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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"

44343 results found.

  1. GRB 260312A: Swift detection of a burst
  2. GRB 260311B: Fermi GBM Final Real-time Localization
  3. GRB 260131A/B: radio detection with the VLA
  4. EP260302a: MeerKAT radio counterpart
  5. GRB260307A: GECAM-B observation of a burst
  6. GRB 260308A: SVOM/GRM observation of a short GRB
  7. EP260306a: Mondy optical upper limit
  8. GRB 260310A: AstroSat CZTI detection of a long burst
  9. GRB 260311A: Fermi GBM Final Real-time Localization
  10. Fermi GRB 260310B: Global MASTER-Net observations report
  11. GRB 260310B: Fermi GBM Final Real-time Localization
  12. Fermi GRB 260310A: Global MASTER-Net observations report
  13. GRB 260307B: SVOM/ECLAIRs refined analysis
  14. GRB 260208A: radio detection with the VLA
  15. GRB 260310A: Fermi GBM Final Real-time Localization
  16. GRB 260307A: Glowbug gamma-ray detection
  17. GRB 260308A: Fermi GBM Final Real-time Localization
  18. Fermi GBM Sub-Threshold Detection of GRB 260307B
  19. GRB 260307B: Mephisto optical upper limits
  20. GRB 260307B: possible NOT optical counterpart
  21. GRB 260307B: SVOM/VT upper limit with X band data analysis
  22. Fermi GRB 260307A: Global MASTER-Net observations report
  23. GRB260307B: GROWTH-India Telescope optical upper limit
  24. GRB 260307B: SVOM/VT optical candidate
  25. GRB 260307B: SVOM/C-GFT upper limit
  26. GRB 260307B: SVOM detection of a burst
  27. GRB 260307A: Fermi GBM Final Localization
  28. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  29. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  30. GRB 260207A: TESS Detection and Possible VLA Counterpart
  31. EP260302a: SVOM/VT optical observation
  32. EP260306a: Gemini-North redshift z = 4.773
  33. EP260306a: SVOM/VT optical observation
  34. EP260302a: Gemini-South redshift z = 1.535
  35. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  36. EP260306a: Einstein Probe detection of an X-ray transient
  37. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  38. EP260302a: Optical afterglow rebrightening
  39. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  40. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  41. GRB 260303A: 1.3m DFOT optical upper limit
  42. EP260214b: ATCA 6 GHz observations
  43. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  44. GRB 260303A: SVOM/ECLAIRs refined analysis
  45. Fermi GRB 260305A: Global MASTER-Net observations report
  46. GRB 260305A: Fermi GBM Final Real-time Localization
  47. GRB 260303B: AstroSat CZTI detection
  48. GRB 260304A: AstroSat CZTI detection of a long burst
  49. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  50. GRB 260303A: SVOM/VT optical observations
  51. GRB 260303A: J-band observations with WINTER
  52. GRB 260303B: NuSTAR detection of prompt emission
  53. EP260302a: Global MASTER-Net observations report
  54. Fermi GRB 260303B: Global MASTER-Net observations report
  55. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  56. GRB 260228A: SVOM/ECLAIRs refined analysis
  57. GRB 260225A: SVOM/ECLAIRs refined analysis
  58. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  59. GRB 260303B: Fermi GBM Final Real-time Localization
  60. EP260302a: analysis of the follow-up EP-FXT observation
  61. EP260227a: Gemini-South optical observations
  62. EP260302a: LCO observations
  63. EP260302a: BOOTES-7 optical counterpart detection at early times
  64. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  65. GRB 260303A: SVOM detection of a burst
  66. GRB 260228A: EP-FXT follow-up observation
  67. EP260302a: Einstein Probe detection of an X-ray transient
  68. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  69. GRB 251130B: TERI Gamma-ray detection
  70. GRB 260208A: TERI Gamma-ray detection
  71. GRB 260302A: Fermi GBM Final Real-time Localization
  72. EP260227a: Mondy optical observations
  73. GRB 260228A: CAHA 2.2m telescope optical upper limit
  74. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  75. EP260227a: Mephisto optical detection
  76. GRID detection of GRB 260225D
  77. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  78. EP260227a: further LCO observations
  79. EP260227a: SVOM/VT optical observation
  80. GRB 260228A: SVOM/VT optical upper limits
  81. GRB 260225D: SVOM/GRM observation
  82. EP260227A: 3.6m DOT optical afterglow detection
  83. GRB 260225B: SVOM/GRM observation
  84. GRB 260228A: SVOM detection of a burst
  85. EP260227a: FTW optical and NIR observations
  86. EP260227a: Liverpool Telescope optical observations
  87. EP260227a: LCOGT Optical Observations
  88. GRB 260226A: Asiago r-band upper limit
  89. EP260227a: Thai National Telescope observations
  90. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  91. EP260227a: Liverpool Telescope observations
  92. EP260227a: COLIBRÍ optical observations
  93. EP260227a: NOT optical observations
  94. GRB 260225A: SVOM/VT optical continued observations and upper limit
  95. GRID detection of GRB 260223A
  96. EP260227a: Global MASTER-Net observations report
  97. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  98. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  99. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  100. IceCube cascade alert 142200_1517143 retraction

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