378: NOT optical upper limits
  4. GRB 260212A: SVOM/GRM observation of a long burst
  5. GRB 260211A - SVOM/ECLAIRs refined analysis
  6. GRB 260204A: SVOM/ECLAIRs refined analysis
  7. GRB 260211A: LAST optical upper limit
  8. GRB 260210A: SVOM/GRM observation
  9. GRB 260128B: SVOM/ECLAIRs refined analysis
  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. GRB 260211A: SVOM detection of a burst
  15. EP260209a: COLIBRÍ optical upper limit
  16. EP260209a: LCO optical upper limits
  17. EP260210a: refined analysis of the EP-FXT observation
  18. GRB 260208A: LCO detection of the optical counterpart
  19. EP260209a: Einstein Probe detection of a fast X-ray transient
  20. EP260210a: Optical upper limits with Kinder observations
  21. GRB 260208C: AstroSat CZTI detection
  22. EP260210a: COLIBRÍ optical upper limit
  23. EP260210a: SVOM/C-GFT upper limit
  24. EP260210a: Einstein Probe detection of an X-ray transient
  25. GRB 260208C: SVOM/GRM observation
  26. GRB 260204A: Swift-XRT afterglow detection
  27. GRB 260208B: AstroSat CZTI detection of a bright long burst
  28. GRB260208A: Liverpool Telescope optical follow-up observations
  29. GRB 260131A/B: continued Mondy optical observations
  30. GRB 260204A: Swift/UVOT Upper Limits
  31. GRB 260208B: COLIBRÍ optical observations
  32. GRB 260208A: Mondy optical observations
  33. GRB 260208A: 1.3m DFOT optical detection
  34. GRB 260208A: COLIBRÍ optical observations
  35. GRB 260208A: NOT spectroscopic redshift z = 2.36
  36. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  37. GRB 260208A: SVOM/VT optical observation
  38. Fermi GRB 260208D: Global MASTER-Net observations report
  39. GRB 260208B: SVOM/GRM observation of a bright burst
  40. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  41. GRB 260131A/B: Mondy and Terskol optical observations
  42. GRB 260204A: Swift-XRT observations
  43. GRB 260204A: SVOM/VT optical candidate
  44. GRB 260204A: LCO optical upper limits
  45. EP260110a: Late GTC/EMIR near-infrared observations
  46. GRB 260204B: Fermi GBM Final Real-time Localization
  47. Konus-Wind detection of GRB 260121A
  48. GRB 260131A: KAIT optical observations
  49. GRB 251230A: MeerLICHT afterglow detection
  50. GRID detection of GRB 260131A/B
  51. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  52. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  53. GRB 260131A: NOT spectroscopic redshift z = 1.434
  54. EP260131a: Liverpool Telescope optical upper limits
  55. EP260131a: COLIBRÍ further observations
  56. Konus-Wind detection of GRB 260128A / EP260128a
  57. EP260131a: SVOM/VT optical observation
  58. EP260131a: Xinglong optical upper limit
  59. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  60. EP260131a: COLIBRÍ observations of slow optical fading
  61. EP260131a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  62. EP260131a: VLT/X-shooter spectroscopic redshift z = 0.937
  63. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  64. EP260131a: COLIBRÍ optical observations of the counterpart
  65. EP260131a: Einstein Probe detection of an X-ray transient
  66. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  67. GRB 260128B: LCO optical upper limits
  68. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  69. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  70. GRB 260128B: SVOM detection of a burst through offline search
  71. GRB 260127B: Swift-XRT observations
  72. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  73. EP260128a: NOT optical counterpart candidate
  74. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  75. EP260128a: Liverpool Telescope optical observations and possible counterpart
  76. EP260128a: LCO optical upper limits
  77. EP260128a: Einstein Probe detection of an X-ray transient
  78. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  79. GRB 260127A: COLIBRÍ optical observations
  80. EP260126a: Seimei/TriCCS optical upper limit
  81. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  82. GRB 260127A: SVOM/C-GFT optical observations
  83. GRB 260127A: Enhanced Swift-XRT position
  84. GRB 260127A: LCO optical afterglow discovery
  85. GRB 260127A: Swift detection of a burst
  86. GRB 260125A: Swift-XRT observations
  87. EP260126a: Optical upper limit with Kinder observations
  88. EP260126a: Liverpool Telescope optical upper limits
  89. EP260126a: Further NOT optical upper limits
  90. EP260126a: COLIBRÍ optical upper limits
  91. EP260126a: NOT optical observations
  92. EP260126a: Einstein Probe detection of a fast X-ray transient
  93. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  94. GRB 251222A: SVOM/ECLAIRs refined analysis
  95. GRB 260125A: GOTO candidate optical counterpart
  96. GRB 260114A: SVOM/VT optical upper limits
  97. GRB 260120B: SVOM/GRM observation
  98. GRB 260120B: AstroSat CZTI detection
  99. EP260119a: Assy AZT-20 optical observations
  100. EP260119a: Mondy and SAO RAS 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