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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. Fermi GRB 260303B: Global MASTER-Net observations report
  2. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  3. GRB 260228A: SVOM/ECLAIRs refined analysis
  4. GRB 260225A: SVOM/ECLAIRs refined analysis
  5. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  6. GRB 260303B: Fermi GBM Final Real-time Localization
  7. EP260302a: analysis of the follow-up EP-FXT observation
  8. EP260227a: Gemini-South optical observations
  9. EP260302a: LCO observations
  10. EP260302a: BOOTES-7 optical counterpart detection at early times
  11. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  12. GRB 260303A: SVOM detection of a burst
  13. GRB 260228A: EP-FXT follow-up observation
  14. EP260302a: Einstein Probe detection of an X-ray transient
  15. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  16. GRB 251130B: TERI Gamma-ray detection
  17. GRB 260208A: TERI Gamma-ray detection
  18. GRB 260302A: Fermi GBM Final Real-time Localization
  19. EP260227a: Mondy optical observations
  20. GRB 260228A: CAHA 2.2m telescope optical upper limit
  21. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  22. EP260227a: Mephisto optical detection
  23. GRID detection of GRB 260225D
  24. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  25. EP260227a: further LCO observations
  26. EP260227a: SVOM/VT optical observation
  27. GRB 260228A: SVOM/VT optical upper limits
  28. GRB 260225D: SVOM/GRM observation
  29. EP260227A: 3.6m DOT optical afterglow detection
  30. GRB 260225B: SVOM/GRM observation
  31. GRB 260228A: SVOM detection of a burst
  32. EP260227a: FTW optical and NIR observations
  33. EP260227a: Liverpool Telescope optical observations
  34. EP260227a: LCOGT Optical Observations
  35. GRB 260226A: Asiago r-band upper limit
  36. EP260227a: Thai National Telescope observations
  37. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  38. EP260227a: Liverpool Telescope observations
  39. EP260227a: COLIBRÍ optical observations
  40. EP260227a: NOT optical observations
  41. GRB 260225A: SVOM/VT optical continued observations and upper limit
  42. GRID detection of GRB 260223A
  43. EP260227a: Global MASTER-Net observations report
  44. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  45. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  46. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  47. IceCube cascade alert 142200_1517143 retraction
  48. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  49. Konus-Wind detection of GRB 260226A
  50. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  51. EP260214a: VLT/FORS2 optical observations
  52. GRB 260225A: WINTER J-band upper limit
  53. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  54. GRB 260226A: COLIBRÍ optical upper limits
  55. GRB 260226A: LCOGT Optical Upper Limit
  56. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  57. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  58. GRB 260226A: Glowbug gamma-ray detection
  59. GRB 260226A: NuSTAR detection of bright prompt emission
  60. GRB 260226A : GROWTH-India Telescope optical observations
  61. GRB 260226A: LAST optical upper limit
  62. GRB 260226A: Fermi GBM observation
  63. GRB 260226A: Fermi-LAT refined analysis
  64. The EP-WXT trigger 01709258652 is likely a flaring star
  65. LAT GRB260226.44: Global MASTER-Net observations report
  66. Fermi GRB 260226A: Global MASTER-Net observations report
  67. GRB 260226A: AstroSat CZTI detection of bright long burst
  68. EP260214a: VLA 6 GHz detection
  69. GRB 260226A: Fermi-LAT detection of a bright burst
  70. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  71. EP260224a: LCO optical upper limits
  72. GRB260225A: SVOM/ECLAIRs refined position
  73. GRB 260226A: Fermi GBM Final Real-time Localization
  74. GRB 260225A: EP-FXT follow-up observation
  75. GRB 260225A: SVOM/VT optical observation
  76. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  77. GRB 260225C: Fermi GBM Final Real-time Localization
  78. GRB 260223A: Fermi GBM Observation
  79. GRB 260225A: SVOM/VT optical upper limits
  80. GRB 260225B: Fermi GBM Final Real-time Localization
  81. EP260126a: VLA 6 GHz detection
  82. EP260223a: Liverpool Telescope upper limits
  83. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  84. GRB 260225A: SVOM detection of a burst
  85. EP260224a: Einstein Probe detection of an X-ray transient
  86. EP 260225.148: COLIBRÍ Confirmation of flaring star
  87. EP260223a: Xinglong optical upper limit
  88. The EP-WXT trigger 01709258631 is likely a flaring star
  89. GRB 260223A: Glowbug gamma-ray detection
  90. EP260213a: Mephisto optical upper limits
  91. EP260223a: EP-FXT follow-up observation
  92. sb26021801: SVOM/VT optical upper limits
  93. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  94. sb26021801: SVOM/C-GFT upper limit
  95. EP260223a: COLIBRÍ optical upper limits
  96. EP260223a: Einstein Probe detection of an X-ray transient
  97. GRB 260223A: SVOM/VT optical observation
  98. GRB 260223A: SVOM/GRM observation
  99. GRB 260223A: COLIBRÍ further optical observations and a brightening
  100. EP260221a: Optical upper limit with Kinder observations

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