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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 260307B: SVOM/VT upper limit with X band data analysis
  2. Fermi GRB 260307A: Global MASTER-Net observations report
  3. GRB260307B: GROWTH-India Telescope optical upper limit
  4. GRB 260307B: SVOM/VT optical candidate
  5. GRB 260307B: SVOM/C-GFT upper limit
  6. GRB 260307B: SVOM detection of a burst
  7. GRB 260307A: Fermi GBM Final Localization
  8. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  9. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  10. GRB 260207A: TESS Detection and Possible VLA Counterpart
  11. EP260302a: SVOM/VT optical observation
  12. EP260306a: Gemini-North redshift z = 4.773
  13. EP260306a: SVOM/VT optical observation
  14. EP260302a: Gemini-South redshift z = 1.535
  15. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  16. EP260306a: Einstein Probe detection of an X-ray transient
  17. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  18. EP260302a: Optical afterglow rebrightening
  19. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  20. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  21. GRB 260303A: 1.3m DFOT optical upper limit
  22. EP260214b: ATCA 6 GHz observations
  23. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  24. GRB 260303A: SVOM/ECLAIRs refined analysis
  25. Fermi GRB 260305A: Global MASTER-Net observations report
  26. GRB 260305A: Fermi GBM Final Real-time Localization
  27. GRB 260303B: AstroSat CZTI detection
  28. GRB 260304A: AstroSat CZTI detection of a long burst
  29. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  30. GRB 260303A: SVOM/VT optical observations
  31. GRB 260303A: J-band observations with WINTER
  32. GRB 260303B: NuSTAR detection of prompt emission
  33. EP260302a: Global MASTER-Net observations report
  34. Fermi GRB 260303B: Global MASTER-Net observations report
  35. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  36. GRB 260228A: SVOM/ECLAIRs refined analysis
  37. GRB 260225A: SVOM/ECLAIRs refined analysis
  38. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  39. GRB 260303B: Fermi GBM Final Real-time Localization
  40. EP260302a: analysis of the follow-up EP-FXT observation
  41. EP260227a: Gemini-South optical observations
  42. EP260302a: LCO observations
  43. EP260302a: BOOTES-7 optical counterpart detection at early times
  44. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  45. GRB 260303A: SVOM detection of a burst
  46. GRB 260228A: EP-FXT follow-up observation
  47. EP260302a: Einstein Probe detection of an X-ray transient
  48. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  49. GRB 251130B: TERI Gamma-ray detection
  50. GRB 260208A: TERI Gamma-ray detection
  51. GRB 260302A: Fermi GBM Final Real-time Localization
  52. EP260227a: Mondy optical observations
  53. GRB 260228A: CAHA 2.2m telescope optical upper limit
  54. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  55. EP260227a: Mephisto optical detection
  56. GRID detection of GRB 260225D
  57. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  58. EP260227a: further LCO observations
  59. EP260227a: SVOM/VT optical observation
  60. GRB 260228A: SVOM/VT optical upper limits
  61. GRB 260225D: SVOM/GRM observation
  62. EP260227A: 3.6m DOT optical afterglow detection
  63. GRB 260225B: SVOM/GRM observation
  64. GRB 260228A: SVOM detection of a burst
  65. EP260227a: FTW optical and NIR observations
  66. EP260227a: Liverpool Telescope optical observations
  67. EP260227a: LCOGT Optical Observations
  68. GRB 260226A: Asiago r-band upper limit
  69. EP260227a: Thai National Telescope observations
  70. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  71. EP260227a: Liverpool Telescope observations
  72. EP260227a: COLIBRÍ optical observations
  73. EP260227a: NOT optical observations
  74. GRB 260225A: SVOM/VT optical continued observations and upper limit
  75. GRID detection of GRB 260223A
  76. EP260227a: Global MASTER-Net observations report
  77. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  78. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  79. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  80. IceCube cascade alert 142200_1517143 retraction
  81. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  82. Konus-Wind detection of GRB 260226A
  83. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  84. EP260214a: VLT/FORS2 optical observations
  85. GRB 260225A: WINTER J-band upper limit
  86. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  87. GRB 260226A: COLIBRÍ optical upper limits
  88. GRB 260226A: LCOGT Optical Upper Limit
  89. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  90. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  91. GRB 260226A: Glowbug gamma-ray detection
  92. GRB 260226A: NuSTAR detection of bright prompt emission
  93. GRB 260226A : GROWTH-India Telescope optical observations
  94. GRB 260226A: LAST optical upper limit
  95. GRB 260226A: Fermi GBM observation
  96. GRB 260226A: Fermi-LAT refined analysis
  97. The EP-WXT trigger 01709258652 is likely a flaring star
  98. LAT GRB260226.44: Global MASTER-Net observations report
  99. Fermi GRB 260226A: Global MASTER-Net observations report
  100. GRB 260226A: AstroSat CZTI detection of bright long burst

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