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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"

43898 results found.

  1. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT follow up of AT 2025smm
  2. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  3. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  4. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  5. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  6. GRB 250725A: AstroSat CZTI detection
  7. GRB 250727A: EP-FXT follow-up observation
  8. GRB 250725A: PRIME near-infrared observations
  9. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  10. GRB: Clarification on Gamma-Ray Burst Naming Convention
  11. GRB 250728A: Swift-XRT observations
  12. GRB 250727A: SVOM/ECLAIRs refined analysis
  13. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  14. GRB 250728A: COLIBRÍ optical upper limit
  15. GRB 250728A: Fermi GBM Observation
  16. Fermi trigger No 775387550: Global MASTER-Net observations report
  17. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  18. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT detection of a new source, AT 2025smm
  19. GRB 250728A: Swift ToO observations
  20. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  21. GRB 250727A: AST3-2 Upper limit
  22. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  23. GRB 250727A: EP-FXT counterpart detection
  24. GRB250727A: SVOM/VT optical upper limit
  25. GRB 250727A: Swift-XRT observations
  26. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  27. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  28. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  29. GRB 250727A: SVOM detection of a burst
  30. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  31. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  32. The EP-WXT trigger 01709195487 is likely a flaring star
  33. Swift detection of the Soft Gamma Repeater PSR J1647-4552
  34. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  35. GRB 250725A: Swift-XRT refined Analysis
  36. GRB 250725A: Fermi GBM Observation
  37. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  38. GRB 250725A: Swift-BAT refined analysis
  39. Konus-Wind detection of GRB 250725A
  40. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  41. GRB 250725A: SVOM/GRM observation
  42. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  43. GRB 250725A: Swift/UVOT Upper Limits
  44. GRB 250725A: Fermi-LAT detection
  45. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  46. GRB 250725A: BOOTES-7 early optical detection
  47. GRB 250725A: SVOM/VT optical candidate
  48. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  49. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate (duplicate submission)
  50. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  51. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  52. GRB 250725A: Enhanced Swift-XRT position
  53. GRB 250725A: Swift detection of a burst
  54. Swift GRB 250725A: Global MASTER-Net OT detection
  55. GRB 250725A: Fermi GBM Final Real-time Localization
  56. Fermi GRB 250725A: Global MASTER-Net observations report
  57. Swift GRB 250725A: Global MASTER-Net observations report
  58. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  59. SVOM J195836+32283 is not a real source
  60. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  61. SVOM J195836+32283/sb25072103: Second VT observation
  62. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  63. GRB 250723B: Fermi GBM Final Real-time Localization
  64. GRB 250721A: Fermi GBM Observation
  65. GRB 250723A: Fermi GBM Final Real-time Localization
  66. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  67. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  68. Swift-BAT trigger 1334535 is not a GRB
  69. GRB 250721A: Swift-XRT observations
  70. GRB 250722A: Fermi GBM Final Real-time Localization
  71. GRB 250713A : SVOM/ECLAIRs refined analysis
  72. GRB 250717B: SVOM/GRM observation
  73. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  74. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  75. GRB 250721A: Tiled Swift observations
  76. GRB 250721A: MAXI/GSC detection
  77. GRB 250721A: Fermi GBM Final Localization
  78. GRB 250720B: Fermi GBM Final Localization Correction
  79. GRB 250720A: Fermi GBM Final Localization
  80. Fermi trigger No 774730635: Global MASTER-Net observations report
  81. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  82. Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB
  83. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  84. GRB 250717B: COLIBRÍ optical upper limit
  85. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  86. GRB 250717B: Swift-XRT observations
  87. GRB 250718B: Fermi GBM Final Localization Correction
  88. GRB 250718B: Fermi GBM Final Real-time Localization
  89. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  90. Swift Trigger 1334535: a possible GRB 250718A
  91. Swift GRB250718.01: Global MASTER-Net observations report
  92. GRB 250717B: Swift ToO observations
  93. GRB 270713A: Kitab and AbAO Optical Observations
  94. GRB 250717B: Fermi GBM Observation
  95. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  96. Konus-Wind detection of GRB 250716A
  97. GRB 250716A: Swift-XRT afterglow detection
  98. GRB 250717B: Fermi GBM Final Real-time Localization
  99. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  100. GRB 250717A: Fermi GBM Final Real-time Localization

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