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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

28292 results found.

  1. GRB 250128B: VLT/HAWKI near-infrared observations
  2. GRB 250127A: CrAO and Terskol optical upper limits
  3. GRB 250129A: Enhanced Swift-XRT position
  4. GRB 250128B: NOT optical upper limit
  5. GRB 250128B: VLT/FORS2 optical observations
  6. GRB 250129A: REM optical/NIR afterglow detection
  7. GRB 250129A: OHP/T193 optical and spectroscopy observations
  8. GRB 250129A: Early afterglow detection by LCO.
  9. GRB 250128B: OHP/T193 optical upper limit
  10. GRB 250129A: LCO optical observations
  11. GRB 250128B: Enhanced Swift-XRT position
  12. GRB 250129A: Swift detection of a burst with an optical counterpart
  13. Swift GRB 250129A: Global MASTER-Net OT detection
  14. GRB 250128B: Swift-XRT refined Analysis
  15. GRB 250128B: GOTO optical upper limit
  16. EP250125a: Upper limits from Swift/BAT-GUANO
  17. GRB 250128B: LCO optical observations
  18. GRB 250128B: Swift detection of a short burst
  19. GRB 250127A: Swift-XRT observations
  20. GRB 250127B: DDOTI Upper Limit on the Afterglow
  21. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  22. Fermi GRB 250128A: Global MASTER-Net observations report
  23. GRB 250117A: Fermi GBM Observation
  24. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  25. IPN triangulation of GRB 250119C
  26. GRB 250127A: LCO optical upper limit
  27. GRB 241223A: cubesat Avion detection
  28. EP250125A: Non-detection from Fermi-GBM Observations
  29. GRB 250126A: MAXI/GSC detection
  30. GRB 250126A: BALROG localization (Fermi Trigger 759560335 / GRB 250126208)
  31. EP250125a: Optical upper limit with Kinder observations
  32. EP250125a: REM optical counterpart detection
  33. GRB 250119C: Fermi GBM Observation
  34. EP250125a: Swift/XRT detection of a fading counterpart
  35. EP250125a: a new X-ray transient detected by Einstein Probe
  36. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  37. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  38. EP250108a: AbAO, CMO and Terskol optical upper limits
  39. GRB 250121A: Fermi GBM Observation
  40. IPN triangulation of GRB 250118B
  41. IPN triangulation of GRB 250119B
  42. GRB 250114A: Swift-BAT refined analysis
  43. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  44. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  45. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  46. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  47. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  48. GRB 250119B: Fermi GBM Observation
  49. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  50. IPN triangulation of GRB 250117A (short)
  51. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  52. EP 250108A: Late-time optical observation by LCO
  53. LIGO/Virgo/KAGRA S250105bn: 1 counterpart neutrino candidate event from an IceCube neutrino search
  54. LIGO/Virgo/KAGRA S250119cv: Updated NED Galaxies in the Localization Volume
  55. LIGO/Virgo/KAGRA S250119cv: Updated Sky localization and EM Bright Classification
  56. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  57. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  58. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  59. LIGO/Virgo/KAGRA S250119ag: Updated Sky localization
  60. GRB 250117A: GECAM observation of a short burst
  61. LIGO/Virgo/KAGRA S250118dp: Updated Sky localization
  62. GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)
  63. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  64. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  65. LIGO/Virgo/KAGRA S250118t: Updated Sky localization
  66. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  67. EP250108a / AT2025kg: GMG Optical Observations
  68. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  69. GRB 241217A / EP241217B: radio detection with the VLA
  70. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  71. GRB 250114B: Swift-XRT afterglow detection
  72. EP250108a: MeerKAT radio upper limit
  73. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  74. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  75. LIGO/Virgo/KAGRA S250114ax: Updated Sky localization
  76. IPN triangulation of GRB 250113A
  77. GRB 250114B: Liverpool Telescope optical upper limit
  78. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  79. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  80. GRB 250114B: Swift-XRT observations
  81. GRB 250114A: LCO optical counterpart detection.
  82. GRB 250114B: OHP/T193 optical upper limit
  83. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  84. GRB 250114A: Swift-XRT refined Analysis
  85. GRB 250114A: LCOGT optical afterglow i-band detection
  86. GRB 250114B : GIT optical upper limit
  87. EP250111a: SAO RAS optical upper limit
  88. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  89. GRB 250114B: a short GRB detected with INTEGRAL
  90. GRB 250114A: Enhanced Swift-XRT position
  91. GRB 250114A: REM detection of the optical and NIR counterpart
  92. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  93. Swift GRB250114A: Global MASTER-Net OT detection
  94. GRB 250114A: LCO optical observations
  95. GRB 250114A: TRT optical observations
  96. GRB 250114A: Swift detection of a burst with an optical counterpart
  97. GRB 250101A: Terskol Zeiss-2000 optical observations
  98. EP250108a / AT 2025kg: SAO RAS optical observations
  99. EP241021a: SMA radio observation
  100. GRB 250113A: SVOM/GRM observation of a long burst

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