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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 260228A: further EP-FXT observations and X-ray afterglow confirmation
  2. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  3. GRB 260303A: 1.3m DFOT optical upper limit
  4. EP260214b: ATCA 6 GHz observations
  5. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  6. GRB 260303A: SVOM/ECLAIRs refined analysis
  7. Fermi GRB 260305A: Global MASTER-Net observations report
  8. GRB 260305A: Fermi GBM Final Real-time Localization
  9. GRB 260303B: AstroSat CZTI detection
  10. GRB 260304A: AstroSat CZTI detection of a long burst
  11. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  12. GRB 260303A: SVOM/VT optical observations
  13. GRB 260303A: J-band observations with WINTER
  14. GRB 260303B: NuSTAR detection of prompt emission
  15. EP260302a: Global MASTER-Net observations report
  16. Fermi GRB 260303B: Global MASTER-Net observations report
  17. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  18. GRB 260228A: SVOM/ECLAIRs refined analysis
  19. GRB 260225A: SVOM/ECLAIRs refined analysis
  20. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  21. GRB 260303B: Fermi GBM Final Real-time Localization
  22. EP260302a: analysis of the follow-up EP-FXT observation
  23. EP260227a: Gemini-South optical observations
  24. EP260302a: LCO observations
  25. EP260302a: BOOTES-7 optical counterpart detection at early times
  26. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  27. GRB 260303A: SVOM detection of a burst
  28. GRB 260228A: EP-FXT follow-up observation
  29. EP260302a: Einstein Probe detection of an X-ray transient
  30. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  31. GRB 251130B: TERI Gamma-ray detection
  32. GRB 260208A: TERI Gamma-ray detection
  33. GRB 260302A: Fermi GBM Final Real-time Localization
  34. EP260227a: Mondy optical observations
  35. GRB 260228A: CAHA 2.2m telescope optical upper limit
  36. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  37. EP260227a: Mephisto optical detection
  38. GRID detection of GRB 260225D
  39. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  40. EP260227a: further LCO observations
  41. EP260227a: SVOM/VT optical observation
  42. GRB 260228A: SVOM/VT optical upper limits
  43. GRB 260225D: SVOM/GRM observation
  44. EP260227A: 3.6m DOT optical afterglow detection
  45. GRB 260225B: SVOM/GRM observation
  46. GRB 260228A: SVOM detection of a burst
  47. EP260227a: FTW optical and NIR observations
  48. EP260227a: Liverpool Telescope optical observations
  49. EP260227a: LCOGT Optical Observations
  50. GRB 260226A: Asiago r-band upper limit
  51. EP260227a: Thai National Telescope observations
  52. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  53. EP260227a: Liverpool Telescope observations
  54. EP260227a: COLIBRÍ optical observations
  55. EP260227a: NOT optical observations
  56. GRB 260225A: SVOM/VT optical continued observations and upper limit
  57. GRID detection of GRB 260223A
  58. EP260227a: Global MASTER-Net observations report
  59. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  60. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  61. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  62. IceCube cascade alert 142200_1517143 retraction
  63. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  64. Konus-Wind detection of GRB 260226A
  65. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  66. EP260214a: VLT/FORS2 optical observations
  67. GRB 260225A: WINTER J-band upper limit
  68. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  69. GRB 260226A: COLIBRÍ optical upper limits
  70. GRB 260226A: LCOGT Optical Upper Limit
  71. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  72. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  73. GRB 260226A: Glowbug gamma-ray detection
  74. GRB 260226A: NuSTAR detection of bright prompt emission
  75. GRB 260226A : GROWTH-India Telescope optical observations
  76. GRB 260226A: LAST optical upper limit
  77. GRB 260226A: Fermi GBM observation
  78. GRB 260226A: Fermi-LAT refined analysis
  79. The EP-WXT trigger 01709258652 is likely a flaring star
  80. LAT GRB260226.44: Global MASTER-Net observations report
  81. Fermi GRB 260226A: Global MASTER-Net observations report
  82. GRB 260226A: AstroSat CZTI detection of bright long burst
  83. EP260214a: VLA 6 GHz detection
  84. GRB 260226A: Fermi-LAT detection of a bright burst
  85. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  86. EP260224a: LCO optical upper limits
  87. GRB260225A: SVOM/ECLAIRs refined position
  88. GRB 260226A: Fermi GBM Final Real-time Localization
  89. GRB 260225A: EP-FXT follow-up observation
  90. GRB 260225A: SVOM/VT optical observation
  91. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  92. GRB 260225C: Fermi GBM Final Real-time Localization
  93. GRB 260223A: Fermi GBM Observation
  94. GRB 260225A: SVOM/VT optical upper limits
  95. GRB 260225B: Fermi GBM Final Real-time Localization
  96. EP260126a: VLA 6 GHz detection
  97. EP260223a: Liverpool Telescope upper limits
  98. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  99. GRB 260225A: SVOM detection of a burst
  100. EP260224a: Einstein Probe detection of an X-ray transient

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