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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"

28101 results found.

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

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