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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"

21925 results found.

  1. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  2. GRB 250225B: REM NIR upper limits
  3. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  4. Konus-Wind detection of GRB 250225B
  5. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  6. EP250223a: CrAO ZTSH optical observation
  7. GRB 250225B: VLT optical and near-infrared candidate counterpart
  8. GRB 250225B: VLT/FORS2 candidate optical afterglow
  9. GRB 250225B: SVOM/GRM observation of a long burst
  10. GRB 250226A: GECAM-B detection
  11. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  12. EP250226a / GRB 250226A: TRT optical counterpart observation
  13. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  14. EP250223a: GMG Optical Observation
  15. EP250225a: Einstein Probe detected of a fast X-ray transient
  16. EP250223a: GROWTH-India Telescope optical observations
  17. EP250215A: J band upper limit by SYSU 80cm telescope
  18. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  19. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  20. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  21. EP250223a: Kinder optical follow-up observations
  22. GRB 250119B: VZLUSAT-2 detection
  23. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  24. GRB 250202B: VZLUSAT-2 detection
  25. GRB 250222A: SVOM/GRM observation of a burst
  26. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  27. GRB 250210A: VZLUSAT-2 detection
  28. GRB 250206A: VZLUSAT-2 detection
  29. EP250223a: REM NIR upper limit
  30. EP250223a: TRT optical afterglow observation
  31. EP250223a: refined analysis of the EP-WXT and FXT observations
  32. EP250223a: 1.6m Mephisto and 50cm array observations
  33. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  34. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO trigger with ID 762004910: Identification of a GW compact binary merger candidate possibly associated with a sub-threshold Swift/BAT-GUANO trigger
  35. EP250223a: OASDG optical observations
  36. EP250223a: NOT optical afterglow candidate
  37. EP250223a: Einstein Probe detection of an X-ray transient
  38. GRB 250221A: Optical counterpart detection by LCO.
  39. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  40. GRB 250221A: GRANDMA/TAROT Detection
  41. GRB 250221A: 1.6m Mephisto optical detection
  42. GRB 250221A: AKO Optical Upper Limit
  43. GRB 250221A: Swift/UVOT Detection
  44. EP250220a: Liverpool Telescope upper limits
  45. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  46. GRB 250221A: REM optical/NIR afterglow detection
  47. GRB 250221A: Enhanced Swift-XRT position
  48. EP250220a: 1.6m Mephisto observations
  49. EP250220a: Liverpool Telescope optical upper limits
  50. EP250220a: Optical upper limit with Kinder observations
  51. SVOM trigger sb25022102 is not an astrophysical event
  52. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  53. GRB 250221A: Swift detection of a burst with an optical counterpart
  54. Swift GRB250221.15: Global MASTER-Net OT detection
  55. EP250220a: Xinglong optical upper limit
  56. Konus-Wind detection of GRB 250217C (short)
  57. GRB 250219A: Swift/UVOT Upper Limits
  58. GRB 250219A: OHP/T193 optical upper limit
  59. GRB 250219A: NOT optical observations
  60. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  61. GRB 250219A: 1.6m Mephisto optical upper limits
  62. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  63. GRB 250219A: SVOM detection of a burst
  64. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  65. GRB 250217C: Swift-XRT observations
  66. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  67. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  68. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  69. GRB 250217C: SVOM/GRM observation
  70. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  71. SVOM/sb25021804: SVOM detection of a long X-ray transient
  72. GRANDMA/OPD observations of GRB250215A
  73. GRB 250215A / EP250215a: LCO detection of the afterglow
  74. GRB 250215A: Swift/UVOT Upper Limits
  75. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  76. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  77. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  78. GRB 250215A: SVOM/GRM observation
  79. EP250215a / GRB 250215A: AstroSat CZTI detection
  80. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  81. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  82. EP250207b: Xinglong optical upper limit
  83. EP250212a: Xinglong optical upper limit
  84. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  85. GRB 250205A: VIRT Optical Upper Limit
  86. GRB 250205A: Leavitt Observatory optical upper limit
  87. GRB 250210A: GRBAlpha detection
  88. EP250207B: Chandra localization of the X-ray counterpart
  89. EP250212a: Liverpool Telescope optical upper limits
  90. GRB250101A: Radio upper limits from GMRT observations
  91. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  92. EP250207B: GTC z-band Observations
  93. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  94. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  95. EP250207b: NOT optical counterpart candidate
  96. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  97. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  98. GRB 250205A / EP250205A: radio detection with the VLA
  99. EP250207b: Tentative z-band brightening source
  100. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo

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