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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"

27022 results found.

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

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