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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

38642 results found.

  1. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  2. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  3. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  4. GRB260310A / AT2026fgk: P200 Spectroscopy
  5. GRB 260312B: Glowbug gamma-ray detection
  6. GRB 260310A: Fermi GBM Observation
  7. GRB 260310A: potential optical counterpart
  8. Swift BAT trigger 1500148: A solar flare
  9. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  10. GRB 260312B: Fermi GBM Final Real-time Localization
  11. The EP-WXT trigger 01709258843 is not a real source
  12. GRB 260310B: GECAM-B observation of a burst
  13. Retraction of GCN 43965: GRB is actually solar flare
  14. GRB 260312A: Swift detection of a burst
  15. GRB 260311B: Fermi GBM Final Real-time Localization
  16. GRB 260131A/B: radio detection with the VLA
  17. EP260302a: MeerKAT radio counterpart
  18. GRB260307A: GECAM-B observation of a burst
  19. GRB 260308A: SVOM/GRM observation of a short GRB
  20. EP260306a: Mondy optical upper limit
  21. GRB 260310A: AstroSat CZTI detection of a long burst
  22. GRB 260311A: Fermi GBM Final Real-time Localization
  23. GRB 260310B: Fermi GBM Final Real-time Localization
  24. GRB 260307B: SVOM/ECLAIRs refined analysis
  25. GRB 260208A: radio detection with the VLA
  26. GRB 260310A: Fermi GBM Final Real-time Localization
  27. GRB 260307A: Glowbug gamma-ray detection
  28. GRB 260308A: Fermi GBM Final Real-time Localization
  29. Fermi GBM Sub-Threshold Detection of GRB 260307B
  30. GRB 260307B: Mephisto optical upper limits
  31. GRB 260307B: possible NOT optical counterpart
  32. GRB 260307B: SVOM/VT upper limit with X band data analysis
  33. GRB260307B: GROWTH-India Telescope optical upper limit
  34. GRB 260307B: SVOM/VT optical candidate
  35. GRB 260307B: SVOM/C-GFT upper limit
  36. GRB 260307B: SVOM detection of a burst
  37. GRB 260307A: Fermi GBM Final Localization
  38. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  39. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  40. EP260302a: SVOM/VT optical observation
  41. EP260306a: Gemini-North redshift z = 4.773
  42. EP260306a: SVOM/VT optical observation
  43. EP260302a: Gemini-South redshift z = 1.535
  44. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  45. EP260306a: Einstein Probe detection of an X-ray transient
  46. EP260302a: Optical afterglow rebrightening
  47. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  48. GRB 260303A: 1.3m DFOT optical upper limit
  49. EP260214b: ATCA 6 GHz observations
  50. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  51. GRB 260303A: SVOM/ECLAIRs refined analysis
  52. GRB 260305A: Fermi GBM Final Real-time Localization
  53. GRB 260303B: AstroSat CZTI detection
  54. GRB 260304A: AstroSat CZTI detection of a long burst
  55. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  56. GRB 260303A: SVOM/VT optical observations
  57. GRB 260303B: NuSTAR detection of prompt emission
  58. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  59. GRB 260228A: SVOM/ECLAIRs refined analysis
  60. GRB 260225A: SVOM/ECLAIRs refined analysis
  61. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  62. GRB 260303B: Fermi GBM Final Real-time Localization
  63. EP260302a: analysis of the follow-up EP-FXT observation
  64. EP260227a: Gemini-South optical observations
  65. EP260302a: LCO observations
  66. EP260302a: BOOTES-7 optical counterpart detection at early times
  67. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  68. GRB 260303A: SVOM detection of a burst
  69. GRB 260228A: EP-FXT follow-up observation
  70. EP260302a: Einstein Probe detection of an X-ray transient
  71. GRB 251130B: TERI Gamma-ray detection
  72. GRB 260208A: TERI Gamma-ray detection
  73. GRB 260302A: Fermi GBM Final Real-time Localization
  74. EP260227a: Mondy optical observations
  75. GRB 260228A: CAHA 2.2m telescope optical upper limit
  76. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  77. EP260227a: Mephisto optical detection
  78. GRID detection of GRB 260225D
  79. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  80. EP260227a: further LCO observations
  81. EP260227a: SVOM/VT optical observation
  82. GRB 260228A: SVOM/VT optical upper limits
  83. GRB 260225D: SVOM/GRM observation
  84. EP260227A: 3.6m DOT optical afterglow detection
  85. GRB 260225B: SVOM/GRM observation
  86. GRB 260228A: SVOM detection of a burst
  87. EP260227a: Liverpool Telescope optical observations
  88. EP260227a: LCOGT Optical Observations
  89. GRB 260226A: Asiago r-band upper limit
  90. EP260227a: Thai National Telescope observations
  91. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  92. EP260227a: Liverpool Telescope observations
  93. EP260227a: COLIBRÍ optical observations
  94. EP260227a: NOT optical observations
  95. GRB 260225A: SVOM/VT optical continued observations and upper limit
  96. GRID detection of GRB 260223A
  97. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  98. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  99. IceCube cascade alert 142200_1517143 retraction
  100. GRB 260226A: Insight-HXMT/HE detection of the very bright burst

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