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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"

27392 results found.

  1. GRB 260303A: SVOM/VT optical observations
  2. GRB 260303A: J-band observations with WINTER
  3. GRB 260303B: NuSTAR detection of prompt emission
  4. EP260302a: Global MASTER-Net observations report
  5. Fermi GRB 260303B: Global MASTER-Net observations report
  6. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  7. EP260302a: analysis of the follow-up EP-FXT observation
  8. EP260302a: LCO observations
  9. EP260302a: BOOTES-7 optical counterpart detection at early times
  10. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  11. GRB 260303A: SVOM detection of a burst
  12. GRB 260228A: EP-FXT follow-up observation
  13. EP260302a: Einstein Probe detection of an X-ray transient
  14. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  15. GRB 251130B: TERI Gamma-ray detection
  16. GRB 260208A: TERI Gamma-ray detection
  17. EP260227a: Mondy optical observations
  18. GRB 260228A: CAHA 2.2m telescope optical upper limit
  19. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  20. EP260227a: Mephisto optical detection
  21. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  22. EP260227a: SVOM/VT optical observation
  23. GRB 260228A: SVOM/VT optical upper limits
  24. GRB 260225D: SVOM/GRM observation
  25. EP260227A: 3.6m DOT optical afterglow detection
  26. GRB 260225B: SVOM/GRM observation
  27. EP260227a: Liverpool Telescope optical observations
  28. EP260227a: LCOGT Optical Observations
  29. GRB 260226A: Asiago r-band upper limit
  30. EP260227a: Liverpool Telescope observations
  31. EP260227a: COLIBRÍ optical observations
  32. EP260227a: NOT optical observations
  33. EP260227a: Global MASTER-Net observations report
  34. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  35. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  36. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  37. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  38. EP260214a: VLT/FORS2 optical observations
  39. GRB 260225A: WINTER J-band upper limit
  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. LAT GRB260226.44: Global MASTER-Net observations report
  50. Fermi GRB 260226A: Global MASTER-Net observations report
  51. GRB 260226A: AstroSat CZTI detection of bright long burst
  52. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  53. EP260224a: LCO optical upper limits
  54. GRB 260225A: EP-FXT follow-up observation
  55. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  56. GRB 260223A: Fermi GBM Observation
  57. GRB 260225A: SVOM/VT optical upper limits
  58. EP260223a: Liverpool Telescope upper limits
  59. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  60. EP260224a: Einstein Probe detection of an X-ray transient
  61. EP 260225.148: COLIBRÍ Confirmation of flaring star
  62. EP260223a: Xinglong optical upper limit
  63. GRB 260223A: Glowbug gamma-ray detection
  64. EP260213a: Mephisto optical upper limits
  65. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  66. sb26021801: SVOM/C-GFT upper limit
  67. EP260223a: COLIBRÍ optical upper limits
  68. EP260223a: Einstein Probe detection of an X-ray transient
  69. GRB 260223A: SVOM/GRM observation
  70. GRB 260223A: COLIBRÍ further optical observations and a brightening
  71. EP260221a: Optical upper limit with Kinder observations
  72. GRB 260223A: COLIBRÍ optical observations
  73. GRB 260223A: DDOTI Optical Candidate
  74. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  75. Fermi GRB 260223A: Global MASTER-Net observations report
  76. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  77. EP260221a: COLIBRÍ optical counterpart candidate
  78. EP260221a: Gemini South z-band upper limit
  79. EP260221a: Global MASTER-Net observations report
  80. EP260221a: EP-FXT follow-up observation
  81. Fermi GRB 260221B: Global MASTER-Net observations report
  82. EP-WXT01709258519: Xinglong optical upper limit
  83. EP260221a: Xinglong optical upper limit
  84. Fermi GRB 260221A: Global MASTER-Net observations report
  85. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  86. EP260221a: GOTO optical upper limit
  87. EP260221a: COLIBRÍ optical upper limit
  88. SVOM alert sb26021801: LCO optical upper limit
  89. EP260221a: Einstein Probe detection of an X-ray transient
  90. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  91. Fermi GRB 260219A: Global MASTER-Net observations report
  92. SVOM alert sb26021801: LAST optical upper limit
  93. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  94. IceCube Alert 260217A: Global MASTER-Net observations report
  95. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  96. sb26021801: SVOM detection of a long faint X-ray transient
  97. EP-WXT 01709258455: NOT optical upper limits
  98. EP260214b: Mondy optical observations
  99. EP260214b: 1.3m DFOT optical upper limit
  100. EP260210a: Mondy optical upper limits

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