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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"
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submitter:"Judith Racusin"

23445 results found.

  1. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  2. IPN triangulation of GRB 250406B (short/hard)
  3. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  4. IceCube 250406.951: DDOTI Optical Observations
  5. Fermi trigger No 765663719: Global MASTER-Net observations report
  6. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  7. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  8. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  9. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  10. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  11. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  12. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  13. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  14. EP250402a: Optical upper limit with PD 1.3m observations
  15. GRB 250404A / EP250404a: NOT optical observations
  16. GRB 250331D: Swift-XRT afterglow detection
  17. GRB 250403A: AstroSat CZTI detection
  18. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  19. EP250404a: REM optical/NIR observations
  20. EP250404a: Seimei/TriCCS optical counterpart detection
  21. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  22. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  23. EP250404a: LCO optical counterpart detection
  24. EP250404a: Xinglong decaying optical counterpart
  25. GRB 250403A: Montarrenti Observatory optical detection
  26. GRB 250403A: KAIT optical observations
  27. EP250404a: AKO Optical Afterglow Detection
  28. EP250404a: LAST detection of optical counterpart
  29. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  30. GRB 250327B: VIRT Optical Upper Limit
  31. EP250404a: Mephisto multi-band optical detection
  32. EP250321A: J band upper limit by SYSU 80cm telescope
  33. EP250404a: Nanshan/HMT optical counterpart detection
  34. EP250404a: Einstein Probe detection of an X-ray transient
  35. GRB 250403A: Swift/UVOT Detection
  36. GRB 250402A: Swift/UVOT Upper Limits
  37. EP250402a: Optical upper limit with Kinder observations
  38. GRB 250403A: REM NIR afterglow detection
  39. GRB 250403A: LCO optical counterpart detection
  40. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  41. GRB 250403A: JinShan optical observations
  42. GRB 250403A: Optical counterpart detection by LCO.
  43. GRB 250322A: 10 GHz VLA radio upper limits
  44. GRB 250403A: GMG Optical Observation
  45. GRB 250403A: 1.6m Mephisto multi-band optical detection
  46. GRB 250403A: SVOM/C-GFT optical observations
  47. GRB 250403A: Fermi GBM Final Real-time Localization
  48. GRB 250225B: VLT host galaxy redshift z = 0.950
  49. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  50. GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
  51. GRB 250402A: REM optical/NIR upper limits
  52. GRB 250402A: LCO optical counterpart detection
  53. EP250402a: Einstein Probe detection of a fast X-ray transient
  54. GRB 250402A: SVOM/VT optical counterpart
  55. GRB 250402A: SVOM detection of a burst
  56. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  57. GRB 250329B: Swift/UVOT Upper Limit
  58. GRB 250329A: Swift/UVOT Upper Limit
  59. GRB 250327B: Swift/UVOT Detection
  60. GRB 250327A: Swift/UVOT Upper Limits
  61. GRB 250331E: SVOM/GRM observation
  62. GRB 250327B: Kilonova-Catcher Observations
  63. GRB250331D: AbAO optical observations
  64. GRB 250331C: Swift/UVOT Upper Limits
  65. GRB 250331B: Swift/UVOT Upper Limits
  66. GRB 250328A: AbAO AS-32 Optical Observations
  67. GRB 250219A: NOT candidate host galaxy detection
  68. GRB 250331D: Swift-XRT observations
  69. GRB 250322B possible detection by the AstroSat Satellite
  70. GRB 250330B: SVOM/GRM observation of a short burst
  71. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  72. GRB 250331C: Enhanced Swift-XRT position
  73. LIGO/Virgo/KAGRA S250331o: NED Galaxies in the 3-Initial Localization Volume
  74. GRB 250331B: Enhanced Swift-XRT position
  75. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  76. GRB 250330A: VLT/FORS2 Afterglow Detection
  77. GRB20250327B: 45th Parallel Observatory upper limit
  78. GRB 250328A: Swift/UVOT Detection
  79. GRB 250328A: Swift-XRT refined Analysis
  80. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  81. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  82. GRB 250331C: Swift detection of a burst
  83. GRB 250331B: Swift detection of a burst
  84. GRB 250330A: SVOM/VT optical upper limit
  85. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  86. GRB 250330A: Swift/UVOT Upper Limits
  87. GRB 250330A: Swift-XRT afterglow detection
  88. GRB 250328A: 1.6m Mephisto optical observations
  89. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  90. GRB 250330A: VLT/FORS2 Optical Observations
  91. GRB 250329B: Swift-XRT afterglow detection
  92. GRB 250330A: Swift detection of a burst
  93. GRB 250329B: SVOM/C-GFT optical upper limit
  94. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 1)
  95. GRB 250329B: SVOM/VT optical upper limit
  96. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  97. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  98. LIGO/Virgo/KAGRA S250329fl: 2 counterpart neutrino candidate events from an IceCube neutrino search
  99. GRB250329A: REM optical afterglow detection
  100. GRB 250329B: GWAC-F50A optical upper limit

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