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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"
  1. EP260302a: analysis of the follow-up EP-FXT observation
  2. EP260227a: Gemini-South optical observations
  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. EP260302a: Einstein Probe detection of an X-ray transient
  9. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  10. GRB 251130B: TERI Gamma-ray detection
  11. GRB 260208A: TERI Gamma-ray detection
  12. GRB 260302A: Fermi GBM Final Real-time Localization
  13. EP260227a: Mondy optical observations
  14. GRB 260228A: CAHA 2.2m telescope optical upper limit
  15. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  16. EP260227a: Mephisto optical detection
  17. GRID detection of GRB 260225D
  18. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  19. EP260227a: further LCO 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: Liverpool Telescope observations
  33. EP260227a: COLIBRÍ optical observations
  34. EP260227a: NOT optical observations
  35. GRB 260225A: SVOM/VT optical continued observations and upper limit
  36. GRID detection of GRB 260223A
  37. EP260227a: Global MASTER-Net observations report
  38. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  39. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  40. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  41. IceCube cascade alert 142200_1517143 retraction
  42. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  43. Konus-Wind detection of GRB 260226A
  44. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  45. EP260214a: VLT/FORS2 optical observations
  46. GRB 260225A: WINTER J-band upper limit
  47. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  48. GRB 260226A: COLIBRÍ optical upper limits
  49. GRB 260226A: LCOGT Optical Upper Limit
  50. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  51. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  52. GRB 260226A: Glowbug gamma-ray detection
  53. GRB 260226A: NuSTAR detection of bright prompt emission
  54. GRB 260226A : GROWTH-India Telescope optical observations
  55. GRB 260226A: LAST optical upper limit
  56. GRB 260226A: Fermi GBM observation
  57. GRB 260226A: Fermi-LAT refined analysis
  58. The EP-WXT trigger 01709258652 is likely a flaring star
  59. LAT GRB260226.44: Global MASTER-Net observations report
  60. Fermi GRB 260226A: Global MASTER-Net observations report
  61. GRB 260226A: AstroSat CZTI detection of bright long burst
  62. EP260214a: VLA 6 GHz detection
  63. GRB 260226A: Fermi-LAT detection of a bright burst
  64. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  65. EP260224a: LCO optical upper limits
  66. GRB260225A: SVOM/ECLAIRs refined position
  67. GRB 260226A: Fermi GBM Final Real-time Localization
  68. GRB 260225A: EP-FXT follow-up observation
  69. GRB 260225A: SVOM/VT optical observation
  70. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  71. GRB 260225C: Fermi GBM Final Real-time Localization
  72. GRB 260223A: Fermi GBM Observation
  73. GRB 260225A: SVOM/VT optical upper limits
  74. GRB 260225B: Fermi GBM Final Real-time Localization
  75. EP260126a: VLA 6 GHz detection
  76. EP260223a: Liverpool Telescope upper limits
  77. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  78. GRB 260225A: SVOM detection of a burst
  79. EP260224a: Einstein Probe detection of an X-ray transient
  80. EP 260225.148: COLIBRÍ Confirmation of flaring star
  81. EP260223a: Xinglong optical upper limit
  82. The EP-WXT trigger 01709258631 is likely a flaring star
  83. GRB 260223A: Glowbug gamma-ray detection
  84. EP260213a: Mephisto optical upper limits
  85. EP260223a: EP-FXT follow-up observation
  86. sb26021801: SVOM/VT optical upper limits
  87. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  88. sb26021801: SVOM/C-GFT upper limit
  89. EP260223a: COLIBRÍ optical upper limits
  90. EP260223a: Einstein Probe detection of an X-ray transient
  91. GRB 260223A: SVOM/VT optical observation
  92. GRB 260223A: SVOM/GRM observation
  93. GRB 260223A: COLIBRÍ further optical observations and a brightening
  94. EP260221a: Optical upper limit with Kinder observations
  95. GRB 260223A: COLIBRÍ optical observations
  96. GRB 260223A: DDOTI Optical Candidate
  97. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  98. Fermi GRB 260223A: Global MASTER-Net observations report
  99. GRB 260223A: Fermi GBM Final Real-time Localization
  100. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate

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