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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').
Advanced Search

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"

45477 results found.

  1. Konus-Wind detection of GRB 250119B
  2. IPN triangulation of GRB 250119B
  3. GRB 250122A: Fermi GBM Final Real-time Localization
  4. Improved IPN triangulation of GRB 250107C
  5. GRB 250114A: Swift-BAT refined analysis
  6. GRB 250121A: INTEGRAL/SPI-ACS detection
  7. GRB 250121A: Fermi-LAT detection
  8. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  9. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  10. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  11. GRB 250121A: Fermi GBM Final Real-time Localization
  12. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  13. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  14. GRB 250119B: Fermi GBM Observation
  15. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  16. Konus-Wind detection of GRB 250117A
  17. IPN triangulation of GRB 250117A (short)
  18. ATCA detection of possible radio counterpart to GRB 250114A
  19. EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
  20. GRB 250119B: INTEGRAL/SPI-ACS detection
  21. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  22. EP 250108A: Late-time optical observation by LCO
  23. GRB 250117A: SVOM/GRM observation of a short burst
  24. LIGO/Virgo/KAGRA S250105bn: 1 counterpart neutrino candidate event from an IceCube neutrino search
  25. LIGO/Virgo/KAGRA S250119cv: Updated NED Galaxies in the Localization Volume
  26. LIGO/Virgo/KAGRA S250119cv: Updated Sky localization and EM Bright Classification
  27. GRB 250119C: Fermi GBM Final Real-time Localization
  28. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  29. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  30. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  31. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  32. LIGO/Virgo/KAGRA S250119ag: Updated Sky localization
  33. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  34. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  35. GRB 250117A: GECAM observation of a short burst
  36. LIGO/Virgo/KAGRA S250118dp: Updated Sky localization
  37. GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)
  38. GRB 250119B: Fermi GBM Final Real-time Localization
  39. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  40. GRB 250119A: Fermi GBM Final Real-time Localization
  41. GRB 250118A: Fermi GBM Final Real-time Localization
  42. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo/KAGRA S250118t: Updated Sky localization
  44. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  45. EP250108a / AT2025kg: GMG Optical Observations
  46. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  47. EP250108a / AT2025kg: VLA radio upper limit
  48. Fermi Gamma-ray Burst Monitor trigger 758829338/250117747 is not a GRB
  49. Konus-Wind detection of GRB 250116A
  50. GRB 250116A: GECAM-B detection of a long burst
  51. GRB 241217A / EP241217B: radio detection with the VLA
  52. GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
  53. Swift Trigger 1282245 is not a GRB
  54. GRB 250116A: Fermi-LAT detection
  55. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  56. GRB 250114B: Swift-XRT afterglow detection
  57. GRB 250114B: SVOM/VT upper limit
  58. Fermi Gamma-ray Burst Monitor trigger 758659047/250115776 is not a GRB
  59. EP250108a: MeerKAT radio upper limit
  60. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  61. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  62. LIGO/Virgo/KAGRA S250114ax: Updated Sky localization
  63. Konus-Wind detection of GRB 250113A
  64. IPN triangulation of GRB 250113A
  65. GRB 250114B: Liverpool Telescope optical upper limit
  66. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  67. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  68. GRB 250114B: Swift-XRT observations
  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: Swift-XRT refined Analysis
  73. Integral GRB250114.55: Global MASTER-Net observations report
  74. GRB 250114A: LCOGT optical afterglow i-band detection
  75. GRB 250114B : GIT optical upper limit
  76. GRB 250114B: Swift ToO observations
  77. EP250111a: SAO RAS optical upper limit
  78. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  79. GRB 250114B: a short GRB detected with INTEGRAL
  80. EP250108a: correction to GCN 38908
  81. GRB 250114A: Enhanced Swift-XRT position
  82. GRB 250113A: INTEGRAL/SPI-ACS detection
  83. GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
  84. GRB 250114A: REM detection of the optical and NIR counterpart
  85. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  86. Swift GRB250114A: Global MASTER-Net OT detection
  87. GRB 250114A: LCO optical observations
  88. GRB 250114A: TRT optical observations
  89. Swift GRB 250114A: Global MASTER-Net observations report
  90. GRB 250114A: Swift detection of a burst with an optical counterpart
  91. GRB 250101A: Terskol Zeiss-2000 optical observations
  92. EP250108a / AT 2025kg: SAO RAS optical observations
  93. EP241021a: SMA radio observation
  94. GRB 250113A: SVOM/GRM observation of a long burst
  95. GRB 250107A: VZLUSAT-2 detection
  96. EP250109b: optical upper limits with the Liverpool Telescope
  97. GRB 250109A / EP250109a: GRBAlpha detection
  98. GRB 250107D: GRBAlpha detection
  99. GRB 250106A: Swift-XRT afterglow detection
  100. Fermi trigger No 758442826: Global MASTER-Net observations report

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