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

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