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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"

28075 results found.

  1. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  2. GRB 260303A: SVOM detection of a burst
  3. GRB 260228A: EP-FXT follow-up observation
  4. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  5. GRB 251130B: TERI Gamma-ray detection
  6. GRB 260208A: TERI Gamma-ray detection
  7. GRB 260302A: Fermi GBM Final Real-time Localization
  8. GRB 260228A: CAHA 2.2m telescope optical upper limit
  9. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  10. EP260227a: Mephisto optical detection
  11. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  12. EP260227a: SVOM/VT optical observation
  13. GRB 260228A: SVOM/VT optical upper limits
  14. GRB 260225D: SVOM/GRM observation
  15. EP260227A: 3.6m DOT optical afterglow detection
  16. GRB 260225B: SVOM/GRM observation
  17. GRB 260228A: SVOM detection of a burst
  18. EP260227a: FTW optical and NIR observations
  19. EP260227a: Liverpool Telescope optical observations
  20. EP260227a: LCOGT Optical Observations
  21. GRB 260226A: Asiago r-band upper limit
  22. EP260227a: Thai National Telescope observations
  23. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  24. EP260227a: COLIBRÍ optical observations
  25. EP260227a: NOT optical observations
  26. GRID detection of GRB 260223A
  27. EP260227a: Global MASTER-Net observations report
  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. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  31. Konus-Wind detection of GRB 260226A
  32. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  33. EP260214a: VLT/FORS2 optical observations
  34. GRB 260225A: WINTER J-band upper limit
  35. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  36. GRB 260226A: COLIBRÍ optical upper limits
  37. GRB 260226A: LCOGT Optical Upper Limit
  38. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  39. GRB 260226A: Glowbug gamma-ray detection
  40. GRB 260226A: NuSTAR detection of bright prompt emission
  41. GRB 260226A : GROWTH-India Telescope optical observations
  42. GRB 260226A: LAST optical upper limit
  43. GRB 260226A: Fermi GBM observation
  44. GRB 260226A: Fermi-LAT refined analysis
  45. The EP-WXT trigger 01709258652 is likely a flaring star
  46. LAT GRB260226.44: Global MASTER-Net observations report
  47. Fermi GRB 260226A: Global MASTER-Net observations report
  48. GRB 260226A: AstroSat CZTI detection of bright long burst
  49. EP260214a: VLA 6 GHz detection
  50. GRB 260226A: Fermi-LAT detection of a bright burst
  51. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  52. EP260224a: LCO optical upper limits
  53. GRB 260226A: Fermi GBM Final Real-time Localization
  54. GRB 260225A: EP-FXT follow-up observation
  55. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  56. GRB 260225C: Fermi GBM Final Real-time Localization
  57. GRB 260223A: Fermi GBM Observation
  58. GRB 260225A: SVOM/VT optical upper limits
  59. GRB 260225B: Fermi GBM Final Real-time Localization
  60. EP260126a: VLA 6 GHz detection
  61. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  62. GRB 260225A: SVOM detection of a burst
  63. EP260224a: Einstein Probe detection of an X-ray transient
  64. EP 260225.148: COLIBRÍ Confirmation of flaring star
  65. EP260223a: Xinglong optical upper limit
  66. The EP-WXT trigger 01709258631 is likely a flaring star
  67. GRB 260223A: Glowbug gamma-ray detection
  68. EP260213a: Mephisto optical upper limits
  69. sb26021801: SVOM/VT optical upper limits
  70. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  71. sb26021801: SVOM/C-GFT upper limit
  72. EP260223a: COLIBRÍ optical upper limits
  73. EP260223a: Einstein Probe detection of an X-ray transient
  74. GRB 260223A: SVOM/VT optical observation
  75. GRB 260223A: SVOM/GRM observation
  76. GRB 260223A: COLIBRÍ further optical observations and a brightening
  77. EP260221a: Optical upper limit with Kinder observations
  78. GRB 260223A: COLIBRÍ optical observations
  79. GRB 260223A: DDOTI Optical Candidate
  80. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  81. Fermi GRB 260223A: Global MASTER-Net observations report
  82. GRB 260223A: Fermi GBM Final Real-time Localization
  83. EP260221a: COLIBRÍ optical counterpart candidate
  84. EP260221a: Gemini South z-band upper limit
  85. GRB 260222A: Fermi GBM Final Real-time Localization
  86. EP260221a: Global MASTER-Net observations report
  87. Fermi GRB 260221B: Global MASTER-Net observations report
  88. GRB 260221B: Fermi GBM Final Real-time Localization
  89. EP-WXT01709258519: Xinglong optical upper limit
  90. EP260221a: Xinglong optical upper limit
  91. Fermi GRB 260221A: Global MASTER-Net observations report
  92. GRB 260221A: Fermi GBM Final Real-time Localization
  93. EP260221a: GOTO optical upper limit
  94. EP260221a: COLIBRÍ optical upper limit
  95. SVOM alert sb26021801: LCO optical upper limit
  96. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  97. GRB 260219A: AstroSat CZTI detection
  98. GRB 260219A: GECAM-B observation of a long burst
  99. Fermi GRB 260219A: Global MASTER-Net observations report
  100. GRB 260219A: Fermi GBM Final Real-time Localization

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