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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"

28879 results found.

  1. GRB 260303B: Fermi GBM Final Real-time Localization
  2. EP260302a: analysis of the follow-up EP-FXT observation
  3. EP260302a: LCO observations
  4. EP260302a: BOOTES-7 optical counterpart detection at early times
  5. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  6. GRB 260303A: SVOM detection of a burst
  7. GRB 260228A: EP-FXT follow-up observation
  8. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  9. GRB 251130B: TERI Gamma-ray detection
  10. GRB 260208A: TERI Gamma-ray detection
  11. GRB 260302A: Fermi GBM Final Real-time Localization
  12. GRB 260228A: CAHA 2.2m telescope optical upper limit
  13. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  14. EP260227a: Mephisto optical detection
  15. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  16. EP260227a: SVOM/VT optical observation
  17. GRB 260228A: SVOM/VT optical upper limits
  18. GRB 260225D: SVOM/GRM observation
  19. EP260227A: 3.6m DOT optical afterglow detection
  20. GRB 260225B: SVOM/GRM observation
  21. GRB 260228A: SVOM detection of a burst
  22. EP260227a: FTW optical and NIR observations
  23. EP260227a: Liverpool Telescope optical observations
  24. EP260227a: LCOGT Optical Observations
  25. GRB 260226A: Asiago r-band upper limit
  26. EP260227a: Thai National Telescope observations
  27. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  28. EP260227a: COLIBRÍ optical observations
  29. EP260227a: NOT optical observations
  30. GRID detection of GRB 260223A
  31. EP260227a: Global MASTER-Net observations report
  32. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  33. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  34. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  35. Konus-Wind detection of GRB 260226A
  36. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  37. EP260214a: VLT/FORS2 optical observations
  38. GRB 260225A: WINTER J-band upper limit
  39. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  40. GRB 260226A: COLIBRÍ optical upper limits
  41. GRB 260226A: LCOGT Optical Upper Limit
  42. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  43. GRB 260226A: Glowbug gamma-ray detection
  44. GRB 260226A: NuSTAR detection of bright prompt emission
  45. GRB 260226A : GROWTH-India Telescope optical observations
  46. GRB 260226A: LAST optical upper limit
  47. GRB 260226A: Fermi GBM observation
  48. GRB 260226A: Fermi-LAT refined analysis
  49. The EP-WXT trigger 01709258652 is likely a flaring star
  50. LAT GRB260226.44: Global MASTER-Net observations report
  51. Fermi GRB 260226A: Global MASTER-Net observations report
  52. GRB 260226A: AstroSat CZTI detection of bright long burst
  53. EP260214a: VLA 6 GHz detection
  54. GRB 260226A: Fermi-LAT detection of a bright burst
  55. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  56. EP260224a: LCO optical upper limits
  57. GRB 260226A: Fermi GBM Final Real-time Localization
  58. GRB 260225A: EP-FXT follow-up observation
  59. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  60. GRB 260225C: Fermi GBM Final Real-time Localization
  61. GRB 260223A: Fermi GBM Observation
  62. GRB 260225A: SVOM/VT optical upper limits
  63. GRB 260225B: Fermi GBM Final Real-time Localization
  64. EP260126a: VLA 6 GHz detection
  65. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  66. GRB 260225A: SVOM detection of a burst
  67. EP260224a: Einstein Probe detection of an X-ray transient
  68. EP 260225.148: COLIBRÍ Confirmation of flaring star
  69. EP260223a: Xinglong optical upper limit
  70. The EP-WXT trigger 01709258631 is likely a flaring star
  71. GRB 260223A: Glowbug gamma-ray detection
  72. EP260213a: Mephisto optical upper limits
  73. sb26021801: SVOM/VT optical upper limits
  74. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  75. sb26021801: SVOM/C-GFT upper limit
  76. EP260223a: COLIBRÍ optical upper limits
  77. EP260223a: Einstein Probe detection of an X-ray transient
  78. GRB 260223A: SVOM/VT optical observation
  79. GRB 260223A: SVOM/GRM observation
  80. GRB 260223A: COLIBRÍ further optical observations and a brightening
  81. EP260221a: Optical upper limit with Kinder observations
  82. GRB 260223A: COLIBRÍ optical observations
  83. GRB 260223A: DDOTI Optical Candidate
  84. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  85. Fermi GRB 260223A: Global MASTER-Net observations report
  86. GRB 260223A: Fermi GBM Final Real-time Localization
  87. EP260221a: COLIBRÍ optical counterpart candidate
  88. EP260221a: Gemini South z-band upper limit
  89. GRB 260222A: Fermi GBM Final Real-time Localization
  90. EP260221a: Global MASTER-Net observations report
  91. Fermi GRB 260221B: Global MASTER-Net observations report
  92. GRB 260221B: Fermi GBM Final Real-time Localization
  93. EP-WXT01709258519: Xinglong optical upper limit
  94. EP260221a: Xinglong optical upper limit
  95. Fermi GRB 260221A: Global MASTER-Net observations report
  96. GRB 260221A: Fermi GBM Final Real-time Localization
  97. EP260221a: GOTO optical upper limit
  98. EP260221a: COLIBRÍ optical upper limit
  99. SVOM alert sb26021801: LCO optical upper limit
  100. The EP-WXT trigger 01709258519 is likely caused by Mrk 421

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