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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 260303A: SVOM/VT optical observations
  2. GRB 260303A: J-band observations with WINTER
  3. GRB 260303B: NuSTAR detection of prompt emission
  4. EP260302a: Global MASTER-Net observations report
  5. Fermi GRB 260303B: Global MASTER-Net observations report
  6. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  7. GRB 260228A: SVOM/ECLAIRs refined analysis
  8. GRB 260225A: SVOM/ECLAIRs refined analysis
  9. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  10. GRB 260303B: Fermi GBM Final Real-time Localization
  11. EP260302a: analysis of the follow-up EP-FXT observation
  12. EP260227a: Gemini-South optical observations
  13. EP260302a: LCO observations
  14. EP260302a: BOOTES-7 optical counterpart detection at early times
  15. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  16. GRB 260303A: SVOM detection of a burst
  17. GRB 260228A: EP-FXT follow-up observation
  18. EP260302a: Einstein Probe detection of an X-ray transient
  19. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  20. GRB 251130B: TERI Gamma-ray detection
  21. GRB 260208A: TERI Gamma-ray detection
  22. GRB 260302A: Fermi GBM Final Real-time Localization
  23. EP260227a: Mondy optical observations
  24. GRB 260228A: CAHA 2.2m telescope optical upper limit
  25. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  26. EP260227a: Mephisto optical detection
  27. GRID detection of GRB 260225D
  28. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  29. EP260227a: further LCO observations
  30. EP260227a: SVOM/VT optical observation
  31. GRB 260228A: SVOM/VT optical upper limits
  32. GRB 260225D: SVOM/GRM observation
  33. EP260227A: 3.6m DOT optical afterglow detection
  34. GRB 260225B: SVOM/GRM observation
  35. GRB 260228A: SVOM detection of a burst
  36. EP260227a: FTW optical and NIR observations
  37. EP260227a: Liverpool Telescope optical observations
  38. EP260227a: LCOGT Optical Observations
  39. GRB 260226A: Asiago r-band upper limit
  40. EP260227a: Thai National Telescope observations
  41. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  42. EP260227a: Liverpool Telescope observations
  43. EP260227a: COLIBRÍ optical observations
  44. EP260227a: NOT optical observations
  45. GRB 260225A: SVOM/VT optical continued observations and upper limit
  46. GRID detection of GRB 260223A
  47. EP260227a: Global MASTER-Net observations report
  48. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  49. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  50. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  51. IceCube cascade alert 142200_1517143 retraction
  52. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  53. Konus-Wind detection of GRB 260226A
  54. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  55. EP260214a: VLT/FORS2 optical observations
  56. GRB 260225A: WINTER J-band upper limit
  57. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  58. GRB 260226A: COLIBRÍ optical upper limits
  59. GRB 260226A: LCOGT Optical Upper Limit
  60. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  61. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  62. GRB 260226A: Glowbug gamma-ray detection
  63. GRB 260226A: NuSTAR detection of bright prompt emission
  64. GRB 260226A : GROWTH-India Telescope optical observations
  65. GRB 260226A: LAST optical upper limit
  66. GRB 260226A: Fermi GBM observation
  67. GRB 260226A: Fermi-LAT refined analysis
  68. The EP-WXT trigger 01709258652 is likely a flaring star
  69. LAT GRB260226.44: Global MASTER-Net observations report
  70. Fermi GRB 260226A: Global MASTER-Net observations report
  71. GRB 260226A: AstroSat CZTI detection of bright long burst
  72. EP260214a: VLA 6 GHz detection
  73. GRB 260226A: Fermi-LAT detection of a bright burst
  74. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  75. EP260224a: LCO optical upper limits
  76. GRB260225A: SVOM/ECLAIRs refined position
  77. GRB 260226A: Fermi GBM Final Real-time Localization
  78. GRB 260225A: EP-FXT follow-up observation
  79. GRB 260225A: SVOM/VT optical observation
  80. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  81. GRB 260225C: Fermi GBM Final Real-time Localization
  82. GRB 260223A: Fermi GBM Observation
  83. GRB 260225A: SVOM/VT optical upper limits
  84. GRB 260225B: Fermi GBM Final Real-time Localization
  85. EP260126a: VLA 6 GHz detection
  86. EP260223a: Liverpool Telescope upper limits
  87. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  88. GRB 260225A: SVOM detection of a burst
  89. EP260224a: Einstein Probe detection of an X-ray transient
  90. EP 260225.148: COLIBRÍ Confirmation of flaring star
  91. EP260223a: Xinglong optical upper limit
  92. The EP-WXT trigger 01709258631 is likely a flaring star
  93. GRB 260223A: Glowbug gamma-ray detection
  94. EP260213a: Mephisto optical upper limits
  95. EP260223a: EP-FXT follow-up observation
  96. sb26021801: SVOM/VT optical upper limits
  97. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  98. sb26021801: SVOM/C-GFT upper limit
  99. EP260223a: COLIBRÍ optical upper limits
  100. EP260223a: Einstein Probe detection of an X-ray transient

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