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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"

35947 results found.

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

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