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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"

11527 results found.

  1. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  2. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  3. GRB260310A / AT2026fgk: P200 Spectroscopy
  4. GRB 260312B: Glowbug gamma-ray detection
  5. GRB 260310A: Fermi GBM Observation
  6. GRB 260310A: potential optical counterpart
  7. Fermi GRB 260312B: Global MASTER-Net observations report
  8. Fermi GRB 260311B: Global MASTER-Net observations report
  9. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  10. GRB 260312B: Fermi GBM Final Real-time Localization
  11. GRB 260310B: GECAM-B observation of a burst
  12. GRB 260311B: Fermi GBM Final Real-time Localization
  13. GRB 260131A/B: radio detection with the VLA
  14. GRB260307A: GECAM-B observation of a burst
  15. GRB 260308A: SVOM/GRM observation of a short GRB
  16. GRB 260310A: AstroSat CZTI detection of a long burst
  17. GRB 260311A: Fermi GBM Final Real-time Localization
  18. Fermi GRB 260310B: Global MASTER-Net observations report
  19. GRB 260310B: Fermi GBM Final Real-time Localization
  20. Fermi GRB 260310A: Global MASTER-Net observations report
  21. GRB 260307B: SVOM/ECLAIRs refined analysis
  22. GRB 260208A: radio detection with the VLA
  23. GRB 260310A: Fermi GBM Final Real-time Localization
  24. GRB 260307A: Glowbug gamma-ray detection
  25. GRB 260308A: Fermi GBM Final Real-time Localization
  26. Fermi GBM Sub-Threshold Detection of GRB 260307B
  27. Fermi GRB 260307A: Global MASTER-Net observations report
  28. GRB 260307A: Fermi GBM Final Localization
  29. GRB 260207A: TESS Detection and Possible VLA Counterpart
  30. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  31. Fermi GRB 260305A: Global MASTER-Net observations report
  32. GRB 260305A: Fermi GBM Final Real-time Localization
  33. GRB 260303B: AstroSat CZTI detection
  34. GRB 260303B: NuSTAR detection of prompt emission
  35. Fermi GRB 260303B: Global MASTER-Net observations report
  36. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  37. GRB 260303B: Fermi GBM Final Real-time Localization
  38. GRB 251130B: TERI Gamma-ray detection
  39. GRB 260208A: TERI Gamma-ray detection
  40. GRB 260302A: Fermi GBM Final Real-time Localization
  41. GRB 260225B: SVOM/GRM observation
  42. GRB 260226A: Asiago r-band upper limit
  43. GRID detection of GRB 260223A
  44. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  45. Konus-Wind detection of GRB 260226A
  46. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  47. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  48. GRB 260226A: COLIBRÍ optical upper limits
  49. GRB 260226A: LCOGT Optical Upper Limit
  50. GRB 260226A: Glowbug gamma-ray detection
  51. GRB 260226A: NuSTAR detection of bright prompt emission
  52. GRB 260226A : GROWTH-India Telescope optical observations
  53. GRB 260226A: LAST optical upper limit
  54. GRB 260226A: Fermi GBM observation
  55. GRB 260226A: Fermi-LAT refined analysis
  56. Fermi GRB 260226A: Global MASTER-Net observations report
  57. GRB 260226A: AstroSat CZTI detection of bright long burst
  58. GRB 260226A: Fermi-LAT detection of a bright burst
  59. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  60. GRB 260226A: Fermi GBM Final Real-time Localization
  61. GRB 260225C: Fermi GBM Final Real-time Localization
  62. GRB 260223A: Fermi GBM Observation
  63. GRB 260225B: Fermi GBM Final Real-time Localization
  64. GRB 260223A: Glowbug gamma-ray detection
  65. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  66. GRB 260223A: SVOM/VT optical observation
  67. GRB 260223A: SVOM/GRM observation
  68. GRB 260223A: COLIBRÍ further optical observations and a brightening
  69. GRB 260223A: COLIBRÍ optical observations
  70. GRB 260223A: DDOTI Optical Candidate
  71. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  72. Fermi GRB 260223A: Global MASTER-Net observations report
  73. GRB 260223A: Fermi GBM Final Real-time Localization
  74. GRB 260222A: Fermi GBM Final Real-time Localization
  75. Fermi GRB 260221B: Global MASTER-Net observations report
  76. GRB 260221B: Fermi GBM Final Real-time Localization
  77. Fermi GRB 260221A: Global MASTER-Net observations report
  78. GRB 260221A: Fermi GBM Final Real-time Localization
  79. GRB 260219A: AstroSat CZTI detection
  80. GRB 260219A: GECAM-B observation of a long burst
  81. Fermi GRB 260219A: Global MASTER-Net observations report
  82. GRB 260219A: Fermi GBM Final Real-time Localization
  83. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  84. GRB 260217A: Fermi GBM Final Localization
  85. Konus-Wind detection of GRB 260212A
  86. GRB 260208A: AbAO and Terskol optical upper limits
  87. GRB 260208A: continued Mondy optical observations
  88. IPN triangulation of GRB 260212A
  89. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  90. GRB 260213A: GECAM-B observation of a short burst
  91. GRB 260216A: Fermi Gamma-ray Burst Monitor trigger 792969362/260216886 is not a GRB
  92. GRB 260216A: Fermi GBM Final Real-time Localization
  93. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  94. GRB 260211A: SVOM/VT optical counterpart
  95. GRB 260212A: AstroSat CZTI detection
  96. GRB 260212A: Fermi GBM Observation
  97. GRB 260212A: GECAM-B observation
  98. GRB 260212A: SVOM/GRM observation of a long burst
  99. GRB 260213B: Fermi GBM Final Localization
  100. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)

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