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

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