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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

42910 results found.

  1. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  2. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  3. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  4. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  5. Konus-Wind detection of GRB 260226A
  6. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  7. EP260214a: VLT/FORS2 optical observations
  8. GRB 260225A: WINTER J-band upper limit
  9. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  10. GRB 260226A: COLIBRÍ optical upper limits
  11. GRB 260226A: LCOGT Optical Upper Limit
  12. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  13. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  14. GRB 260226A: Glowbug gamma-ray detection
  15. GRB 260226A: NuSTAR detection of bright prompt emission
  16. GRB 260226A : GROWTH-India Telescope optical observations
  17. GRB 260226A: LAST optical upper limit
  18. GRB 260226A: Fermi GBM observation
  19. GRB 260226A: Fermi-LAT refined analysis
  20. The EP-WXT trigger 01709258652 is likely a flaring star
  21. LAT GRB260226.44: Global MASTER-Net observations report
  22. Fermi GRB 260226A: Global MASTER-Net observations report
  23. GRB 260226A: AstroSat CZTI detection of bright long burst
  24. EP260214a: VLA 6 GHz detection
  25. GRB 260226A: Fermi-LAT detection of a bright burst
  26. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  27. EP260224a: LCO optical upper limits
  28. GRB260225A: SVOM/ECLAIRs refined position
  29. GRB 260226A: Fermi GBM Final Real-time Localization
  30. GRB 260225A: EP-FXT follow-up observation
  31. GRB 260225A: SVOM/VT optical observation
  32. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  33. GRB 260225C: Fermi GBM Final Real-time Localization
  34. GRB 260223A: Fermi GBM Observation
  35. GRB 260225A: SVOM/VT optical upper limits
  36. GRB 260225B: Fermi GBM Final Real-time Localization
  37. EP260126a: VLA 6 GHz detection
  38. EP260223a: Liverpool Telescope upper limits
  39. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  40. GRB 260225A: SVOM detection of a burst
  41. EP260224a: Einstein Probe detection of an X-ray transient
  42. EP 260225.148: COLIBRÍ Confirmation of flaring star
  43. EP260223a: Xinglong optical upper limit
  44. The EP-WXT trigger 01709258631 is likely a flaring star
  45. GRB 260223A: Glowbug gamma-ray detection
  46. EP260213a: Mephisto optical upper limits
  47. EP260223a: EP-FXT follow-up observation
  48. sb26021801: SVOM/VT optical upper limits
  49. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  50. sb26021801: SVOM/C-GFT upper limit
  51. EP260223a: COLIBRÍ optical upper limits
  52. EP260223a: Einstein Probe detection of an X-ray transient
  53. GRB 260223A: SVOM/VT optical observation
  54. GRB 260223A: SVOM/GRM observation
  55. GRB 260223A: COLIBRÍ further optical observations and a brightening
  56. EP260221a: Optical upper limit with Kinder observations
  57. GRB 260223A: COLIBRÍ optical observations
  58. GRB 260223A: DDOTI Optical Candidate
  59. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  60. Fermi GRB 260223A: Global MASTER-Net observations report
  61. GRB 260223A: Fermi GBM Final Real-time Localization
  62. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  63. EP260221a: COLIBRÍ optical counterpart candidate
  64. EP260221a: Gemini South z-band upper limit
  65. GRB 260222A: Fermi GBM Final Real-time Localization
  66. EP260221a: Global MASTER-Net observations report
  67. EP260221a: EP-FXT follow-up observation
  68. Fermi GRB 260221B: Global MASTER-Net observations report
  69. GRB 260221B: Fermi GBM Final Real-time Localization
  70. EP260221a: Xinglong optical upper limit
  71. Fermi GRB 260221A: Global MASTER-Net observations report
  72. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  73. GRB 260221A: Fermi GBM Final Real-time Localization
  74. EP260221a: GOTO optical upper limit
  75. EP260221a: COLIBRÍ optical upper limit
  76. SVOM alert sb26021801: LCO optical upper limit
  77. EP260221a: Einstein Probe detection of an X-ray transient
  78. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  79. GRB 260219A: AstroSat CZTI detection
  80. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  81. GRB 260219A: GECAM-B observation of a long burst
  82. Fermi GRB 260219A: Global MASTER-Net observations report
  83. GRB 260219A: Fermi GBM Final Real-time Localization
  84. SVOM alert sb26021801: LAST optical upper limit
  85. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  86. IceCube Alert 260217A: Global MASTER-Net observations report
  87. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  88. GRB 260217A: Fermi GBM Final Localization
  89. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  90. sb26021801: SVOM detection of a long faint X-ray transient
  91. The EP-WXT trigger 01709258455 is likely a flaring star
  92. EP-WXT 01709258455: NOT optical upper limits
  93. EP260214b: Mondy optical observations
  94. EP260214b: 1.3m DFOT optical upper limit
  95. EP260210a: Mondy optical upper limits
  96. Konus-Wind detection of GRB 260212A
  97. GRB 260208A: AbAO and Terskol optical upper limits
  98. GRB 260208A: continued Mondy optical observations
  99. IPN triangulation of GRB 260212A
  100. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event

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