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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"

28247 results found.

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

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