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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"

35946 results found.

  1. Konus-Wind detection of GRB 260226A
  2. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  3. GRB 260225A: WINTER J-band upper limit
  4. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  5. GRB 260226A: COLIBRÍ optical upper limits
  6. GRB 260226A: LCOGT Optical Upper Limit
  7. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  8. GRB 260226A: Glowbug gamma-ray detection
  9. GRB 260226A: NuSTAR detection of bright prompt emission
  10. GRB 260226A : GROWTH-India Telescope optical observations
  11. GRB 260226A: LAST optical upper limit
  12. GRB 260226A: Fermi GBM observation
  13. GRB 260226A: Fermi-LAT refined analysis
  14. Fermi GRB 260226A: Global MASTER-Net observations report
  15. GRB 260226A: AstroSat CZTI detection of bright long burst
  16. GRB 260226A: Fermi-LAT detection of a bright burst
  17. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  18. GRB260225A: SVOM/ECLAIRs refined position
  19. GRB 260226A: Fermi GBM Final Real-time Localization
  20. GRB 260225A: EP-FXT follow-up observation
  21. GRB 260225A: SVOM/VT optical observation
  22. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  23. GRB 260225C: Fermi GBM Final Real-time Localization
  24. GRB 260223A: Fermi GBM Observation
  25. GRB 260225A: SVOM/VT optical upper limits
  26. GRB 260225B: Fermi GBM Final Real-time Localization
  27. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  28. GRB 260225A: SVOM detection of a burst
  29. GRB 260223A: Glowbug gamma-ray detection
  30. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  31. GRB 260223A: SVOM/VT optical observation
  32. GRB 260223A: SVOM/GRM observation
  33. GRB 260223A: COLIBRÍ further optical observations and a brightening
  34. GRB 260223A: COLIBRÍ optical observations
  35. GRB 260223A: DDOTI Optical Candidate
  36. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  37. Fermi GRB 260223A: Global MASTER-Net observations report
  38. GRB 260223A: Fermi GBM Final Real-time Localization
  39. GRB 260222A: Fermi GBM Final Real-time Localization
  40. Fermi GRB 260221B: Global MASTER-Net observations report
  41. GRB 260221B: Fermi GBM Final Real-time Localization
  42. Fermi GRB 260221A: Global MASTER-Net observations report
  43. GRB 260221A: Fermi GBM Final Real-time Localization
  44. GRB 260219A: AstroSat CZTI detection
  45. GRB 260219A: GECAM-B observation of a long burst
  46. Fermi GRB 260219A: Global MASTER-Net observations report
  47. GRB 260219A: Fermi GBM Final Real-time Localization
  48. GRB 260217A: Fermi GBM Final Localization
  49. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  50. EP260214b: Mondy optical observations
  51. EP260210a: Mondy optical upper limits
  52. Konus-Wind detection of GRB 260212A
  53. GRB 260208A: AbAO and Terskol optical upper limits
  54. GRB 260208A: continued Mondy optical observations
  55. IPN triangulation of GRB 260212A
  56. GRB 260213A: GECAM-B observation of a short burst
  57. GRB 260216A: Fermi Gamma-ray Burst Monitor trigger 792969362/260216886 is not a GRB
  58. GRB 260216A: Fermi GBM Final Real-time Localization
  59. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  60. EP260214a: Optical upper limits with Kinder observations
  61. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  62. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  63. GRB 260211A: SVOM/VT optical counterpart
  64. GRB 260212A: AstroSat CZTI detection
  65. GRB 260212A: Fermi GBM Observation
  66. GRB 260212A: GECAM-B observation
  67. EP260213a: Mondy R-band optical upper limit
  68. GRB 260212A: SVOM/GRM observation of a long burst
  69. GRB 260213B: Fermi GBM Final Localization
  70. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  71. GRB 260211A - SVOM/ECLAIRs refined analysis
  72. GRB 260204A: SVOM/ECLAIRs refined analysis
  73. GRB 260213A: Fermi GBM Final Localization
  74. GRB 260211A: EP-FXT follow-up observation
  75. GRB 260211A: SVOM/VT optical observation
  76. GRB 260212A: Glowbug gamma-ray detection
  77. GRB 260211A: GOTO optical upper limit
  78. Fermi GRB 260212A: Global MASTER-Net observations report
  79. GRB 260212A: Fermi GBM Final Real-time Localization
  80. GRB 260211A: LAST optical upper limit
  81. GRB 260210A: SVOM/GRM observation
  82. Fermi GBM Sub-Threshold Detection of GRB 260211A
  83. Konus-Wind detection of GRB 260207B
  84. GRB 260128B: SVOM/ECLAIRs refined analysis
  85. GRID detection of GRB 260207B
  86. GRB 260211A: LCO optical upper limits
  87. GRB260131A/B: 3.6m DOT Optical Observations
  88. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  89. GRB 260211A: SVOM detection of a burst
  90. Konus-Wind detection of GRB 260209B
  91. GRB 260208A: Swift UVOT detection
  92. Konus-Wind detection of GRB 260127B
  93. Fermi GRB 260210C: Global MASTER-Net observations report
  94. GRB 260208A: LCO detection of the optical counterpart
  95. IPN triangulation of GRB 260207B (short/hard with EE)
  96. GRB 260210C: Fermi GBM Final Real-time Localization
  97. GRB 260210A: Glowbug gamma-ray detection
  98. GRB 260210B: Fermi GBM Final Real-time Localization
  99. GRB 260210A: AstroSat CZTI detection
  100. GRB 260208C: AstroSat CZTI detection

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