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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"

24608 results found.

  1. GRB 250129A: TNG NIR afterglow detection
  2. GRB 250129A: AKO Optical Afterglow Detection
  3. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  4. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  5. GRB 250128B: VLA radio upper limit
  6. Ep250125A: 1.3m DFOT optical upper limit
  7. GRB 250129A: Skynet optical observations
  8. GRB 250129A: Swift-XRT refined Analysis
  9. GRB 250128B: Gemini-North optical extended source detection
  10. GRB 250128B: TNG optical upper limit
  11. GRB 250129A: Swift/UVOT Detection
  12. GRB 250128B: VLT/HAWKI near-infrared observations
  13. GRB 250127A: CrAO and Terskol optical upper limits
  14. GRB 250129A: Enhanced Swift-XRT position
  15. GRB 250128B: NOT optical upper limit
  16. GRB 250128B: VLT/FORS2 optical observations
  17. GRB 250129A: REM optical/NIR afterglow detection
  18. GRB 250129A: OHP/T193 optical and spectroscopy observations
  19. GRB 250129A: Early afterglow detection by LCO.
  20. GRB 250128B: OHP/T193 optical upper limit
  21. GRB 250129A: LCO optical observations
  22. GRB 250128B: Enhanced Swift-XRT position
  23. GRB 250129A: Swift detection of a burst with an optical counterpart
  24. Swift GRB 250129A: Global MASTER-Net OT detection
  25. GRB 250128B: Swift-XRT refined Analysis
  26. GRB 250128B: GOTO optical upper limit
  27. EP250125a: Upper limits from Swift/BAT-GUANO
  28. GRB 250128B: LCO optical observations
  29. GRB 250128B: Swift detection of a short burst
  30. GRB 250127A: Swift-XRT observations
  31. GRB 250127B: DDOTI Upper Limit on the Afterglow
  32. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  33. Fermi GRB 250128A: Global MASTER-Net observations report
  34. GRB 250117A: Fermi GBM Observation
  35. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  36. IPN triangulation of GRB 250119C
  37. GRB 250127A: LCO optical upper limit
  38. GRB 241223A: cubesat Avion detection
  39. EP250125A: Non-detection from Fermi-GBM Observations
  40. GRB 250126A: MAXI/GSC detection
  41. GRB 250126A: BALROG localization (Fermi Trigger 759560335 / GRB 250126208)
  42. EP250125a: Optical upper limit with Kinder observations
  43. EP250125a: REM optical counterpart detection
  44. GRB 250119C: Fermi GBM Observation
  45. EP250125a: Swift/XRT detection of a fading counterpart
  46. EP250125a: a new X-ray transient detected by Einstein Probe
  47. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  48. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  49. EP250108a: AbAO, CMO and Terskol optical upper limits
  50. GRB 250121A: Fermi GBM Observation
  51. IPN triangulation of GRB 250118B
  52. IPN triangulation of GRB 250119B
  53. GRB 250114A: Swift-BAT refined analysis
  54. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  55. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  56. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  57. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  58. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  59. GRB 250119B: Fermi GBM Observation
  60. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  61. IPN triangulation of GRB 250117A (short)
  62. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  63. EP 250108A: Late-time optical observation by LCO
  64. LIGO/Virgo/KAGRA S250105bn: 1 counterpart neutrino candidate event from an IceCube neutrino search
  65. LIGO/Virgo/KAGRA S250119cv: Updated NED Galaxies in the Localization Volume
  66. LIGO/Virgo/KAGRA S250119cv: Updated Sky localization and EM Bright Classification
  67. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  68. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  69. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  70. LIGO/Virgo/KAGRA S250119ag: Updated Sky localization
  71. GRB 250117A: GECAM observation of a short burst
  72. LIGO/Virgo/KAGRA S250118dp: Updated Sky localization
  73. GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)
  74. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  75. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  76. LIGO/Virgo/KAGRA S250118t: Updated Sky localization
  77. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  78. EP250108a / AT2025kg: GMG Optical Observations
  79. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  80. GRB 241217A / EP241217B: radio detection with the VLA
  81. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  82. GRB 250114B: Swift-XRT afterglow detection
  83. EP250108a: MeerKAT radio upper limit
  84. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  85. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  86. LIGO/Virgo/KAGRA S250114ax: Updated Sky localization
  87. IPN triangulation of GRB 250113A
  88. GRB 250114B: Liverpool Telescope optical upper limit
  89. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  90. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  91. GRB 250114B: Swift-XRT observations
  92. GRB 250114A: LCO optical counterpart detection.
  93. GRB 250114B: OHP/T193 optical upper limit
  94. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  95. GRB 250114A: Swift-XRT refined Analysis
  96. GRB 250114A: LCOGT optical afterglow i-band detection
  97. GRB 250114B : GIT optical upper limit
  98. EP250111a: SAO RAS optical upper limit
  99. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  100. GRB 250114B: a short GRB detected with INTEGRAL

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