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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"

20515 results found.

  1. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  2. EP250223a: GMG Optical Observation
  3. EP250225a: Einstein Probe detected of a fast X-ray transient
  4. EP250223a: GROWTH-India Telescope optical observations
  5. EP250215A: J band upper limit by SYSU 80cm telescope
  6. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  7. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  8. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  9. EP250223a: Kinder optical follow-up observations
  10. GRB 250222A: SVOM/GRM observation of a burst
  11. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  12. EP250223a: REM NIR upper limit
  13. EP250223a: TRT optical afterglow observation
  14. EP250223a: refined analysis of the EP-WXT and FXT observations
  15. EP250223a: 1.6m Mephisto and 50cm array observations
  16. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  17. 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
  18. EP250223a: OASDG optical observations
  19. EP250223a: early optical detection by BOOTES-4
  20. EP250223a: NOT redshift z = 2.756
  21. EP250223a: NOT optical afterglow candidate
  22. GRB 250221A: VLA radio detection
  23. EP250223a: Einstein Probe detection of an X-ray transient
  24. GRB 250221A: Optical counterpart detection by LCO.
  25. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  26. GRB 250221A: GRANDMA/TAROT Detection
  27. GRB 250221A: 1.6m Mephisto optical detection
  28. GRB 250221A: AKO Optical Upper Limit
  29. GRB 250221A: Swift/UVOT Detection
  30. EP250220a: Liverpool Telescope upper limits
  31. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  32. GRB 250221A: REM optical/NIR afterglow detection
  33. GRB 250221A: Enhanced Swift-XRT position
  34. EP250220a: 1.6m Mephisto observations
  35. EP250220a: Liverpool Telescope optical upper limits
  36. EP250220a: Optical upper limit with Kinder observations
  37. SVOM trigger sb25022102 is not an astrophysical event
  38. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  39. GRB 250221A: Swift detection of a burst with an optical counterpart
  40. EP250220a: Xinglong optical upper limit
  41. EP250220a: EP-WXT detection of a fast X-ray transient
  42. Konus-Wind detection of GRB 250217C (short)
  43. GRB 250219A: Swift/UVOT Upper Limits
  44. GRB 250219A: OHP/T193 optical upper limit
  45. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  46. GRB 250219A: 1.6m Mephisto optical upper limits
  47. Konus-Wind detection of GRB 250215A / EP250215a
  48. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  49. GRB 250217C: Swift-XRT observations
  50. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  51. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  52. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  53. GRB 250217C: SVOM/GRM observation
  54. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  55. SVOM/sb25021804: SVOM detection of a long X-ray transient
  56. GRB 250213A: Swift-XRT observations
  57. IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
  58. GRANDMA/OPD observations of GRB250215A
  59. GRB 250215A / EP250215a: LCO detection of the afterglow
  60. GRB 250215A: Swift/UVOT Upper Limits
  61. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  62. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  63. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  64. GRB 250215A: SVOM/GRM observation
  65. EP250215a / GRB 250215A: AstroSat CZTI detection
  66. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  67. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  68. EP250207b: Xinglong optical upper limit
  69. Fermi GRB 250214A: Global MASTER-Net observations report
  70. EP250212a: Xinglong optical upper limit
  71. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  72. GRB 250205A: VIRT Optical Upper Limit
  73. GRB 250205A: Leavitt Observatory optical upper limit
  74. EP250207B: Chandra localization of the X-ray counterpart
  75. EP250207b: VLA radio upper limits
  76. EP250212a: Liverpool Telescope optical upper limits
  77. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  78. GRB250101A: Radio upper limits from GMRT observations
  79. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  80. EP250207B: GTC z-band Observations
  81. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  82. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  83. EP250207b: NOT optical counterpart candidate
  84. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  85. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  86. GRB 250205A / EP250205A: radio detection with the VLA
  87. EP250207b: Tentative z-band brightening source
  88. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  89. Konus-Wind detection of GRB 250206A
  90. GRB 250210A: SVOM/GRM observation of a long burst
  91. EP250207b: Liverpool Telescope possible optical counterpart
  92. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  93. LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
  94. GRB 250207A: Skynet optical afterglow observations
  95. GRB 241128A: VIRT Optical Upper Limit
  96. EP250207b: Gemini GMOS-N z-band observations
  97. EP250207b: a new X-ray transient detected by Einstein Probe
  98. IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube
  99. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  100. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER

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