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

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