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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"

20517 results found.

  1. EP250226a / GRB 250226A: TRT optical counterpart observation
  2. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  3. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  4. EP250223a: GMG Optical Observation
  5. EP250225a: Einstein Probe detected of a fast X-ray transient
  6. EP250223a: GROWTH-India Telescope optical observations
  7. EP250215A: J band upper limit by SYSU 80cm telescope
  8. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  9. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  10. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  11. EP250223a: Kinder optical follow-up observations
  12. GRB 250222A: SVOM/GRM observation of a burst
  13. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  14. EP250223a: REM NIR upper limit
  15. EP250223a: TRT optical afterglow observation
  16. EP250223a: refined analysis of the EP-WXT and FXT observations
  17. EP250223a: 1.6m Mephisto and 50cm array observations
  18. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  19. 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
  20. EP250223a: OASDG optical observations
  21. EP250223a: early optical detection by BOOTES-4
  22. EP250223a: NOT redshift z = 2.756
  23. EP250223a: NOT optical afterglow candidate
  24. GRB 250221A: VLA radio detection
  25. EP250223a: Einstein Probe detection of an X-ray transient
  26. GRB 250221A: Optical counterpart detection by LCO.
  27. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  28. GRB 250221A: GRANDMA/TAROT Detection
  29. GRB 250221A: 1.6m Mephisto optical detection
  30. GRB 250221A: AKO Optical Upper Limit
  31. GRB 250221A: Swift/UVOT Detection
  32. EP250220a: Liverpool Telescope upper limits
  33. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  34. GRB 250221A: REM optical/NIR afterglow detection
  35. GRB 250221A: Enhanced Swift-XRT position
  36. EP250220a: 1.6m Mephisto observations
  37. EP250220a: Liverpool Telescope optical upper limits
  38. EP250220a: Optical upper limit with Kinder observations
  39. SVOM trigger sb25022102 is not an astrophysical event
  40. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  41. GRB 250221A: Swift detection of a burst with an optical counterpart
  42. EP250220a: Xinglong optical upper limit
  43. EP250220a: EP-WXT detection of a fast X-ray transient
  44. Konus-Wind detection of GRB 250217C (short)
  45. GRB 250219A: Swift/UVOT Upper Limits
  46. GRB 250219A: OHP/T193 optical upper limit
  47. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  48. GRB 250219A: 1.6m Mephisto optical upper limits
  49. Konus-Wind detection of GRB 250215A / EP250215a
  50. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  51. GRB 250217C: Swift-XRT observations
  52. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  53. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  54. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  55. GRB 250217C: SVOM/GRM observation
  56. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  57. SVOM/sb25021804: SVOM detection of a long X-ray transient
  58. GRB 250213A: Swift-XRT observations
  59. IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
  60. GRANDMA/OPD observations of GRB250215A
  61. GRB 250215A / EP250215a: LCO detection of the afterglow
  62. GRB 250215A: Swift/UVOT Upper Limits
  63. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  64. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  65. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  66. GRB 250215A: SVOM/GRM observation
  67. EP250215a / GRB 250215A: AstroSat CZTI detection
  68. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  69. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  70. EP250207b: Xinglong optical upper limit
  71. Fermi GRB 250214A: Global MASTER-Net observations report
  72. EP250212a: Xinglong optical upper limit
  73. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  74. GRB 250205A: VIRT Optical Upper Limit
  75. GRB 250205A: Leavitt Observatory optical upper limit
  76. EP250207B: Chandra localization of the X-ray counterpart
  77. EP250207b: VLA radio upper limits
  78. EP250212a: Liverpool Telescope optical upper limits
  79. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  80. GRB250101A: Radio upper limits from GMRT observations
  81. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  82. EP250207B: GTC z-band Observations
  83. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  84. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  85. EP250207b: NOT optical counterpart candidate
  86. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  87. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  88. GRB 250205A / EP250205A: radio detection with the VLA
  89. EP250207b: Tentative z-band brightening source
  90. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  91. Konus-Wind detection of GRB 250206A
  92. GRB 250210A: SVOM/GRM observation of a long burst
  93. EP250207b: Liverpool Telescope possible optical counterpart
  94. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  95. LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
  96. GRB 250207A: Skynet optical afterglow observations
  97. GRB 241128A: VIRT Optical Upper Limit
  98. EP250207b: Gemini GMOS-N z-band observations
  99. EP250207b: a new X-ray transient detected by Einstein Probe
  100. IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube

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