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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

19309 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. EP260302a: Einstein Probe detection of an X-ray transient
  5. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  6. GRB 251130B: TERI Gamma-ray detection
  7. GRB 260208A: TERI Gamma-ray detection
  8. GRB 260302A: Fermi GBM Final Real-time Localization
  9. EP260227a: Mondy optical observations
  10. GRB 260228A: CAHA 2.2m telescope optical upper limit
  11. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  12. EP260227a: Mephisto optical detection
  13. GRID detection of GRB 260225D
  14. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  15. EP260227a: further LCO 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. EP260227a: Thai National Telescope observations
  26. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  27. EP260227a: Liverpool Telescope observations
  28. EP260227a: COLIBRÍ optical observations
  29. EP260227a: NOT optical observations
  30. GRID detection of GRB 260223A
  31. EP260227a: Global MASTER-Net observations report
  32. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  33. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  34. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  35. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  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 260225D: Glowbug gamma-ray detection of a likely short burst
  44. GRB 260226A: Glowbug gamma-ray detection
  45. GRB 260226A: NuSTAR detection of bright prompt emission
  46. GRB 260226A : GROWTH-India Telescope optical observations
  47. GRB 260226A: LAST optical upper limit
  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. GRB 260226A: Fermi GBM Final Real-time Localization
  59. GRB 260225A: EP-FXT follow-up observation
  60. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  61. GRB 260225C: Fermi GBM Final Real-time Localization
  62. GRB 260223A: Fermi GBM Observation
  63. GRB 260225A: SVOM/VT optical upper limits
  64. GRB 260225B: Fermi GBM Final Real-time Localization
  65. EP260126a: VLA 6 GHz detection
  66. EP260223a: Liverpool Telescope upper limits
  67. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  68. GRB 260225A: SVOM detection of a burst
  69. EP260224a: Einstein Probe detection of an X-ray transient
  70. EP 260225.148: COLIBRÍ Confirmation of flaring star
  71. EP260223a: Xinglong optical upper limit
  72. The EP-WXT trigger 01709258631 is likely a flaring star
  73. GRB 260223A: Glowbug gamma-ray detection
  74. EP260213a: Mephisto optical upper limits
  75. EP260223a: EP-FXT follow-up observation
  76. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  77. sb26021801: SVOM/C-GFT upper limit
  78. EP260223a: COLIBRÍ optical upper limits
  79. EP260223a: Einstein Probe detection of an X-ray transient
  80. GRB 260223A: SVOM/VT optical observation
  81. GRB 260223A: SVOM/GRM observation
  82. GRB 260223A: COLIBRÍ further optical observations and a brightening
  83. EP260221a: Optical upper limit with Kinder observations
  84. GRB 260223A: COLIBRÍ optical observations
  85. GRB 260223A: DDOTI Optical Candidate
  86. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  87. Fermi GRB 260223A: Global MASTER-Net observations report
  88. GRB 260223A: Fermi GBM Final Real-time Localization
  89. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  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. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations

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