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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"
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submitter:"Judith Racusin"

45698 results found.

  1. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  2. The EP-WXT trigger 01709198251 is likely a flaring star
  3. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  4. The EP-WXT trigger 01709198202 is likely a flaring star
  5. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  6. GRB 250702B: SMA observations
  7. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  8. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  9. EP250711a: CrAO and Assy optical observations
  10. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  11. EP250730a: Global MASTER-Net observations report
  12. EP250730a: COLIBRÍ optical upper limit
  13. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  14. EP250730a: Einstein Probe detection of an X-ray transient
  15. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  16. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT follow up of AT 2025smm
  17. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  18. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  19. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  20. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  21. GRB 250725A: AstroSat CZTI detection
  22. GRB 250727A: EP-FXT follow-up observation
  23. GRB 250725A: PRIME near-infrared observations
  24. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  25. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  26. GRB: Clarification on Gamma-Ray Burst Naming Convention
  27. GRB 250728A: Swift-XRT observations
  28. GRB 250727A: SVOM/ECLAIRs refined analysis
  29. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  30. GRB 250728A: COLIBRÍ optical upper limit
  31. GRB 250728A: Fermi GBM Observation
  32. Fermi trigger No 775387550: Global MASTER-Net observations report
  33. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  34. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT detection of a new source, AT 2025smm
  35. GRB 250728A: Swift ToO observations
  36. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  37. GRB 250727A: AST3-2 Upper limit
  38. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  39. GRB 250727A: EP-FXT counterpart detection
  40. GRB250727A: SVOM/VT optical upper limit
  41. GRB 250727A: Swift-XRT observations
  42. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  44. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  45. GRB 250727A: SVOM detection of a burst
  46. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  47. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  48. The EP-WXT trigger 01709195487 is likely a flaring star
  49. Swift detection of the Soft Gamma Repeater PSR J1647-4552
  50. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  51. GRB 250725A: Swift-XRT refined Analysis
  52. GRB 250725A: Fermi GBM Observation
  53. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  54. GRB 250725A: Swift-BAT refined analysis
  55. Konus-Wind detection of GRB 250725A
  56. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  57. GRB 250725A: SVOM/GRM observation
  58. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  59. GRB 250725A: Swift/UVOT Upper Limits
  60. GRB 250725A: Fermi-LAT detection
  61. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  62. GRB 250725A: BOOTES-7 early optical detection
  63. GRB 250725A: SVOM/VT optical candidate
  64. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  65. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate (duplicate submission)
  66. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  67. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  68. GRB 250725A: Enhanced Swift-XRT position
  69. GRB 250725A: Swift detection of a burst
  70. Swift GRB 250725A: Global MASTER-Net OT detection
  71. GRB 250725A: Fermi GBM Final Real-time Localization
  72. Fermi GRB 250725A: Global MASTER-Net observations report
  73. Swift GRB 250725A: Global MASTER-Net observations report
  74. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  75. SVOM J195836+32283 is not a real source
  76. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  77. SVOM J195836+32283/sb25072103: Second VT observation
  78. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  79. GRB 250723B: Fermi GBM Final Real-time Localization
  80. GRB 250721A: Fermi GBM Observation
  81. GRB 250723A: Fermi GBM Final Real-time Localization
  82. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  83. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  84. Swift-BAT trigger 1334535 is not a GRB
  85. GRB 250721A: Swift-XRT observations
  86. GRB 250722A: Fermi GBM Final Real-time Localization
  87. GRB 250713A : SVOM/ECLAIRs refined analysis
  88. GRB 250717B: SVOM/GRM observation
  89. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  90. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  91. GRB 250721A: Tiled Swift observations
  92. GRB 250721A: MAXI/GSC detection
  93. GRB 250721A: Fermi GBM Final Localization
  94. GRB 250720B: Fermi GBM Final Localization Correction
  95. GRB 250720A: Fermi GBM Final Localization
  96. Fermi trigger No 774730635: Global MASTER-Net observations report
  97. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  98. Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB
  99. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  100. GRB 250717B: COLIBRÍ optical upper limit

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