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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"

20379 results found.

  1. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  2. GRB 260207A: TESS Detection and Possible VLA Counterpart
  3. EP260302a: SVOM/VT optical observation
  4. EP260306a: SVOM/VT optical observation
  5. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  6. EP260306a: Einstein Probe detection of an X-ray transient
  7. GRB 260303A: 1.3m DFOT optical upper limit
  8. EP260214b: ATCA 6 GHz observations
  9. GRB 260303A: SVOM/ECLAIRs refined analysis
  10. GRB 260304A: AstroSat CZTI detection of a long burst
  11. GRB 260303A: SVOM/VT optical observations
  12. GRB 260303A: J-band observations with WINTER
  13. GRB 260228A: SVOM/ECLAIRs refined analysis
  14. GRB 260225A: SVOM/ECLAIRs refined analysis
  15. EP260302a: analysis of the follow-up EP-FXT observation
  16. EP260302a: LCO observations
  17. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  18. GRB 260303A: SVOM detection of a burst
  19. EP260302a: Einstein Probe detection of an X-ray transient
  20. EP260227a: Mondy optical observations
  21. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  22. EP260227a: Mephisto optical detection
  23. GRID detection of GRB 260225D
  24. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  25. EP260227a: SVOM/VT optical observation
  26. GRB 260228A: SVOM/VT optical upper limits
  27. GRB 260225D: SVOM/GRM observation
  28. EP260227A: 3.6m DOT optical afterglow detection
  29. GRB 260225B: SVOM/GRM observation
  30. EP260227a: Liverpool Telescope optical observations
  31. EP260227a: LCOGT Optical Observations
  32. GRB 260226A: Asiago r-band upper limit
  33. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  34. EP260227a: Liverpool Telescope observations
  35. EP260227a: COLIBRÍ optical observations
  36. EP260227a: NOT optical observations
  37. GRID detection of GRB 260223A
  38. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  39. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  40. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  41. Konus-Wind detection of GRB 260226A
  42. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  43. EP260214a: VLT/FORS2 optical observations
  44. GRB 260225A: WINTER J-band upper limit
  45. GRB 260226A: COLIBRÍ optical upper limits
  46. GRB 260226A: LCOGT Optical Upper Limit
  47. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  48. GRB 260226A : GROWTH-India Telescope optical observations
  49. GRB 260226A: LAST optical upper limit
  50. GRB 260226A: Fermi-LAT refined analysis
  51. GRB 260226A: AstroSat CZTI detection of bright long burst
  52. EP260214a: VLA 6 GHz detection
  53. EP260224a: LCO optical upper limits
  54. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  55. GRB 260225A: SVOM/VT optical upper limits
  56. EP260126a: VLA 6 GHz detection
  57. EP260223a: Liverpool Telescope upper limits
  58. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  59. EP260224a: Einstein Probe detection of an X-ray transient
  60. EP 260225.148: COLIBRÍ Confirmation of flaring star
  61. EP260223a: Xinglong optical upper limit
  62. EP260213a: Mephisto optical upper limits
  63. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  64. sb26021801: SVOM/C-GFT upper limit
  65. EP260223a: COLIBRÍ optical upper limits
  66. EP260223a: Einstein Probe detection of an X-ray transient
  67. GRB 260223A: SVOM/GRM observation
  68. GRB 260223A: COLIBRÍ further optical observations and a brightening
  69. EP260221a: Optical upper limit with Kinder observations
  70. GRB 260223A: COLIBRÍ optical observations
  71. GRB 260223A: DDOTI Optical Candidate
  72. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  73. EP260221a: COLIBRÍ optical counterpart candidate
  74. EP260221a: Gemini South z-band upper limit
  75. EP260221a: EP-FXT follow-up observation
  76. EP-WXT01709258519: Xinglong optical upper limit
  77. EP260221a: Xinglong optical upper limit
  78. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  79. EP260221a: GOTO optical upper limit
  80. EP260221a: COLIBRÍ optical upper limit
  81. SVOM alert sb26021801: LCO optical upper limit
  82. EP260221a: Einstein Probe detection of an X-ray transient
  83. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  84. GRB 260219A: GECAM-B observation of a long burst
  85. SVOM alert sb26021801: LAST optical upper limit
  86. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  87. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  88. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  89. EP-WXT 01709258455: NOT optical upper limits
  90. EP260214b: Mondy optical observations
  91. EP260214b: 1.3m DFOT optical upper limit
  92. EP260210a: Mondy optical upper limits
  93. GRB 260208A: AbAO and Terskol optical upper limits
  94. GRB 260208A: continued Mondy optical observations
  95. IPN triangulation of GRB 260212A
  96. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  97. EP260214b: Liverpool Telescope optical observations
  98. EP260214b: Optical upper limit with Kinder observations
  99. EP260214a: Optical upper limits with Kinder observations
  100. EP260214b: EP-FXT follow-up observation

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