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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

45700 results found.

  1. EP250802a: GROWTH-India Telescope optical upper limit
  2. EP250802a: Einstein Probe detection of an X-ray transient
  3. LIGO/Virgo/KAGRA S250802dn: Updated Sky localization
  4. The EP-WXT trigger 01709198251 is likely a flaring star
  5. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  6. The EP-WXT trigger 01709198202 is likely a flaring star
  7. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  8. GRB 250702B: SMA observations
  9. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  10. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  11. EP250711a: CrAO and Assy optical observations
  12. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  13. EP250730a: Global MASTER-Net observations report
  14. EP250730a: COLIBRÍ optical upper limit
  15. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  16. EP250730a: Einstein Probe detection of an X-ray transient
  17. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  18. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT follow up of AT 2025smm
  19. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  20. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  21. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  22. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  23. GRB 250725A: AstroSat CZTI detection
  24. GRB 250727A: EP-FXT follow-up observation
  25. GRB 250725A: PRIME near-infrared observations
  26. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  27. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  28. GRB: Clarification on Gamma-Ray Burst Naming Convention
  29. GRB 250728A: Swift-XRT observations
  30. GRB 250727A: SVOM/ECLAIRs refined analysis
  31. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  32. GRB 250728A: COLIBRÍ optical upper limit
  33. GRB 250728A: Fermi GBM Observation
  34. Fermi trigger No 775387550: Global MASTER-Net observations report
  35. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  36. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT detection of a new source, AT 2025smm
  37. GRB 250728A: Swift ToO observations
  38. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  39. GRB 250727A: AST3-2 Upper limit
  40. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  41. GRB 250727A: EP-FXT counterpart detection
  42. GRB250727A: SVOM/VT optical upper limit
  43. GRB 250727A: Swift-XRT observations
  44. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  45. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  46. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  47. GRB 250727A: SVOM detection of a burst
  48. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  49. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  50. The EP-WXT trigger 01709195487 is likely a flaring star
  51. Swift detection of the Soft Gamma Repeater PSR J1647-4552
  52. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  53. GRB 250725A: Swift-XRT refined Analysis
  54. GRB 250725A: Fermi GBM Observation
  55. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  56. GRB 250725A: Swift-BAT refined analysis
  57. Konus-Wind detection of GRB 250725A
  58. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  59. GRB 250725A: SVOM/GRM observation
  60. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  61. GRB 250725A: Swift/UVOT Upper Limits
  62. GRB 250725A: Fermi-LAT detection
  63. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  64. GRB 250725A: BOOTES-7 early optical detection
  65. GRB 250725A: SVOM/VT optical candidate
  66. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  67. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate (duplicate submission)
  68. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  69. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  70. GRB 250725A: Enhanced Swift-XRT position
  71. GRB 250725A: Swift detection of a burst
  72. Swift GRB 250725A: Global MASTER-Net OT detection
  73. GRB 250725A: Fermi GBM Final Real-time Localization
  74. Fermi GRB 250725A: Global MASTER-Net observations report
  75. Swift GRB 250725A: Global MASTER-Net observations report
  76. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  77. SVOM J195836+32283 is not a real source
  78. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  79. SVOM J195836+32283/sb25072103: Second VT observation
  80. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  81. GRB 250723B: Fermi GBM Final Real-time Localization
  82. GRB 250721A: Fermi GBM Observation
  83. GRB 250723A: Fermi GBM Final Real-time Localization
  84. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  85. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  86. Swift-BAT trigger 1334535 is not a GRB
  87. GRB 250721A: Swift-XRT observations
  88. GRB 250722A: Fermi GBM Final Real-time Localization
  89. GRB 250713A : SVOM/ECLAIRs refined analysis
  90. GRB 250717B: SVOM/GRM observation
  91. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  92. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  93. GRB 250721A: Tiled Swift observations
  94. GRB 250721A: MAXI/GSC detection
  95. GRB 250721A: Fermi GBM Final Localization
  96. GRB 250720B: Fermi GBM Final Localization Correction
  97. GRB 250720A: Fermi GBM Final Localization
  98. Fermi trigger No 774730635: Global MASTER-Net observations report
  99. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  100. Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB

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