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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"

28234 results found.

  1. EP250223a: GMG Optical Observation
  2. EP250225a: Einstein Probe detected of a fast X-ray transient
  3. GRB 250225B: Swift detection of a burst
  4. EP250223a: GROWTH-India Telescope optical observations
  5. GRB 250221A: Swift-BAT refined analysis
  6. EP250215A: J band upper limit by SYSU 80cm telescope
  7. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  8. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  9. EP250223a: Kinder optical follow-up observations
  10. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  11. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  12. GRB 250119B: VZLUSAT-2 detection
  13. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  14. GRB 250202B: VZLUSAT-2 detection
  15. GRB 250222A: SVOM/GRM observation of a burst
  16. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  17. GRB 250206A: VZLUSAT-2 detection
  18. EP250223a: REM NIR upper limit
  19. EP250223a: TRT optical afterglow observation
  20. EP250223a: refined analysis of the EP-WXT and FXT observations
  21. EP250223a: 1.6m Mephisto and 50cm array observations
  22. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  23. 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
  24. EP250223a: OASDG optical observations
  25. EP250223a: LCO detection of the afterglow
  26. EP250223a: Swift/XRT localization
  27. EP250223a: NOT optical afterglow candidate
  28. EP250223a: Einstein Probe detection of an X-ray transient
  29. LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
  30. GRB 250221A: Optical counterpart detection by LCO.
  31. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  32. GRB 250221A: GRANDMA/TAROT Detection
  33. GRB 250221A: Swift-XRT refined Analysis
  34. GRB 250221A: NOT optical observations
  35. GRB 250221A: 1.6m Mephisto optical detection
  36. GRB 250221A: AKO Optical Upper Limit
  37. GRB 250221A: Swift/UVOT Detection
  38. EP250220a: Liverpool Telescope upper limits
  39. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  40. GRB 250221A: REM optical/NIR afterglow detection
  41. IceCube-250207A: MASTER flaring blazar QSOJ0854+2006 with Zhirkov effect
  42. GRB 250221A: Enhanced Swift-XRT position
  43. EP250220a: 1.6m Mephisto observations
  44. EP250220a: Liverpool Telescope optical upper limits
  45. EP250220a: Optical upper limit with Kinder observations
  46. SVOM trigger sb25022102 is not an astrophysical event
  47. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  48. GRB 250221A: Swift detection of a burst with an optical counterpart
  49. Swift GRB250221.15: Global MASTER-Net OT detection
  50. EP250220a: Xinglong optical upper limit
  51. GRB 250219A: Swift/UVOT Upper Limits
  52. GRB 250219A: OHP/T193 optical upper limit
  53. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  54. GRB 250219A: 1.6m Mephisto optical upper limits
  55. GRB 250219A: Swift-XRT observations
  56. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  57. Konus-Wind detection of GRB 250215A / EP250215a
  58. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  59. GRB 250217C: Swift-XRT observations
  60. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  61. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  62. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  63. GRB 250217C: SVOM/GRM observation
  64. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  65. SVOM/sb25021804: SVOM detection of a long X-ray transient
  66. GRB 250213A: Swift-XRT observations
  67. GRB 250216A: AstroSat CZTI detection
  68. GRB 250217C: AstroSat CZTI detection of a short burst
  69. IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
  70. GRANDMA/OPD observations of GRB250215A
  71. GRB 250215A / EP250215a: LCO detection of the afterglow
  72. GRB 250215A: Swift/UVOT Upper Limits
  73. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  74. GRB 250215A: Fermi GBM Observation
  75. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  76. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  77. GRB 250215A: Swift-XRT refined Analysis
  78. GRB 250215A: SVOM/GRM observation
  79. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  80. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  81. EP250207b: Xinglong optical upper limit
  82. EP250212a: Xinglong optical upper limit
  83. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  84. EP250212a: Global MASTER-Net observations report
  85. GRB 250205A: VIRT Optical Upper Limit
  86. GRB 250205A: Leavitt Observatory optical upper limit
  87. EP250207B: Chandra localization of the X-ray counterpart
  88. EP250212a: Liverpool Telescope optical upper limits
  89. GRB250101A: Radio upper limits from GMRT observations
  90. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  91. EP250207B: GTC z-band Observations
  92. Fermi GRB 250212A: Global MASTER-Net observations report
  93. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  94. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  95. Fermi trigger No 760945500: Global MASTER-Net observations report
  96. EP250207b: NOT optical counterpart candidate
  97. GRB 250211B: A long GRB detected by INTEGRAL
  98. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  99. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  100. LIGO/Virgo/KAGRA S250211be: Updated Sky localization

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