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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"
  1. GRB 260312B: Fermi GBM Final Real-time Localization
  2. The EP-WXT trigger 01709258843 is not a real source
  3. GRB 260310B: GECAM-B observation of a burst
  4. Retraction of GCN 43965: GRB is actually solar flare
  5. GRB 260312A: Swift detection of a burst
  6. GRB 260311B: Fermi GBM Final Real-time Localization
  7. GRB 260131A/B: radio detection with the VLA
  8. EP260302a: MeerKAT radio counterpart
  9. GRB260307A: GECAM-B observation of a burst
  10. GRB 260308A: SVOM/GRM observation of a short GRB
  11. EP260306a: Mondy optical upper limit
  12. GRB 260310A: AstroSat CZTI detection of a long burst
  13. GRB 260311A: Fermi GBM Final Real-time Localization
  14. Fermi GRB 260310B: Global MASTER-Net observations report
  15. GRB 260310B: Fermi GBM Final Real-time Localization
  16. Fermi GRB 260310A: Global MASTER-Net observations report
  17. GRB 260307B: SVOM/ECLAIRs refined analysis
  18. GRB 260208A: radio detection with the VLA
  19. GRB 260310A: Fermi GBM Final Real-time Localization
  20. GRB 260307A: Glowbug gamma-ray detection
  21. GRB 260308A: Fermi GBM Final Real-time Localization
  22. Fermi GBM Sub-Threshold Detection of GRB 260307B
  23. GRB 260307B: Mephisto optical upper limits
  24. GRB 260307B: possible NOT optical counterpart
  25. GRB 260307B: SVOM/VT upper limit with X band data analysis
  26. Fermi GRB 260307A: Global MASTER-Net observations report
  27. GRB260307B: GROWTH-India Telescope optical upper limit
  28. GRB 260307B: SVOM/VT optical candidate
  29. GRB 260307B: SVOM/C-GFT upper limit
  30. GRB 260307B: SVOM detection of a burst
  31. GRB 260307A: Fermi GBM Final Localization
  32. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  33. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  34. GRB 260207A: TESS Detection and Possible VLA Counterpart
  35. EP260302a: SVOM/VT optical observation
  36. EP260306a: Gemini-North redshift z = 4.773
  37. EP260306a: SVOM/VT optical observation
  38. EP260302a: Gemini-South redshift z = 1.535
  39. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  40. EP260306a: Einstein Probe detection of an X-ray transient
  41. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  42. EP260302a: Optical afterglow rebrightening
  43. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  44. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  45. GRB 260303A: 1.3m DFOT optical upper limit
  46. EP260214b: ATCA 6 GHz observations
  47. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  48. GRB 260303A: SVOM/ECLAIRs refined analysis
  49. Fermi GRB 260305A: Global MASTER-Net observations report
  50. GRB 260305A: Fermi GBM Final Real-time Localization
  51. GRB 260303B: AstroSat CZTI detection
  52. GRB 260304A: AstroSat CZTI detection of a long burst
  53. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  54. GRB 260303A: SVOM/VT optical observations
  55. GRB 260303A: J-band observations with WINTER
  56. GRB 260303B: NuSTAR detection of prompt emission
  57. EP260302a: Global MASTER-Net observations report
  58. Fermi GRB 260303B: Global MASTER-Net observations report
  59. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  60. GRB 260228A: SVOM/ECLAIRs refined analysis
  61. GRB 260225A: SVOM/ECLAIRs refined analysis
  62. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  63. GRB 260303B: Fermi GBM Final Real-time Localization
  64. EP260302a: analysis of the follow-up EP-FXT observation
  65. EP260227a: Gemini-South optical observations
  66. EP260302a: LCO observations
  67. EP260302a: BOOTES-7 optical counterpart detection at early times
  68. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  69. GRB 260303A: SVOM detection of a burst
  70. GRB 260228A: EP-FXT follow-up observation
  71. EP260302a: Einstein Probe detection of an X-ray transient
  72. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  73. GRB 251130B: TERI Gamma-ray detection
  74. GRB 260208A: TERI Gamma-ray detection
  75. GRB 260302A: Fermi GBM Final Real-time Localization
  76. EP260227a: Mondy optical observations
  77. GRB 260228A: CAHA 2.2m telescope optical upper limit
  78. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  79. EP260227a: Mephisto optical detection
  80. GRID detection of GRB 260225D
  81. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  82. EP260227a: further LCO observations
  83. EP260227a: SVOM/VT optical observation
  84. GRB 260228A: SVOM/VT optical upper limits
  85. GRB 260225D: SVOM/GRM observation
  86. EP260227A: 3.6m DOT optical afterglow detection
  87. GRB 260225B: SVOM/GRM observation
  88. GRB 260228A: SVOM detection of a burst
  89. EP260227a: FTW optical and NIR observations
  90. EP260227a: Liverpool Telescope optical observations
  91. EP260227a: LCOGT Optical Observations
  92. GRB 260226A: Asiago r-band upper limit
  93. EP260227a: Thai National Telescope observations
  94. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  95. EP260227a: Liverpool Telescope observations
  96. EP260227a: COLIBRÍ optical observations
  97. EP260227a: NOT optical observations
  98. GRB 260225A: SVOM/VT optical continued observations and upper limit
  99. GRID detection of GRB 260223A
  100. EP260227a: Global MASTER-Net observations report

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