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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"

42240 results found.

  1. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  2. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  3. GRB 260226A: Glowbug gamma-ray detection
  4. GRB 260226A: NuSTAR detection of bright prompt emission
  5. GRB 260226A : GROWTH-India Telescope optical observations
  6. GRB 260226A: LAST optical upper limit
  7. GRB 260226A: Fermi GBM observation
  8. GRB 260226A: Fermi-LAT refined analysis
  9. The EP-WXT trigger 01709258652 is likely a flaring star
  10. LAT GRB260226.44: Global MASTER-Net observations report
  11. Fermi GRB 260226A: Global MASTER-Net observations report
  12. GRB 260226A: AstroSat CZTI detection of bright long burst
  13. EP260214a: VLA 6 GHz detection
  14. GRB 260226A: Fermi-LAT detection of a bright burst
  15. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  16. EP260224a: LCO optical upper limits
  17. GRB260225A: SVOM/ECLAIRs refined position
  18. GRB 260226A: Fermi GBM Final Real-time Localization
  19. GRB 260225A: EP-FXT follow-up observation
  20. GRB 260225A: SVOM/VT optical observation
  21. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  22. GRB 260225C: Fermi GBM Final Real-time Localization
  23. GRB 260223A: Fermi GBM Observation
  24. GRB 260225A: SVOM/VT optical upper limits
  25. GRB 260225B: Fermi GBM Final Real-time Localization
  26. EP260126a: VLA 6 GHz detection
  27. EP260223a: Liverpool Telescope upper limits
  28. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  29. GRB 260225A: SVOM detection of a burst
  30. EP260224a: Einstein Probe detection of an X-ray transient
  31. EP 260225.148: COLIBRÍ Confirmation of flaring star
  32. EP260223a: Xinglong optical upper limit
  33. The EP-WXT trigger 01709258631 is likely a flaring star
  34. GRB 260223A: Glowbug gamma-ray detection
  35. EP260213a: Mephisto optical upper limits
  36. EP260223a: EP-FXT follow-up observation
  37. sb26021801: SVOM/VT optical upper limits
  38. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  39. sb26021801: SVOM/C-GFT upper limit
  40. EP260223a: COLIBRÍ optical upper limits
  41. EP260223a: Einstein Probe detection of an X-ray transient
  42. GRB 260223A: SVOM/VT optical observation
  43. GRB 260223A: SVOM/GRM observation
  44. GRB 260223A: COLIBRÍ further optical observations and a brightening
  45. EP260221a: Optical upper limit with Kinder observations
  46. GRB 260223A: COLIBRÍ optical observations
  47. GRB 260223A: DDOTI Optical Candidate
  48. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  49. Fermi GRB 260223A: Global MASTER-Net observations report
  50. GRB 260223A: Fermi GBM Final Real-time Localization
  51. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  52. EP260221a: COLIBRÍ optical counterpart candidate
  53. EP260221a: Gemini South z-band upper limit
  54. GRB 260222A: Fermi GBM Final Real-time Localization
  55. EP260221a: Global MASTER-Net observations report
  56. EP260221a: EP-FXT follow-up observation
  57. Fermi GRB 260221B: Global MASTER-Net observations report
  58. GRB 260221B: Fermi GBM Final Real-time Localization
  59. EP-WXT01709258519: Xinglong optical upper limit
  60. EP260221a: Xinglong optical upper limit
  61. Fermi GRB 260221A: Global MASTER-Net observations report
  62. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  63. GRB 260221A: Fermi GBM Final Real-time Localization
  64. EP260221a: GOTO optical upper limit
  65. EP260221a: COLIBRÍ optical upper limit
  66. SVOM alert sb26021801: LCO optical upper limit
  67. EP260221a: Einstein Probe detection of an X-ray transient
  68. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  69. GRB 260219A: AstroSat CZTI detection
  70. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  71. GRB 260219A: GECAM-B observation of a long burst
  72. Fermi GRB 260219A: Global MASTER-Net observations report
  73. GRB 260219A: Fermi GBM Final Real-time Localization
  74. SVOM alert sb26021801: LAST optical upper limit
  75. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  76. IceCube Alert 260217A: Global MASTER-Net observations report
  77. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  78. GRB 260217A: Fermi GBM Final Localization
  79. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  80. sb26021801: SVOM detection of a long faint X-ray transient
  81. The EP-WXT trigger 01709258455 is likely a flaring star
  82. EP-WXT 01709258455: NOT optical upper limits
  83. EP260214b: Mondy optical observations
  84. EP260214b: 1.3m DFOT optical upper limit
  85. EP260210a: Mondy optical upper limits
  86. Konus-Wind detection of GRB 260212A
  87. GRB 260208A: AbAO and Terskol optical upper limits
  88. GRB 260208A: continued Mondy optical observations
  89. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  90. GRB 260213A: GECAM-B observation of a short burst
  91. GRB 260216A: Fermi GBM Final Real-time Localization
  92. EP260214b: Liverpool Telescope optical observations
  93. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  94. EP260214b: Optical upper limit with Kinder observations
  95. EP260214a: Optical upper limits with Kinder observations
  96. EP260214b: EP-FXT follow-up observation
  97. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  98. EP260214b: DDOTI Optical Detection
  99. EP260214b: GROWTH-India Telescope optical upper limit
  100. EP260214a: VLT near-infrared observation

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