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

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