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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.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

11760 results found.

  1. GRB 250213A: Swift-XRT observations
  2. GRB 250216A: AstroSat CZTI detection
  3. GRB 250217C: AstroSat CZTI detection of a short burst
  4. Fermi GRB 250217A: Global MASTER-Net observations report
  5. GRB 250216A: Fermi GBM Final Real-time Localization
  6. GRB 250215A: Swift-XRT refined Analysis
  7. EP250215a / GRB 250215A: AstroSat CZTI detection
  8. EP250215a: Global MASTER-Net observations report
  9. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  10. Fermi GRB 250215A: Global MASTER-Net observations report
  11. Fermi trigger No 761206993: Global MASTER-Net observations report
  12. EP250212a: Liverpool Telescope optical upper limits
  13. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  14. Fermi GRB 250212A: Global MASTER-Net observations report
  15. Fermi trigger No 760945500: Global MASTER-Net observations report
  16. GRB 250211B: A long GRB detected by INTEGRAL
  17. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  18. GRB 250207A: Fermi GBM Observation
  19. Konus-Wind detection of GRB 250207A
  20. Konus-Wind detection of GRB 250206A
  21. EP250207b: Global MASTER-Net observations report
  22. GRB 250207A: Skynet optical afterglow observations
  23. GRB 250210A: AstroSat CZTI detection
  24. EP250207b: a new X-ray transient detected by Einstein Probe
  25. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  26. Fermi GRB 250210A: Global MASTER-Net observations report
  27. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  28. IceCube Alert 250207.09: Global MASTER-Net observations report
  29. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  30. LIGO/Virgo/KAGRA S250207bg: Updated NED Galaxies in the Localization Volume
  31. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  32. LIGO/Virgo/KAGRA S250206dm: (Update-7) NED Galaxies in the Localization Volume
  33. GRB 250206A: Fermi-LAT detection
  34. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
  35. GRB 250207A: Swift-XRT refined Analysis
  36. LIGO/Virgo/KAGRA S250207bg: NED Galaxies in the Localization Volume
  37. Konus-Wind detection of GRB 250204B
  38. GRB 250129A: Continued AbAO and Mondy optical observations
  39. GRB 250207B: MAXI/GSC detection
  40. The EP-WXT trigger 01709131332 is likely a flaring star
  41. LIGO/Virgo/KAGRA S250206dm: Updated-6 NED Galaxies in the Localization Volume
  42. Fermi-LAT Gamma-ray Observations of IceCube-250203A
  43. LIGO/Virgo/KAGRA S250206dm: Coverage and upper limits from MAXI/GSC observations
  44. LIGO/Virgo/KAGRA S250206dm: Updated NED Galaxies in the Localization Volume
  45. LIGO/Virgo/KAGRA S250206dm: NED Galaxies in the Localization Volume
  46. EP250205a/GRB 250205A: Einstein Probe observation
  47. LIGO/Virgo/KAGRA S250205bk: NED Galaxies in the Localization Volume
  48. Konus-Wind detection of GRB 250201A
  49. Konus-Wind detection of GRB 250202B
  50. GRB 250204B: AstroSat CZTI detection of a short burst
  51. GRB 250202C: GRBAlpha detection
  52. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  53. GRB 250202C: Fermi GBM Final Real-time Localization
  54. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  55. Swift GRB250129A: MASTER 4 days observations report
  56. GRB 250201A: INTEGRAL SPI/ACS detection
  57. Konus-Wind detection of GRB 250129A
  58. LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations
  59. EP250108A / SN 2025kg: Upper limits from a neutrino search with IceCube
  60. GRB 250128B: VLA possible radio detection
  61. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  62. GRB 250129A: Skynet optical observations
  63. GRB 250129A: Swift-XRT refined Analysis
  64. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  65. GRB 250128B: VLT/FORS2 optical observations
  66. GRB 250128B: Swift-XRT refined Analysis
  67. Swift GRB 250128B: Global MASTER-Net observations report
  68. EP250125a: Upper limits from Swift/BAT-GUANO
  69. GRB 250128B: Swift detection of a short burst
  70. GRB 250127B: DDOTI Upper Limit on the Afterglow
  71. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  72. GRB 250127A: EP-FXT afterglow detection
  73. GRB 250117A: Fermi GBM Observation
  74. Fermi GRB 250127B: Global MASTER-Net observations report
  75. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  76. GRB 250126A: MAXI/GSC detection
  77. EP250108a / SN 2025kg: Refined Analysis of EP-WXT Detection
  78. EP250125a: a new X-ray transient detected by Einstein Probe
  79. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  80. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  81. IPN triangulation of a bright burst from SGR 1E1841-045
  82. EP250108a: AbAO, CMO and Terskol optical upper limits
  83. Konus-Wind detection of GRB 250118B
  84. GRB 250121A: Fermi GBM Observation
  85. IPN triangulation of GRB 250118B
  86. Konus-Wind detection of GRB 250119B
  87. IPN triangulation of GRB 250119B
  88. GRB 250121A: Fermi-LAT detection
  89. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  90. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  91. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  92. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  93. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  94. Konus-Wind detection of GRB 250117A
  95. IPN triangulation of GRB 250117A (short)
  96. LIGO/Virgo/KAGRA S250119cv: Updated NED Galaxies in the Localization Volume
  97. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  98. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  99. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  100. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening

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