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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"

16099 results found.

  1. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  2. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  3. IceCube 250406.951: DDOTI Optical Observations
  4. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  5. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  6. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  7. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  8. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  9. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  10. GRB 250404A / EP250404a: Mondy optical observations
  11. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  12. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  13. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  14. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  15. EP250402a: Optical upper limit with PD 1.3m observations
  16. GRB 250404A / EP250404a: NOT optical observations
  17. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  18. EP250404a: REM optical/NIR observations
  19. EP250404a: Seimei/TriCCS optical counterpart detection
  20. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  21. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  22. EP250404a: LCO optical counterpart detection
  23. EP250404a: Xinglong decaying optical counterpart
  24. GRB 250403A: Montarrenti Observatory optical detection
  25. GRB 250403A: KAIT optical observations
  26. EP250404a: AKO Optical Afterglow Detection
  27. EP250404a: LAST detection of optical counterpart
  28. EP250404a: Xinglong-2.16m spectroscopic redshift
  29. GRB 250327B: VIRT Optical Upper Limit
  30. EP250404a: Mephisto multi-band optical detection
  31. EP250321A: J band upper limit by SYSU 80cm telescope
  32. EP250404a: BOOTES-4/JGT optical afterglow detection
  33. EP250404a: Nanshan/HMT optical counterpart detection
  34. GRB 250402A: Mondy optical observations
  35. GRB 250403A: Swift/UVOT Detection
  36. GRB 250402A: Swift/UVOT Upper Limits
  37. EP250402a: Optical upper limit with Kinder observations
  38. GRB 250403A: SVOM/VT optical observation
  39. GRB 250403A: REM NIR afterglow detection
  40. GRB 250403A: LCO optical counterpart detection
  41. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  42. GRB 250403A: JinShan optical observations
  43. GRB 250402A: EP-FXT afterglow detection
  44. GRB 250403A: Optical counterpart detection by LCO.
  45. GRB 250403A: Swift-XRT observations
  46. GRB 250403A: GOTO optical counterpart follow-up observations
  47. GRB 250402A: NUTTelA-TAO Early Optical Limits
  48. GRB 250403A: GMG Optical Observation
  49. GRB 250403A: 1.6m Mephisto multi-band optical detection
  50. GRB 250403A: SVOM/C-GFT optical observations
  51. GRB 250403A: GOTO detection of the optical afterglow
  52. GRB 250402A: Swift-XRT observations
  53. GRB 250225B: VLT host galaxy redshift z = 0.950
  54. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  55. GRB 250402A: REM optical/NIR upper limits
  56. GRB 250402A: LCO optical counterpart detection
  57. GRB 250402A: SVOM/VT optical counterpart
  58. GRB 250402A: SVOM detection of a burst
  59. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  60. GRB 250314A: ALMA detection
  61. GRB 250329A: Swift/UVOT Upper Limit
  62. GRB 250327B: Swift/UVOT Detection
  63. GRB 250327A: Swift/UVOT Upper Limits
  64. GRB 250331E: SVOM/GRM observation
  65. GRB 250327B: Kilonova-Catcher Observations
  66. GRB250331D: AbAO optical observations
  67. GRB 250331C: Swift/UVOT Upper Limits
  68. GRB 250331B: Swift/UVOT Upper Limits
  69. GRB 250328A: AbAO AS-32 Optical Observations
  70. GRB 250219A: NOT candidate host galaxy detection
  71. GRB 250330B: SVOM/GRM observation of a short burst
  72. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  73. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  74. GRB 250329B: CAHA 2.2m telescope optical limit
  75. GRB20250327B: 45th Parallel Observatory upper limit
  76. GRB 250328A: Swift-XRT refined Analysis
  77. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  78. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  79. GRB 250330A: SVOM/VT optical upper limit
  80. GRB 250314A: VLA detection
  81. GRB 250330A: BOOTES-7 early optical upper limit
  82. GRB 250330A: Swift/UVOT Upper Limits
  83. GRB 250328A: 1.6m Mephisto optical observations
  84. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  85. GRB 250330A: VLT/FORS2 Optical Observations
  86. GRB 250328A: A fading optical afterglow confirmed by SVOM/VT
  87. GRB 250329B: SVOM/C-GFT optical upper limit
  88. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 1)
  89. GRB 250327B: ALMA detection
  90. GRB 250327B: VLA detection
  91. GRB 250329B: SVOM/VT optical upper limit
  92. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  93. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  94. GRB250329A: REM optical afterglow detection
  95. GRB 250329B: GWAC-F50A optical upper limit
  96. GRB 250329A: Swift-XRT afterglow detection
  97. GRB 250328A: SVOM/VT optical observation
  98. GRB 250329A: Fading optical counterpart detection by LCO.
  99. GRB 250328A: SVOM/C-GFT optical upper limit
  100. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate

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