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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"

28280 results found.

  1. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  2. GRB 250219A: 1.6m Mephisto optical upper limits
  3. GRB 250219A: Swift-XRT observations
  4. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  5. Konus-Wind detection of GRB 250215A / EP250215a
  6. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  7. GRB 250217C: Swift-XRT observations
  8. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  9. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  10. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  11. GRB 250217C: SVOM/GRM observation
  12. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  13. SVOM/sb25021804: SVOM detection of a long X-ray transient
  14. GRB 250213A: Swift-XRT observations
  15. GRB 250216A: AstroSat CZTI detection
  16. GRB 250217C: AstroSat CZTI detection of a short burst
  17. IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
  18. GRANDMA/OPD observations of GRB250215A
  19. GRB 250215A / EP250215a: LCO detection of the afterglow
  20. GRB 250215A: Swift/UVOT Upper Limits
  21. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  22. GRB 250215A: Fermi GBM Observation
  23. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  24. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  25. GRB 250215A: Swift-XRT refined Analysis
  26. GRB 250215A: SVOM/GRM observation
  27. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  28. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  29. EP250207b: Xinglong optical upper limit
  30. EP250212a: Xinglong optical upper limit
  31. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  32. EP250212a: Global MASTER-Net observations report
  33. GRB 250205A: VIRT Optical Upper Limit
  34. GRB 250205A: Leavitt Observatory optical upper limit
  35. EP250207B: Chandra localization of the X-ray counterpart
  36. EP250212a: Liverpool Telescope optical upper limits
  37. GRB250101A: Radio upper limits from GMRT observations
  38. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  39. EP250207B: GTC z-band Observations
  40. Fermi GRB 250212A: Global MASTER-Net observations report
  41. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  42. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  43. Fermi trigger No 760945500: Global MASTER-Net observations report
  44. EP250207b: NOT optical counterpart candidate
  45. GRB 250211B: A long GRB detected by INTEGRAL
  46. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  47. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  48. LIGO/Virgo/KAGRA S250211be: Updated Sky localization
  49. GRB 250207A: Fermi GBM Observation
  50. GRB 250206A: Fermi GBM Observation
  51. GRB 250205A / EP250205A: radio detection with the VLA
  52. EP250207b: Tentative z-band brightening source
  53. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  54. Konus-Wind detection of GRB 250206A
  55. GRB 250210A: SVOM/GRM observation of a long burst
  56. EP250207b: Liverpool Telescope possible optical counterpart
  57. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  58. LIGO/Virgo/KAGRA S250211aa: Updated Sky localization and EM Bright Classification
  59. LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
  60. GRB 250207A: Skynet optical afterglow observations
  61. GRB 241128A: VIRT Optical Upper Limit
  62. EP250207b: Gemini GMOS-N z-band observations
  63. EP250207A: Upper limits from Fermi-GBM Observations
  64. EP250207b: a new X-ray transient detected by Einstein Probe
  65. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  66. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  67. IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube
  68. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  69. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  70. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
  71. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  72. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  73. GRB 250207A: 1.3m DFOT Optical observations
  74. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  75. GRB 250206A: Swift-XRT observations
  76. GRB 250129A: GRANDMA Continued Afterglow Detection
  77. GRB 250207A: Swift-BAT refined analysis
  78. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  79. LIGO/Virgo/KAGRA S250207bg: Updated NED Galaxies in the Localization Volume
  80. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  81. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  82. GRB 250205A: 1.3m DFOT optical upper limit
  83. LIGO/Virgo/KAGRA S250118az: Updated Sky localization
  84. LIGO/Virgo/KAGRA S250208ad: Updated Sky localization
  85. GRB 250206A: EIRSAT-1 GMOD Detection
  86. LIGO/Virgo/KAGRA S250206dm: (Update-7) NED Galaxies in the Localization Volume
  87. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  88. GRB 250207B: Swift-XRT observations
  89. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  90. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
  91. LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate
  92. LIGO/Virgo/KAGRA S250206dm: MMT galaxy targeted observations
  93. GRB 250207A: Swift-XRT refined Analysis
  94. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A & "Time Machine" Effect.
  95. EP trigger 01709131361 (possible EP250207a): NOT optical observations and flaring star
  96. GRB 250207A: Enhanced Swift-XRT position
  97. CHIME/FRB source FRB 20250206A detected less than 1 minute after LIGO-Virgo-Kagra (LVK) S250206dm, however the probability of spatial coincidence is order 0.1%
  98. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  99. GRB 250207A: REM IR afterglow detection
  100. LIGO/Virgo/KAGRA S250206dm: ATLAS observations of the skymap

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