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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"

28281 results found.

  1. GRB 250128B: LCO optical observations
  2. GRB 250128B: Swift detection of a short burst
  3. GRB 250127A: Swift-XRT observations
  4. GRB 250127B: DDOTI Upper Limit on the Afterglow
  5. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  6. Fermi GRB 250128A: Global MASTER-Net observations report
  7. GRB 250117A: Fermi GBM Observation
  8. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  9. IPN triangulation of GRB 250119C
  10. GRB 250127A: LCO optical upper limit
  11. GRB 241223A: cubesat Avion detection
  12. EP250125A: Non-detection from Fermi-GBM Observations
  13. GRB 250126A: MAXI/GSC detection
  14. GRB 250126A: BALROG localization (Fermi Trigger 759560335 / GRB 250126208)
  15. EP250125a: Optical upper limit with Kinder observations
  16. EP250125a: REM optical counterpart detection
  17. GRB 250119C: Fermi GBM Observation
  18. EP250125a: Swift/XRT detection of a fading counterpart
  19. EP250125a: a new X-ray transient detected by Einstein Probe
  20. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  21. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  22. EP250108a: AbAO, CMO and Terskol optical upper limits
  23. GRB 250121A: Fermi GBM Observation
  24. IPN triangulation of GRB 250118B
  25. IPN triangulation of GRB 250119B
  26. GRB 250114A: Swift-BAT refined analysis
  27. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  28. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  29. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  30. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  31. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  32. GRB 250119B: Fermi GBM Observation
  33. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  34. IPN triangulation of GRB 250117A (short)
  35. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  36. EP 250108A: Late-time optical observation by LCO
  37. LIGO/Virgo/KAGRA S250105bn: 1 counterpart neutrino candidate event from an IceCube neutrino search
  38. LIGO/Virgo/KAGRA S250119cv: Updated NED Galaxies in the Localization Volume
  39. LIGO/Virgo/KAGRA S250119cv: Updated Sky localization and EM Bright Classification
  40. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  41. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  42. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo/KAGRA S250119ag: Updated Sky localization
  44. GRB 250117A: GECAM observation of a short burst
  45. LIGO/Virgo/KAGRA S250118dp: Updated Sky localization
  46. GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)
  47. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  48. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  49. LIGO/Virgo/KAGRA S250118t: Updated Sky localization
  50. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  51. EP250108a / AT2025kg: GMG Optical Observations
  52. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  53. GRB 241217A / EP241217B: radio detection with the VLA
  54. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  55. GRB 250114B: Swift-XRT afterglow detection
  56. EP250108a: MeerKAT radio upper limit
  57. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  58. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  59. LIGO/Virgo/KAGRA S250114ax: Updated Sky localization
  60. IPN triangulation of GRB 250113A
  61. GRB 250114B: Liverpool Telescope optical upper limit
  62. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  63. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  64. GRB 250114B: Swift-XRT observations
  65. GRB 250114A: LCO optical counterpart detection.
  66. GRB 250114B: OHP/T193 optical upper limit
  67. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  68. GRB 250114A: Swift-XRT refined Analysis
  69. GRB 250114A: LCOGT optical afterglow i-band detection
  70. GRB 250114B : GIT optical upper limit
  71. EP250111a: SAO RAS optical upper limit
  72. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  73. GRB 250114B: a short GRB detected with INTEGRAL
  74. GRB 250114A: Enhanced Swift-XRT position
  75. GRB 250114A: REM detection of the optical and NIR counterpart
  76. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  77. Swift GRB250114A: Global MASTER-Net OT detection
  78. GRB 250114A: LCO optical observations
  79. GRB 250114A: TRT optical observations
  80. GRB 250114A: Swift detection of a burst with an optical counterpart
  81. GRB 250101A: Terskol Zeiss-2000 optical observations
  82. EP250108a / AT 2025kg: SAO RAS optical observations
  83. EP241021a: SMA radio observation
  84. GRB 250113A: SVOM/GRM observation of a long burst
  85. GRB 250107A: VZLUSAT-2 detection
  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: Swift UVOT detections
  94. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  95. EP250111a: NOT likely optical counterpart
  96. GRB 250101B: Fermi GBM Observation
  97. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  98. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  99. GRB 250108A: Swift/XRT afterglow fading
  100. LIGO/Virgo/KAGRA S250109bi: Updated Sky localization

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