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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: BOOTES-7 optical counterpart detection at early times
  2. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  3. GRB 260303A: SVOM detection of a burst
  4. GRB 260228A: EP-FXT follow-up observation
  5. EP260302a: Einstein Probe detection of an X-ray transient
  6. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  7. GRB 251130B: TERI Gamma-ray detection
  8. GRB 260208A: TERI Gamma-ray detection
  9. GRB 260302A: Fermi GBM Final Real-time Localization
  10. EP260227a: Mondy optical observations
  11. GRB 260228A: CAHA 2.2m telescope optical upper limit
  12. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  13. EP260227a: Mephisto optical detection
  14. GRID detection of GRB 260225D
  15. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  16. EP260227a: further LCO observations
  17. EP260227a: SVOM/VT optical observation
  18. GRB 260228A: SVOM/VT optical upper limits
  19. GRB 260225D: SVOM/GRM observation
  20. EP260227A: 3.6m DOT optical afterglow detection
  21. GRB 260225B: SVOM/GRM observation
  22. GRB 260228A: SVOM detection of a burst
  23. EP260227a: FTW optical and NIR observations
  24. EP260227a: Liverpool Telescope optical observations
  25. EP260227a: LCOGT Optical Observations
  26. GRB 260226A: Asiago r-band upper limit
  27. EP260227a: Thai National Telescope observations
  28. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  29. EP260227a: Liverpool Telescope observations
  30. EP260227a: COLIBRÍ optical observations
  31. EP260227a: NOT optical observations
  32. GRB 260225A: SVOM/VT optical continued observations and upper limit
  33. GRID detection of GRB 260223A
  34. EP260227a: Global MASTER-Net observations report
  35. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  36. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  37. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  38. IceCube cascade alert 142200_1517143 retraction
  39. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  40. Konus-Wind detection of GRB 260226A
  41. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  42. EP260214a: VLT/FORS2 optical observations
  43. GRB 260225A: WINTER J-band upper limit
  44. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  45. GRB 260226A: COLIBRÍ optical upper limits
  46. GRB 260226A: LCOGT Optical Upper Limit
  47. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  48. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  49. GRB 260226A: Glowbug gamma-ray detection
  50. GRB 260226A: NuSTAR detection of bright prompt emission
  51. GRB 260226A : GROWTH-India Telescope optical observations
  52. GRB 260226A: LAST optical upper limit
  53. GRB 260226A: Fermi GBM observation
  54. GRB 260226A: Fermi-LAT refined analysis
  55. The EP-WXT trigger 01709258652 is likely a flaring star
  56. LAT GRB260226.44: Global MASTER-Net observations report
  57. Fermi GRB 260226A: Global MASTER-Net observations report
  58. GRB 260226A: AstroSat CZTI detection of bright long burst
  59. EP260214a: VLA 6 GHz detection
  60. GRB 260226A: Fermi-LAT detection of a bright burst
  61. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  62. EP260224a: LCO optical upper limits
  63. GRB260225A: SVOM/ECLAIRs refined position
  64. GRB 260226A: Fermi GBM Final Real-time Localization
  65. GRB 260225A: EP-FXT follow-up observation
  66. GRB 260225A: SVOM/VT optical observation
  67. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  68. GRB 260225C: Fermi GBM Final Real-time Localization
  69. GRB 260223A: Fermi GBM Observation
  70. GRB 260225A: SVOM/VT optical upper limits
  71. GRB 260225B: Fermi GBM Final Real-time Localization
  72. EP260126a: VLA 6 GHz detection
  73. EP260223a: Liverpool Telescope upper limits
  74. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  75. GRB 260225A: SVOM detection of a burst
  76. EP260224a: Einstein Probe detection of an X-ray transient
  77. EP 260225.148: COLIBRÍ Confirmation of flaring star
  78. EP260223a: Xinglong optical upper limit
  79. The EP-WXT trigger 01709258631 is likely a flaring star
  80. GRB 260223A: Glowbug gamma-ray detection
  81. EP260213a: Mephisto optical upper limits
  82. EP260223a: EP-FXT follow-up observation
  83. sb26021801: SVOM/VT optical upper limits
  84. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  85. sb26021801: SVOM/C-GFT upper limit
  86. EP260223a: COLIBRÍ optical upper limits
  87. EP260223a: Einstein Probe detection of an X-ray transient
  88. GRB 260223A: SVOM/VT optical observation
  89. GRB 260223A: SVOM/GRM observation
  90. GRB 260223A: COLIBRÍ further optical observations and a brightening
  91. EP260221a: Optical upper limit with Kinder observations
  92. GRB 260223A: COLIBRÍ optical observations
  93. GRB 260223A: DDOTI Optical Candidate
  94. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  95. Fermi GRB 260223A: Global MASTER-Net observations report
  96. GRB 260223A: Fermi GBM Final Real-time Localization
  97. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  98. EP260221a: COLIBRÍ optical counterpart candidate
  99. EP260221a: Gemini South z-band upper limit
  100. GRB 260222A: Fermi GBM Final Real-time Localization

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