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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"

17798 results found.

  1. EP260306a: Mondy optical upper limit
  2. GRB 260208A: radio detection with the VLA
  3. GRB 260307B: Mephisto optical upper limits
  4. GRB 260307B: possible NOT optical counterpart
  5. GRB 260307B: SVOM/VT upper limit with X band data analysis
  6. GRB260307B: GROWTH-India Telescope optical upper limit
  7. GRB 260307B: SVOM/VT optical candidate
  8. GRB 260307B: SVOM/C-GFT upper limit
  9. GRB 260307B: SVOM detection of a burst
  10. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  11. GRB 260207A: TESS Detection and Possible VLA Counterpart
  12. EP260302a: SVOM/VT optical observation
  13. EP260306a: SVOM/VT optical observation
  14. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  15. EP260306a: Einstein Probe detection of an X-ray transient
  16. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  17. GRB 260303A: 1.3m DFOT optical upper limit
  18. GRB 260304A: AstroSat CZTI detection of a long burst
  19. GRB 260303A: SVOM/VT optical observations
  20. GRB 260303A: J-band observations with WINTER
  21. EP260302a: analysis of the follow-up EP-FXT observation
  22. EP260302a: LCO observations
  23. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  24. GRB 260303A: SVOM detection of a burst
  25. GRB 260228A: EP-FXT follow-up observation
  26. EP260302a: Einstein Probe detection of an X-ray transient
  27. EP260227a: Mondy optical observations
  28. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  29. EP260227a: Mephisto optical detection
  30. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  31. EP260227a: SVOM/VT optical observation
  32. GRB 260228A: SVOM/VT optical upper limits
  33. GRB 260225D: SVOM/GRM observation
  34. EP260227A: 3.6m DOT optical afterglow detection
  35. GRB 260225B: SVOM/GRM observation
  36. EP260227a: Liverpool Telescope optical observations
  37. EP260227a: LCOGT Optical Observations
  38. GRB 260226A: Asiago r-band upper limit
  39. EP260227a: Liverpool Telescope observations
  40. EP260227a: COLIBRÍ optical observations
  41. EP260227a: NOT optical observations
  42. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  43. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  44. Konus-Wind detection of GRB 260226A
  45. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  46. EP260214a: VLT/FORS2 optical observations
  47. GRB 260225A: WINTER J-band upper limit
  48. GRB 260226A: COLIBRÍ optical upper limits
  49. GRB 260226A: LCOGT Optical Upper Limit
  50. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  51. GRB 260226A : GROWTH-India Telescope optical observations
  52. GRB 260226A: LAST optical upper limit
  53. The EP-WXT trigger 01709258652 is likely a flaring star
  54. EP260224a: LCO optical upper limits
  55. GRB 260225A: EP-FXT follow-up observation
  56. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  57. GRB 260225A: SVOM/VT optical upper limits
  58. EP260223a: Liverpool Telescope upper limits
  59. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  60. EP260224a: Einstein Probe detection of an X-ray transient
  61. EP 260225.148: COLIBRÍ Confirmation of flaring star
  62. EP260223a: Xinglong optical upper limit
  63. The EP-WXT trigger 01709258631 is likely a flaring star
  64. EP260213a: Mephisto optical upper limits
  65. EP260223a: EP-FXT follow-up observation
  66. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  67. sb26021801: SVOM/C-GFT upper limit
  68. EP260223a: COLIBRÍ optical upper limits
  69. EP260223a: Einstein Probe detection of an X-ray transient
  70. GRB 260223A: SVOM/GRM observation
  71. GRB 260223A: COLIBRÍ further optical observations and a brightening
  72. EP260221a: Optical upper limit with Kinder observations
  73. GRB 260223A: COLIBRÍ optical observations
  74. GRB 260223A: DDOTI Optical Candidate
  75. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  76. EP260221a: COLIBRÍ optical counterpart candidate
  77. EP260221a: Gemini South z-band upper limit
  78. EP260221a: EP-FXT follow-up observation
  79. EP-WXT01709258519: Xinglong optical upper limit
  80. EP260221a: Xinglong optical upper limit
  81. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  82. EP260221a: GOTO optical upper limit
  83. EP260221a: COLIBRÍ optical upper limit
  84. SVOM alert sb26021801: LCO optical upper limit
  85. EP260221a: Einstein Probe detection of an X-ray transient
  86. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  87. SVOM alert sb26021801: LAST optical upper limit
  88. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  89. The EP-WXT trigger 01709258455 is likely a flaring star
  90. EP-WXT 01709258455: NOT optical upper limits
  91. EP260214b: Mondy optical observations
  92. EP260214b: 1.3m DFOT optical upper limit
  93. EP260210a: Mondy optical upper limits
  94. Konus-Wind detection of GRB 260212A
  95. GRB 260208A: AbAO and Terskol optical upper limits
  96. GRB 260208A: continued Mondy optical observations
  97. IPN triangulation of GRB 260212A
  98. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  99. EP260214b: Liverpool Telescope optical observations
  100. EP260214b: Optical upper limit with Kinder observations

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