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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"

28233 results found.

  1. GRB 250805A: Kilonova-Catcher optical upper limits
  2. GRB 250805A: Swift/UVOT Upper Limits
  3. GRB 250806A: Swift/UVOT U-band detection
  4. EP250806a: Liverpool telescope optical upper limit
  5. GRB 250807A: Swift detection of a burst with an optical counterpart
  6. EP250802a: EP-FXT follow-up observation
  7. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  8. EP250806a: SVOM /VT optical candidate
  9. GRB 250806A: J-band upper limit from WINTER
  10. GRB 250805A: Swift-BAT refined analysis
  11. GRB 250806A: KAIT optical upper limit
  12. GRB 250806A: Swift-XRT counterpart detection
  13. EP250806a: COLIBRÍ optical upper limit
  14. GRB 250806A: Kilonova-Catcher optical upper limits
  15. EP250806a: Einstein Probe detection of an X-ray transient
  16. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  17. GRB 250806A: SVOM/VT optical upper limit
  18. GRB 250806A: SVOM detection of a soft burst
  19. GRB 250805A: SVOM/VT optical counterpart
  20. GRB 250805A: Swift-XRT refined Analysis
  21. GRB 250804B: Swift-XRT observations
  22. GRB 250805A: Enhanced Swift-XRT position
  23. GRB 250805A: TRT optical upper limits
  24. GRB 250805A: Swift-XRT observations
  25. GRB 250804B: SVOM/GRM observation of a short burst
  26. GRB 250804A: Fermi GBM Final Localization
  27. EP250802a: additional Liverpool Telescope upper limits
  28. EP250730a: SVOM/VT optical upper limit
  29. EP250802a: Liverpool Telescope optical upper limits
  30. EP250802a: Global MASTER-Net observations report
  31. EP250802a: GROWTH-India Telescope optical upper limit
  32. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  33. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  34. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  35. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  36. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  37. EP250711a: CrAO and Assy optical observations
  38. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  39. EP250730a: COLIBRÍ optical upper limit
  40. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  41. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  42. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  43. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  44. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  45. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  46. GRB 250727A: EP-FXT follow-up observation
  47. GRB 250725A: PRIME near-infrared observations
  48. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  49. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  50. GRB 250728A: Swift-XRT observations
  51. GRB 250728A: COLIBRÍ optical upper limit
  52. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  53. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  54. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  55. GRB 250727A: EP-FXT counterpart detection
  56. GRB 250727A: Swift-XRT observations
  57. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  58. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  59. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  60. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  61. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  62. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  63. GRB 250725A: Swift-XRT refined Analysis
  64. GRB 250725A: Fermi GBM Observation
  65. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  66. GRB 250725A: Swift-BAT refined analysis
  67. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  68. GRB 250725A: SVOM/GRM observation
  69. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  70. GRB 250725A: Swift/UVOT Upper Limits
  71. GRB 250725A: Fermi-LAT detection
  72. GRB 250725A: BOOTES-7 early optical detection
  73. GRB 250725A: SVOM/VT optical candidate
  74. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  75. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  76. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  77. GRB 250725A: Enhanced Swift-XRT position
  78. GRB 250725A: Swift detection of a burst
  79. Swift GRB 250725A: Global MASTER-Net OT detection
  80. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  81. SVOM J195836+32283 is not a real source
  82. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  83. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  84. GRB 250721A: Fermi GBM Observation
  85. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  86. GRB 250721A: Swift-XRT observations
  87. GRB 250717B: SVOM/GRM observation
  88. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  89. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  90. GRB 250721A: MAXI/GSC detection
  91. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  92. GRB 250717B: COLIBRÍ optical upper limit
  93. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  94. GRB 250717B: Swift-XRT observations
  95. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  96. Swift GRB250718.01: Global MASTER-Net observations report
  97. GRB 270713A: Kitab and AbAO Optical Observations
  98. GRB 250717B: Fermi GBM Observation
  99. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  100. GRB 250716A: Swift-XRT afterglow detection

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