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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

19386 results found.

  1. GRB 250402A: REM optical/NIR upper limits
  2. GRB 250402A: LCO optical counterpart detection
  3. EP250402a: Einstein Probe detection of a fast X-ray transient
  4. GRB 250402A: SVOM/VT optical counterpart
  5. GRB 250402A: SVOM detection of a burst
  6. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  7. GRB 250329B: Swift/UVOT Upper Limit
  8. GRB 250329A: Swift/UVOT Upper Limit
  9. GRB 250327B: Swift/UVOT Detection
  10. GRB 250327A: Swift/UVOT Upper Limits
  11. GRB 250331E: SVOM/GRM observation
  12. GRB 250327B: Kilonova-Catcher Observations
  13. GRB250331D: AbAO optical observations
  14. GRB 250331C: Swift/UVOT Upper Limits
  15. GRB 250331B: Swift/UVOT Upper Limits
  16. GRB 250328A: AbAO AS-32 Optical Observations
  17. GRB 250219A: NOT candidate host galaxy detection
  18. GRB 250322B: GRBAlpha detection
  19. GRB 250330B: SVOM/GRM observation of a short burst
  20. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  21. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  22. Konus-Wind detection of GRB 250327B
  23. GRB 250331C: Enhanced Swift-XRT position
  24. GRB 250331B: Enhanced Swift-XRT position
  25. GRB 250330A: VLT/FORS2 Afterglow Detection
  26. GRB20250327B: 45th Parallel Observatory upper limit
  27. GRB 250328A: Swift/UVOT Detection
  28. GRB 250328A: Swift-XRT refined Analysis
  29. Fermi-LAT gamma-ray observations of IceCube-250330A
  30. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  31. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  32. GRB 250331C: Swift detection of a burst
  33. GRB 250331B: Swift detection of a burst
  34. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  35. GRB 250330A: Swift/UVOT Upper Limits
  36. GRB 250330A: Swift-XRT afterglow detection
  37. GRB 250328A: 1.6m Mephisto optical observations
  38. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  39. GRB 250330A: VLT/FORS2 Optical Observations
  40. GRB 250329B: Swift-XRT afterglow detection
  41. GRB 250330A: Swift detection of a burst
  42. GRB 250329B: SVOM/C-GFT optical upper limit
  43. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  44. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  45. GRB250329A: REM optical afterglow detection
  46. GRB 250329A: Swift-XRT afterglow detection
  47. GRB 250328A: SVOM/VT optical observation
  48. GRB 250329A: Fading optical counterpart detection by LCO.
  49. GRB 250328A: SVOM/C-GFT optical upper limit
  50. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  51. GRB 250329A: SVOM/VT optical counterpart confirmation
  52. GRB 250329A: SVOM detection of a burst
  53. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  54. GRB 250327B: J-band observations with WINTER
  55. GRB 250327B: LCO optical counterpart detection
  56. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  57. GRB 250327B: CrAO and SAO RAS Optical Observations
  58. GRB 250327b: Liverpool Telescope optical observations
  59. GRB 250322A: GRANDMA/TNOT optical upper limits
  60. GRB 250327A: SVOM/VT upper limits on the XRT position
  61. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  62. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  63. GRB 250327B: Las Cumbres optical counterpart detection
  64. GRB 250327B: 1.6m Mephisto optical observations
  65. GRB 250327B: SVOM/VT optically bright counterpart
  66. GRB 250327B: SAO RAS optical candidate
  67. GRB 250327B: SVOM detection of a burst
  68. GRB 250327A: J-band observations with WINTER
  69. GRB 250327A: SVOM/VT optical candidate
  70. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  71. GRB 250327A: DDOTI Optical Observations
  72. GRB 250327A: COLIBRÍ optical upper limit
  73. Konus-Wind detection of GRB 250322A (short)
  74. IPN triangulation of GRB 250322B
  75. LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
  76. EP250321a: Mondy AZT-33IK Continued Optical Observations
  77. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  78. GRB 250322A: third epoch of NOT optical observations
  79. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  80. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  81. GRB 250322A: further NOT optical observations
  82. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  83. GRB 250322A: Swift/UVOT Upper Limits
  84. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  85. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  86. GRB 250322B: NuSTAR detection of the prompt emission and regular dips during the burst
  87. GRB 250321B: Swift-XRT observations
  88. EP250321a: TNOT Observation of Optical Counterpart
  89. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  90. SVOM/sb25032302: SVOM detection of a long X-ray transient
  91. GRB 250322A: VLT optical observations
  92. GRB 250322A: VLT near-infrared observations
  93. FRB 250316A: DDOTI Continued Optical Observations
  94. GRB 250322A: NOT optical upper limits
  95. GRB 250322A: Enhanced Swift-XRT position
  96. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  97. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  98. EP250321a: Liverpool Telescope optical follow-up
  99. EP250321a: Mondy AZT-33IK Optical Observations
  100. GRB 250322A: Swift detection of a short burst

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