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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"

45687 results found.

  1. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  2. GRB 250213A: SVOM detection of a burst
  3. EP250212a: Global MASTER-Net observations report
  4. GRB 250205A: VIRT Optical Upper Limit
  5. GRB 250205A: Leavitt Observatory optical upper limit
  6. GRB 250210A: GRBAlpha detection
  7. EP250207B: Chandra localization of the X-ray counterpart
  8. LIGO/Virgo/KAGRA S250206dm: FTW observations of counterpart candidates AT2025bbo and AT2025bcx, and of NED galaxies
  9. EP250207b: VLA radio upper limits
  10. EP250212a: Liverpool Telescope optical upper limits
  11. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  12. GRB250101A: Radio upper limits from GMRT observations
  13. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  14. EP250207B: GTC z-band Observations
  15. Fermi GRB 250212A: Global MASTER-Net observations report
  16. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  17. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  18. Fermi trigger No 760945500: Global MASTER-Net observations report
  19. EP250207b: NOT optical counterpart candidate
  20. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  21. GRB 250211B: A long GRB detected by INTEGRAL
  22. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  23. GRB 250211A: Swift ToO observations
  24. Integral GRB250211.89: Global MASTER-Net observations report
  25. GRB 250212A: Fermi GBM Final Real-time Localization
  26. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  27. LIGO/Virgo/KAGRA S250211be: Updated Sky localization
  28. GRB 250207A: Fermi GBM Observation
  29. GRB 250206A: Fermi GBM Observation
  30. GRB 250205A / EP250205A: radio detection with the VLA
  31. IceCube-250207A: One candidate from the Zwicky Transient Facility
  32. EP250207b: Tentative z-band brightening source
  33. LIGO/Virgo/KAGRA S250206dm: continued in SOAR galaxy targeted observations and identification of one possible transient
  34. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  35. Konus-Wind detection of GRB 250207A
  36. Konus-Wind detection of GRB 250206A
  37. GRB 250210A: SVOM/GRM observation of a long burst
  38. EP250207b: Liverpool Telescope possible optical counterpart
  39. EP250207b: Global MASTER-Net observations report
  40. Fermi Gamma-ray Burst Monitor trigger 760945500/250211240 is not a GRB
  41. Gemini-South spectroscopic redshift of EP250207b host galaxy candidate (z=0.082)
  42. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo/KAGRA S250211aa: Updated Sky localization and EM Bright Classification
  44. LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
  45. GRB 250207A: Skynet optical afterglow observations
  46. LIGO/VIRGO/KAGRA S250206dm: AT 2025bbo spectroscopic observations with NIRES on Keck II
  47. LIGO/Virgo/KAGRA S250206dm: Gemini-North spectroscopic observation of AT2025bbo and its host galaxy
  48. GRB 241128A: VIRT Optical Upper Limit
  49. EP250207b: Gemini GMOS-N z-band observations
  50. EP250207A: Upper limits from Fermi-GBM Observations
  51. GRB 250210A: INTEGRAL SPI-ACS detection
  52. GRB 250210A: AstroSat CZTI detection
  53. EP250207b: a new X-ray transient detected by Einstein Probe
  54. LIGO/Virgo/KAGRA S250206dm: MASTER detection AT2025bbo
  55. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  56. Fermi GRB 250210A: Global MASTER-Net observations report
  57. GRB 250210A: Fermi GBM Final Real-time Localization
  58. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  59. IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube
  60. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  61. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  62. IceCube Alert 250207.09: Global MASTER-Net observations report
  63. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
  64. GRB 250204B: GRBAlpha detection
  65. GRB 250204A: GRBAlpha detection
  66. LIGO/Virgo/KAGRA S250206dm & FRB 20250206A: MASTER observations and possible mother galaxy
  67. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  68. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  69. GRB 250207A: 1.3m DFOT Optical observations
  70. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  71. GRB 250206A: Swift-XRT observations
  72. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A BOOTES-5 and 2.2m CAHA optical upper limits
  73. GRB 250129A: GRANDMA Continued Afterglow Detection
  74. GRB 250207A: Swift-BAT refined analysis
  75. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  76. LIGO/Virgo/KAGRA S250207bg: Updated NED Galaxies in the Localization Volume
  77. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  78. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  79. GRB 250205A: 1.3m DFOT optical upper limit
  80. GRB 250206A: Tiled Swift observations
  81. LIGO/Virgo/KAGRA S250118az: Updated Sky localization
  82. LIGO/Virgo/KAGRA S250208ad: Updated Sky localization
  83. GRB 250206A: EIRSAT-1 GMOD Detection
  84. LIGO/Virgo/KAGRA S250206dm: (Update-7) NED Galaxies in the Localization Volume
  85. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  86. GRB 250206A: Fermi-LAT detection
  87. GRB 250207B: Swift-XRT observations
  88. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  89. IceCube-250203A: No transient candidates from the Zwicky Transient Facility
  90. LIGO/Virgo/KAGRA S250206dm: Spectroscopic Classification of AT2025bay and AT2025baz with Keck I/LRIS
  91. LIGO/Virgo/KAGRA S250206dm: Candidates from the Zwicky Transient Facility
  92. LIGO/Virgo/KAGRA S250206dm: ePESSTO+ classification of AT2025bar
  93. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
  94. GRB 250208A: Fermi GBM Final Real-time Localization
  95. EP250207a: EP-WXT detection and XRT follow-up observation
  96. LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate
  97. LIGO/Virgo/KAGRA S250206dm: MMT galaxy targeted observations
  98. GRB 250207A: Swift-XRT refined Analysis
  99. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A & "Time Machine" Effect.
  100. EP-WXT trigger 01709131361: correction to GCN 39214

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