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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"

11525 results found.

  1. GRB260310A / AT2026fgk: P200 Spectroscopy
  2. GRB 260312B: Glowbug gamma-ray detection
  3. GRB 260310A: Fermi GBM Observation
  4. GRB 260310A: potential optical counterpart
  5. Fermi GRB 260312B: Global MASTER-Net observations report
  6. Fermi GRB 260311B: Global MASTER-Net observations report
  7. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  8. GRB 260312B: Fermi GBM Final Real-time Localization
  9. GRB 260310B: GECAM-B observation of a burst
  10. GRB 260311B: Fermi GBM Final Real-time Localization
  11. GRB 260131A/B: radio detection with the VLA
  12. GRB260307A: GECAM-B observation of a burst
  13. GRB 260308A: SVOM/GRM observation of a short GRB
  14. GRB 260310A: AstroSat CZTI detection of a long burst
  15. GRB 260311A: Fermi GBM Final Real-time Localization
  16. Fermi GRB 260310B: Global MASTER-Net observations report
  17. GRB 260310B: Fermi GBM Final Real-time Localization
  18. Fermi GRB 260310A: Global MASTER-Net observations report
  19. GRB 260307B: SVOM/ECLAIRs refined analysis
  20. GRB 260208A: radio detection with the VLA
  21. GRB 260310A: Fermi GBM Final Real-time Localization
  22. GRB 260307A: Glowbug gamma-ray detection
  23. GRB 260308A: Fermi GBM Final Real-time Localization
  24. Fermi GBM Sub-Threshold Detection of GRB 260307B
  25. Fermi GRB 260307A: Global MASTER-Net observations report
  26. GRB 260307A: Fermi GBM Final Localization
  27. GRB 260207A: TESS Detection and Possible VLA Counterpart
  28. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  29. Fermi GRB 260305A: Global MASTER-Net observations report
  30. GRB 260305A: Fermi GBM Final Real-time Localization
  31. GRB 260303B: AstroSat CZTI detection
  32. GRB 260303B: NuSTAR detection of prompt emission
  33. Fermi GRB 260303B: Global MASTER-Net observations report
  34. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  35. GRB 260303B: Fermi GBM Final Real-time Localization
  36. GRB 251130B: TERI Gamma-ray detection
  37. GRB 260208A: TERI Gamma-ray detection
  38. GRB 260302A: Fermi GBM Final Real-time Localization
  39. GRB 260225B: SVOM/GRM observation
  40. GRB 260226A: Asiago r-band upper limit
  41. GRID detection of GRB 260223A
  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 260226A: CALET Gamma-Ray Burst Monitor detection
  46. GRB 260226A: COLIBRÍ optical upper limits
  47. GRB 260226A: LCOGT Optical Upper Limit
  48. GRB 260226A: Glowbug gamma-ray detection
  49. GRB 260226A: NuSTAR detection of bright prompt emission
  50. GRB 260226A : GROWTH-India Telescope optical observations
  51. GRB 260226A: LAST optical upper limit
  52. GRB 260226A: Fermi GBM observation
  53. GRB 260226A: Fermi-LAT refined analysis
  54. Fermi GRB 260226A: Global MASTER-Net observations report
  55. GRB 260226A: AstroSat CZTI detection of bright long burst
  56. GRB 260226A: Fermi-LAT detection of a bright burst
  57. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  58. GRB 260226A: Fermi GBM Final Real-time Localization
  59. GRB 260225C: Fermi GBM Final Real-time Localization
  60. GRB 260223A: Fermi GBM Observation
  61. GRB 260225B: Fermi GBM Final Real-time Localization
  62. GRB 260223A: Glowbug gamma-ray detection
  63. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  64. GRB 260223A: SVOM/VT optical observation
  65. GRB 260223A: SVOM/GRM observation
  66. GRB 260223A: COLIBRÍ further optical observations and a brightening
  67. GRB 260223A: COLIBRÍ optical observations
  68. GRB 260223A: DDOTI Optical Candidate
  69. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  70. Fermi GRB 260223A: Global MASTER-Net observations report
  71. GRB 260223A: Fermi GBM Final Real-time Localization
  72. GRB 260222A: Fermi GBM Final Real-time Localization
  73. Fermi GRB 260221B: Global MASTER-Net observations report
  74. GRB 260221B: Fermi GBM Final Real-time Localization
  75. Fermi GRB 260221A: Global MASTER-Net observations report
  76. GRB 260221A: Fermi GBM Final Real-time Localization
  77. GRB 260219A: AstroSat CZTI detection
  78. GRB 260219A: GECAM-B observation of a long burst
  79. Fermi GRB 260219A: Global MASTER-Net observations report
  80. GRB 260219A: Fermi GBM Final Real-time Localization
  81. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  82. GRB 260217A: Fermi GBM Final Localization
  83. Konus-Wind detection of GRB 260212A
  84. GRB 260208A: AbAO and Terskol optical upper limits
  85. GRB 260208A: continued Mondy optical observations
  86. IPN triangulation of GRB 260212A
  87. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  88. GRB 260213A: GECAM-B observation of a short burst
  89. GRB 260216A: Fermi Gamma-ray Burst Monitor trigger 792969362/260216886 is not a GRB
  90. GRB 260216A: Fermi GBM Final Real-time Localization
  91. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  92. GRB 260211A: SVOM/VT optical counterpart
  93. GRB 260212A: AstroSat CZTI detection
  94. GRB 260212A: Fermi GBM Observation
  95. GRB 260212A: GECAM-B observation
  96. GRB 260212A: SVOM/GRM observation of a long burst
  97. GRB 260213B: Fermi GBM Final Localization
  98. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  99. GRB 260211A - SVOM/ECLAIRs refined analysis
  100. GRB 260204A: SVOM/ECLAIRs refined analysis

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