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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"

28287 results found.

  1. Swift GRB250221.15: Global MASTER-Net OT detection
  2. EP250220a: Xinglong optical upper limit
  3. GRB 250219A: Swift/UVOT Upper Limits
  4. GRB 250219A: OHP/T193 optical upper limit
  5. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  6. GRB 250219A: 1.6m Mephisto optical upper limits
  7. GRB 250219A: Swift-XRT observations
  8. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  9. Konus-Wind detection of GRB 250215A / EP250215a
  10. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  11. GRB 250217C: Swift-XRT observations
  12. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  13. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  14. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  15. GRB 250217C: SVOM/GRM observation
  16. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  17. SVOM/sb25021804: SVOM detection of a long X-ray transient
  18. GRB 250213A: Swift-XRT observations
  19. GRB 250216A: AstroSat CZTI detection
  20. GRB 250217C: AstroSat CZTI detection of a short burst
  21. IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
  22. GRANDMA/OPD observations of GRB250215A
  23. GRB 250215A / EP250215a: LCO detection of the afterglow
  24. GRB 250215A: Swift/UVOT Upper Limits
  25. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  26. GRB 250215A: Fermi GBM Observation
  27. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  28. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  29. GRB 250215A: Swift-XRT refined Analysis
  30. GRB 250215A: SVOM/GRM observation
  31. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  32. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  33. EP250207b: Xinglong optical upper limit
  34. EP250212a: Xinglong optical upper limit
  35. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  36. EP250212a: Global MASTER-Net observations report
  37. GRB 250205A: VIRT Optical Upper Limit
  38. GRB 250205A: Leavitt Observatory optical upper limit
  39. EP250207B: Chandra localization of the X-ray counterpart
  40. EP250212a: Liverpool Telescope optical upper limits
  41. GRB250101A: Radio upper limits from GMRT observations
  42. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  43. EP250207B: GTC z-band Observations
  44. Fermi GRB 250212A: Global MASTER-Net observations report
  45. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  46. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  47. Fermi trigger No 760945500: Global MASTER-Net observations report
  48. EP250207b: NOT optical counterpart candidate
  49. GRB 250211B: A long GRB detected by INTEGRAL
  50. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  51. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  52. LIGO/Virgo/KAGRA S250211be: Updated Sky localization
  53. GRB 250207A: Fermi GBM Observation
  54. GRB 250206A: Fermi GBM Observation
  55. GRB 250205A / EP250205A: radio detection with the VLA
  56. EP250207b: Tentative z-band brightening source
  57. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  58. Konus-Wind detection of GRB 250206A
  59. GRB 250210A: SVOM/GRM observation of a long burst
  60. EP250207b: Liverpool Telescope possible optical counterpart
  61. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  62. LIGO/Virgo/KAGRA S250211aa: Updated Sky localization and EM Bright Classification
  63. LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
  64. GRB 250207A: Skynet optical afterglow observations
  65. GRB 241128A: VIRT Optical Upper Limit
  66. EP250207b: Gemini GMOS-N z-band observations
  67. EP250207A: Upper limits from Fermi-GBM Observations
  68. EP250207b: a new X-ray transient detected by Einstein Probe
  69. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  70. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  71. IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube
  72. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  73. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  74. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
  75. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  76. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  77. GRB 250207A: 1.3m DFOT Optical observations
  78. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  79. GRB 250206A: Swift-XRT observations
  80. GRB 250129A: GRANDMA Continued Afterglow Detection
  81. GRB 250207A: Swift-BAT refined analysis
  82. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  83. LIGO/Virgo/KAGRA S250207bg: Updated NED Galaxies in the Localization Volume
  84. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  85. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  86. GRB 250205A: 1.3m DFOT optical upper limit
  87. LIGO/Virgo/KAGRA S250118az: Updated Sky localization
  88. LIGO/Virgo/KAGRA S250208ad: Updated Sky localization
  89. GRB 250206A: EIRSAT-1 GMOD Detection
  90. LIGO/Virgo/KAGRA S250206dm: (Update-7) NED Galaxies in the Localization Volume
  91. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  92. GRB 250207B: Swift-XRT observations
  93. LIGO/Virgo/KAGRA S250206dm: Updated Sky localization and EM Bright Classification
  94. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
  95. LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate
  96. LIGO/Virgo/KAGRA S250206dm: MMT galaxy targeted observations
  97. GRB 250207A: Swift-XRT refined Analysis
  98. LIGO/Virgo/KAGRA S250206dm: FRB 20250206A & "Time Machine" Effect.
  99. EP trigger 01709131361 (possible EP250207a): NOT optical observations and flaring star
  100. GRB 250207A: Enhanced Swift-XRT position

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