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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"

3820 results found.

  1. GRB 250213A: Swift-XRT observations
  2. Fermi GRB 250217A: Global MASTER-Net observations report
  3. EP250215a: Global MASTER-Net observations report
  4. Fermi trigger No 761206993: Global MASTER-Net observations report
  5. EP250212a: Xinglong optical upper limit
  6. EP250207b: VLA radio upper limits
  7. Fermi GRB 250212A: Global MASTER-Net observations report
  8. Fermi trigger No 760945500: Global MASTER-Net observations report
  9. LIGO/Virgo/KAGRA S250206dm: continued in SOAR galaxy targeted observations and identification of one possible transient
  10. LIGO/VIRGO/KAGRA S250206dm: AT 2025bbo spectroscopic observations with NIRES on Keck II
  11. GRB 241128A: VIRT Optical Upper Limit
  12. GRB 250210A: AstroSat CZTI detection
  13. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  14. Fermi GRB 250210A: Global MASTER-Net observations report
  15. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  16. IceCube Alert 250207.09: Global MASTER-Net observations report
  17. LIGO/Virgo/KAGRA S250206dm & FRB 20250206A: MASTER observations and possible mother galaxy
  18. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  19. LIGO/Virgo/KAGRA S250206dm: Candidates from the Zwicky Transient Facility
  20. EP250207a: EP-WXT detection and XRT follow-up observation
  21. LIGO/Virgo/KAGRA S250206dm: DDOTI Upper Limits
  22. LIGO/Virgo/KAGRA S250207bg: Identification of a GW compact binary merger candidate
  23. LIGO/Virgo/KAGRA S250206dm: SOAR galaxy targeted observations
  24. GRB 250207B: MAXI/GSC detection
  25. GRB 250202B: Fermi GBM Detection
  26. The EP-WXT trigger 01709131196 is likely a flaring star
  27. Swift GRB250129A: MASTER 4 days observations report
  28. GRB 250129A: optical photometry from Konkoly
  29. GRB 250128B: VLA possible radio detection
  30. GRB 250129A: AKO Optical Afterglow Detection
  31. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  32. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  33. GRB 250128B: VLA radio upper limit
  34. GRB 250129A: Skynet optical observations
  35. GRB 250128B: Gemini-North optical extended source detection
  36. GRB 250128B: TNG optical upper limit
  37. GRB 250129A: REM optical/NIR afterglow detection
  38. GRB 250129A: Early afterglow detection by LCO.
  39. GRB 250129A: LCO optical observations
  40. GRB 250129A: GOTO optical observations show brightening afterglow
  41. Swift GRB 250129A: Global MASTER-Net observations report
  42. The EP-WXT trigger 01709131085 is likely a flaring star
  43. Fermi GRB 250128B: Global MASTER-Net observations report
  44. Swift GRB 250129A: Global MASTER-Net OT detection
  45. GRB 250127A: EP-FXT afterglow detection
  46. Fermi GRB 250127B: Global MASTER-Net observations report
  47. GRB 250126A: MAXI/GSC detection
  48. GECAM-A detection of a bright burst from SGR 1E1841-045
  49. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  50. IPN triangulation of a bright burst from SGR 1E1841-045
  51. IPN triangulation of GRB 250119B
  52. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  53. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  54. GRB 250116A: GECAM-B detection of a long burst
  55. GRB 250114B: OHP/T193 optical upper limit
  56. EP250111a: Global MASTER-Net observations report
  57. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  58. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  59. IPN triangulation of GRB 250107D (short/hard)
  60. EP250109a: SVOM/VT optical candidate
  61. GRB 250106A: SVOM detection of a long burst
  62. Fermi trigger No 757753930: Global MASTER-Net observations report
  63. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  64. Swift GRB 250103B: Global MASTER-Net observations report
  65. EP241231b and EP250101a: EP-WXT detection of two X-ray transients
  66. Fermi GRB 250101B: Global MASTER-Net observations report
  67. GRB 250101A: SAO RAS optical observations
  68. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  69. GRB 241228B: SAO RAS optical observations
  70. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  71. IceCube-Cascade 241228A: Upper limits from a search for additional neutrino events in IceCube
  72. GRB 241229A: EP-FXT afterglow candidates
  73. Fermi Gamma-ray Burst Monitor trigger 757207662/241229978 (GRB 241229C) is not a GRB
  74. GRB 241229C: Fermi GBM Final Real-time Localization
  75. GRB 241229B: Fermi GBM Observation
  76. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  77. Swift GRB 241229B: Global MASTER-Net observations report
  78. GRB 241229A: GOTO optical upper limits
  79. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  80. GRB 241229B: Fermi GBM Final Real-time Localization
  81. GRB 241223A: GRBAlpha detection
  82. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  83. GRB 241029A: AbAO AS-32 optical observations
  84. Fermi trigger No 756678579: Global MASTER-Net observations report
  85. IceCube Alert 241224.30: Global MASTER-Net observations report
  86. Fermi Gamma-ray Burst Monitor trigger 756678579 / 241223854 is not a GRB
  87. Fermi trigger No 756447119: Global MASTER-Net observations report
  88. Fermi GRB 241221A: Global MASTER-Net observations report
  89. EP241217a: Liverpool Telescope optical upper limit
  90. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  91. GRB 241218A: NUTTelA-TAO / BSTI Optical Limits
  92. EP241119a: 7DT Optical upper limits
  93. GRB 241213A: REM optical/NIR upper limits
  94. GRB 241207A: TSHAO Zeiss-1000 optical observations
  95. GRB 241129A: Fermi GBM Observation
  96. GRB 241209A: Swift-XRT refined Analysis
  97. LIGO/Virgo/KAGRA S241210cw: Identification of a GW compact binary merger candidate
  98. EP241208a: Global MASTER-Net observations report
  99. LIGO/Virgo/KAGRA S241210d: Identification of a GW compact binary merger candidate
  100. Fermi GRB 241209E: Global MASTER-Net observations report

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