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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').
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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"
body:"GRB"
submitter:"Judith Racusin"

32510 results found.

  1. GRB 250129A: optical photometry from Konkoly
  2. GRB 250129A: COLIBRÍ Optical Observations
  3. GRB 250128B: VLA possible radio detection
  4. GRB 250129A: continued KAIT observations indicating steep decay after 28.5h
  5. GRB 250129A: iTelescope optical observation
  6. GRB 250129A: NOT optical observations of continuining activity
  7. GRB 250129a: Liverpool Telescope optical follow-up
  8. GRB 250129A: TNG NIR afterglow detection
  9. GRB 250129A: AKO Optical Afterglow Detection
  10. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  11. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  12. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  13. GRB 250128B: VLA radio upper limit
  14. Ep250125A: 1.3m DFOT optical upper limit
  15. GRB 250129A: Skynet optical observations
  16. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  17. GRB 250128B: Gemini-North optical extended source detection
  18. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  19. GRB 250128B: TNG optical upper limit
  20. GRB 250129A: Swift/UVOT Detection
  21. GRB 250128B: VLT/HAWKI near-infrared observations
  22. GRB 250127A: CrAO and Terskol optical upper limits
  23. GRB 250128B: NOT optical upper limit
  24. GRB 250128B: VLT/FORS2 optical observations
  25. GRB 250129A: REM optical/NIR afterglow detection
  26. GRB 250129A: OHP/T193 optical and spectroscopy observations
  27. GRB 250129A: Early afterglow detection by LCO.
  28. GRB 250128B: OHP/T193 optical upper limit
  29. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  30. GRB 250129A: LCO optical observations
  31. GRB 250129A: NOT optical observations and redshift confirmation
  32. GRB 250129A: GOTO optical observations show brightening afterglow
  33. GRB 250129A: VLT/X-shooter redshift of z = 2.151
  34. Swift GRB 250129A: Global MASTER-Net observations report
  35. Fermi GRB 250128B: Global MASTER-Net observations report
  36. GRB 250128B: Fermi GBM Observation
  37. GRB 250128B: GOTO optical upper limit
  38. Swift GRB 250128B: Global MASTER-Net observations report
  39. EP250125a: Upper limits from Swift/BAT-GUANO
  40. GRB 250128B: LCO optical observations
  41. GRB 250127A: Swift-XRT observations
  42. GRB 250127B: DDOTI Upper Limit on the Afterglow
  43. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  44. GRB 250127A: EP-FXT afterglow detection
  45. Fermi GRB 250128A: Global MASTER-Net observations report
  46. GRB 250117A: Fermi GBM Observation
  47. Fermi GRB 250127B: Global MASTER-Net observations report
  48. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  49. GRB 250127A: SVOM/VT upper limit
  50. IPN triangulation of GRB 250119C
  51. GRB 250127A: Swift ToO observations
  52. GRB 250127A: LCO optical upper limit
  53. GRB 241223A: cubesat Avion detection
  54. GRB 250126A: CALET Gamma-Ray Burst Monitor detection
  55. EP250125A: Non-detection from Fermi-GBM Observations
  56. GRB 250126A: MAXI/GSC detection
  57. EP250108a / SN 2025kg: Refined Analysis of EP-WXT Detection
  58. GECAM-A detection of a bright burst from SGR 1E1841-045
  59. GRB 250118A: Fermi GBM Observation
  60. EP250125a: Optical upper limit with Kinder observations
  61. EP250125a: REM optical counterpart detection
  62. GRB 250119C: Fermi GBM Observation
  63. EP250125a: Swift/XRT detection of a fading counterpart
  64. EP250125a: a new X-ray transient detected by Einstein Probe
  65. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  66. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  67. IPN triangulation of a bright burst from SGR 1E1841-045
  68. GRB 250121A: CALET Gamma-Ray Burst Monitor detection
  69. EP250108a: AbAO, CMO and Terskol optical upper limits
  70. Konus-Wind detection of GRB 250118B
  71. GRB 250121A: Fermi GBM Observation
  72. IPN triangulation of GRB 250118B
  73. Konus-Wind detection of GRB 250119B
  74. IPN triangulation of GRB 250119B
  75. Improved IPN triangulation of GRB 250107C
  76. GRB 250114A: Swift-BAT refined analysis
  77. GRB 250121A: INTEGRAL/SPI-ACS detection
  78. GRB 250121A: Fermi-LAT detection
  79. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  80. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  81. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  82. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  83. GRB 250119B: Fermi GBM Observation
  84. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  85. Konus-Wind detection of GRB 250117A
  86. IPN triangulation of GRB 250117A (short)
  87. ATCA detection of possible radio counterpart to GRB 250114A
  88. EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
  89. GRB 250119B: INTEGRAL/SPI-ACS detection
  90. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  91. EP 250108A: Late-time optical observation by LCO
  92. GRB 250117A: SVOM/GRM observation of a short burst
  93. LIGO/Virgo/KAGRA S250119cv: Updated Sky localization and EM Bright Classification
  94. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  95. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  96. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  97. LIGO/Virgo/KAGRA S250119ag: Updated Sky localization
  98. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  99. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  100. GRB 250117A: GECAM observation of a short burst

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