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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"

27032 results found.

  1. Fermi GRB 260303B: Global MASTER-Net observations report
  2. GRB 260228A: SVOM/ECLAIRs refined analysis
  3. GRB 260225A: SVOM/ECLAIRs refined analysis
  4. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  5. GRB 260303B: Fermi GBM Final Real-time Localization
  6. EP260302a: analysis of the follow-up EP-FXT observation
  7. EP260302a: LCO observations
  8. EP260302a: BOOTES-7 optical counterpart detection at early times
  9. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  10. GRB 260303A: SVOM detection of a burst
  11. GRB 260228A: EP-FXT follow-up observation
  12. EP260302a: Einstein Probe detection of an X-ray transient
  13. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  14. GRB 260302A: Fermi GBM Final Real-time Localization
  15. GRB 260228A: CAHA 2.2m telescope optical upper limit
  16. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  17. EP260227a: Mephisto optical detection
  18. GRID detection of GRB 260225D
  19. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  20. EP260227a: SVOM/VT optical observation
  21. GRB 260228A: SVOM/VT optical upper limits
  22. GRB 260225D: SVOM/GRM observation
  23. EP260227A: 3.6m DOT optical afterglow detection
  24. GRB 260225B: SVOM/GRM observation
  25. GRB 260228A: SVOM detection of a burst
  26. EP260227a: FTW optical and NIR observations
  27. EP260227a: Liverpool Telescope optical observations
  28. EP260227a: LCOGT Optical Observations
  29. GRB 260226A: Asiago r-band upper limit
  30. EP260227a: Thai National Telescope observations
  31. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  32. EP260227a: COLIBRÍ optical observations
  33. EP260227a: NOT optical observations
  34. GRB 260225A: SVOM/VT optical continued observations and upper limit
  35. GRID detection of GRB 260223A
  36. EP260227a: Global MASTER-Net observations report
  37. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  38. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  39. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  40. EP260214a: VLT/FORS2 optical observations
  41. GRB 260225A: WINTER J-band upper limit
  42. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  43. GRB 260226A: COLIBRÍ optical upper limits
  44. GRB 260226A: LCOGT Optical Upper Limit
  45. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  46. GRB 260226A: Glowbug gamma-ray detection
  47. GRB 260226A : GROWTH-India Telescope optical observations
  48. GRB 260226A: Fermi GBM observation
  49. GRB 260226A: Fermi-LAT refined analysis
  50. The EP-WXT trigger 01709258652 is likely a flaring star
  51. LAT GRB260226.44: Global MASTER-Net observations report
  52. Fermi GRB 260226A: Global MASTER-Net observations report
  53. GRB 260226A: AstroSat CZTI detection of bright long burst
  54. EP260214a: VLA 6 GHz detection
  55. GRB 260226A: Fermi-LAT detection of a bright burst
  56. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  57. EP260224a: LCO optical upper limits
  58. GRB260225A: SVOM/ECLAIRs refined position
  59. GRB 260226A: Fermi GBM Final Real-time Localization
  60. GRB 260225A: EP-FXT follow-up observation
  61. GRB 260225A: SVOM/VT optical observation
  62. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  63. GRB 260225C: Fermi GBM Final Real-time Localization
  64. GRB 260223A: Fermi GBM Observation
  65. GRB 260225A: SVOM/VT optical upper limits
  66. GRB 260225B: Fermi GBM Final Real-time Localization
  67. EP260126a: VLA 6 GHz detection
  68. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  69. GRB 260225A: SVOM detection of a burst
  70. EP260224a: Einstein Probe detection of an X-ray transient
  71. EP 260225.148: COLIBRÍ Confirmation of flaring star
  72. EP260223a: Xinglong optical upper limit
  73. The EP-WXT trigger 01709258631 is likely a flaring star
  74. EP260213a: Mephisto optical upper limits
  75. EP260223a: EP-FXT follow-up observation
  76. sb26021801: SVOM/VT optical upper limits
  77. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  78. sb26021801: SVOM/C-GFT upper limit
  79. EP260223a: COLIBRÍ optical upper limits
  80. EP260223a: Einstein Probe detection of an X-ray transient
  81. GRB 260223A: SVOM/VT optical observation
  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. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  88. Fermi GRB 260223A: Global MASTER-Net observations report
  89. GRB 260223A: Fermi GBM Final Real-time Localization
  90. EP260221a: COLIBRÍ optical counterpart candidate
  91. EP260221a: Gemini South z-band upper limit
  92. GRB 260222A: Fermi GBM Final Real-time Localization
  93. EP260221a: Global MASTER-Net observations report
  94. EP260221a: EP-FXT follow-up observation
  95. Fermi GRB 260221B: Global MASTER-Net observations report
  96. GRB 260221B: Fermi GBM Final Real-time Localization
  97. EP-WXT01709258519: Xinglong optical upper limit
  98. EP260221a: Xinglong optical upper limit
  99. Fermi GRB 260221A: Global MASTER-Net observations report
  100. GRB 260221A: Fermi GBM Final Real-time Localization

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