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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"
body:"GRB"
submitter:"Judith Racusin"

28238 results found.

  1. EP250806a: Upper limit from Fermi-GBM Observations
  2. GRB 250807B: Enhanced Swift-XRT position
  3. GRB 250807A: Enhanced Swift-XRT position
  4. IceCube-Cascade 250804A: Upper limits from a search for additional neutrino events in IceCube
  5. GRB 250807B: Swift detection of a burst with an optical counterpart.
  6. GRB 250805A: Kilonova-Catcher optical upper limits
  7. GRB 250805A: Swift/UVOT Upper Limits
  8. GRB 250806A: Swift/UVOT U-band detection
  9. EP250806a: Liverpool telescope optical upper limit
  10. GRB 250807A: Swift detection of a burst with an optical counterpart
  11. EP250802a: EP-FXT follow-up observation
  12. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  13. EP250806a: SVOM /VT optical candidate
  14. GRB 250806A: J-band upper limit from WINTER
  15. GRB 250805A: Swift-BAT refined analysis
  16. GRB 250806A: KAIT optical upper limit
  17. GRB 250806A: Swift-XRT counterpart detection
  18. EP250806a: COLIBRÍ optical upper limit
  19. GRB 250806A: Kilonova-Catcher optical upper limits
  20. EP250806a: Einstein Probe detection of an X-ray transient
  21. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  22. GRB 250806A: SVOM/VT optical upper limit
  23. GRB 250806A: SVOM detection of a soft burst
  24. GRB 250805A: SVOM/VT optical counterpart
  25. GRB 250805A: Swift-XRT refined Analysis
  26. GRB 250804B: Swift-XRT observations
  27. GRB 250805A: Enhanced Swift-XRT position
  28. GRB 250805A: TRT optical upper limits
  29. GRB 250805A: Swift-XRT observations
  30. GRB 250804B: SVOM/GRM observation of a short burst
  31. GRB 250804A: Fermi GBM Final Localization
  32. EP250802a: additional Liverpool Telescope upper limits
  33. EP250730a: SVOM/VT optical upper limit
  34. EP250802a: Liverpool Telescope optical upper limits
  35. EP250802a: Global MASTER-Net observations report
  36. EP250802a: GROWTH-India Telescope optical upper limit
  37. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  38. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  39. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  40. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  41. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  42. EP250711a: CrAO and Assy optical observations
  43. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  44. EP250730a: COLIBRÍ optical upper limit
  45. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  46. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  47. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  48. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  49. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  50. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  51. GRB 250727A: EP-FXT follow-up observation
  52. GRB 250725A: PRIME near-infrared observations
  53. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  54. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  55. GRB 250728A: Swift-XRT observations
  56. GRB 250728A: COLIBRÍ optical upper limit
  57. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  58. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  59. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  60. GRB 250727A: EP-FXT counterpart detection
  61. GRB 250727A: Swift-XRT observations
  62. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  63. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  64. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  65. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  66. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  67. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  68. GRB 250725A: Swift-XRT refined Analysis
  69. GRB 250725A: Fermi GBM Observation
  70. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  71. GRB 250725A: Swift-BAT refined analysis
  72. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  73. GRB 250725A: SVOM/GRM observation
  74. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  75. GRB 250725A: Swift/UVOT Upper Limits
  76. GRB 250725A: Fermi-LAT detection
  77. GRB 250725A: BOOTES-7 early optical detection
  78. GRB 250725A: SVOM/VT optical candidate
  79. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  80. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  81. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  82. GRB 250725A: Enhanced Swift-XRT position
  83. GRB 250725A: Swift detection of a burst
  84. Swift GRB 250725A: Global MASTER-Net OT detection
  85. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  86. SVOM J195836+32283 is not a real source
  87. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  88. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  89. GRB 250721A: Fermi GBM Observation
  90. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  91. GRB 250721A: Swift-XRT observations
  92. GRB 250717B: SVOM/GRM observation
  93. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  94. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  95. GRB 250721A: MAXI/GSC detection
  96. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  97. GRB 250717B: COLIBRÍ optical upper limit
  98. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  99. GRB 250717B: Swift-XRT observations
  100. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits

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