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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"

36280 results found.

  1. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  2. GRB 260303A: SVOM/ECLAIRs refined analysis
  3. Fermi GRB 260305A: Global MASTER-Net observations report
  4. GRB 260305A: Fermi GBM Final Real-time Localization
  5. GRB 260303B: AstroSat CZTI detection
  6. GRB 260304A: AstroSat CZTI detection of a long burst
  7. GRB 260303A: SVOM/VT optical observations
  8. GRB 260303A: J-band observations with WINTER
  9. GRB 260303B: NuSTAR detection of prompt emission
  10. Fermi GRB 260303B: Global MASTER-Net observations report
  11. GRB 260228A: SVOM/ECLAIRs refined analysis
  12. GRB 260225A: SVOM/ECLAIRs refined analysis
  13. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  14. GRB 260303B: Fermi GBM Final Real-time Localization
  15. EP260302a: analysis of the follow-up EP-FXT observation
  16. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  17. GRB 260303A: SVOM detection of a burst
  18. GRB 260228A: EP-FXT follow-up observation
  19. GRB 251130B: TERI Gamma-ray detection
  20. GRB 260208A: TERI Gamma-ray detection
  21. GRB 260302A: Fermi GBM Final Real-time Localization
  22. EP260227a: Mondy optical observations
  23. GRB 260228A: CAHA 2.2m telescope optical upper limit
  24. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  25. EP260227a: Mephisto optical detection
  26. GRID detection of GRB 260225D
  27. GRB 260228A: SVOM/VT optical upper limits
  28. GRB 260225D: SVOM/GRM observation
  29. GRB 260225B: SVOM/GRM observation
  30. GRB 260228A: SVOM detection of a burst
  31. EP260227a: Liverpool Telescope optical observations
  32. GRB 260226A: Asiago r-band upper limit
  33. GRB 260225A: SVOM/VT optical continued observations and upper limit
  34. GRID detection of GRB 260223A
  35. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  36. Konus-Wind detection of GRB 260226A
  37. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  38. GRB 260225A: WINTER J-band upper limit
  39. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  40. GRB 260226A: COLIBRÍ optical upper limits
  41. GRB 260226A: LCOGT Optical Upper Limit
  42. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  43. GRB 260226A: Glowbug gamma-ray detection
  44. GRB 260226A: NuSTAR detection of bright prompt emission
  45. GRB 260226A : GROWTH-India Telescope optical observations
  46. GRB 260226A: LAST optical upper limit
  47. GRB 260226A: Fermi GBM observation
  48. GRB 260226A: Fermi-LAT refined analysis
  49. Fermi GRB 260226A: Global MASTER-Net observations report
  50. GRB 260226A: AstroSat CZTI detection of bright long burst
  51. GRB 260226A: Fermi-LAT detection of a bright burst
  52. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  53. GRB260225A: SVOM/ECLAIRs refined position
  54. GRB 260226A: Fermi GBM Final Real-time Localization
  55. GRB 260225A: EP-FXT follow-up observation
  56. GRB 260225A: SVOM/VT optical observation
  57. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  58. GRB 260225C: Fermi GBM Final Real-time Localization
  59. GRB 260223A: Fermi GBM Observation
  60. GRB 260225A: SVOM/VT optical upper limits
  61. GRB 260225B: Fermi GBM Final Real-time Localization
  62. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  63. GRB 260225A: SVOM detection of a burst
  64. GRB 260223A: Glowbug gamma-ray detection
  65. EP260213a: Mephisto optical upper limits
  66. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  67. GRB 260223A: SVOM/VT optical observation
  68. GRB 260223A: SVOM/GRM observation
  69. GRB 260223A: COLIBRÍ further optical observations and a brightening
  70. EP260221a: Optical upper limit with Kinder observations
  71. GRB 260223A: COLIBRÍ optical observations
  72. GRB 260223A: DDOTI Optical Candidate
  73. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  74. Fermi GRB 260223A: Global MASTER-Net observations report
  75. GRB 260223A: Fermi GBM Final Real-time Localization
  76. EP260221a: COLIBRÍ optical counterpart candidate
  77. GRB 260222A: Fermi GBM Final Real-time Localization
  78. Fermi GRB 260221B: Global MASTER-Net observations report
  79. GRB 260221B: Fermi GBM Final Real-time Localization
  80. Fermi GRB 260221A: Global MASTER-Net observations report
  81. GRB 260221A: Fermi GBM Final Real-time Localization
  82. GRB 260219A: AstroSat CZTI detection
  83. GRB 260219A: GECAM-B observation of a long burst
  84. Fermi GRB 260219A: Global MASTER-Net observations report
  85. GRB 260219A: Fermi GBM Final Real-time Localization
  86. SVOM alert sb26021801: LAST optical upper limit
  87. GRB 260217A: Fermi GBM Final Localization
  88. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  89. EP260214b: Mondy optical observations
  90. EP260210a: Mondy optical upper limits
  91. Konus-Wind detection of GRB 260212A
  92. GRB 260208A: AbAO and Terskol optical upper limits
  93. GRB 260208A: continued Mondy optical observations
  94. IPN triangulation of GRB 260212A
  95. GRB 260213A: GECAM-B observation of a short burst
  96. GRB 260216A: Fermi Gamma-ray Burst Monitor trigger 792969362/260216886 is not a GRB
  97. GRB 260216A: Fermi GBM Final Real-time Localization
  98. EP260214b: Liverpool Telescope optical observations
  99. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  100. EP260214b: Optical upper limit with Kinder observations

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