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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"

21954 results found.

  1. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  2. EP250223a: GOTO optical afterglow detections
  3. EP250223a: REM NIR upper limit
  4. EP250223a: TRT optical afterglow observation
  5. EP250223a: refined analysis of the EP-WXT and FXT observations
  6. EP250223a: 1.6m Mephisto and 50cm array observations
  7. EP250223a: SVOM/VT optical observation
  8. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  9. 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
  10. EP250223a: OASDG optical observations
  11. EP250223a: LCO detection of the afterglow
  12. EP250223a: NOT redshift z = 2.756
  13. EP250223a: NOT optical afterglow candidate
  14. EP250223a: Global MASTER-Net observations report
  15. GRB 250221A: VLA radio detection
  16. Fermi GRB 250223A: Global MASTER-Net observations report
  17. Fermi trigger No 762020305: Global MASTER-Net observations report
  18. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  19. GRB 250221A: continued Mondy optical observations, brightening afterglow
  20. GRB 250221A: Optical counterpart detection by LCO.
  21. GRB 250221A: Mondy optical observations
  22. GRB 250221A: Assy optical observations
  23. EP250220a: FTW optical and NIR observations and upper limits
  24. EP250220a: EP-FXT follow-up observations
  25. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  26. Fermi trigger No 761805304: Global MASTER-Net observations report
  27. GRB 250221A: NOT optical observations
  28. GRB 250221A: 1.6m Mephisto optical detection
  29. GRB 250221A: Swift/UVOT Detection
  30. EP250220a: Liverpool Telescope upper limits
  31. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  32. GRB 250221A: REM optical/NIR afterglow detection
  33. IceCube-250207A: MASTER flaring blazar QSOJ0854+2006 with Zhirkov effect
  34. EP250220a: 1.6m Mephisto observations
  35. EP250220a: Optical upper limit with Kinder observations
  36. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  37. Swift GRB250221.15: Global MASTER-Net observations report
  38. EP250220a: Global MASTER-Net observations report
  39. GRB 250219A: Swift/UVOT Upper Limits
  40. GRB 250219A: OHP/T193 optical upper limit
  41. GRB 250219A: NOT optical observations
  42. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  43. GRB 250219A: 1.6m Mephisto optical upper limits
  44. GRB 250219A: SVOM/VT optical counterpart
  45. GRB 250219A: Swift-XRT observations
  46. LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
  47. GRB 250219A: Swift ToO observations
  48. GRB 250217C: Swift-XRT observations
  49. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  50. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  51. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  52. GRB 250217C: Tiled Swift observations
  53. GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
  54. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  55. GRB 250213A: Swift-XRT observations
  56. LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
  57. Fermi GRB 250217C: Global MASTER-Net observations report
  58. LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
  59. Fermi GRB 250217A: Global MASTER-Net observations report
  60. GRANDMA/OPD observations of GRB250215A
  61. Fermi GRB 250216A: Global MASTER-Net observations report
  62. GRB 250215A / EP250215a: LCO detection of the afterglow
  63. EP250212a: FTW optical and NIR upper limits
  64. GRB 250215A: Swift/UVOT Upper Limits
  65. EP250215a / GRB 250215A : NOT optical observations
  66. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  67. LIGO/Virgo/KAGRA S250206dm: MASTER LC AT2025bbo
  68. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  69. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  70. EP250215a: Global MASTER-Net observations report
  71. EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
  72. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  73. Fermi GRB 250215A: Global MASTER-Net observations report
  74. Fermi trigger No 761206993: Global MASTER-Net observations report
  75. GRB 250213A：SVOM/VT optical candidate
  76. Fermi GRB 250214A: Global MASTER-Net observations report
  77. GRB 250213A: Swift ToO observations
  78. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  79. EP250212a: Global MASTER-Net observations report
  80. GRB 250205A: Leavitt Observatory optical upper limit
  81. EP250207B: Chandra localization of the X-ray counterpart
  82. LIGO/Virgo/KAGRA S250206dm: FTW observations of counterpart candidates AT2025bbo and AT2025bcx, and of NED galaxies
  83. EP250207b: VLA radio upper limits
  84. GRB250101A: Radio upper limits from GMRT observations
  85. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  86. EP250207B: GTC z-band Observations
  87. Fermi GRB 250212A: Global MASTER-Net observations report
  88. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  89. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  90. Fermi trigger No 760945500: Global MASTER-Net observations report
  91. EP250207b: NOT optical counterpart candidate
  92. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  93. GRB 250211A: Swift ToO observations
  94. Integral GRB250211.89: Global MASTER-Net observations report
  95. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  96. GRB 250205A / EP250205A: radio detection with the VLA
  97. IceCube-250207A: One candidate from the Zwicky Transient Facility
  98. EP250207b: Tentative z-band brightening source
  99. LIGO/Virgo/KAGRA S250206dm: continued in SOAR galaxy targeted observations and identification of one possible transient
  100. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo

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