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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 260305A: Fermi GBM Final Real-time Localization
  2. GRB 260303B: AstroSat CZTI detection
  3. GRB 260304A: AstroSat CZTI detection of a long burst
  4. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  5. GRB 260303A: SVOM/VT optical observations
  6. GRB 260303A: J-band observations with WINTER
  7. GRB 260303B: NuSTAR detection of prompt emission
  8. EP260302a: Global MASTER-Net observations report
  9. Fermi GRB 260303B: Global MASTER-Net observations report
  10. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  11. GRB 260228A: SVOM/ECLAIRs refined analysis
  12. GRB 260225A: SVOM/ECLAIRs refined analysis
  13. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  14. GRB 260303B: Fermi GBM Final Real-time Localization
  15. EP260302a: analysis of the follow-up EP-FXT observation
  16. EP260227a: Gemini-South optical observations
  17. EP260302a: LCO observations
  18. EP260302a: BOOTES-7 optical counterpart detection at early times
  19. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  20. GRB 260303A: SVOM detection of a burst
  21. GRB 260228A: EP-FXT follow-up observation
  22. EP260302a: Einstein Probe detection of an X-ray transient
  23. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  24. GRB 251130B: TERI Gamma-ray detection
  25. GRB 260208A: TERI Gamma-ray detection
  26. GRB 260302A: Fermi GBM Final Real-time Localization
  27. EP260227a: Mondy optical observations
  28. GRB 260228A: CAHA 2.2m telescope optical upper limit
  29. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  30. EP260227a: Mephisto optical detection
  31. GRID detection of GRB 260225D
  32. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  33. EP260227a: further LCO observations
  34. EP260227a: SVOM/VT optical observation
  35. GRB 260228A: SVOM/VT optical upper limits
  36. GRB 260225D: SVOM/GRM observation
  37. EP260227A: 3.6m DOT optical afterglow detection
  38. GRB 260225B: SVOM/GRM observation
  39. GRB 260228A: SVOM detection of a burst
  40. EP260227a: FTW optical and NIR observations
  41. EP260227a: Liverpool Telescope optical observations
  42. EP260227a: LCOGT Optical Observations
  43. GRB 260226A: Asiago r-band upper limit
  44. EP260227a: Thai National Telescope observations
  45. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  46. EP260227a: Liverpool Telescope observations
  47. EP260227a: COLIBRÍ optical observations
  48. EP260227a: NOT optical observations
  49. GRB 260225A: SVOM/VT optical continued observations and upper limit
  50. GRID detection of GRB 260223A
  51. EP260227a: Global MASTER-Net observations report
  52. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  53. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  54. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  55. IceCube cascade alert 142200_1517143 retraction
  56. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  57. Konus-Wind detection of GRB 260226A
  58. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  59. EP260214a: VLT/FORS2 optical observations
  60. GRB 260225A: WINTER J-band upper limit
  61. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  62. GRB 260226A: COLIBRÍ optical upper limits
  63. GRB 260226A: LCOGT Optical Upper Limit
  64. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  65. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  66. GRB 260226A: Glowbug gamma-ray detection
  67. GRB 260226A: NuSTAR detection of bright prompt emission
  68. GRB 260226A : GROWTH-India Telescope optical observations
  69. GRB 260226A: LAST optical upper limit
  70. GRB 260226A: Fermi GBM observation
  71. GRB 260226A: Fermi-LAT refined analysis
  72. The EP-WXT trigger 01709258652 is likely a flaring star
  73. LAT GRB260226.44: Global MASTER-Net observations report
  74. Fermi GRB 260226A: Global MASTER-Net observations report
  75. GRB 260226A: AstroSat CZTI detection of bright long burst
  76. EP260214a: VLA 6 GHz detection
  77. GRB 260226A: Fermi-LAT detection of a bright burst
  78. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  79. EP260224a: LCO optical upper limits
  80. GRB260225A: SVOM/ECLAIRs refined position
  81. GRB 260226A: Fermi GBM Final Real-time Localization
  82. GRB 260225A: EP-FXT follow-up observation
  83. GRB 260225A: SVOM/VT optical observation
  84. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  85. GRB 260225C: Fermi GBM Final Real-time Localization
  86. GRB 260223A: Fermi GBM Observation
  87. GRB 260225A: SVOM/VT optical upper limits
  88. GRB 260225B: Fermi GBM Final Real-time Localization
  89. EP260126a: VLA 6 GHz detection
  90. EP260223a: Liverpool Telescope upper limits
  91. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  92. GRB 260225A: SVOM detection of a burst
  93. EP260224a: Einstein Probe detection of an X-ray transient
  94. EP 260225.148: COLIBRÍ Confirmation of flaring star
  95. EP260223a: Xinglong optical upper limit
  96. The EP-WXT trigger 01709258631 is likely a flaring star
  97. GRB 260223A: Glowbug gamma-ray detection
  98. EP260213a: Mephisto optical upper limits
  99. EP260223a: EP-FXT follow-up observation
  100. sb26021801: SVOM/VT optical upper limits

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