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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"

15268 results found.

  1. GRB 260303A: SVOM/ECLAIRs refined analysis
  2. GRB 260303B: AstroSat CZTI detection
  3. GRB 260304A: AstroSat CZTI detection of a long burst
  4. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  5. GRB 260303A: SVOM/VT optical observations
  6. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  7. GRB 260228A: SVOM/ECLAIRs refined analysis
  8. GRB 260225A: SVOM/ECLAIRs refined analysis
  9. EP260302a: LCO observations
  10. EP260302a: BOOTES-7 optical counterpart detection at early times
  11. GRB 260303A: SVOM detection of a burst
  12. GRB 251130B: TERI Gamma-ray detection
  13. GRB 260208A: TERI Gamma-ray detection
  14. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  15. EP260227a: Mephisto optical detection
  16. GRID detection of GRB 260225D
  17. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  18. GRB 260225D: SVOM/GRM observation
  19. GRB 260225B: SVOM/GRM observation
  20. GRB 260228A: SVOM detection of a burst
  21. EP260227a: Liverpool Telescope optical observations
  22. EP260227a: COLIBRÍ optical observations
  23. EP260227a: NOT optical observations
  24. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  25. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  26. IceCube cascade alert 142200_1517143 retraction
  27. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  28. Konus-Wind detection of GRB 260226A
  29. EP260214a: VLT/FORS2 optical observations
  30. GRB 260225A: WINTER J-band upper limit
  31. GRB 260226A: COLIBRÍ optical upper limits
  32. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  33. GRB 260226A: LAST optical upper limit
  34. GRB 260226A: Fermi-LAT refined analysis
  35. GRB 260226A: AstroSat CZTI detection of bright long burst
  36. GRB 260226A: Fermi-LAT detection of a bright burst
  37. GRB 260225A: EP-FXT follow-up observation
  38. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  39. GRB 260225A: SVOM detection of a burst
  40. EP260213a: Mephisto optical upper limits
  41. sb26021801: SVOM/VT optical upper limits
  42. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  43. GRB 260223A: SVOM/GRM observation
  44. GRB 260223A: COLIBRÍ further optical observations and a brightening
  45. GRB 260223A: COLIBRÍ optical observations
  46. EP260221a: COLIBRÍ optical counterpart candidate
  47. EP260221a: EP-FXT follow-up observation
  48. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  49. GRB 260219A: AstroSat CZTI detection
  50. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  51. GRB 260219A: GECAM-B observation of a long burst
  52. SVOM alert sb26021801: LAST optical upper limit
  53. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  54. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  55. sb26021801: SVOM detection of a long faint X-ray transient
  56. EP260214b: 1.3m DFOT optical upper limit
  57. Konus-Wind detection of GRB 260212A
  58. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  59. GRB 260213A: GECAM-B observation of a short burst
  60. EP260214b: Liverpool Telescope optical observations
  61. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  62. EP260214b: Optical upper limit with Kinder observations
  63. EP260214a: Optical upper limits with Kinder observations
  64. EP260214b: DDOTI Optical Detection
  65. EP260214a: NOT optical upper limits
  66. EP260214a: COLIBRÍ optical upper limits
  67. GRB 260211A: SVOM/VT optical counterpart
  68. EP260214b: COLIBRÍ optical observations
  69. GRB 260212A: AstroSat CZTI detection
  70. GRB 260212A: Fermi GBM Observation
  71. EP260213a: COLIBRÍ optical upper limits
  72. GRB 260212A: GECAM-B observation
  73. EP260213a: Optical upper limits with Kinder observations
  74. GRB 260212A: SVOM/GRM observation of a long burst
  75. GRB 260211A - SVOM/ECLAIRs refined analysis
  76. GRB 260204A: SVOM/ECLAIRs refined analysis
  77. GRB 260211A: LAST optical upper limit
  78. GRB 260210A: SVOM/GRM observation
  79. Konus-Wind detection of GRB 260207B
  80. GRB 260128B: SVOM/ECLAIRs refined analysis
  81. GRID detection of GRB 260207B
  82. GRB260131A/B: 3.6m DOT Optical Observations
  83. GRB 260211A: SVOM detection of a burst
  84. Konus-Wind detection of GRB 260209B
  85. Konus-Wind detection of GRB 260127B
  86. GRB 260208A: LCO detection of the optical counterpart
  87. EP260210a: Optical upper limits with Kinder observations
  88. GRB 260210A: AstroSat CZTI detection
  89. GRB 260208C: AstroSat CZTI detection
  90. GRB 260208B: refined analysis of the EP-FXT observation
  91. GRB 260207B: AstroSat CZTI detection
  92. GRB 260208C: SVOM/GRM observation
  93. GRB 260208B: AstroSat CZTI detection of a bright long burst
  94. GRB260208A: Liverpool Telescope optical follow-up observations
  95. GRB 260208A: Fermi GBM Observation
  96. GRB 260208B: Swift-XRT observations
  97. GRB 260131A/B: continued Mondy optical observations
  98. GRB 260204A: Swift/UVOT Upper Limits
  99. GRB 260208A: 1.3m DFOT optical detection
  100. GRB 260208A: GECAM-B observation of a bright burst

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