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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.

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

28243 results found.

  1. GRB 250807A: AstroSat CZTI detection of bright long burst
  2. GRB 250807B: Swift-XRT refined Analysis
  3. EP250807a: EP-WXT detection of a fast X-ray transient
  4. EP 250807.979: GOTO optical upper limit
  5. EP250807a: COLIBRÍ optical upper limit
  6. EP250806a: Upper limit from Fermi-GBM Observations
  7. GRB 250807B: Enhanced Swift-XRT position
  8. GRB 250807A: Enhanced Swift-XRT position
  9. IceCube-Cascade 250804A: Upper limits from a search for additional neutrino events in IceCube
  10. GRB 250807B: Swift detection of a burst with an optical counterpart.
  11. GRB 250805A: Kilonova-Catcher optical upper limits
  12. GRB 250805A: Swift/UVOT Upper Limits
  13. GRB 250806A: Swift/UVOT U-band detection
  14. EP250806a: Liverpool telescope optical upper limit
  15. GRB 250807A: Swift detection of a burst with an optical counterpart
  16. EP250802a: EP-FXT follow-up observation
  17. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  18. EP250806a: SVOM /VT optical candidate
  19. GRB 250806A: J-band upper limit from WINTER
  20. GRB 250805A: Swift-BAT refined analysis
  21. GRB 250806A: KAIT optical upper limit
  22. GRB 250806A: Swift-XRT counterpart detection
  23. EP250806a: COLIBRÍ optical upper limit
  24. GRB 250806A: Kilonova-Catcher optical upper limits
  25. EP250806a: Einstein Probe detection of an X-ray transient
  26. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  27. GRB 250806A: SVOM/VT optical upper limit
  28. GRB 250806A: SVOM detection of a soft burst
  29. GRB 250805A: SVOM/VT optical counterpart
  30. GRB 250805A: Swift-XRT refined Analysis
  31. GRB 250804B: Swift-XRT observations
  32. GRB 250805A: Enhanced Swift-XRT position
  33. GRB 250805A: TRT optical upper limits
  34. GRB 250805A: Swift-XRT observations
  35. GRB 250804B: SVOM/GRM observation of a short burst
  36. GRB 250804A: Fermi GBM Final Localization
  37. EP250802a: additional Liverpool Telescope upper limits
  38. EP250730a: SVOM/VT optical upper limit
  39. EP250802a: Liverpool Telescope optical upper limits
  40. EP250802a: Global MASTER-Net observations report
  41. EP250802a: GROWTH-India Telescope optical upper limit
  42. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  43. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  44. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  45. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  46. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  47. EP250711a: CrAO and Assy optical observations
  48. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  49. EP250730a: COLIBRÍ optical upper limit
  50. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  51. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  52. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  53. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  54. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  55. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  56. GRB 250727A: EP-FXT follow-up observation
  57. GRB 250725A: PRIME near-infrared observations
  58. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  59. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  60. GRB 250728A: Swift-XRT observations
  61. GRB 250728A: COLIBRÍ optical upper limit
  62. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  63. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  64. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  65. GRB 250727A: EP-FXT counterpart detection
  66. GRB 250727A: Swift-XRT observations
  67. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  68. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  69. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  70. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  71. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  72. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  73. GRB 250725A: Swift-XRT refined Analysis
  74. GRB 250725A: Fermi GBM Observation
  75. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  76. GRB 250725A: Swift-BAT refined analysis
  77. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  78. GRB 250725A: SVOM/GRM observation
  79. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  80. GRB 250725A: Swift/UVOT Upper Limits
  81. GRB 250725A: Fermi-LAT detection
  82. GRB 250725A: BOOTES-7 early optical detection
  83. GRB 250725A: SVOM/VT optical candidate
  84. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  85. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  86. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  87. GRB 250725A: Enhanced Swift-XRT position
  88. GRB 250725A: Swift detection of a burst
  89. Swift GRB 250725A: Global MASTER-Net OT detection
  90. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  91. SVOM J195836+32283 is not a real source
  92. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  93. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  94. GRB 250721A: Fermi GBM Observation
  95. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  96. GRB 250721A: Swift-XRT observations
  97. GRB 250717B: SVOM/GRM observation
  98. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  99. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  100. GRB 250721A: MAXI/GSC detection

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