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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"

36147 results found.

  1. GRB 260307B: SVOM detection of a burst
  2. GRB 260307A: Fermi GBM Final Localization
  3. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  4. GRB 260207A: TESS Detection and Possible VLA Counterpart
  5. EP260302a: Optical afterglow rebrightening
  6. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  7. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  8. GRB 260303A: 1.3m DFOT optical upper limit
  9. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  10. GRB 260303A: SVOM/ECLAIRs refined analysis
  11. Fermi GRB 260305A: Global MASTER-Net observations report
  12. GRB 260305A: Fermi GBM Final Real-time Localization
  13. GRB 260303B: AstroSat CZTI detection
  14. GRB 260304A: AstroSat CZTI detection of a long burst
  15. GRB 260303A: SVOM/VT optical observations
  16. GRB 260303A: J-band observations with WINTER
  17. GRB 260303B: NuSTAR detection of prompt emission
  18. Fermi GRB 260303B: Global MASTER-Net observations report
  19. GRB 260228A: SVOM/ECLAIRs refined analysis
  20. GRB 260225A: SVOM/ECLAIRs refined analysis
  21. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  22. GRB 260303B: Fermi GBM Final Real-time Localization
  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. GRB 251130B: TERI Gamma-ray detection
  27. GRB 260208A: TERI Gamma-ray detection
  28. GRB 260302A: Fermi GBM Final Real-time Localization
  29. EP260227a: Mondy optical observations
  30. GRB 260228A: CAHA 2.2m telescope optical upper limit
  31. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  32. GRID detection of GRB 260225D
  33. GRB 260228A: SVOM/VT optical upper limits
  34. GRB 260225D: SVOM/GRM observation
  35. GRB 260225B: SVOM/GRM observation
  36. GRB 260228A: SVOM detection of a burst
  37. GRB 260226A: Asiago r-band upper limit
  38. GRB 260225A: SVOM/VT optical continued observations and upper limit
  39. GRID detection of GRB 260223A
  40. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  41. Konus-Wind detection of GRB 260226A
  42. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  43. GRB 260225A: WINTER J-band upper limit
  44. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  45. GRB 260226A: COLIBRÍ optical upper limits
  46. GRB 260226A: LCOGT Optical Upper Limit
  47. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  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. GRB260225A: SVOM/ECLAIRs refined position
  59. GRB 260226A: Fermi GBM Final Real-time Localization
  60. GRB 260225A: EP-FXT follow-up observation
  61. GRB 260225A: SVOM/VT optical observation
  62. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  63. GRB 260225C: Fermi GBM Final Real-time Localization
  64. GRB 260223A: Fermi GBM Observation
  65. GRB 260225A: SVOM/VT optical upper limits
  66. GRB 260225B: Fermi GBM Final Real-time Localization
  67. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  68. GRB 260225A: SVOM detection of a burst
  69. GRB 260223A: Glowbug gamma-ray detection
  70. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  71. GRB 260223A: SVOM/VT optical observation
  72. GRB 260223A: SVOM/GRM observation
  73. GRB 260223A: COLIBRÍ further optical observations and a brightening
  74. GRB 260223A: COLIBRÍ optical observations
  75. GRB 260223A: DDOTI Optical Candidate
  76. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  77. Fermi GRB 260223A: Global MASTER-Net observations report
  78. GRB 260223A: Fermi GBM Final Real-time Localization
  79. GRB 260222A: Fermi GBM Final Real-time Localization
  80. Fermi GRB 260221B: Global MASTER-Net observations report
  81. GRB 260221B: Fermi GBM Final Real-time Localization
  82. Fermi GRB 260221A: Global MASTER-Net observations report
  83. GRB 260221A: Fermi GBM Final Real-time Localization
  84. GRB 260219A: AstroSat CZTI detection
  85. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  86. GRB 260219A: GECAM-B observation of a long burst
  87. Fermi GRB 260219A: Global MASTER-Net observations report
  88. GRB 260219A: Fermi GBM Final Real-time Localization
  89. GRB 260217A: Fermi GBM Final Localization
  90. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  91. EP260214b: Mondy optical observations
  92. EP260210a: Mondy optical upper limits
  93. Konus-Wind detection of GRB 260212A
  94. GRB 260208A: AbAO and Terskol optical upper limits
  95. GRB 260208A: continued Mondy optical observations
  96. IPN triangulation of GRB 260212A
  97. GRB 260213A: GECAM-B observation of a short burst
  98. GRB 260216A: Fermi Gamma-ray Burst Monitor trigger 792969362/260216886 is not a GRB
  99. GRB 260216A: Fermi GBM Final Real-time Localization
  100. GRB 260206A: probable hard X-ray burst from 4U 0513-40

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