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

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