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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"

27324 results found.

  1. GRB 260131A/B: radio detection with the VLA
  2. EP260302a: MeerKAT radio counterpart
  3. GRB 260308A: SVOM/GRM observation of a short GRB
  4. EP260306a: Mondy optical upper limit
  5. Fermi GRB 260310B: Global MASTER-Net observations report
  6. Fermi GRB 260310A: Global MASTER-Net observations report
  7. GRB 260208A: radio detection with the VLA
  8. GRB 260307A: Glowbug gamma-ray detection
  9. Fermi GBM Sub-Threshold Detection of GRB 260307B
  10. GRB 260307B: Mephisto optical upper limits
  11. GRB 260307B: possible NOT optical counterpart
  12. GRB 260307B: SVOM/VT upper limit with X band data analysis
  13. Fermi GRB 260307A: Global MASTER-Net observations report
  14. GRB260307B: GROWTH-India Telescope optical upper limit
  15. GRB 260307B: SVOM/VT optical candidate
  16. GRB 260307B: SVOM/C-GFT upper limit
  17. GRB 260307B: SVOM detection of a burst
  18. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  19. GRB 260207A: TESS Detection and Possible VLA Counterpart
  20. EP260302a: SVOM/VT optical observation
  21. EP260306a: Gemini-North redshift z = 4.773
  22. EP260306a: SVOM/VT optical observation
  23. EP260302a: Gemini-South redshift z = 1.535
  24. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  25. EP260306a: Einstein Probe detection of an X-ray transient
  26. EP260302a: Optical afterglow rebrightening
  27. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  28. GRB 260303A: 1.3m DFOT optical upper limit
  29. Fermi GRB 260305A: Global MASTER-Net observations report
  30. GRB 260303B: AstroSat CZTI detection
  31. GRB 260303A: SVOM/VT optical observations
  32. GRB 260303A: J-band observations with WINTER
  33. GRB 260303B: NuSTAR detection of prompt emission
  34. EP260302a: Global MASTER-Net observations report
  35. Fermi GRB 260303B: Global MASTER-Net observations report
  36. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  37. EP260302a: analysis of the follow-up EP-FXT observation
  38. EP260302a: LCO observations
  39. EP260302a: BOOTES-7 optical counterpart detection at early times
  40. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  41. GRB 260303A: SVOM detection of a burst
  42. GRB 260228A: EP-FXT follow-up observation
  43. EP260302a: Einstein Probe detection of an X-ray transient
  44. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  45. GRB 251130B: TERI Gamma-ray detection
  46. GRB 260208A: TERI Gamma-ray detection
  47. EP260227a: Mondy optical observations
  48. GRB 260228A: CAHA 2.2m telescope optical upper limit
  49. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  50. EP260227a: Mephisto optical detection
  51. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  52. EP260227a: SVOM/VT optical observation
  53. GRB 260228A: SVOM/VT optical upper limits
  54. GRB 260225D: SVOM/GRM observation
  55. EP260227A: 3.6m DOT optical afterglow detection
  56. GRB 260225B: SVOM/GRM observation
  57. EP260227a: Liverpool Telescope optical observations
  58. EP260227a: LCOGT Optical Observations
  59. GRB 260226A: Asiago r-band upper limit
  60. EP260227a: Liverpool Telescope observations
  61. EP260227a: COLIBRÍ optical observations
  62. EP260227a: NOT optical observations
  63. EP260227a: Global MASTER-Net observations report
  64. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  65. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  66. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  67. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  68. EP260214a: VLT/FORS2 optical observations
  69. GRB 260225A: WINTER J-band upper limit
  70. GRB 260226A: COLIBRÍ optical upper limits
  71. GRB 260226A: LCOGT Optical Upper Limit
  72. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  73. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  74. GRB 260226A: Glowbug gamma-ray detection
  75. GRB 260226A: NuSTAR detection of bright prompt emission
  76. GRB 260226A : GROWTH-India Telescope optical observations
  77. GRB 260226A: LAST optical upper limit
  78. GRB 260226A: Fermi GBM observation
  79. LAT GRB260226.44: Global MASTER-Net observations report
  80. Fermi GRB 260226A: Global MASTER-Net observations report
  81. GRB 260226A: AstroSat CZTI detection of bright long burst
  82. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  83. EP260224a: LCO optical upper limits
  84. GRB 260225A: EP-FXT follow-up observation
  85. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  86. GRB 260223A: Fermi GBM Observation
  87. GRB 260225A: SVOM/VT optical upper limits
  88. EP260223a: Liverpool Telescope upper limits
  89. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  90. EP260224a: Einstein Probe detection of an X-ray transient
  91. EP 260225.148: COLIBRÍ Confirmation of flaring star
  92. EP260223a: Xinglong optical upper limit
  93. GRB 260223A: Glowbug gamma-ray detection
  94. EP260213a: Mephisto optical upper limits
  95. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  96. sb26021801: SVOM/C-GFT upper limit
  97. EP260223a: COLIBRÍ optical upper limits
  98. EP260223a: Einstein Probe detection of an X-ray transient
  99. GRB 260223A: SVOM/GRM observation
  100. GRB 260223A: COLIBRÍ further optical observations and a brightening

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