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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"

21832 results found.

  1. IceCube Alert 250804.84: Global MASTER-Net observations report
  2. EP#01709198415/EP250806a: Swift-XRT observations
  3. EP250806a: Global MASTER-Net observations report
  4. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  5. EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS
  6. GRB 250806A: J-band upper limit from WINTER
  7. GRB 250806A: KAIT optical upper limit
  8. GRB 250806A: Kilonova-Catcher optical upper limits
  9. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  10. GRB 250805A: ESO/VLT observations
  11. GRB 250804B: Swift-XRT observations
  12. GRB 250805A: TRT optical upper limits
  13. GRB 250805A: Swift-XRT observations
  14. Swift GRB250805.26: Global MASTER-Net observations report
  15. GRB 250804B: Tiled Swift observations
  16. Fermi trigger No 776041355: Global MASTER-Net observations report
  17. EP250802a: Global MASTER-Net observations report
  18. EP250802a: Einstein Probe detection of an X-ray transient
  19. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  20. GRB 250702B: SMA observations
  21. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  22. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  23. EP250711a: CrAO and Assy optical observations
  24. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  25. EP250730a: Global MASTER-Net observations report
  26. EP250730a: Einstein Probe detection of an X-ray transient
  27. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  28. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  29. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  30. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  31. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  32. GRB 250725A: PRIME near-infrared observations
  33. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  34. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  35. GRB 250728A: Swift-XRT observations
  36. GRB 250727A: SVOM/ECLAIRs refined analysis
  37. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  38. GRB 250728A: COLIBRÍ optical upper limit
  39. Fermi trigger No 775387550: Global MASTER-Net observations report
  40. GRB 250728A: Swift ToO observations
  41. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  42. GRB 250727A: AST3-2 Upper limit
  43. GRB250727A: SVOM/VT optical upper limit
  44. GRB 250727A: Swift-XRT observations
  45. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  46. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  47. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  48. GRB 250725A: Swift/UVOT Upper Limits
  49. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  50. Fermi GRB 250725A: Global MASTER-Net observations report
  51. Swift GRB 250725A: Global MASTER-Net observations report
  52. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  53. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  54. SVOM J195836+32283/sb25072103: Second VT observation
  55. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  56. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  57. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  58. GRB 250721A: Swift-XRT observations
  59. GRB 250713A : SVOM/ECLAIRs refined analysis
  60. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  61. GRB 250721A: Tiled Swift observations
  62. Fermi trigger No 774730635: Global MASTER-Net observations report
  63. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  64. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  65. GRB 250717B: Swift-XRT observations
  66. Swift GRB250718.01: Global MASTER-Net observations report
  67. GRB 250717B: Swift ToO observations
  68. GRB 270713A: Kitab and AbAO Optical Observations
  69. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  70. GRB 250716A: Swift-XRT afterglow detection
  71. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  72. GRB 250716A: Swift ToO observations
  73. GRB 250716A: GOTO tentative optical counterpart candidate
  74. Fermi GRB 250716A: Global MASTER-Net observations report
  75. Fermi GRB 250715A: Global MASTER-Net observations report
  76. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  77. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  78. GRB 250713A: Mephisto optical upper limits
  79. Fermi GRB 250714A: Global MASTER-Net observations report
  80. GRB 250713A: NOT optical upper limits
  81. GRB 250713A: OHP/T193 upper limit
  82. GRB 250713A: SVOM/C-GFT upper limit
  83. GRB 250706B/C: 7DT Follow-up Observations
  84. GRB 250713A: Swift-XRT observations
  85. EP250711a: COLIBRÍ continuous optical observations
  86. GRB 250713A: JinShan optical upper limits
  87. EP250711a: Global MASTER-Net observations report
  88. GRB 250711A: DDOTI Optical Upper Limit
  89. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  90. Fermi GRB 250711A: Global MASTER-Net observations report
  91. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  92. GRB 250704A: GRANDMA observations
  93. GRB 250704A: SVOM/ECLAIRs refined analysis
  94. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  95. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  96. GRB 250702B,D,E / EP250702a: ALMA detection
  97. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  98. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  99. IceCube-250708A: No Candidates from WINTER
  100. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility

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