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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"

28129 results found.

  1. EP250223a: GROWTH-India Telescope optical observations
  2. GRB 250221A: Swift-BAT refined analysis
  3. EP250215A: J band upper limit by SYSU 80cm telescope
  4. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  5. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  6. EP250223a: Kinder optical follow-up observations
  7. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  8. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  9. GRB 250119B: VZLUSAT-2 detection
  10. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  11. GRB 250202B: VZLUSAT-2 detection
  12. GRB 250222A: SVOM/GRM observation of a burst
  13. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  14. GRB 250206A: VZLUSAT-2 detection
  15. EP250223a: REM NIR upper limit
  16. EP250223a: TRT optical afterglow observation
  17. EP250223a: refined analysis of the EP-WXT and FXT observations
  18. EP250223a: 1.6m Mephisto and 50cm array observations
  19. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  20. 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
  21. EP250223a: OASDG optical observations
  22. EP250223a: LCO detection of the afterglow
  23. EP250223a: Swift/XRT localization
  24. EP250223a: NOT optical afterglow candidate
  25. EP250223a: Einstein Probe detection of an X-ray transient
  26. LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
  27. GRB 250221A: Optical counterpart detection by LCO.
  28. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  29. GRB 250221A: GRANDMA/TAROT Detection
  30. GRB 250221A: Swift-XRT refined Analysis
  31. GRB 250221A: NOT optical observations
  32. GRB 250221A: 1.6m Mephisto optical detection
  33. GRB 250221A: AKO Optical Upper Limit
  34. GRB 250221A: Swift/UVOT Detection
  35. EP250220a: Liverpool Telescope upper limits
  36. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  37. GRB 250221A: REM optical/NIR afterglow detection
  38. IceCube-250207A: MASTER flaring blazar QSOJ0854+2006 with Zhirkov effect
  39. GRB 250221A: Enhanced Swift-XRT position
  40. EP250220a: 1.6m Mephisto observations
  41. EP250220a: Liverpool Telescope optical upper limits
  42. EP250220a: Optical upper limit with Kinder observations
  43. SVOM trigger sb25022102 is not an astrophysical event
  44. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  45. GRB 250221A: Swift detection of a burst with an optical counterpart
  46. Swift GRB250221.15: Global MASTER-Net OT detection
  47. EP250220a: Xinglong optical upper limit
  48. GRB 250219A: Swift/UVOT Upper Limits
  49. GRB 250219A: OHP/T193 optical upper limit
  50. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  51. GRB 250219A: 1.6m Mephisto optical upper limits
  52. GRB 250219A: Swift-XRT observations
  53. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  54. Konus-Wind detection of GRB 250215A / EP250215a
  55. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  56. GRB 250217C: Swift-XRT observations
  57. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  58. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  59. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  60. GRB 250217C: SVOM/GRM observation
  61. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  62. SVOM/sb25021804: SVOM detection of a long X-ray transient
  63. GRB 250213A: Swift-XRT observations
  64. GRB 250216A: AstroSat CZTI detection
  65. GRB 250217C: AstroSat CZTI detection of a short burst
  66. IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
  67. GRANDMA/OPD observations of GRB250215A
  68. GRB 250215A / EP250215a: LCO detection of the afterglow
  69. GRB 250215A: Swift/UVOT Upper Limits
  70. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  71. GRB 250215A: Fermi GBM Observation
  72. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  73. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  74. GRB 250215A: Swift-XRT refined Analysis
  75. GRB 250215A: SVOM/GRM observation
  76. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  77. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  78. EP250207b: Xinglong optical upper limit
  79. EP250212a: Xinglong optical upper limit
  80. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  81. EP250212a: Global MASTER-Net observations report
  82. GRB 250205A: VIRT Optical Upper Limit
  83. GRB 250205A: Leavitt Observatory optical upper limit
  84. EP250207B: Chandra localization of the X-ray counterpart
  85. EP250212a: Liverpool Telescope optical upper limits
  86. GRB250101A: Radio upper limits from GMRT observations
  87. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  88. EP250207B: GTC z-band Observations
  89. Fermi GRB 250212A: Global MASTER-Net observations report
  90. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  91. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  92. Fermi trigger No 760945500: Global MASTER-Net observations report
  93. EP250207b: NOT optical counterpart candidate
  94. GRB 250211B: A long GRB detected by INTEGRAL
  95. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  96. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  97. LIGO/Virgo/KAGRA S250211be: Updated Sky localization
  98. GRB 250207A: Fermi GBM Observation
  99. GRB 250206A: Fermi GBM Observation
  100. GRB 250205A / EP250205A: radio detection with the VLA

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