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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"

35237 results found.

  1. GRID detection of GRB 260225D
  2. GRB 260228A: SVOM/VT optical upper limits
  3. GRB 260225D: SVOM/GRM observation
  4. GRB 260225B: SVOM/GRM observation
  5. GRB 260228A: SVOM detection of a burst
  6. GRB 260226A: Asiago r-band upper limit
  7. GRB 260225A: SVOM/VT optical continued observations and upper limit
  8. GRID detection of GRB 260223A
  9. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  10. Konus-Wind detection of GRB 260226A
  11. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  12. GRB 260225A: WINTER J-band upper limit
  13. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  14. GRB 260226A: COLIBRÍ optical upper limits
  15. GRB 260226A: LCOGT Optical Upper Limit
  16. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  17. GRB 260226A: Glowbug gamma-ray detection
  18. GRB 260226A: NuSTAR detection of bright prompt emission
  19. GRB 260226A : GROWTH-India Telescope optical observations
  20. GRB 260226A: LAST optical upper limit
  21. GRB 260226A: Fermi GBM observation
  22. GRB 260226A: Fermi-LAT refined analysis
  23. Fermi GRB 260226A: Global MASTER-Net observations report
  24. GRB 260226A: AstroSat CZTI detection of bright long burst
  25. GRB 260226A: Fermi-LAT detection of a bright burst
  26. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  27. GRB260225A: SVOM/ECLAIRs refined position
  28. GRB 260226A: Fermi GBM Final Real-time Localization
  29. GRB 260225A: EP-FXT follow-up observation
  30. GRB 260225A: SVOM/VT optical observation
  31. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  32. GRB 260225C: Fermi GBM Final Real-time Localization
  33. GRB 260223A: Fermi GBM Observation
  34. GRB 260225A: SVOM/VT optical upper limits
  35. GRB 260225B: Fermi GBM Final Real-time Localization
  36. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  37. GRB 260225A: SVOM detection of a burst
  38. GRB 260223A: Glowbug gamma-ray detection
  39. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  40. GRB 260223A: SVOM/VT optical observation
  41. GRB 260223A: SVOM/GRM observation
  42. GRB 260223A: COLIBRÍ further optical observations and a brightening
  43. GRB 260223A: COLIBRÍ optical observations
  44. GRB 260223A: DDOTI Optical Candidate
  45. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  46. Fermi GRB 260223A: Global MASTER-Net observations report
  47. GRB 260223A: Fermi GBM Final Real-time Localization
  48. GRB 260222A: Fermi GBM Final Real-time Localization
  49. Fermi GRB 260221B: Global MASTER-Net observations report
  50. GRB 260221B: Fermi GBM Final Real-time Localization
  51. Fermi GRB 260221A: Global MASTER-Net observations report
  52. GRB 260221A: Fermi GBM Final Real-time Localization
  53. GRB 260219A: AstroSat CZTI detection
  54. GRB 260219A: GECAM-B observation of a long burst
  55. Fermi GRB 260219A: Global MASTER-Net observations report
  56. GRB 260219A: Fermi GBM Final Real-time Localization
  57. GRB 260217A: Fermi GBM Final Localization
  58. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  59. EP260214b: Mondy optical observations
  60. EP260210a: Mondy optical upper limits
  61. Konus-Wind detection of GRB 260212A
  62. GRB 260208A: AbAO and Terskol optical upper limits
  63. GRB 260208A: continued Mondy optical observations
  64. IPN triangulation of GRB 260212A
  65. GRB 260213A: GECAM-B observation of a short burst
  66. GRB 260216A: Fermi Gamma-ray Burst Monitor trigger 792969362/260216886 is not a GRB
  67. GRB 260216A: Fermi GBM Final Real-time Localization
  68. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  69. EP260214a: Optical upper limits with Kinder observations
  70. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  71. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  72. GRB 260211A: SVOM/VT optical counterpart
  73. GRB 260212A: AstroSat CZTI detection
  74. GRB 260212A: Fermi GBM Observation
  75. GRB 260212A: GECAM-B observation
  76. EP260213a: Mondy R-band optical upper limit
  77. GRB 260212A: SVOM/GRM observation of a long burst
  78. GRB 260213B: Fermi GBM Final Localization
  79. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  80. GRB 260211A - SVOM/ECLAIRs refined analysis
  81. GRB 260204A: SVOM/ECLAIRs refined analysis
  82. GRB 260213A: Fermi GBM Final Localization
  83. GRB 260211A: EP-FXT follow-up observation
  84. GRB 260211A: SVOM/VT optical observation
  85. GRB 260212A: Glowbug gamma-ray detection
  86. GRB 260211A: GOTO optical upper limit
  87. Fermi GRB 260212A: Global MASTER-Net observations report
  88. GRB 260212A: Fermi GBM Final Real-time Localization
  89. GRB 260211A: LAST optical upper limit
  90. GRB 260210A: SVOM/GRM observation
  91. Fermi GBM Sub-Threshold Detection of GRB 260211A
  92. Konus-Wind detection of GRB 260207B
  93. GRB 260128B: SVOM/ECLAIRs refined analysis
  94. GRID detection of GRB 260207B
  95. GRB 260211A: LCO optical upper limits
  96. GRB260131A/B: 3.6m DOT Optical Observations
  97. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  98. GRB 260211A: SVOM detection of a burst
  99. Konus-Wind detection of GRB 260209B
  100. GRB 260208A: Swift UVOT detection

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