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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: SVOM/VT optical observation
  2. EP260306a: Gemini-North redshift z = 4.773
  3. EP260306a: SVOM/VT optical observation
  4. EP260302a: Gemini-South redshift z = 1.535
  5. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  6. EP260306a: Einstein Probe detection of an X-ray transient
  7. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  8. EP260302a: Optical afterglow rebrightening
  9. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  10. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  11. GRB 260303A: 1.3m DFOT optical upper limit
  12. EP260214b: ATCA 6 GHz observations
  13. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  14. GRB 260303A: SVOM/ECLAIRs refined analysis
  15. Fermi GRB 260305A: Global MASTER-Net observations report
  16. GRB 260305A: Fermi GBM Final Real-time Localization
  17. GRB 260303B: AstroSat CZTI detection
  18. GRB 260304A: AstroSat CZTI detection of a long burst
  19. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  20. GRB 260303A: SVOM/VT optical observations
  21. GRB 260303A: J-band observations with WINTER
  22. GRB 260303B: NuSTAR detection of prompt emission
  23. EP260302a: Global MASTER-Net observations report
  24. Fermi GRB 260303B: Global MASTER-Net observations report
  25. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  26. GRB 260228A: SVOM/ECLAIRs refined analysis
  27. GRB 260225A: SVOM/ECLAIRs refined analysis
  28. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  29. GRB 260303B: Fermi GBM Final Real-time Localization
  30. EP260302a: analysis of the follow-up EP-FXT observation
  31. EP260227a: Gemini-South optical observations
  32. EP260302a: LCO observations
  33. EP260302a: BOOTES-7 optical counterpart detection at early times
  34. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  35. GRB 260303A: SVOM detection of a burst
  36. GRB 260228A: EP-FXT follow-up observation
  37. EP260302a: Einstein Probe detection of an X-ray transient
  38. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  39. GRB 251130B: TERI Gamma-ray detection
  40. GRB 260208A: TERI Gamma-ray detection
  41. GRB 260302A: Fermi GBM Final Real-time Localization
  42. EP260227a: Mondy optical observations
  43. GRB 260228A: CAHA 2.2m telescope optical upper limit
  44. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  45. EP260227a: Mephisto optical detection
  46. GRID detection of GRB 260225D
  47. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  48. EP260227a: further LCO observations
  49. EP260227a: SVOM/VT optical observation
  50. GRB 260228A: SVOM/VT optical upper limits
  51. GRB 260225D: SVOM/GRM observation
  52. EP260227A: 3.6m DOT optical afterglow detection
  53. GRB 260225B: SVOM/GRM observation
  54. GRB 260228A: SVOM detection of a burst
  55. EP260227a: FTW optical and NIR observations
  56. EP260227a: Liverpool Telescope optical observations
  57. EP260227a: LCOGT Optical Observations
  58. GRB 260226A: Asiago r-band upper limit
  59. EP260227a: Thai National Telescope observations
  60. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  61. EP260227a: Liverpool Telescope observations
  62. EP260227a: COLIBRÍ optical observations
  63. EP260227a: NOT optical observations
  64. GRB 260225A: SVOM/VT optical continued observations and upper limit
  65. GRID detection of GRB 260223A
  66. EP260227a: Global MASTER-Net observations report
  67. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  68. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  69. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  70. IceCube cascade alert 142200_1517143 retraction
  71. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  72. Konus-Wind detection of GRB 260226A
  73. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  74. EP260214a: VLT/FORS2 optical observations
  75. GRB 260225A: WINTER J-band upper limit
  76. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  77. GRB 260226A: COLIBRÍ optical upper limits
  78. GRB 260226A: LCOGT Optical Upper Limit
  79. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  80. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  81. GRB 260226A: Glowbug gamma-ray detection
  82. GRB 260226A: NuSTAR detection of bright prompt emission
  83. GRB 260226A : GROWTH-India Telescope optical observations
  84. GRB 260226A: LAST optical upper limit
  85. GRB 260226A: Fermi GBM observation
  86. GRB 260226A: Fermi-LAT refined analysis
  87. The EP-WXT trigger 01709258652 is likely a flaring star
  88. LAT GRB260226.44: Global MASTER-Net observations report
  89. Fermi GRB 260226A: Global MASTER-Net observations report
  90. GRB 260226A: AstroSat CZTI detection of bright long burst
  91. EP260214a: VLA 6 GHz detection
  92. GRB 260226A: Fermi-LAT detection of a bright burst
  93. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  94. EP260224a: LCO optical upper limits
  95. GRB260225A: SVOM/ECLAIRs refined position
  96. GRB 260226A: Fermi GBM Final Real-time Localization
  97. GRB 260225A: EP-FXT follow-up observation
  98. GRB 260225A: SVOM/VT optical observation
  99. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  100. GRB 260225C: Fermi GBM Final Real-time Localization

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