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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"

35264 results found.

  1. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  2. GRB 260303A: SVOM detection of a burst
  3. GRB 260228A: EP-FXT follow-up observation
  4. GRB 251130B: TERI Gamma-ray detection
  5. GRB 260208A: TERI Gamma-ray detection
  6. GRB 260302A: Fermi GBM Final Real-time Localization
  7. EP260227a: Mondy optical observations
  8. GRB 260228A: CAHA 2.2m telescope optical upper limit
  9. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  10. GRID detection of GRB 260225D
  11. GRB 260228A: SVOM/VT optical upper limits
  12. GRB 260225D: SVOM/GRM observation
  13. GRB 260225B: SVOM/GRM observation
  14. GRB 260228A: SVOM detection of a burst
  15. GRB 260226A: Asiago r-band upper limit
  16. GRB 260225A: SVOM/VT optical continued observations and upper limit
  17. GRID detection of GRB 260223A
  18. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  19. Konus-Wind detection of GRB 260226A
  20. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  21. GRB 260225A: WINTER J-band upper limit
  22. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  23. GRB 260226A: COLIBRÍ optical upper limits
  24. GRB 260226A: LCOGT Optical Upper Limit
  25. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  26. GRB 260226A: Glowbug gamma-ray detection
  27. GRB 260226A: NuSTAR detection of bright prompt emission
  28. GRB 260226A : GROWTH-India Telescope optical observations
  29. GRB 260226A: LAST optical upper limit
  30. GRB 260226A: Fermi GBM observation
  31. GRB 260226A: Fermi-LAT refined analysis
  32. Fermi GRB 260226A: Global MASTER-Net observations report
  33. GRB 260226A: AstroSat CZTI detection of bright long burst
  34. GRB 260226A: Fermi-LAT detection of a bright burst
  35. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  36. GRB260225A: SVOM/ECLAIRs refined position
  37. GRB 260226A: Fermi GBM Final Real-time Localization
  38. GRB 260225A: EP-FXT follow-up observation
  39. GRB 260225A: SVOM/VT optical observation
  40. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  41. GRB 260225C: Fermi GBM Final Real-time Localization
  42. GRB 260223A: Fermi GBM Observation
  43. GRB 260225A: SVOM/VT optical upper limits
  44. GRB 260225B: Fermi GBM Final Real-time Localization
  45. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  46. GRB 260225A: SVOM detection of a burst
  47. GRB 260223A: Glowbug gamma-ray detection
  48. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  49. GRB 260223A: SVOM/VT optical observation
  50. GRB 260223A: SVOM/GRM observation
  51. GRB 260223A: COLIBRÍ further optical observations and a brightening
  52. GRB 260223A: COLIBRÍ optical observations
  53. GRB 260223A: DDOTI Optical Candidate
  54. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  55. Fermi GRB 260223A: Global MASTER-Net observations report
  56. GRB 260223A: Fermi GBM Final Real-time Localization
  57. GRB 260222A: Fermi GBM Final Real-time Localization
  58. Fermi GRB 260221B: Global MASTER-Net observations report
  59. GRB 260221B: Fermi GBM Final Real-time Localization
  60. Fermi GRB 260221A: Global MASTER-Net observations report
  61. GRB 260221A: Fermi GBM Final Real-time Localization
  62. GRB 260219A: AstroSat CZTI detection
  63. GRB 260219A: GECAM-B observation of a long burst
  64. Fermi GRB 260219A: Global MASTER-Net observations report
  65. GRB 260219A: Fermi GBM Final Real-time Localization
  66. GRB 260217A: Fermi GBM Final Localization
  67. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  68. EP260214b: Mondy optical observations
  69. EP260210a: Mondy optical upper limits
  70. Konus-Wind detection of GRB 260212A
  71. GRB 260208A: AbAO and Terskol optical upper limits
  72. GRB 260208A: continued Mondy optical observations
  73. IPN triangulation of GRB 260212A
  74. GRB 260213A: GECAM-B observation of a short burst
  75. GRB 260216A: Fermi Gamma-ray Burst Monitor trigger 792969362/260216886 is not a GRB
  76. GRB 260216A: Fermi GBM Final Real-time Localization
  77. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  78. EP260214a: Optical upper limits with Kinder observations
  79. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  80. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  81. GRB 260211A: SVOM/VT optical counterpart
  82. GRB 260212A: AstroSat CZTI detection
  83. GRB 260212A: Fermi GBM Observation
  84. GRB 260212A: GECAM-B observation
  85. EP260213a: Mondy R-band optical upper limit
  86. GRB 260212A: SVOM/GRM observation of a long burst
  87. GRB 260213B: Fermi GBM Final Localization
  88. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  89. GRB 260211A - SVOM/ECLAIRs refined analysis
  90. GRB 260204A: SVOM/ECLAIRs refined analysis
  91. GRB 260213A: Fermi GBM Final Localization
  92. GRB 260211A: EP-FXT follow-up observation
  93. GRB 260211A: SVOM/VT optical observation
  94. GRB 260212A: Glowbug gamma-ray detection
  95. GRB 260211A: GOTO optical upper limit
  96. Fermi GRB 260212A: Global MASTER-Net observations report
  97. GRB 260212A: Fermi GBM Final Real-time Localization
  98. GRB 260211A: LAST optical upper limit
  99. GRB 260210A: SVOM/GRM observation
  100. Fermi GBM Sub-Threshold Detection of GRB 260211A

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