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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"

26921 results found.

  1. EP260302a: Einstein Probe detection of an X-ray transient
  2. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  3. GRB 260302A: Fermi GBM Final Real-time Localization
  4. GRB 260228A: CAHA 2.2m telescope optical upper limit
  5. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  6. EP260227a: Mephisto optical detection
  7. GRID detection of GRB 260225D
  8. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  9. EP260227a: SVOM/VT optical observation
  10. GRB 260228A: SVOM/VT optical upper limits
  11. GRB 260225D: SVOM/GRM observation
  12. EP260227A: 3.6m DOT optical afterglow detection
  13. GRB 260225B: SVOM/GRM observation
  14. GRB 260228A: SVOM detection of a burst
  15. EP260227a: FTW optical and NIR observations
  16. EP260227a: Liverpool Telescope optical observations
  17. EP260227a: LCOGT Optical Observations
  18. GRB 260226A: Asiago r-band upper limit
  19. EP260227a: Thai National Telescope observations
  20. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  21. EP260227a: COLIBRÍ optical observations
  22. EP260227a: NOT optical observations
  23. GRB 260225A: SVOM/VT optical continued observations and upper limit
  24. GRID detection of GRB 260223A
  25. EP260227a: Global MASTER-Net observations report
  26. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  27. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  28. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  29. EP260214a: VLT/FORS2 optical observations
  30. GRB 260225A: WINTER J-band upper limit
  31. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  32. GRB 260226A: COLIBRÍ optical upper limits
  33. GRB 260226A: LCOGT Optical Upper Limit
  34. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  35. GRB 260226A: Glowbug gamma-ray detection
  36. GRB 260226A : GROWTH-India Telescope optical observations
  37. GRB 260226A: Fermi GBM observation
  38. GRB 260226A: Fermi-LAT refined analysis
  39. The EP-WXT trigger 01709258652 is likely a flaring star
  40. LAT GRB260226.44: Global MASTER-Net observations report
  41. Fermi GRB 260226A: Global MASTER-Net observations report
  42. GRB 260226A: AstroSat CZTI detection of bright long burst
  43. EP260214a: VLA 6 GHz detection
  44. GRB 260226A: Fermi-LAT detection of a bright burst
  45. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  46. EP260224a: LCO optical upper limits
  47. GRB260225A: SVOM/ECLAIRs refined position
  48. GRB 260226A: Fermi GBM Final Real-time Localization
  49. GRB 260225A: EP-FXT follow-up observation
  50. GRB 260225A: SVOM/VT optical observation
  51. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  52. GRB 260225C: Fermi GBM Final Real-time Localization
  53. GRB 260223A: Fermi GBM Observation
  54. GRB 260225A: SVOM/VT optical upper limits
  55. GRB 260225B: Fermi GBM Final Real-time Localization
  56. EP260126a: VLA 6 GHz detection
  57. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  58. GRB 260225A: SVOM detection of a burst
  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. The EP-WXT trigger 01709258631 is likely a flaring star
  63. EP260213a: Mephisto optical upper limits
  64. EP260223a: EP-FXT follow-up observation
  65. sb26021801: SVOM/VT optical upper limits
  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/VT optical observation
  71. GRB 260223A: SVOM/GRM observation
  72. GRB 260223A: COLIBRÍ further optical observations and a brightening
  73. EP260221a: Optical upper limit with Kinder observations
  74. GRB 260223A: COLIBRÍ optical observations
  75. GRB 260223A: DDOTI Optical Candidate
  76. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  77. Fermi GRB 260223A: Global MASTER-Net observations report
  78. GRB 260223A: Fermi GBM Final Real-time Localization
  79. EP260221a: COLIBRÍ optical counterpart candidate
  80. EP260221a: Gemini South z-band upper limit
  81. GRB 260222A: Fermi GBM Final Real-time Localization
  82. EP260221a: Global MASTER-Net observations report
  83. EP260221a: EP-FXT follow-up observation
  84. Fermi GRB 260221B: Global MASTER-Net observations report
  85. GRB 260221B: Fermi GBM Final Real-time Localization
  86. EP-WXT01709258519: Xinglong optical upper limit
  87. EP260221a: Xinglong optical upper limit
  88. Fermi GRB 260221A: Global MASTER-Net observations report
  89. GRB 260221A: Fermi GBM Final Real-time Localization
  90. EP260221a: GOTO optical upper limit
  91. EP260221a: COLIBRÍ optical upper limit
  92. SVOM alert sb26021801: LCO optical upper limit
  93. EP260221a: Einstein Probe detection of an X-ray transient
  94. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  95. GRB 260219A: GECAM-B observation of a long burst
  96. Fermi GRB 260219A: Global MASTER-Net observations report
  97. GRB 260219A: Fermi GBM Final Real-time Localization
  98. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  99. IceCube Alert 260217A: Global MASTER-Net observations report
  100. GRB 260217A: Fermi GBM Final Localization

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