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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"

20538 results found.

  1. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  2. GRB 250128B: VLA radio upper limit
  3. Ep250125A: 1.3m DFOT optical upper limit
  4. GRB 250129A: Skynet optical observations
  5. GRB 250128B: TNG optical upper limit
  6. GRB 250129A: Swift/UVOT Detection
  7. GRB 250128B: VLT/HAWKI near-infrared observations
  8. GRB 250127A: CrAO and Terskol optical upper limits
  9. GRB 250129A: Enhanced Swift-XRT position
  10. GRB 250128B: NOT optical upper limit
  11. GRB 250128B: VLT/FORS2 optical observations
  12. GRB 250129A: REM optical/NIR afterglow detection
  13. GRB 250129A: OHP/T193 optical and spectroscopy observations
  14. GRB 250129A: Early afterglow detection by LCO.
  15. GRB 250128B: OHP/T193 optical upper limit
  16. GRB 250129A: LCO optical observations
  17. GRB 250129A: NOT optical observations and redshift confirmation
  18. GRB 250128B: Enhanced Swift-XRT position
  19. GRB 250129A: Swift detection of a burst with an optical counterpart
  20. GRB 250128B: Swift-XRT refined Analysis
  21. GRB 250128B: GOTO optical upper limit
  22. GRB 250128B: LCO optical observations
  23. GRB 250128B: Swift detection of a short burst
  24. GRB 250127A: Swift-XRT observations
  25. GRB 250127B: DDOTI Upper Limit on the Afterglow
  26. IPN triangulation of GRB 250119C
  27. GRB 250127A: LCO optical upper limit
  28. EP250108a / SN 2025kg: Refined Analysis of EP-WXT Detection
  29. EP250125a: Optical upper limit with Kinder observations
  30. EP250125a: REM optical counterpart detection
  31. EP250125a: a new X-ray transient detected by Einstein Probe
  32. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  33. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  34. EP250108a: AbAO, CMO and Terskol optical upper limits
  35. IPN triangulation of GRB 250118B
  36. Konus-Wind detection of GRB 250119B
  37. IPN triangulation of GRB 250119B
  38. GRB 250121A: INTEGRAL/SPI-ACS detection
  39. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  40. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  41. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  42. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  43. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  44. GRB 250119B: Fermi GBM Observation
  45. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  46. IPN triangulation of GRB 250117A (short)
  47. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  48. EP 250108A: Late-time optical observation by LCO
  49. LIGO/Virgo/KAGRA S250119cv: Updated NED Galaxies in the Localization Volume
  50. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  51. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  52. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  53. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  54. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  55. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  56. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  57. EP250108a / AT2025kg: GMG Optical Observations
  58. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  59. Konus-Wind detection of GRB 250116A
  60. GRB 241217A / EP241217B: radio detection with the VLA
  61. GRB 250114B: Swift-XRT afterglow detection
  62. EP250108a: MeerKAT radio upper limit
  63. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  64. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  65. IPN triangulation of GRB 250113A
  66. GRB 250114B: Liverpool Telescope optical upper limit
  67. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  68. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  69. GRB 250114A: LCO optical counterpart detection.
  70. GRB 250114B: OHP/T193 optical upper limit
  71. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  72. GRB 250114A: LCOGT optical afterglow i-band detection
  73. GRB 250114B : GIT optical upper limit
  74. EP250111a: SAO RAS optical upper limit
  75. GRB 250114A: Enhanced Swift-XRT position
  76. GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
  77. GRB 250114A: REM detection of the optical and NIR counterpart
  78. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  79. GRB 250114A: LCO optical observations
  80. GRB 250114A: TRT optical observations
  81. GRB 250114A: Swift detection of a burst with an optical counterpart
  82. GRB 250101A: Terskol Zeiss-2000 optical observations
  83. EP250108a / AT 2025kg: SAO RAS optical observations
  84. EP241021a: SMA radio observation
  85. GRB 250113A: SVOM/GRM observation of a long burst
  86. EP250109b: optical upper limits with the Liverpool Telescope
  87. GRB 250106A: Swift-XRT afterglow detection
  88. EP250111a: KAIT optical observations
  89. GRB 250109A / EP250109a: Mephisto optical upper limits
  90. EP250108a: Mephisto detection
  91. EP250111a: Mondy optical observation
  92. EP250108a / AT 2025kg: LCO optical observations
  93. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  94. EP250111a: NOT likely optical counterpart
  95. EP250111a: a new X-ray transient detected by Einstein Probe
  96. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  97. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  98. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  99. Konus-Wind detection of GRB 250107C
  100. EP-WXT trigger EP250108a：Xinglong optical follow-up observations

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