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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. EP260214b: ATCA 6 GHz observations
  2. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  3. GRB 260303A: SVOM/ECLAIRs refined analysis
  4. Fermi GRB 260305A: Global MASTER-Net observations report
  5. GRB 260305A: Fermi GBM Final Real-time Localization
  6. GRB 260303B: AstroSat CZTI detection
  7. GRB 260304A: AstroSat CZTI detection of a long burst
  8. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  9. GRB 260303A: SVOM/VT optical observations
  10. GRB 260303A: J-band observations with WINTER
  11. GRB 260303B: NuSTAR detection of prompt emission
  12. EP260302a: Global MASTER-Net observations report
  13. Fermi GRB 260303B: Global MASTER-Net observations report
  14. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  15. GRB 260228A: SVOM/ECLAIRs refined analysis
  16. GRB 260225A: SVOM/ECLAIRs refined analysis
  17. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  18. GRB 260303B: Fermi GBM Final Real-time Localization
  19. EP260302a: analysis of the follow-up EP-FXT observation
  20. EP260227a: Gemini-South optical observations
  21. EP260302a: LCO observations
  22. EP260302a: BOOTES-7 optical counterpart detection at early times
  23. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  24. GRB 260303A: SVOM detection of a burst
  25. GRB 260228A: EP-FXT follow-up observation
  26. EP260302a: Einstein Probe detection of an X-ray transient
  27. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  28. GRB 251130B: TERI Gamma-ray detection
  29. GRB 260208A: TERI Gamma-ray detection
  30. GRB 260302A: Fermi GBM Final Real-time Localization
  31. EP260227a: Mondy optical observations
  32. GRB 260228A: CAHA 2.2m telescope optical upper limit
  33. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  34. EP260227a: Mephisto optical detection
  35. GRID detection of GRB 260225D
  36. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  37. EP260227a: further LCO observations
  38. EP260227a: SVOM/VT optical observation
  39. GRB 260228A: SVOM/VT optical upper limits
  40. GRB 260225D: SVOM/GRM observation
  41. EP260227A: 3.6m DOT optical afterglow detection
  42. GRB 260225B: SVOM/GRM observation
  43. GRB 260228A: SVOM detection of a burst
  44. EP260227a: FTW optical and NIR observations
  45. EP260227a: Liverpool Telescope optical observations
  46. EP260227a: LCOGT Optical Observations
  47. GRB 260226A: Asiago r-band upper limit
  48. EP260227a: Thai National Telescope observations
  49. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  50. EP260227a: Liverpool Telescope observations
  51. EP260227a: COLIBRÍ optical observations
  52. EP260227a: NOT optical observations
  53. GRB 260225A: SVOM/VT optical continued observations and upper limit
  54. GRID detection of GRB 260223A
  55. EP260227a: Global MASTER-Net observations report
  56. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  57. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  58. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  59. IceCube cascade alert 142200_1517143 retraction
  60. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  61. Konus-Wind detection of GRB 260226A
  62. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  63. EP260214a: VLT/FORS2 optical observations
  64. GRB 260225A: WINTER J-band upper limit
  65. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  66. GRB 260226A: COLIBRÍ optical upper limits
  67. GRB 260226A: LCOGT Optical Upper Limit
  68. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  69. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  70. GRB 260226A: Glowbug gamma-ray detection
  71. GRB 260226A: NuSTAR detection of bright prompt emission
  72. GRB 260226A : GROWTH-India Telescope optical observations
  73. GRB 260226A: LAST optical upper limit
  74. GRB 260226A: Fermi GBM observation
  75. GRB 260226A: Fermi-LAT refined analysis
  76. The EP-WXT trigger 01709258652 is likely a flaring star
  77. LAT GRB260226.44: Global MASTER-Net observations report
  78. Fermi GRB 260226A: Global MASTER-Net observations report
  79. GRB 260226A: AstroSat CZTI detection of bright long burst
  80. EP260214a: VLA 6 GHz detection
  81. GRB 260226A: Fermi-LAT detection of a bright burst
  82. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  83. EP260224a: LCO optical upper limits
  84. GRB260225A: SVOM/ECLAIRs refined position
  85. GRB 260226A: Fermi GBM Final Real-time Localization
  86. GRB 260225A: EP-FXT follow-up observation
  87. GRB 260225A: SVOM/VT optical observation
  88. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  89. GRB 260225C: Fermi GBM Final Real-time Localization
  90. GRB 260223A: Fermi GBM Observation
  91. GRB 260225A: SVOM/VT optical upper limits
  92. GRB 260225B: Fermi GBM Final Real-time Localization
  93. EP260126a: VLA 6 GHz detection
  94. EP260223a: Liverpool Telescope upper limits
  95. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  96. GRB 260225A: SVOM detection of a burst
  97. EP260224a: Einstein Probe detection of an X-ray transient
  98. EP 260225.148: COLIBRÍ Confirmation of flaring star
  99. EP260223a: Xinglong optical upper limit
  100. The EP-WXT trigger 01709258631 is likely a flaring star

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