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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').
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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"
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submitter:"Judith Racusin"

28226 results found.

  1. EP250806a: SVOM /VT optical candidate
  2. GRB 250806A: J-band upper limit from WINTER
  3. GRB 250805A: Swift-BAT refined analysis
  4. GRB 250806A: KAIT optical upper limit
  5. GRB 250806A: Swift-XRT counterpart detection
  6. EP250806a: COLIBRÍ optical upper limit
  7. GRB 250806A: Kilonova-Catcher optical upper limits
  8. EP250806a: Einstein Probe detection of an X-ray transient
  9. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  10. GRB 250806A: SVOM/VT optical upper limit
  11. GRB 250806A: SVOM detection of a soft burst
  12. GRB 250805A: SVOM/VT optical counterpart
  13. GRB 250805A: Swift-XRT refined Analysis
  14. GRB 250804B: Swift-XRT observations
  15. GRB 250805A: Enhanced Swift-XRT position
  16. GRB 250805A: TRT optical upper limits
  17. GRB 250805A: Swift-XRT observations
  18. GRB 250804B: SVOM/GRM observation of a short burst
  19. GRB 250804A: Fermi GBM Final Localization
  20. EP250802a: additional Liverpool Telescope upper limits
  21. EP250730a: SVOM/VT optical upper limit
  22. EP250802a: Liverpool Telescope optical upper limits
  23. EP250802a: Global MASTER-Net observations report
  24. EP250802a: GROWTH-India Telescope optical upper limit
  25. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  26. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  27. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  28. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  29. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  30. EP250711a: CrAO and Assy optical observations
  31. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  32. EP250730a: COLIBRÍ optical upper limit
  33. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  34. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  35. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  36. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  37. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  38. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  39. GRB 250727A: EP-FXT follow-up observation
  40. GRB 250725A: PRIME near-infrared observations
  41. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  42. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  43. GRB 250728A: Swift-XRT observations
  44. GRB 250728A: COLIBRÍ optical upper limit
  45. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  46. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  47. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  48. GRB 250727A: EP-FXT counterpart detection
  49. GRB 250727A: Swift-XRT observations
  50. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  51. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  52. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  53. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  54. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  55. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  56. GRB 250725A: Swift-XRT refined Analysis
  57. GRB 250725A: Fermi GBM Observation
  58. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  59. GRB 250725A: Swift-BAT refined analysis
  60. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  61. GRB 250725A: SVOM/GRM observation
  62. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  63. GRB 250725A: Swift/UVOT Upper Limits
  64. GRB 250725A: Fermi-LAT detection
  65. GRB 250725A: BOOTES-7 early optical detection
  66. GRB 250725A: SVOM/VT optical candidate
  67. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  68. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  69. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  70. GRB 250725A: Enhanced Swift-XRT position
  71. GRB 250725A: Swift detection of a burst
  72. Swift GRB 250725A: Global MASTER-Net OT detection
  73. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  74. SVOM J195836+32283 is not a real source
  75. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  76. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  77. GRB 250721A: Fermi GBM Observation
  78. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  79. GRB 250721A: Swift-XRT observations
  80. GRB 250717B: SVOM/GRM observation
  81. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  82. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  83. GRB 250721A: MAXI/GSC detection
  84. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  85. GRB 250717B: COLIBRÍ optical upper limit
  86. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  87. GRB 250717B: Swift-XRT observations
  88. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  89. Swift GRB250718.01: Global MASTER-Net observations report
  90. GRB 270713A: Kitab and AbAO Optical Observations
  91. GRB 250717B: Fermi GBM Observation
  92. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  93. GRB 250716A: Swift-XRT afterglow detection
  94. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  95. GRB 250716A: Fermi GBM Observation
  96. GRB 250714A: SVOM/GRM observation
  97. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  98. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  99. GRB 250713A: Mephisto optical upper limits
  100. GRB 250713A: SVOM/VT optical upper limit

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