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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"

26499 results found.

  1. GRB 260307B: SVOM/ECLAIRs refined analysis
  2. GRB 260208A: radio detection with the VLA
  3. GRB 260307A: Glowbug gamma-ray detection
  4. GRB 260307B: Mephisto optical upper limits
  5. GRB 260307B: possible NOT optical counterpart
  6. GRB 260307B: SVOM/VT upper limit with X band data analysis
  7. GRB260307B: GROWTH-India Telescope optical upper limit
  8. GRB 260307B: SVOM/VT optical candidate
  9. GRB 260307B: SVOM/C-GFT upper limit
  10. GRB 260307B: SVOM detection of a burst
  11. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  12. GRB 260207A: TESS Detection and Possible VLA Counterpart
  13. EP260302a: SVOM/VT optical observation
  14. EP260306a: SVOM/VT optical observation
  15. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  16. EP260306a: Einstein Probe detection of an X-ray transient
  17. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  18. GRB 260303A: 1.3m DFOT optical upper limit
  19. GRB 260304A: AstroSat CZTI detection of a long burst
  20. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  21. GRB 260303A: SVOM/VT optical observations
  22. GRB 260303A: J-band observations with WINTER
  23. GRB 260228A: SVOM/ECLAIRs refined analysis
  24. GRB 260225A: SVOM/ECLAIRs refined analysis
  25. EP260302a: analysis of the follow-up EP-FXT observation
  26. EP260302a: LCO observations
  27. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  28. GRB 260303A: SVOM detection of a burst
  29. EP260302a: Einstein Probe detection of an X-ray transient
  30. GRB 260302A: Fermi GBM Final Real-time Localization
  31. EP260227a: Mondy optical observations
  32. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  33. EP260227a: Mephisto optical detection
  34. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  35. EP260227a: SVOM/VT optical observation
  36. GRB 260228A: SVOM/VT optical upper limits
  37. GRB 260225D: SVOM/GRM observation
  38. EP260227A: 3.6m DOT optical afterglow detection
  39. GRB 260225B: SVOM/GRM observation
  40. GRB 260228A: SVOM detection of a burst
  41. EP260227a: Liverpool Telescope optical observations
  42. EP260227a: LCOGT Optical Observations
  43. GRB 260226A: Asiago r-band upper limit
  44. EP260227a: Liverpool Telescope observations
  45. EP260227a: COLIBRÍ optical observations
  46. EP260227a: NOT optical observations
  47. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  48. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  49. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  50. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  51. EP260214a: VLT/FORS2 optical observations
  52. GRB 260225A: WINTER J-band upper limit
  53. GRB 260226A: COLIBRÍ optical upper limits
  54. GRB 260226A: LCOGT Optical Upper Limit
  55. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  56. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  57. GRB 260226A: Glowbug gamma-ray detection
  58. GRB 260226A : GROWTH-India Telescope optical observations
  59. GRB 260226A: LAST optical upper limit
  60. GRB 260226A: Fermi GBM observation
  61. The EP-WXT trigger 01709258652 is likely a flaring star
  62. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  63. EP260224a: LCO optical upper limits
  64. GRB 260225A: EP-FXT follow-up observation
  65. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  66. GRB 260223A: Fermi GBM Observation
  67. GRB 260225A: SVOM/VT optical upper limits
  68. EP260223a: Liverpool Telescope upper limits
  69. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  70. GRB 260225A: SVOM detection of a burst
  71. EP260224a: Einstein Probe detection of an X-ray transient
  72. EP 260225.148: COLIBRÍ Confirmation of flaring star
  73. EP260223a: Xinglong optical upper limit
  74. The EP-WXT trigger 01709258631 is likely a flaring star
  75. GRB 260223A: Glowbug gamma-ray detection
  76. EP260213a: Mephisto optical upper limits
  77. EP260223a: EP-FXT follow-up observation
  78. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  79. sb26021801: SVOM/C-GFT upper limit
  80. EP260223a: COLIBRÍ optical upper limits
  81. EP260223a: Einstein Probe detection of an X-ray transient
  82. GRB 260223A: SVOM/GRM observation
  83. GRB 260223A: COLIBRÍ further optical observations and a brightening
  84. EP260221a: Optical upper limit with Kinder observations
  85. GRB 260223A: COLIBRÍ optical observations
  86. GRB 260223A: DDOTI Optical Candidate
  87. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  88. EP260221a: COLIBRÍ optical counterpart candidate
  89. EP260221a: Gemini South z-band upper limit
  90. EP260221a: EP-FXT follow-up observation
  91. EP-WXT01709258519: Xinglong optical upper limit
  92. EP260221a: Xinglong optical upper limit
  93. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  94. EP260221a: GOTO optical upper limit
  95. EP260221a: COLIBRÍ optical upper limit
  96. SVOM alert sb26021801: LCO optical upper limit
  97. EP260221a: Einstein Probe detection of an X-ray transient
  98. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  99. GRB 260219A: GECAM-B observation of a long burst
  100. SVOM alert sb26021801: LAST optical upper limit

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