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

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