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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"

38311 results found.

  1. GRB 260303A: 1.3m DFOT optical upper limit
  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. GRB 260228A: SVOM/ECLAIRs refined analysis
  15. GRB 260225A: SVOM/ECLAIRs refined analysis
  16. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  17. GRB 260303B: Fermi GBM Final Real-time Localization
  18. EP260302a: LCO observations
  19. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  20. GRB 260303A: SVOM detection of a burst
  21. GRB 260228A: EP-FXT follow-up observation
  22. GRB 251130B: TERI Gamma-ray detection
  23. GRB 260208A: TERI Gamma-ray detection
  24. GRB 260302A: Fermi GBM Final Real-time Localization
  25. EP260227a: Mondy optical observations
  26. GRB 260228A: CAHA 2.2m telescope optical upper limit
  27. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  28. EP260227a: Mephisto optical detection
  29. GRID detection of GRB 260225D
  30. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  31. EP260227a: further LCO observations
  32. GRB 260228A: SVOM/VT optical upper limits
  33. GRB 260225D: SVOM/GRM observation
  34. EP260227A: 3.6m DOT optical afterglow detection
  35. GRB 260225B: SVOM/GRM observation
  36. GRB 260228A: SVOM detection of a burst
  37. GRB 260226A: Asiago r-band upper limit
  38. EP260227a: COLIBRÍ optical observations
  39. GRB 260225A: SVOM/VT optical continued observations and upper limit
  40. GRID detection of GRB 260223A
  41. EP260227a: Global MASTER-Net observations report
  42. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  43. Konus-Wind detection of GRB 260226A
  44. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  45. GRB 260225A: WINTER J-band upper limit
  46. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  47. GRB 260226A: COLIBRÍ optical upper limits
  48. GRB 260226A: LCOGT Optical Upper Limit
  49. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  50. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  51. GRB 260226A: Glowbug gamma-ray detection
  52. GRB 260226A: NuSTAR detection of bright prompt emission
  53. GRB 260226A : GROWTH-India Telescope optical observations
  54. GRB 260226A: LAST optical upper limit
  55. GRB 260226A: Fermi GBM observation
  56. GRB 260226A: Fermi-LAT refined analysis
  57. LAT GRB260226.44: Global MASTER-Net observations report
  58. Fermi GRB 260226A: Global MASTER-Net observations report
  59. GRB 260226A: AstroSat CZTI detection of bright long burst
  60. GRB 260226A: Fermi-LAT detection of a bright burst
  61. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  62. EP260224a: LCO optical upper limits
  63. GRB260225A: SVOM/ECLAIRs refined position
  64. GRB 260226A: Fermi GBM Final Real-time Localization
  65. GRB 260225A: EP-FXT follow-up observation
  66. GRB 260225A: SVOM/VT optical observation
  67. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  68. GRB 260225C: Fermi GBM Final Real-time Localization
  69. GRB 260223A: Fermi GBM Observation
  70. GRB 260225A: SVOM/VT optical upper limits
  71. GRB 260225B: Fermi GBM Final Real-time Localization
  72. EP260126a: VLA 6 GHz detection
  73. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  74. GRB 260225A: SVOM detection of a burst
  75. EP 260225.148: COLIBRÍ Confirmation of flaring star
  76. GRB 260223A: Glowbug gamma-ray detection
  77. EP260213a: Mephisto optical upper limits
  78. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  79. sb26021801: SVOM/C-GFT upper limit
  80. EP260223a: COLIBRÍ optical upper limits
  81. GRB 260223A: SVOM/VT optical observation
  82. GRB 260223A: SVOM/GRM observation
  83. GRB 260223A: COLIBRÍ further optical observations and a brightening
  84. GRB 260223A: COLIBRÍ optical observations
  85. GRB 260223A: DDOTI Optical Candidate
  86. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  87. Fermi GRB 260223A: Global MASTER-Net observations report
  88. GRB 260223A: Fermi GBM Final Real-time Localization
  89. EP260221a: COLIBRÍ optical counterpart candidate
  90. GRB 260222A: Fermi GBM Final Real-time Localization
  91. EP260221a: Global MASTER-Net observations report
  92. Fermi GRB 260221B: Global MASTER-Net observations report
  93. GRB 260221B: Fermi GBM Final Real-time Localization
  94. Fermi GRB 260221A: Global MASTER-Net observations report
  95. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  96. GRB 260221A: Fermi GBM Final Real-time Localization
  97. EP260221a: COLIBRÍ optical upper limit
  98. GRB 260219A: AstroSat CZTI detection
  99. GRB 260219A: GECAM-B observation of a long burst
  100. Fermi GRB 260219A: Global MASTER-Net observations report

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