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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 260308A: SVOM/GRM observation of a short GRB
  2. EP260306a: Mondy optical upper limit
  3. GRB 260310A: AstroSat CZTI detection of a long burst
  4. GRB 260311A: Fermi GBM Final Real-time Localization
  5. Fermi GRB 260310B: Global MASTER-Net observations report
  6. GRB 260310B: Fermi GBM Final Real-time Localization
  7. Fermi GRB 260310A: Global MASTER-Net observations report
  8. GRB 260307B: SVOM/ECLAIRs refined analysis
  9. GRB 260208A: radio detection with the VLA
  10. GRB 260310A: Fermi GBM Final Real-time Localization
  11. GRB 260307A: Glowbug gamma-ray detection
  12. GRB 260308A: Fermi GBM Final Real-time Localization
  13. Fermi GBM Sub-Threshold Detection of GRB 260307B
  14. GRB 260307B: Mephisto optical upper limits
  15. GRB 260307B: possible NOT optical counterpart
  16. GRB 260307B: SVOM/VT upper limit with X band data analysis
  17. Fermi GRB 260307A: Global MASTER-Net observations report
  18. GRB260307B: GROWTH-India Telescope optical upper limit
  19. GRB 260307B: SVOM/VT optical candidate
  20. GRB 260307B: SVOM/C-GFT upper limit
  21. GRB 260307B: SVOM detection of a burst
  22. GRB 260307A: Fermi GBM Final Localization
  23. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  24. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  25. GRB 260207A: TESS Detection and Possible VLA Counterpart
  26. EP260302a: SVOM/VT optical observation
  27. EP260306a: Gemini-North redshift z = 4.773
  28. EP260306a: SVOM/VT optical observation
  29. EP260302a: Gemini-South redshift z = 1.535
  30. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  31. EP260306a: Einstein Probe detection of an X-ray transient
  32. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  33. EP260302a: Optical afterglow rebrightening
  34. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  35. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  36. GRB 260303A: 1.3m DFOT optical upper limit
  37. EP260214b: ATCA 6 GHz observations
  38. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  39. GRB 260303A: SVOM/ECLAIRs refined analysis
  40. Fermi GRB 260305A: Global MASTER-Net observations report
  41. GRB 260305A: Fermi GBM Final Real-time Localization
  42. GRB 260303B: AstroSat CZTI detection
  43. GRB 260304A: AstroSat CZTI detection of a long burst
  44. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  45. GRB 260303A: SVOM/VT optical observations
  46. GRB 260303A: J-band observations with WINTER
  47. GRB 260303B: NuSTAR detection of prompt emission
  48. EP260302a: Global MASTER-Net observations report
  49. Fermi GRB 260303B: Global MASTER-Net observations report
  50. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  51. GRB 260228A: SVOM/ECLAIRs refined analysis
  52. GRB 260225A: SVOM/ECLAIRs refined analysis
  53. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  54. GRB 260303B: Fermi GBM Final Real-time Localization
  55. EP260302a: analysis of the follow-up EP-FXT observation
  56. EP260227a: Gemini-South optical observations
  57. EP260302a: LCO observations
  58. EP260302a: BOOTES-7 optical counterpart detection at early times
  59. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  60. GRB 260303A: SVOM detection of a burst
  61. GRB 260228A: EP-FXT follow-up observation
  62. EP260302a: Einstein Probe detection of an X-ray transient
  63. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  64. GRB 251130B: TERI Gamma-ray detection
  65. GRB 260208A: TERI Gamma-ray detection
  66. GRB 260302A: Fermi GBM Final Real-time Localization
  67. EP260227a: Mondy optical observations
  68. GRB 260228A: CAHA 2.2m telescope optical upper limit
  69. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  70. EP260227a: Mephisto optical detection
  71. GRID detection of GRB 260225D
  72. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  73. EP260227a: further LCO observations
  74. EP260227a: SVOM/VT optical observation
  75. GRB 260228A: SVOM/VT optical upper limits
  76. GRB 260225D: SVOM/GRM observation
  77. EP260227A: 3.6m DOT optical afterglow detection
  78. GRB 260225B: SVOM/GRM observation
  79. GRB 260228A: SVOM detection of a burst
  80. EP260227a: FTW optical and NIR observations
  81. EP260227a: Liverpool Telescope optical observations
  82. EP260227a: LCOGT Optical Observations
  83. GRB 260226A: Asiago r-band upper limit
  84. EP260227a: Thai National Telescope observations
  85. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  86. EP260227a: Liverpool Telescope observations
  87. EP260227a: COLIBRÍ optical observations
  88. EP260227a: NOT optical observations
  89. GRB 260225A: SVOM/VT optical continued observations and upper limit
  90. GRID detection of GRB 260223A
  91. EP260227a: Global MASTER-Net observations report
  92. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  93. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  94. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  95. IceCube cascade alert 142200_1517143 retraction
  96. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  97. Konus-Wind detection of GRB 260226A
  98. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  99. EP260214a: VLT/FORS2 optical observations
  100. GRB 260225A: WINTER J-band upper limit

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