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

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