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

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