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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"

20366 results found.

  1. GRB 260303A: SVOM detection of a burst
  2. EP260302a: Einstein Probe detection of an X-ray transient
  3. EP260227a: Mondy optical observations
  4. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  5. EP260227a: Mephisto optical detection
  6. GRID detection of GRB 260225D
  7. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  8. EP260227a: SVOM/VT optical observation
  9. GRB 260228A: SVOM/VT optical upper limits
  10. GRB 260225D: SVOM/GRM observation
  11. EP260227A: 3.6m DOT optical afterglow detection
  12. GRB 260225B: SVOM/GRM observation
  13. EP260227a: Liverpool Telescope optical observations
  14. EP260227a: LCOGT Optical Observations
  15. GRB 260226A: Asiago r-band upper limit
  16. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  17. EP260227a: Liverpool Telescope observations
  18. EP260227a: COLIBRÍ optical observations
  19. EP260227a: NOT optical observations
  20. GRID detection of GRB 260223A
  21. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  22. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  23. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  24. Konus-Wind detection of GRB 260226A
  25. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  26. EP260214a: VLT/FORS2 optical observations
  27. GRB 260225A: WINTER J-band upper limit
  28. GRB 260226A: COLIBRÍ optical upper limits
  29. GRB 260226A: LCOGT Optical Upper Limit
  30. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  31. GRB 260226A : GROWTH-India Telescope optical observations
  32. GRB 260226A: LAST optical upper limit
  33. GRB 260226A: Fermi-LAT refined analysis
  34. GRB 260226A: AstroSat CZTI detection of bright long burst
  35. EP260214a: VLA 6 GHz detection
  36. EP260224a: LCO optical upper limits
  37. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  38. GRB 260225A: SVOM/VT optical upper limits
  39. EP260126a: VLA 6 GHz detection
  40. EP260223a: Liverpool Telescope upper limits
  41. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  42. EP260224a: Einstein Probe detection of an X-ray transient
  43. EP 260225.148: COLIBRÍ Confirmation of flaring star
  44. EP260223a: Xinglong optical upper limit
  45. EP260213a: Mephisto optical upper limits
  46. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  47. sb26021801: SVOM/C-GFT upper limit
  48. EP260223a: COLIBRÍ optical upper limits
  49. EP260223a: Einstein Probe detection of an X-ray transient
  50. GRB 260223A: SVOM/GRM observation
  51. GRB 260223A: COLIBRÍ further optical observations and a brightening
  52. EP260221a: Optical upper limit with Kinder observations
  53. GRB 260223A: COLIBRÍ optical observations
  54. GRB 260223A: DDOTI Optical Candidate
  55. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  56. EP260221a: COLIBRÍ optical counterpart candidate
  57. EP260221a: Gemini South z-band upper limit
  58. EP260221a: EP-FXT follow-up observation
  59. EP-WXT01709258519: Xinglong optical upper limit
  60. EP260221a: Xinglong optical upper limit
  61. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  62. EP260221a: GOTO optical upper limit
  63. EP260221a: COLIBRÍ optical upper limit
  64. SVOM alert sb26021801: LCO optical upper limit
  65. EP260221a: Einstein Probe detection of an X-ray transient
  66. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  67. GRB 260219A: GECAM-B observation of a long burst
  68. SVOM alert sb26021801: LAST optical upper limit
  69. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  70. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  71. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  72. EP-WXT 01709258455: NOT optical upper limits
  73. EP260214b: Mondy optical observations
  74. EP260214b: 1.3m DFOT optical upper limit
  75. EP260210a: Mondy optical upper limits
  76. GRB 260208A: AbAO and Terskol optical upper limits
  77. GRB 260208A: continued Mondy optical observations
  78. IPN triangulation of GRB 260212A
  79. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  80. EP260214b: Liverpool Telescope optical observations
  81. EP260214b: Optical upper limit with Kinder observations
  82. EP260214a: Optical upper limits with Kinder observations
  83. EP260214b: EP-FXT follow-up observation
  84. EP260214b: DDOTI Optical Detection
  85. EP260214b: GROWTH-India Telescope optical upper limit
  86. EP260214a: VLT near-infrared observation
  87. EP260214a: NOT optical upper limits
  88. EP260214a: COLIBRÍ optical upper limits
  89. EP260214b: OHP/T120 optical observations
  90. EP260214a: refined analysis of the EP-FXT observation
  91. EP260214b: LCO optical counterpart detection
  92. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  93. EP260214b: COLIBRÍ optical observations
  94. EP260214b: NOT optical counterpart detection
  95. EP260214b: Einstein Probe detection of a fast X-ray transient
  96. EP260214a: Einstein Probe detection of an X-ray transient
  97. EP260213a: Liverpool Telescope optical upper limits
  98. EP260213a: COLIBRÍ optical upper limits
  99. EP260213a: Optical upper limits with Kinder observations
  100. EP260213a: Mondy R-band optical upper limit

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