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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"

19612 results found.

  1. GRB 250807A: Swift detection of a burst with an optical counterpart
  2. GRB 250806A: EP-FXT observation
  3. EP#01709198415/EP250806a: Swift-XRT observations
  4. GRB 250805A: Swift-BAT refined analysis
  5. GRB 250806A: KAIT optical upper limit
  6. GRB 250806A: SVOM/VT refined analysis
  7. GRB 250806A: Swift-XRT counterpart detection
  8. GRB 250805A: SVOM/VT optical counterpart
  9. GRB 250805A: ESO/VLT observations
  10. GRB 250805A: Swift-XRT refined Analysis
  11. GRB 250804B: Swift-XRT observations
  12. GRB 250805A: Enhanced Swift-XRT position
  13. GRB 250805A: TRT optical upper limits
  14. GRB 250805A: Swift-XRT observations
  15. GRB 250805A: Swift detection of a burst
  16. Swift GRB250805.26: Global MASTER-Net observations report
  17. GRB 250804B: Tiled Swift observations
  18. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  19. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  20. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  21. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT follow up of AT 2025smm
  22. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  23. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  24. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  25. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  26. GRB 250725A: AstroSat CZTI detection
  27. GRB 250727A: EP-FXT follow-up observation
  28. GRB 250725A: PRIME near-infrared observations
  29. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  30. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  31. GRB 250728A: Swift-XRT observations
  32. GRB 250728A: COLIBRÍ optical upper limit
  33. GRB 250728A: Fermi GBM Observation
  34. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT detection of a new source, AT 2025smm
  35. GRB 250728A: Swift ToO observations
  36. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  37. GRB 250727A: EP-FXT counterpart detection
  38. GRB250727A: SVOM/VT optical upper limit
  39. GRB 250727A: Swift-XRT observations
  40. Swift detection of the Soft Gamma Repeater PSR J1647-4552
  41. GRB 250725A: Swift-XRT refined Analysis
  42. GRB 250725A: Fermi GBM Observation
  43. GRB 250725A: Swift-BAT refined analysis
  44. Konus-Wind detection of GRB 250725A
  45. GRB 250725A: SVOM/GRM observation
  46. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  47. GRB 250725A: Swift/UVOT Upper Limits
  48. GRB 250725A: Fermi-LAT detection
  49. GRB 250725A: BOOTES-7 early optical detection
  50. GRB 250725A: SVOM/VT optical candidate
  51. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  52. GRB 250725A: Enhanced Swift-XRT position
  53. GRB 250725A: Swift detection of a burst
  54. Swift GRB 250725A: Global MASTER-Net OT detection
  55. Swift GRB 250725A: Global MASTER-Net observations report
  56. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  57. Swift-BAT trigger 1334535 is not a GRB
  58. GRB 250721A: Swift-XRT observations
  59. GRB 250717B: SVOM/GRM observation
  60. GRB 250721A: Tiled Swift observations
  61. GRB 250717B: COLIBRÍ optical upper limit
  62. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  63. GRB 250717B: Swift-XRT observations
  64. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  65. Swift Trigger 1334535: a possible GRB 250718A
  66. Swift GRB250718.01: Global MASTER-Net observations report
  67. GRB 250717B: Swift ToO observations
  68. GRB 270713A: Kitab and AbAO Optical Observations
  69. GRB 250717B: Fermi GBM Observation
  70. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  71. GRB 250716A: Swift-XRT afterglow detection
  72. GRB 250716A: Swift ToO observations
  73. GRB 250713A: SVOM/C-GFT upper limit
  74. GRB 250713A: Swift-XRT observations
  75. GRB 250706A: Swift-BAT refined analysis
  76. GRB 250702F: Swift-BAT refined analysis
  77. GRB 250628A: Swift-BAT refined analysis
  78. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  79. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  80. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  81. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  82. GRB 250706B/C: Fermi-LAT detection
  83. GRB 250706B: Swift/UVOT Detection
  84. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  85. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  86. GRB 250702F: GRANDMA observations
  87. GRB 250706A: Swift-XRT refined Analysis
  88. GRB 250706A: Swift/UVOT Upper Limits
  89. GRB 250706A: REM optical/NIR observations
  90. Swift GRB 250706A: Global MASTER-Net observations report
  91. GRB 250706A: JinShan optical upper limits
  92. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  93. GRB250706B: Swift-XRT counterpart detection
  94. GRB 250706A: GROWTH-India Telescope optical upper limit
  95. GRB 250706A: Swift detection of a burst
  96. GRB 250704B: Swift-XRT refined Analysis
  97. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  98. GRB 250704B: Swift/UVOT Upper Limits
  99. GRB 250704A: Swift/UVOT Detection
  100. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.

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