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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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subject:"Swift"
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21922 results found.

  1. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  2. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  3. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  4. EP250402a: Optical upper limit with PD 1.3m observations
  5. GRB 250404A / EP250404a: NOT optical observations
  6. GRB 250331D: Swift-XRT afterglow detection
  7. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  8. EP250404a: REM optical/NIR observations
  9. EP250404a: Seimei/TriCCS optical counterpart detection
  10. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  11. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  12. EP250404a: LCO optical counterpart detection
  13. EP250404a: Xinglong decaying optical counterpart
  14. GRB 250403A: Montarrenti Observatory optical detection
  15. GRB 250403A: KAIT optical observations
  16. EP250404a: AKO Optical Afterglow Detection
  17. EP250404a: LAST detection of optical counterpart
  18. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  19. GRB 250327B: VIRT Optical Upper Limit
  20. EP250404a: Mephisto multi-band optical detection
  21. EP250321A: J band upper limit by SYSU 80cm telescope
  22. EP250404a: Nanshan/HMT optical counterpart detection
  23. EP250404a: Einstein Probe detection of an X-ray transient
  24. GRB 250403A: Swift/UVOT Detection
  25. GRB 250402A: Swift/UVOT Upper Limits
  26. EP250402a: Optical upper limit with Kinder observations
  27. GRB 250403A: REM NIR afterglow detection
  28. GRB 250403A: LCO optical counterpart detection
  29. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  30. GRB 250403A: JinShan optical observations
  31. GRB 250403A: Optical counterpart detection by LCO.
  32. GRB 250402A: NUTTelA-TAO Early Optical Limits
  33. GRB 250403A: GMG Optical Observation
  34. GRB 250403A: 1.6m Mephisto multi-band optical detection
  35. GRB 250403A: SVOM/C-GFT optical observations
  36. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  37. GRB 250402A: REM optical/NIR upper limits
  38. GRB 250402A: LCO optical counterpart detection
  39. EP250402a: Einstein Probe detection of a fast X-ray transient
  40. GRB 250402A: SVOM/VT optical counterpart
  41. GRB 250402A: SVOM detection of a burst
  42. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  43. GRB 250329B: Swift/UVOT Upper Limit
  44. GRB 250329A: Swift/UVOT Upper Limit
  45. GRB 250327B: Swift/UVOT Detection
  46. GRB 250327A: Swift/UVOT Upper Limits
  47. GRB 250331E: SVOM/GRM observation
  48. GRB 250327B: Kilonova-Catcher Observations
  49. GRB250331D: AbAO optical observations
  50. GRB 250331C: Swift/UVOT Upper Limits
  51. GRB 250331B: Swift/UVOT Upper Limits
  52. GRB 250328A: AbAO AS-32 Optical Observations
  53. GRB 250219A: NOT candidate host galaxy detection
  54. GRB 250322B: GRBAlpha detection
  55. GRB 250330B: SVOM/GRM observation of a short burst
  56. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  57. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  58. Konus-Wind detection of GRB 250327B
  59. GRB 250331C: Enhanced Swift-XRT position
  60. GRB 250331B: Enhanced Swift-XRT position
  61. GRB 250330A: VLT/FORS2 Afterglow Detection
  62. GRB20250327B: 45th Parallel Observatory upper limit
  63. GRB 250328A: Swift/UVOT Detection
  64. GRB 250328A: Swift-XRT refined Analysis
  65. Fermi-LAT gamma-ray observations of IceCube-250330A
  66. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  67. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  68. GRB 250331C: Swift detection of a burst
  69. GRB 250331B: Swift detection of a burst
  70. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  71. GRB 250330A: Swift/UVOT Upper Limits
  72. GRB 250330A: Swift-XRT afterglow detection
  73. GRB 250328A: 1.6m Mephisto optical observations
  74. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  75. GRB 250330A: VLT/FORS2 Optical Observations
  76. GRB 250329B: Swift-XRT afterglow detection
  77. GRB 250330A: Swift detection of a burst
  78. GRB 250329B: SVOM/C-GFT optical upper limit
  79. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  80. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  81. GRB250329A: REM optical afterglow detection
  82. GRB 250329A: Swift-XRT afterglow detection
  83. GRB 250328A: SVOM/VT optical observation
  84. GRB 250329A: Fading optical counterpart detection by LCO.
  85. GRB 250328A: SVOM/C-GFT optical upper limit
  86. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  87. GRB 250329A: SVOM/VT optical counterpart confirmation
  88. GRB 250329A: SVOM detection of a burst
  89. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  90. GRB 250327B: J-band observations with WINTER
  91. GRB 250327B: LCO optical counterpart detection
  92. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  93. GRB 250327B: CrAO and SAO RAS Optical Observations
  94. GRB 250327b: Liverpool Telescope optical observations
  95. GRB 250322A: GRANDMA/TNOT optical upper limits
  96. GRB 250327A: SVOM/VT upper limits on the XRT position
  97. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  98. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  99. GRB 250327B: Las Cumbres optical counterpart detection
  100. GRB 250327B: 1.6m Mephisto optical observations

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