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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"

28266 results found.

  1. GRB 250226A / EP250226a: LCO detection of the afterglow
  2. LIGO/Virgo/KAGRA S250227e: Updated Sky localization
  3. LIGO/Virgo/KAGRA S250226dl: Updated Sky localization
  4. GRB 250225B: VLT/Xshooter imaging
  5. GRB 250205A / EP250205A: further radio observations with the VLA
  6. EP250225a: NOT optical candidate counterpart
  7. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  8. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  9. EP250225a: TRT optical upper limits
  10. EP250226a/GRB 250226A: 1.6m Mephisto observations
  11. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  12. EP250226a/GRB 250226A: Kinder optical follow-up observations
  13. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  14. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  15. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  16. GRB 250225B: Fermi GBM Observation
  17. GRB 250225B: REM NIR upper limits
  18. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  19. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  20. EP250223a: CrAO ZTSH optical observation
  21. GRB 250225B: VLT optical and near-infrared candidate counterpart
  22. GRB 250225B: SVOM/GRM observation of a long burst
  23. EP250226a/GRB 250226A: GSP detects optical counterpart
  24. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  25. EP250226a / GRB 250226A: TRT optical counterpart observation
  26. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  27. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  28. EP250225a: GSP optical upper limit
  29. EP250223a: GMG Optical Observation
  30. EP250225a: Einstein Probe detected of a fast X-ray transient
  31. GRB 250225B: Swift detection of a burst
  32. EP250223a: GROWTH-India Telescope optical observations
  33. GRB 250221A: Swift-BAT refined analysis
  34. EP250215A: J band upper limit by SYSU 80cm telescope
  35. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  36. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  37. EP250223a: Kinder optical follow-up observations
  38. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  39. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  40. GRB 250119B: VZLUSAT-2 detection
  41. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  42. GRB 250202B: VZLUSAT-2 detection
  43. GRB 250222A: SVOM/GRM observation of a burst
  44. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  45. GRB 250206A: VZLUSAT-2 detection
  46. EP250223a: REM NIR upper limit
  47. EP250223a: TRT optical afterglow observation
  48. EP250223a: refined analysis of the EP-WXT and FXT observations
  49. EP250223a: 1.6m Mephisto and 50cm array observations
  50. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  51. 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
  52. EP250223a: OASDG optical observations
  53. EP250223a: LCO detection of the afterglow
  54. EP250223a: Swift/XRT localization
  55. EP250223a: NOT optical afterglow candidate
  56. EP250223a: Einstein Probe detection of an X-ray transient
  57. LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
  58. GRB 250221A: Optical counterpart detection by LCO.
  59. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  60. GRB 250221A: GRANDMA/TAROT Detection
  61. GRB 250221A: Swift-XRT refined Analysis
  62. GRB 250221A: NOT optical observations
  63. GRB 250221A: 1.6m Mephisto optical detection
  64. GRB 250221A: AKO Optical Upper Limit
  65. GRB 250221A: Swift/UVOT Detection
  66. EP250220a: Liverpool Telescope upper limits
  67. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  68. GRB 250221A: REM optical/NIR afterglow detection
  69. IceCube-250207A: MASTER flaring blazar QSOJ0854+2006 with Zhirkov effect
  70. GRB 250221A: Enhanced Swift-XRT position
  71. EP250220a: 1.6m Mephisto observations
  72. EP250220a: Liverpool Telescope optical upper limits
  73. EP250220a: Optical upper limit with Kinder observations
  74. SVOM trigger sb25022102 is not an astrophysical event
  75. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  76. GRB 250221A: Swift detection of a burst with an optical counterpart
  77. Swift GRB250221.15: Global MASTER-Net OT detection
  78. EP250220a: Xinglong optical upper limit
  79. GRB 250219A: Swift/UVOT Upper Limits
  80. GRB 250219A: OHP/T193 optical upper limit
  81. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  82. GRB 250219A: 1.6m Mephisto optical upper limits
  83. GRB 250219A: Swift-XRT observations
  84. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  85. Konus-Wind detection of GRB 250215A / EP250215a
  86. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  87. GRB 250217C: Swift-XRT observations
  88. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  89. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  90. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  91. GRB 250217C: SVOM/GRM observation
  92. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  93. SVOM/sb25021804: SVOM detection of a long X-ray transient
  94. GRB 250213A: Swift-XRT observations
  95. GRB 250216A: AstroSat CZTI detection
  96. GRB 250217C: AstroSat CZTI detection of a short burst
  97. IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
  98. GRANDMA/OPD observations of GRB250215A
  99. GRB 250215A / EP250215a: LCO detection of the afterglow
  100. GRB 250215A: Swift/UVOT Upper Limits

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