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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"

28280 results found.

  1. GRB 250812A: Swift/UVOT Detection
  2. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  3. EP250812a: Liverpool Telescope upper limits
  4. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  5. LIGO/Virgo/KAGRA S250813k: Identification of a GW compact binary merger candidate
  6. GRB 250812A: EP-FXT counterpart detection
  7. GRB 250807B: Swift-BAT refined analysis
  8. EP 250812a: GOTO optical upper limit
  9. GRB 250812A: Kilonova-Catcher optical afterglow detection
  10. EP250812a: Swift-XRT counterpart detection
  11. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  12. EP250812a: Einstein Probe detection of an X-ray transient
  13. GRB 250812A: Swift-XRT afterglow detection
  14. GRB 250812A: TRT likely optical counterpart detection
  15. IceCube-Cascade 250809A: Upper limits from a search for additional neutrino events in IceCube
  16. GRB 250809A: Swift-BAT refined analysis
  17. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  18. GRB 250807A: Swift-BAT refined analysis
  19. LIGO/Virgo/KAGRA S250810ck: Updated Sky localization and EM Bright Classification
  20. GRB 250809A: Swift/UVOT Detection
  21. LIGO/Virgo/KAGRA S250810ck: Identification of a GW compact binary merger candidate
  22. Corrected Swift-XRT Refined Analysis of GRB 250809A
  23. GRB 250809A: Swift-XRT refined Analysis
  24. GRB 250809A: LCOGT Optical Upper Limits
  25. GRB 250808A: VLT X-shooter candidate counterpart
  26. GRB 250809A: Swift detection of a gamma ray burst
  27. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  28. GRB 250808A: Fermi GBM Observation
  29. GRB 250808A: Swift-XRT candidate counterpart detection
  30. GRB 250807B: Swift/UVOT Detection
  31. GRB 250807B: Kilonova-Catcher optical afterglow detection
  32. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  33. GRB 250807A: Swift/UVOT Detection
  34. GRB 250807A: Swift-XRT refined Analysis
  35. GRB 250806A: SVOM/MXT refined analysis
  36. EP250807a: NTT z-band optical upper limit
  37. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  38. GRB 250807A: SVOM/GRM observation
  39. GRB 250807A: AstroSat CZTI detection of bright long burst
  40. GRB 250807B: Swift-XRT refined Analysis
  41. EP250807a: EP-WXT detection of a fast X-ray transient
  42. EP 250807.979: GOTO optical upper limit
  43. EP250807a: COLIBRÍ optical upper limit
  44. EP250806a: Upper limit from Fermi-GBM Observations
  45. GRB 250807B: Enhanced Swift-XRT position
  46. GRB 250807A: Enhanced Swift-XRT position
  47. IceCube-Cascade 250804A: Upper limits from a search for additional neutrino events in IceCube
  48. GRB 250807B: Swift detection of a burst with an optical counterpart.
  49. GRB 250805A: Kilonova-Catcher optical upper limits
  50. GRB 250805A: Swift/UVOT Upper Limits
  51. GRB 250806A: Swift/UVOT U-band detection
  52. EP250806a: Liverpool telescope optical upper limit
  53. GRB 250807A: Swift detection of a burst with an optical counterpart
  54. EP250802a: EP-FXT follow-up observation
  55. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  56. EP250806a: SVOM /VT optical candidate
  57. GRB 250806A: J-band upper limit from WINTER
  58. GRB 250805A: Swift-BAT refined analysis
  59. GRB 250806A: KAIT optical upper limit
  60. GRB 250806A: Swift-XRT counterpart detection
  61. EP250806a: COLIBRÍ optical upper limit
  62. GRB 250806A: Kilonova-Catcher optical upper limits
  63. EP250806a: Einstein Probe detection of an X-ray transient
  64. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  65. GRB 250806A: SVOM/VT optical upper limit
  66. GRB 250806A: SVOM detection of a soft burst
  67. GRB 250805A: SVOM/VT optical counterpart
  68. GRB 250805A: Swift-XRT refined Analysis
  69. GRB 250804B: Swift-XRT observations
  70. GRB 250805A: Enhanced Swift-XRT position
  71. GRB 250805A: TRT optical upper limits
  72. GRB 250805A: Swift-XRT observations
  73. GRB 250804B: SVOM/GRM observation of a short burst
  74. GRB 250804A: Fermi GBM Final Localization
  75. EP250802a: additional Liverpool Telescope upper limits
  76. EP250730a: SVOM/VT optical upper limit
  77. EP250802a: Liverpool Telescope optical upper limits
  78. EP250802a: Global MASTER-Net observations report
  79. EP250802a: GROWTH-India Telescope optical upper limit
  80. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  81. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  82. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  83. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  84. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  85. EP250711a: CrAO and Assy optical observations
  86. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  87. EP250730a: COLIBRÍ optical upper limit
  88. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  89. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  90. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  91. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  92. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  93. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  94. GRB 250727A: EP-FXT follow-up observation
  95. GRB 250725A: PRIME near-infrared observations
  96. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  97. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  98. GRB 250728A: Swift-XRT observations
  99. GRB 250728A: COLIBRÍ optical upper limit
  100. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization

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