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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').
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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"

28227 results found.

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

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