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

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