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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"

40633 results found.

  1. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  2. GRB 251130B: TERI Gamma-ray detection
  3. GRB 260208A: TERI Gamma-ray detection
  4. GRB 260302A: Fermi GBM Final Real-time Localization
  5. EP260227a: Mondy optical observations
  6. GRB 260228A: CAHA 2.2m telescope optical upper limit
  7. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  8. EP260227a: Mephisto optical detection
  9. GRID detection of GRB 260225D
  10. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  11. EP260227a: further LCO 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: Liverpool Telescope observations
  25. EP260227a: COLIBRÍ optical observations
  26. EP260227a: NOT optical observations
  27. GRB 260225A: SVOM/VT optical continued observations and upper limit
  28. GRID detection of GRB 260223A
  29. EP260227a: Global MASTER-Net observations report
  30. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  31. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  32. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  33. IceCube cascade alert 142200_1517143 retraction
  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: COLIBRÍ optical upper limits
  40. GRB 260226A: LCOGT Optical Upper Limit
  41. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  42. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  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. GRB260225A: SVOM/ECLAIRs refined position
  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. sb26021801: SVOM/VT optical upper limits
  77. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  78. sb26021801: SVOM/C-GFT upper limit
  79. EP260223a: COLIBRÍ optical upper limits
  80. EP260223a: Einstein Probe detection of an X-ray transient
  81. GRB 260223A: SVOM/VT optical observation
  82. GRB 260223A: SVOM/GRM observation
  83. GRB 260223A: COLIBRÍ further optical observations and a brightening
  84. EP260221a: Optical upper limit with Kinder observations
  85. GRB 260223A: COLIBRÍ optical observations
  86. GRB 260223A: DDOTI Optical Candidate
  87. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  88. Fermi GRB 260223A: Global MASTER-Net observations report
  89. GRB 260223A: Fermi GBM Final Real-time Localization
  90. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  91. EP260221a: COLIBRÍ optical counterpart candidate
  92. EP260221a: Gemini South z-band upper limit
  93. GRB 260222A: Fermi GBM Final Real-time Localization
  94. EP260221a: Global MASTER-Net observations report
  95. EP260221a: EP-FXT follow-up observation
  96. Fermi GRB 260221B: Global MASTER-Net observations report
  97. GRB 260221B: Fermi GBM Final Real-time Localization
  98. EP-WXT01709258519: Xinglong optical upper limit
  99. EP260221a: Xinglong optical upper limit
  100. Fermi GRB 260221A: Global MASTER-Net observations report

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