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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"

27400 results found.

  1. EP260302a: Gemini-South redshift z = 1.535
  2. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  3. EP260306a: Einstein Probe detection of an X-ray transient
  4. EP260302a: Optical afterglow rebrightening
  5. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  6. GRB 260303A: 1.3m DFOT optical upper limit
  7. Fermi GRB 260305A: Global MASTER-Net observations report
  8. GRB 260303B: AstroSat CZTI detection
  9. GRB 260303A: SVOM/VT optical observations
  10. GRB 260303A: J-band observations with WINTER
  11. GRB 260303B: NuSTAR detection of prompt emission
  12. EP260302a: Global MASTER-Net observations report
  13. Fermi GRB 260303B: Global MASTER-Net observations report
  14. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  15. EP260302a: analysis of the follow-up EP-FXT observation
  16. EP260302a: LCO observations
  17. EP260302a: BOOTES-7 optical counterpart detection at early times
  18. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  19. GRB 260303A: SVOM detection of a burst
  20. GRB 260228A: EP-FXT follow-up observation
  21. EP260302a: Einstein Probe detection of an X-ray transient
  22. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  23. GRB 251130B: TERI Gamma-ray detection
  24. GRB 260208A: TERI Gamma-ray detection
  25. EP260227a: Mondy optical observations
  26. GRB 260228A: CAHA 2.2m telescope optical upper limit
  27. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  28. EP260227a: Mephisto optical detection
  29. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  30. EP260227a: SVOM/VT optical observation
  31. GRB 260228A: SVOM/VT optical upper limits
  32. GRB 260225D: SVOM/GRM observation
  33. EP260227A: 3.6m DOT optical afterglow detection
  34. GRB 260225B: SVOM/GRM observation
  35. EP260227a: Liverpool Telescope optical observations
  36. EP260227a: LCOGT Optical Observations
  37. GRB 260226A: Asiago r-band upper limit
  38. EP260227a: Liverpool Telescope observations
  39. EP260227a: COLIBRÍ optical observations
  40. EP260227a: NOT optical observations
  41. EP260227a: Global MASTER-Net observations report
  42. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  43. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  44. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  45. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  46. EP260214a: VLT/FORS2 optical observations
  47. GRB 260225A: WINTER J-band upper limit
  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. LAT GRB260226.44: Global MASTER-Net observations report
  58. Fermi GRB 260226A: Global MASTER-Net observations report
  59. GRB 260226A: AstroSat CZTI detection of bright long burst
  60. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  61. EP260224a: LCO optical upper limits
  62. GRB 260225A: EP-FXT follow-up observation
  63. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  64. GRB 260223A: Fermi GBM Observation
  65. GRB 260225A: SVOM/VT optical upper limits
  66. EP260223a: Liverpool Telescope upper limits
  67. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  68. EP260224a: Einstein Probe detection of an X-ray transient
  69. EP 260225.148: COLIBRÍ Confirmation of flaring star
  70. EP260223a: Xinglong optical upper limit
  71. GRB 260223A: Glowbug gamma-ray detection
  72. EP260213a: Mephisto optical upper limits
  73. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  74. sb26021801: SVOM/C-GFT upper limit
  75. EP260223a: COLIBRÍ optical upper limits
  76. EP260223a: Einstein Probe detection of an X-ray transient
  77. GRB 260223A: SVOM/GRM observation
  78. GRB 260223A: COLIBRÍ further optical observations and a brightening
  79. EP260221a: Optical upper limit with Kinder observations
  80. GRB 260223A: COLIBRÍ optical observations
  81. GRB 260223A: DDOTI Optical Candidate
  82. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  83. Fermi GRB 260223A: Global MASTER-Net observations report
  84. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  85. EP260221a: COLIBRÍ optical counterpart candidate
  86. EP260221a: Gemini South z-band upper limit
  87. EP260221a: Global MASTER-Net observations report
  88. EP260221a: EP-FXT follow-up observation
  89. Fermi GRB 260221B: Global MASTER-Net observations report
  90. EP-WXT01709258519: Xinglong optical upper limit
  91. EP260221a: Xinglong optical upper limit
  92. Fermi GRB 260221A: Global MASTER-Net observations report
  93. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  94. EP260221a: GOTO optical upper limit
  95. EP260221a: COLIBRÍ optical upper limit
  96. SVOM alert sb26021801: LCO optical upper limit
  97. EP260221a: Einstein Probe detection of an X-ray transient
  98. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  99. Fermi GRB 260219A: Global MASTER-Net observations report
  100. SVOM alert sb26021801: LAST optical upper limit

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