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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"

32495 results found.

  1. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  2. GRB 250128B: Gemini-North optical extended source detection
  3. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  4. GRB 250128B: TNG optical upper limit
  5. GRB 250129A: Swift/UVOT Detection
  6. GRB 250128B: VLT/HAWKI near-infrared observations
  7. GRB 250127A: CrAO and Terskol optical upper limits
  8. GRB 250128B: NOT optical upper limit
  9. GRB 250128B: VLT/FORS2 optical observations
  10. GRB 250129A: REM optical/NIR afterglow detection
  11. GRB 250129A: OHP/T193 optical and spectroscopy observations
  12. GRB 250129A: Early afterglow detection by LCO.
  13. GRB 250128B: OHP/T193 optical upper limit
  14. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  15. GRB 250129A: LCO optical observations
  16. GRB 250129A: NOT optical observations and redshift confirmation
  17. GRB 250129A: GOTO optical observations show brightening afterglow
  18. GRB 250129A: VLT/X-shooter redshift of z = 2.151
  19. Swift GRB 250129A: Global MASTER-Net observations report
  20. Fermi GRB 250128B: Global MASTER-Net observations report
  21. GRB 250128B: Fermi GBM Observation
  22. GRB 250128B: GOTO optical upper limit
  23. Swift GRB 250128B: Global MASTER-Net observations report
  24. EP250125a: Upper limits from Swift/BAT-GUANO
  25. GRB 250128B: LCO optical observations
  26. GRB 250127A: Swift-XRT observations
  27. GRB 250127B: DDOTI Upper Limit on the Afterglow
  28. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  29. GRB 250127A: EP-FXT afterglow detection
  30. Fermi GRB 250128A: Global MASTER-Net observations report
  31. GRB 250117A: Fermi GBM Observation
  32. Fermi GRB 250127B: Global MASTER-Net observations report
  33. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  34. GRB 250127A: SVOM/VT upper limit
  35. IPN triangulation of GRB 250119C
  36. GRB 250127A: Swift ToO observations
  37. GRB 250127A: LCO optical upper limit
  38. GRB 241223A: cubesat Avion detection
  39. GRB 250126A: CALET Gamma-Ray Burst Monitor detection
  40. EP250125A: Non-detection from Fermi-GBM Observations
  41. GRB 250126A: MAXI/GSC detection
  42. EP250108a / SN 2025kg: Refined Analysis of EP-WXT Detection
  43. GECAM-A detection of a bright burst from SGR 1E1841-045
  44. GRB 250118A: Fermi GBM Observation
  45. EP250125a: Optical upper limit with Kinder observations
  46. EP250125a: REM optical counterpart detection
  47. GRB 250119C: Fermi GBM Observation
  48. EP250125a: Swift/XRT detection of a fading counterpart
  49. EP250125a: a new X-ray transient detected by Einstein Probe
  50. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  51. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  52. IPN triangulation of a bright burst from SGR 1E1841-045
  53. GRB 250121A: CALET Gamma-Ray Burst Monitor detection
  54. EP250108a: AbAO, CMO and Terskol optical upper limits
  55. Konus-Wind detection of GRB 250118B
  56. GRB 250121A: Fermi GBM Observation
  57. IPN triangulation of GRB 250118B
  58. Konus-Wind detection of GRB 250119B
  59. IPN triangulation of GRB 250119B
  60. Improved IPN triangulation of GRB 250107C
  61. GRB 250114A: Swift-BAT refined analysis
  62. GRB 250121A: INTEGRAL/SPI-ACS detection
  63. GRB 250121A: Fermi-LAT detection
  64. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  65. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  66. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  67. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  68. GRB 250119B: Fermi GBM Observation
  69. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  70. Konus-Wind detection of GRB 250117A
  71. IPN triangulation of GRB 250117A (short)
  72. ATCA detection of possible radio counterpart to GRB 250114A
  73. EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
  74. GRB 250119B: INTEGRAL/SPI-ACS detection
  75. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  76. EP 250108A: Late-time optical observation by LCO
  77. GRB 250117A: SVOM/GRM observation of a short burst
  78. LIGO/Virgo/KAGRA S250119cv: Updated Sky localization and EM Bright Classification
  79. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  80. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  81. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  82. LIGO/Virgo/KAGRA S250119ag: Updated Sky localization
  83. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  84. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  85. GRB 250117A: GECAM observation of a short burst
  86. LIGO/Virgo/KAGRA S250118dp: Updated Sky localization
  87. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  88. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  89. LIGO/Virgo/KAGRA S250118t: Updated Sky localization
  90. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  91. EP250108a / AT2025kg: GMG Optical Observations
  92. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  93. EP250108a / AT2025kg: VLA radio upper limit
  94. Konus-Wind detection of GRB 250116A
  95. GRB 250116A: GECAM-B detection of a long burst
  96. GRB 241217A / EP241217B: radio detection with the VLA
  97. GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
  98. GRB 250116A: Fermi-LAT detection
  99. GRB 250114B: Swift-XRT afterglow detection
  100. GRB 250114B: SVOM/VT upper limit

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