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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"

21206 results found.

  1. GRB 260131A/B: radio detection with the VLA
  2. EP260302a: MeerKAT radio counterpart
  3. GRB 260308A: SVOM/GRM observation of a short GRB
  4. EP260306a: Mondy optical upper limit
  5. GRB 260307B: SVOM/ECLAIRs refined analysis
  6. GRB 260208A: radio detection with the VLA
  7. GRB 260307B: Mephisto optical upper limits
  8. GRB 260307B: possible NOT optical counterpart
  9. GRB 260307B: SVOM/VT upper limit with X band data analysis
  10. GRB260307B: GROWTH-India Telescope optical upper limit
  11. GRB 260307B: SVOM/VT optical candidate
  12. GRB 260307B: SVOM/C-GFT upper limit
  13. GRB 260307B: SVOM detection of a burst
  14. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  15. GRB 260207A: TESS Detection and Possible VLA Counterpart
  16. EP260302a: SVOM/VT optical observation
  17. EP260306a: SVOM/VT optical observation
  18. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  19. EP260306a: Einstein Probe detection of an X-ray transient
  20. GRB 260303A: 1.3m DFOT optical upper limit
  21. GRB 260303A: SVOM/ECLAIRs refined analysis
  22. GRB 260305A: Fermi GBM Final Real-time Localization
  23. GRB 260303B: AstroSat CZTI detection
  24. GRB 260304A: AstroSat CZTI detection of a long burst
  25. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  26. GRB 260303A: SVOM/VT optical observations
  27. GRB 260303A: J-band observations with WINTER
  28. GRB 260303B: NuSTAR detection of prompt emission
  29. GRB 260228A: SVOM/ECLAIRs refined analysis
  30. GRB 260225A: SVOM/ECLAIRs refined analysis
  31. EP260302a: analysis of the follow-up EP-FXT observation
  32. EP260302a: LCO observations
  33. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  34. GRB 260303A: SVOM detection of a burst
  35. GRB 260228A: EP-FXT follow-up observation
  36. EP260302a: Einstein Probe detection of an X-ray transient
  37. EP260227a: Mondy optical observations
  38. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  39. EP260227a: Mephisto optical detection
  40. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  41. EP260227a: SVOM/VT optical observation
  42. GRB 260228A: SVOM/VT optical upper limits
  43. GRB 260225D: SVOM/GRM observation
  44. EP260227A: 3.6m DOT optical afterglow detection
  45. GRB 260225B: SVOM/GRM observation
  46. GRB 260228A: SVOM detection of a burst
  47. EP260227a: Liverpool Telescope optical observations
  48. EP260227a: LCOGT Optical Observations
  49. GRB 260226A: Asiago r-band upper limit
  50. EP260227a: Liverpool Telescope observations
  51. EP260227a: COLIBRÍ optical observations
  52. EP260227a: NOT optical observations
  53. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  54. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  55. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  56. EP260214a: VLT/FORS2 optical observations
  57. GRB 260225A: WINTER J-band upper limit
  58. GRB 260226A: COLIBRÍ optical upper limits
  59. GRB 260226A: LCOGT Optical Upper Limit
  60. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  61. GRB 260226A : GROWTH-India Telescope optical observations
  62. GRB 260226A: LAST optical upper limit
  63. GRB 260226A: AstroSat CZTI detection of bright long burst
  64. EP260224a: LCO optical upper limits
  65. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  66. GRB 260225A: SVOM/VT optical upper limits
  67. EP260223a: Liverpool Telescope upper limits
  68. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  69. EP260224a: Einstein Probe detection of an X-ray transient
  70. EP 260225.148: COLIBRÍ Confirmation of flaring star
  71. EP260223a: Xinglong optical upper limit
  72. EP260213a: Mephisto optical upper limits
  73. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  74. sb26021801: SVOM/C-GFT upper limit
  75. EP260223a: COLIBRÍ optical upper limits
  76. EP260223a: Einstein Probe detection of an X-ray transient
  77. GRB 260223A: SVOM/GRM observation
  78. GRB 260223A: COLIBRÍ further optical observations and a brightening
  79. EP260221a: Optical upper limit with Kinder observations
  80. GRB 260223A: COLIBRÍ optical observations
  81. GRB 260223A: DDOTI Optical Candidate
  82. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  83. EP260221a: COLIBRÍ optical counterpart candidate
  84. EP260221a: Gemini South z-band upper limit
  85. EP260221a: EP-FXT follow-up observation
  86. EP-WXT01709258519: Xinglong optical upper limit
  87. EP260221a: Xinglong optical upper limit
  88. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  89. EP260221a: GOTO optical upper limit
  90. EP260221a: COLIBRÍ optical upper limit
  91. SVOM alert sb26021801: LCO optical upper limit
  92. EP260221a: Einstein Probe detection of an X-ray transient
  93. SVOM alert sb26021801: LAST optical upper limit
  94. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  95. sb26021801: SVOM detection of a long faint X-ray transient
  96. EP-WXT 01709258455: NOT optical upper limits
  97. EP260214b: Mondy optical observations
  98. EP260214b: 1.3m DFOT optical upper limit
  99. EP260210a: Mondy optical upper limits
  100. GRB 260208A: AbAO and Terskol optical upper limits

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