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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 260307A: Fermi GBM Final Localization
  2. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  3. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  4. GRB 260207A: TESS Detection and Possible VLA Counterpart
  5. EP260302a: SVOM/VT optical observation
  6. EP260306a: Gemini-North redshift z = 4.773
  7. EP260306a: SVOM/VT optical observation
  8. EP260302a: Gemini-South redshift z = 1.535
  9. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  10. EP260306a: Einstein Probe detection of an X-ray transient
  11. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  12. EP260302a: Optical afterglow rebrightening
  13. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  14. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  15. GRB 260303A: 1.3m DFOT optical upper limit
  16. EP260214b: ATCA 6 GHz observations
  17. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  18. GRB 260303A: SVOM/ECLAIRs refined analysis
  19. Fermi GRB 260305A: Global MASTER-Net observations report
  20. GRB 260305A: Fermi GBM Final Real-time Localization
  21. GRB 260303B: AstroSat CZTI detection
  22. GRB 260304A: AstroSat CZTI detection of a long burst
  23. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  24. GRB 260303A: SVOM/VT optical observations
  25. GRB 260303A: J-band observations with WINTER
  26. GRB 260303B: NuSTAR detection of prompt emission
  27. EP260302a: Global MASTER-Net observations report
  28. Fermi GRB 260303B: Global MASTER-Net observations report
  29. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  30. GRB 260228A: SVOM/ECLAIRs refined analysis
  31. GRB 260225A: SVOM/ECLAIRs refined analysis
  32. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  33. GRB 260303B: Fermi GBM Final Real-time Localization
  34. EP260302a: analysis of the follow-up EP-FXT observation
  35. EP260227a: Gemini-South optical observations
  36. EP260302a: LCO observations
  37. EP260302a: BOOTES-7 optical counterpart detection at early times
  38. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  39. GRB 260303A: SVOM detection of a burst
  40. GRB 260228A: EP-FXT follow-up observation
  41. EP260302a: Einstein Probe detection of an X-ray transient
  42. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  43. GRB 251130B: TERI Gamma-ray detection
  44. GRB 260208A: TERI Gamma-ray detection
  45. GRB 260302A: Fermi GBM Final Real-time Localization
  46. EP260227a: Mondy optical observations
  47. GRB 260228A: CAHA 2.2m telescope optical upper limit
  48. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  49. EP260227a: Mephisto optical detection
  50. GRID detection of GRB 260225D
  51. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  52. EP260227a: further LCO observations
  53. EP260227a: SVOM/VT optical observation
  54. GRB 260228A: SVOM/VT optical upper limits
  55. GRB 260225D: SVOM/GRM observation
  56. EP260227A: 3.6m DOT optical afterglow detection
  57. GRB 260225B: SVOM/GRM observation
  58. GRB 260228A: SVOM detection of a burst
  59. EP260227a: FTW optical and NIR observations
  60. EP260227a: Liverpool Telescope optical observations
  61. EP260227a: LCOGT Optical Observations
  62. GRB 260226A: Asiago r-band upper limit
  63. EP260227a: Thai National Telescope observations
  64. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  65. EP260227a: Liverpool Telescope observations
  66. EP260227a: COLIBRÍ optical observations
  67. EP260227a: NOT optical observations
  68. GRB 260225A: SVOM/VT optical continued observations and upper limit
  69. GRID detection of GRB 260223A
  70. EP260227a: Global MASTER-Net observations report
  71. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  72. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  73. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  74. IceCube cascade alert 142200_1517143 retraction
  75. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  76. Konus-Wind detection of GRB 260226A
  77. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  78. EP260214a: VLT/FORS2 optical observations
  79. GRB 260225A: WINTER J-band upper limit
  80. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  81. GRB 260226A: COLIBRÍ optical upper limits
  82. GRB 260226A: LCOGT Optical Upper Limit
  83. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  84. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  85. GRB 260226A: Glowbug gamma-ray detection
  86. GRB 260226A: NuSTAR detection of bright prompt emission
  87. GRB 260226A : GROWTH-India Telescope optical observations
  88. GRB 260226A: LAST optical upper limit
  89. GRB 260226A: Fermi GBM observation
  90. GRB 260226A: Fermi-LAT refined analysis
  91. The EP-WXT trigger 01709258652 is likely a flaring star
  92. LAT GRB260226.44: Global MASTER-Net observations report
  93. Fermi GRB 260226A: Global MASTER-Net observations report
  94. GRB 260226A: AstroSat CZTI detection of bright long burst
  95. EP260214a: VLA 6 GHz detection
  96. GRB 260226A: Fermi-LAT detection of a bright burst
  97. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  98. EP260224a: LCO optical upper limits
  99. GRB260225A: SVOM/ECLAIRs refined position
  100. GRB 260226A: Fermi GBM Final Real-time Localization

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