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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

26913 results found.

  1. Fermi GBM Sub-Threshold Detection of GRB 260307B
  2. GRB 260307B: Mephisto optical upper limits
  3. GRB 260307B: possible NOT optical counterpart
  4. GRB 260307B: SVOM/VT upper limit with X band data analysis
  5. Fermi GRB 260307A: Global MASTER-Net observations report
  6. GRB260307B: GROWTH-India Telescope optical upper limit
  7. GRB 260307B: SVOM/VT optical candidate
  8. GRB 260307B: SVOM/C-GFT upper limit
  9. GRB 260307B: SVOM detection of a burst
  10. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  11. GRB 260207A: TESS Detection and Possible VLA Counterpart
  12. EP260302a: SVOM/VT optical observation
  13. EP260306a: Gemini-North redshift z = 4.773
  14. EP260306a: SVOM/VT optical observation
  15. EP260302a: Gemini-South redshift z = 1.535
  16. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  17. EP260306a: Einstein Probe detection of an X-ray transient
  18. EP260302a: Optical afterglow rebrightening
  19. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  20. GRB 260303A: 1.3m DFOT optical upper limit
  21. Fermi GRB 260305A: Global MASTER-Net observations report
  22. GRB 260303B: AstroSat CZTI detection
  23. GRB 260303A: SVOM/VT optical observations
  24. GRB 260303A: J-band observations with WINTER
  25. GRB 260303B: NuSTAR detection of prompt emission
  26. EP260302a: Global MASTER-Net observations report
  27. Fermi GRB 260303B: Global MASTER-Net observations report
  28. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  29. EP260302a: analysis of the follow-up EP-FXT observation
  30. EP260302a: LCO observations
  31. EP260302a: BOOTES-7 optical counterpart detection at early times
  32. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  33. GRB 260303A: SVOM detection of a burst
  34. GRB 260228A: EP-FXT follow-up observation
  35. EP260302a: Einstein Probe detection of an X-ray transient
  36. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  37. GRB 251130B: TERI Gamma-ray detection
  38. GRB 260208A: TERI Gamma-ray detection
  39. EP260227a: Mondy optical observations
  40. GRB 260228A: CAHA 2.2m telescope optical upper limit
  41. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  42. EP260227a: Mephisto optical detection
  43. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  44. EP260227a: SVOM/VT optical observation
  45. GRB 260228A: SVOM/VT optical upper limits
  46. GRB 260225D: SVOM/GRM observation
  47. EP260227A: 3.6m DOT optical afterglow detection
  48. GRB 260225B: SVOM/GRM observation
  49. EP260227a: Liverpool Telescope optical observations
  50. EP260227a: LCOGT Optical Observations
  51. GRB 260226A: Asiago r-band upper limit
  52. EP260227a: Liverpool Telescope observations
  53. EP260227a: COLIBRÍ optical observations
  54. EP260227a: NOT optical observations
  55. EP260227a: Global MASTER-Net observations report
  56. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  57. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  58. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  59. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  60. EP260214a: VLT/FORS2 optical observations
  61. GRB 260225A: WINTER J-band upper limit
  62. GRB 260226A: COLIBRÍ optical upper limits
  63. GRB 260226A: LCOGT Optical Upper Limit
  64. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  65. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  66. GRB 260226A: Glowbug gamma-ray detection
  67. GRB 260226A: NuSTAR detection of bright prompt emission
  68. GRB 260226A : GROWTH-India Telescope optical observations
  69. GRB 260226A: LAST optical upper limit
  70. GRB 260226A: Fermi GBM observation
  71. LAT GRB260226.44: Global MASTER-Net observations report
  72. Fermi GRB 260226A: Global MASTER-Net observations report
  73. GRB 260226A: AstroSat CZTI detection of bright long burst
  74. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  75. EP260224a: LCO optical upper limits
  76. GRB 260225A: EP-FXT follow-up observation
  77. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  78. GRB 260223A: Fermi GBM Observation
  79. GRB 260225A: SVOM/VT optical upper limits
  80. EP260223a: Liverpool Telescope upper limits
  81. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  82. EP260224a: Einstein Probe detection of an X-ray transient
  83. EP 260225.148: COLIBRÍ Confirmation of flaring star
  84. EP260223a: Xinglong optical upper limit
  85. GRB 260223A: Glowbug gamma-ray detection
  86. EP260213a: Mephisto optical upper limits
  87. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  88. sb26021801: SVOM/C-GFT upper limit
  89. EP260223a: COLIBRÍ optical upper limits
  90. EP260223a: Einstein Probe detection of an X-ray transient
  91. GRB 260223A: SVOM/GRM observation
  92. GRB 260223A: COLIBRÍ further optical observations and a brightening
  93. EP260221a: Optical upper limit with Kinder observations
  94. GRB 260223A: COLIBRÍ optical observations
  95. GRB 260223A: DDOTI Optical Candidate
  96. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  97. Fermi GRB 260223A: Global MASTER-Net observations report
  98. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  99. EP260221a: COLIBRÍ optical counterpart candidate
  100. EP260221a: Gemini South z-band upper limit

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