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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"

28131 results found.

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

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