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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. GRB260307A: GECAM-B observation of a burst
  2. GRB 260308A: SVOM/GRM observation of a short GRB
  3. EP260306a: Mondy optical upper limit
  4. GRB 260310A: AstroSat CZTI detection of a long burst
  5. GRB 260311A: Fermi GBM Final Real-time Localization
  6. Fermi GRB 260310B: Global MASTER-Net observations report
  7. GRB 260310B: Fermi GBM Final Real-time Localization
  8. Fermi GRB 260310A: Global MASTER-Net observations report
  9. GRB 260307B: SVOM/ECLAIRs refined analysis
  10. GRB 260208A: radio detection with the VLA
  11. GRB 260310A: Fermi GBM Final Real-time Localization
  12. GRB 260307A: Glowbug gamma-ray detection
  13. GRB 260308A: Fermi GBM Final Real-time Localization
  14. Fermi GBM Sub-Threshold Detection of GRB 260307B
  15. GRB 260307B: Mephisto optical upper limits
  16. GRB 260307B: possible NOT optical counterpart
  17. GRB 260307B: SVOM/VT upper limit with X band data analysis
  18. Fermi GRB 260307A: Global MASTER-Net observations report
  19. GRB260307B: GROWTH-India Telescope optical upper limit
  20. GRB 260307B: SVOM/VT optical candidate
  21. GRB 260307B: SVOM/C-GFT upper limit
  22. GRB 260307B: SVOM detection of a burst
  23. GRB 260307A: Fermi GBM Final Localization
  24. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  25. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  26. GRB 260207A: TESS Detection and Possible VLA Counterpart
  27. EP260302a: SVOM/VT optical observation
  28. EP260306a: Gemini-North redshift z = 4.773
  29. EP260306a: SVOM/VT optical observation
  30. EP260302a: Gemini-South redshift z = 1.535
  31. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  32. EP260306a: Einstein Probe detection of an X-ray transient
  33. The EP-WXT trigger 01709258759: Las Cumbres discovery of the optical counterpart
  34. EP260302a: Optical afterglow rebrightening
  35. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  36. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  37. GRB 260303A: 1.3m DFOT optical upper limit
  38. EP260214b: ATCA 6 GHz observations
  39. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  40. GRB 260303A: SVOM/ECLAIRs refined analysis
  41. Fermi GRB 260305A: Global MASTER-Net observations report
  42. GRB 260305A: Fermi GBM Final Real-time Localization
  43. GRB 260303B: AstroSat CZTI detection
  44. GRB 260304A: AstroSat CZTI detection of a long burst
  45. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  46. GRB 260303A: SVOM/VT optical observations
  47. GRB 260303A: J-band observations with WINTER
  48. GRB 260303B: NuSTAR detection of prompt emission
  49. EP260302a: Global MASTER-Net observations report
  50. Fermi GRB 260303B: Global MASTER-Net observations report
  51. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  52. GRB 260228A: SVOM/ECLAIRs refined analysis
  53. GRB 260225A: SVOM/ECLAIRs refined analysis
  54. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  55. GRB 260303B: Fermi GBM Final Real-time Localization
  56. EP260302a: analysis of the follow-up EP-FXT observation
  57. EP260227a: Gemini-South optical observations
  58. EP260302a: LCO observations
  59. EP260302a: BOOTES-7 optical counterpart detection at early times
  60. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  61. GRB 260303A: SVOM detection of a burst
  62. GRB 260228A: EP-FXT follow-up observation
  63. EP260302a: Einstein Probe detection of an X-ray transient
  64. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  65. GRB 251130B: TERI Gamma-ray detection
  66. GRB 260208A: TERI Gamma-ray detection
  67. GRB 260302A: Fermi GBM Final Real-time Localization
  68. EP260227a: Mondy optical observations
  69. GRB 260228A: CAHA 2.2m telescope optical upper limit
  70. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  71. EP260227a: Mephisto optical detection
  72. GRID detection of GRB 260225D
  73. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  74. EP260227a: further LCO observations
  75. EP260227a: SVOM/VT optical observation
  76. GRB 260228A: SVOM/VT optical upper limits
  77. GRB 260225D: SVOM/GRM observation
  78. EP260227A: 3.6m DOT optical afterglow detection
  79. GRB 260225B: SVOM/GRM observation
  80. GRB 260228A: SVOM detection of a burst
  81. EP260227a: FTW optical and NIR observations
  82. EP260227a: Liverpool Telescope optical observations
  83. EP260227a: LCOGT Optical Observations
  84. GRB 260226A: Asiago r-band upper limit
  85. EP260227a: Thai National Telescope observations
  86. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  87. EP260227a: Liverpool Telescope observations
  88. EP260227a: COLIBRÍ optical observations
  89. EP260227a: NOT optical observations
  90. GRB 260225A: SVOM/VT optical continued observations and upper limit
  91. GRID detection of GRB 260223A
  92. EP260227a: Global MASTER-Net observations report
  93. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  94. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  95. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  96. IceCube cascade alert 142200_1517143 retraction
  97. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  98. Konus-Wind detection of GRB 260226A
  99. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  100. EP260214a: VLT/FORS2 optical observations

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