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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"

28286 results found.

  1. GRB 250813B: SVOM detection of a bright long burst
  2. LIGO/Virgo/KAGRA S250813k: NED Galaxies in the 4-Update Localization Volume
  3. LIGO/Virgo/KAGRA S250813k: Updated Sky localization
  4. EP250812a: Nickel optical upper limit
  5. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  6. EP250812a: NOT, NTT, and GS observations
  7. GRB 250812A: Swift/UVOT Detection
  8. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  9. EP250812a: Liverpool Telescope upper limits
  10. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  11. LIGO/Virgo/KAGRA S250813k: Identification of a GW compact binary merger candidate
  12. GRB 250812A: EP-FXT counterpart detection
  13. GRB 250807B: Swift-BAT refined analysis
  14. EP 250812a: GOTO optical upper limit
  15. GRB 250812A: Kilonova-Catcher optical afterglow detection
  16. EP250812a: Swift-XRT counterpart detection
  17. GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
  18. EP250812a: Einstein Probe detection of an X-ray transient
  19. GRB 250812A: Swift-XRT afterglow detection
  20. GRB 250812A: TRT likely optical counterpart detection
  21. IceCube-Cascade 250809A: Upper limits from a search for additional neutrino events in IceCube
  22. GRB 250809A: Swift-BAT refined analysis
  23. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  24. GRB 250807A: Swift-BAT refined analysis
  25. LIGO/Virgo/KAGRA S250810ck: Updated Sky localization and EM Bright Classification
  26. GRB 250809A: Swift/UVOT Detection
  27. LIGO/Virgo/KAGRA S250810ck: Identification of a GW compact binary merger candidate
  28. Corrected Swift-XRT Refined Analysis of GRB 250809A
  29. GRB 250809A: Swift-XRT refined Analysis
  30. GRB 250809A: LCOGT Optical Upper Limits
  31. GRB 250808A: VLT X-shooter candidate counterpart
  32. GRB 250809A: Swift detection of a gamma ray burst
  33. GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  34. GRB 250808A: Fermi GBM Observation
  35. GRB 250808A: Swift-XRT candidate counterpart detection
  36. GRB 250807B: Swift/UVOT Detection
  37. GRB 250807B: Kilonova-Catcher optical afterglow detection
  38. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  39. GRB 250807A: Swift/UVOT Detection
  40. GRB 250807A: Swift-XRT refined Analysis
  41. GRB 250806A: SVOM/MXT refined analysis
  42. EP250807a: NTT z-band optical upper limit
  43. GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
  44. GRB 250807A: SVOM/GRM observation
  45. GRB 250807A: AstroSat CZTI detection of bright long burst
  46. GRB 250807B: Swift-XRT refined Analysis
  47. EP250807a: EP-WXT detection of a fast X-ray transient
  48. EP 250807.979: GOTO optical upper limit
  49. EP250807a: COLIBRÍ optical upper limit
  50. EP250806a: Upper limit from Fermi-GBM Observations
  51. GRB 250807B: Enhanced Swift-XRT position
  52. GRB 250807A: Enhanced Swift-XRT position
  53. IceCube-Cascade 250804A: Upper limits from a search for additional neutrino events in IceCube
  54. GRB 250807B: Swift detection of a burst with an optical counterpart.
  55. GRB 250805A: Kilonova-Catcher optical upper limits
  56. GRB 250805A: Swift/UVOT Upper Limits
  57. GRB 250806A: Swift/UVOT U-band detection
  58. EP250806a: Liverpool telescope optical upper limit
  59. GRB 250807A: Swift detection of a burst with an optical counterpart
  60. EP250802a: EP-FXT follow-up observation
  61. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  62. EP250806a: SVOM /VT optical candidate
  63. GRB 250806A: J-band upper limit from WINTER
  64. GRB 250805A: Swift-BAT refined analysis
  65. GRB 250806A: KAIT optical upper limit
  66. GRB 250806A: Swift-XRT counterpart detection
  67. EP250806a: COLIBRÍ optical upper limit
  68. GRB 250806A: Kilonova-Catcher optical upper limits
  69. EP250806a: Einstein Probe detection of an X-ray transient
  70. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  71. GRB 250806A: SVOM/VT optical upper limit
  72. GRB 250806A: SVOM detection of a soft burst
  73. GRB 250805A: SVOM/VT optical counterpart
  74. GRB 250805A: Swift-XRT refined Analysis
  75. GRB 250804B: Swift-XRT observations
  76. GRB 250805A: Enhanced Swift-XRT position
  77. GRB 250805A: TRT optical upper limits
  78. GRB 250805A: Swift-XRT observations
  79. GRB 250804B: SVOM/GRM observation of a short burst
  80. GRB 250804A: Fermi GBM Final Localization
  81. EP250802a: additional Liverpool Telescope upper limits
  82. EP250730a: SVOM/VT optical upper limit
  83. EP250802a: Liverpool Telescope optical upper limits
  84. EP250802a: Global MASTER-Net observations report
  85. EP250802a: GROWTH-India Telescope optical upper limit
  86. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  87. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  88. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  89. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  90. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  91. EP250711a: CrAO and Assy optical observations
  92. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  93. EP250730a: COLIBRÍ optical upper limit
  94. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  95. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  96. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  97. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  98. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  99. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  100. GRB 250727A: EP-FXT follow-up observation

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