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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').
Advanced Search

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"

28301 results found.

  1. GRB 250221A: Swift-XRT refined Analysis
  2. GRB 250221A: NOT optical observations
  3. GRB 250221A: 1.6m Mephisto optical detection
  4. GRB 250221A: AKO Optical Upper Limit
  5. GRB 250221A: Swift/UVOT Detection
  6. EP250220a: Liverpool Telescope upper limits
  7. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  8. GRB 250221A: REM optical/NIR afterglow detection
  9. IceCube-250207A: MASTER flaring blazar QSOJ0854+2006 with Zhirkov effect
  10. GRB 250221A: Enhanced Swift-XRT position
  11. EP250220a: 1.6m Mephisto observations
  12. EP250220a: Liverpool Telescope optical upper limits
  13. EP250220a: Optical upper limit with Kinder observations
  14. SVOM trigger sb25022102 is not an astrophysical event
  15. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  16. GRB 250221A: Swift detection of a burst with an optical counterpart
  17. Swift GRB250221.15: Global MASTER-Net OT detection
  18. EP250220a: Xinglong optical upper limit
  19. GRB 250219A: Swift/UVOT Upper Limits
  20. GRB 250219A: OHP/T193 optical upper limit
  21. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  22. GRB 250219A: 1.6m Mephisto optical upper limits
  23. GRB 250219A: Swift-XRT observations
  24. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  25. Konus-Wind detection of GRB 250215A / EP250215a
  26. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  27. GRB 250217C: Swift-XRT observations
  28. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  29. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  30. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  31. GRB 250217C: SVOM/GRM observation
  32. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  33. SVOM/sb25021804: SVOM detection of a long X-ray transient
  34. GRB 250213A: Swift-XRT observations
  35. GRB 250216A: AstroSat CZTI detection
  36. GRB 250217C: AstroSat CZTI detection of a short burst
  37. IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
  38. GRANDMA/OPD observations of GRB250215A
  39. GRB 250215A / EP250215a: LCO detection of the afterglow
  40. GRB 250215A: Swift/UVOT Upper Limits
  41. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  42. GRB 250215A: Fermi GBM Observation
  43. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  44. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  45. GRB 250215A: Swift-XRT refined Analysis
  46. GRB 250215A: SVOM/GRM observation
  47. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  48. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  49. EP250207b: Xinglong optical upper limit
  50. EP250212a: Xinglong optical upper limit
  51. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  52. EP250212a: Global MASTER-Net observations report
  53. GRB 250205A: VIRT Optical Upper Limit
  54. GRB 250205A: Leavitt Observatory optical upper limit
  55. EP250207B: Chandra localization of the X-ray counterpart
  56. EP250212a: Liverpool Telescope optical upper limits
  57. GRB250101A: Radio upper limits from GMRT observations
  58. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  59. EP250207B: GTC z-band Observations
  60. Fermi GRB 250212A: Global MASTER-Net observations report
  61. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  62. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  63. Fermi trigger No 760945500: Global MASTER-Net observations report
  64. EP250207b: NOT optical counterpart candidate
  65. GRB 250211B: A long GRB detected by INTEGRAL
  66. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  67. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  68. LIGO/Virgo/KAGRA S250211be: Updated Sky localization
  69. GRB 250207A: Fermi GBM Observation
  70. GRB 250206A: Fermi GBM Observation
  71. GRB 250205A / EP250205A: radio detection with the VLA
  72. EP250207b: Tentative z-band brightening source
  73. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  74. Konus-Wind detection of GRB 250206A
  75. GRB 250210A: SVOM/GRM observation of a long burst
  76. EP250207b: Liverpool Telescope possible optical counterpart
  77. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  78. LIGO/Virgo/KAGRA S250211aa: Updated Sky localization and EM Bright Classification
  79. LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
  80. GRB 250207A: Skynet optical afterglow observations
  81. GRB 241128A: VIRT Optical Upper Limit
  82. EP250207b: Gemini GMOS-N z-band observations
  83. EP250207A: Upper limits from Fermi-GBM Observations
  84. EP250207b: a new X-ray transient detected by Einstein Probe
  85. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  86. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  87. IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube
  88. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  89. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  90. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
  91. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  92. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  93. GRB 250207A: 1.3m DFOT Optical observations
  94. LIGO/Virgo/KAGRA S250206dm: WFST follow-up observations
  95. GRB 250206A: Swift-XRT observations
  96. GRB 250129A: GRANDMA Continued Afterglow Detection
  97. GRB 250207A: Swift-BAT refined analysis
  98. LIGO/Virgo/KAGRA S250206dm: further Pan-STARRS observations and one candidate AT2025bbo
  99. LIGO/Virgo/KAGRA S250207bg: Updated NED Galaxies in the Localization Volume
  100. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization

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