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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"

32506 results found.

  1. GRB 250129A: continued KAIT observations indicating steep decay after 28.5h
  2. GRB 250129A: iTelescope optical observation
  3. GRB 250129A: NOT optical observations of continuining activity
  4. GRB 250129a: Liverpool Telescope optical follow-up
  5. GRB 250129A: TNG NIR afterglow detection
  6. GRB 250129A: AKO Optical Afterglow Detection
  7. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  8. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  9. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  10. GRB 250128B: VLA radio upper limit
  11. Ep250125A: 1.3m DFOT optical upper limit
  12. GRB 250129A: Skynet optical observations
  13. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  14. GRB 250128B: Gemini-North optical extended source detection
  15. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  16. GRB 250128B: TNG optical upper limit
  17. GRB 250129A: Swift/UVOT Detection
  18. GRB 250128B: VLT/HAWKI near-infrared observations
  19. GRB 250127A: CrAO and Terskol optical upper limits
  20. GRB 250128B: NOT optical upper limit
  21. GRB 250128B: VLT/FORS2 optical observations
  22. GRB 250129A: REM optical/NIR afterglow detection
  23. GRB 250129A: OHP/T193 optical and spectroscopy observations
  24. GRB 250129A: Early afterglow detection by LCO.
  25. GRB 250128B: OHP/T193 optical upper limit
  26. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  27. GRB 250129A: LCO optical observations
  28. GRB 250129A: NOT optical observations and redshift confirmation
  29. GRB 250129A: GOTO optical observations show brightening afterglow
  30. GRB 250129A: VLT/X-shooter redshift of z = 2.151
  31. Swift GRB 250129A: Global MASTER-Net observations report
  32. Fermi GRB 250128B: Global MASTER-Net observations report
  33. GRB 250128B: Fermi GBM Observation
  34. GRB 250128B: GOTO optical upper limit
  35. Swift GRB 250128B: Global MASTER-Net observations report
  36. EP250125a: Upper limits from Swift/BAT-GUANO
  37. GRB 250128B: LCO optical observations
  38. GRB 250127A: Swift-XRT observations
  39. GRB 250127B: DDOTI Upper Limit on the Afterglow
  40. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  41. GRB 250127A: EP-FXT afterglow detection
  42. Fermi GRB 250128A: Global MASTER-Net observations report
  43. GRB 250117A: Fermi GBM Observation
  44. Fermi GRB 250127B: Global MASTER-Net observations report
  45. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  46. GRB 250127A: SVOM/VT upper limit
  47. IPN triangulation of GRB 250119C
  48. GRB 250127A: Swift ToO observations
  49. GRB 250127A: LCO optical upper limit
  50. GRB 241223A: cubesat Avion detection
  51. GRB 250126A: CALET Gamma-Ray Burst Monitor detection
  52. EP250125A: Non-detection from Fermi-GBM Observations
  53. GRB 250126A: MAXI/GSC detection
  54. EP250108a / SN 2025kg: Refined Analysis of EP-WXT Detection
  55. GECAM-A detection of a bright burst from SGR 1E1841-045
  56. GRB 250118A: Fermi GBM Observation
  57. EP250125a: Optical upper limit with Kinder observations
  58. EP250125a: REM optical counterpart detection
  59. GRB 250119C: Fermi GBM Observation
  60. EP250125a: Swift/XRT detection of a fading counterpart
  61. EP250125a: a new X-ray transient detected by Einstein Probe
  62. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  63. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  64. IPN triangulation of a bright burst from SGR 1E1841-045
  65. GRB 250121A: CALET Gamma-Ray Burst Monitor detection
  66. EP250108a: AbAO, CMO and Terskol optical upper limits
  67. Konus-Wind detection of GRB 250118B
  68. GRB 250121A: Fermi GBM Observation
  69. IPN triangulation of GRB 250118B
  70. Konus-Wind detection of GRB 250119B
  71. IPN triangulation of GRB 250119B
  72. Improved IPN triangulation of GRB 250107C
  73. GRB 250114A: Swift-BAT refined analysis
  74. GRB 250121A: INTEGRAL/SPI-ACS detection
  75. GRB 250121A: Fermi-LAT detection
  76. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  77. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  78. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  79. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  80. GRB 250119B: Fermi GBM Observation
  81. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  82. Konus-Wind detection of GRB 250117A
  83. IPN triangulation of GRB 250117A (short)
  84. ATCA detection of possible radio counterpart to GRB 250114A
  85. EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
  86. GRB 250119B: INTEGRAL/SPI-ACS detection
  87. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  88. EP 250108A: Late-time optical observation by LCO
  89. GRB 250117A: SVOM/GRM observation of a short burst
  90. LIGO/Virgo/KAGRA S250119cv: Updated Sky localization and EM Bright Classification
  91. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  92. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  93. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  94. LIGO/Virgo/KAGRA S250119ag: Updated Sky localization
  95. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  96. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  97. GRB 250117A: GECAM observation of a short burst
  98. LIGO/Virgo/KAGRA S250118dp: Updated Sky localization
  99. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  100. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate

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