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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.

Advanced Search Examples (click to copy):

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

11774 results found.

  1. Swift GRB250221.15: Global MASTER-Net observations report
  2. Fermi Gamma-ray Burst Monitor trigger 761788229/250220993 is not a GRB
  3. GRB 250220B: Fermi GBM Final Real-time Localization
  4. Fermi Gamma-ray Burst Monitor trigger 761782146/250220923 is not a GRB
  5. GRB 250220A: Fermi GBM Final Real-time Localization
  6. EP250220a: Global MASTER-Net observations report
  7. EP250220a: EP-WXT detection of a fast X-ray transient
  8. Konus-Wind detection of GRB 250217C (short)
  9. GRB 250219A: OHP/T193 optical upper limit
  10. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  11. Konus-Wind detection of GRB 250215A / EP250215a
  12. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  13. GRB 250217C: SVOM/GRM observation
  14. SVOM/sb25021804: SVOM detection of a long X-ray transient
  15. GRB 250213A: Swift-XRT observations
  16. GRB 250216A: AstroSat CZTI detection
  17. GRB 250217C: AstroSat CZTI detection of a short burst
  18. Fermi GRB 250217A: Global MASTER-Net observations report
  19. GRB 250216A: Fermi GBM Final Real-time Localization
  20. GRB 250215A: Swift-XRT refined Analysis
  21. EP250215a / GRB 250215A: AstroSat CZTI detection
  22. EP250215a: Global MASTER-Net observations report
  23. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  24. Fermi GRB 250215A: Global MASTER-Net observations report
  25. Fermi trigger No 761206993: Global MASTER-Net observations report
  26. EP250212a: Liverpool Telescope optical upper limits
  27. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  28. Fermi GRB 250212A: Global MASTER-Net observations report
  29. Fermi trigger No 760945500: Global MASTER-Net observations report
  30. GRB 250211B: A long GRB detected by INTEGRAL
  31. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  32. GRB 250207A: Fermi GBM Observation
  33. Konus-Wind detection of GRB 250207A
  34. Konus-Wind detection of GRB 250206A
  35. EP250207b: Global MASTER-Net observations report
  36. GRB 250207A: Skynet optical afterglow observations
  37. GRB 250210A: AstroSat CZTI detection
  38. EP250207b: a new X-ray transient detected by Einstein Probe
  39. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  40. Fermi GRB 250210A: Global MASTER-Net observations report
  41. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  42. IceCube Alert 250207.09: Global MASTER-Net observations report
  43. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  44. LIGO/Virgo/KAGRA S250207bg: Updated NED Galaxies in the Localization Volume
  45. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  46. LIGO/Virgo/KAGRA S250206dm: (Update-7) NED Galaxies in the Localization Volume
  47. GRB 250206A: Fermi-LAT detection
  48. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
  49. GRB 250207A: Swift-XRT refined Analysis
  50. LIGO/Virgo/KAGRA S250207bg: NED Galaxies in the Localization Volume
  51. Konus-Wind detection of GRB 250204B
  52. GRB 250129A: Continued AbAO and Mondy optical observations
  53. GRB 250207B: MAXI/GSC detection
  54. The EP-WXT trigger 01709131332 is likely a flaring star
  55. LIGO/Virgo/KAGRA S250206dm: Updated-6 NED Galaxies in the Localization Volume
  56. Fermi-LAT Gamma-ray Observations of IceCube-250203A
  57. LIGO/Virgo/KAGRA S250206dm: Coverage and upper limits from MAXI/GSC observations
  58. LIGO/Virgo/KAGRA S250206dm: Updated NED Galaxies in the Localization Volume
  59. LIGO/Virgo/KAGRA S250206dm: NED Galaxies in the Localization Volume
  60. EP250205a/GRB 250205A: Einstein Probe observation
  61. LIGO/Virgo/KAGRA S250205bk: NED Galaxies in the Localization Volume
  62. Konus-Wind detection of GRB 250201A
  63. Konus-Wind detection of GRB 250202B
  64. GRB 250204B: AstroSat CZTI detection of a short burst
  65. GRB 250202C: GRBAlpha detection
  66. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  67. GRB 250202C: Fermi GBM Final Real-time Localization
  68. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  69. Swift GRB250129A: MASTER 4 days observations report
  70. GRB 250201A: INTEGRAL SPI/ACS detection
  71. Konus-Wind detection of GRB 250129A
  72. LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations
  73. EP250108A / SN 2025kg: Upper limits from a neutrino search with IceCube
  74. GRB 250128B: VLA possible radio detection
  75. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  76. GRB 250129A: Skynet optical observations
  77. GRB 250129A: Swift-XRT refined Analysis
  78. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  79. GRB 250128B: VLT/FORS2 optical observations
  80. GRB 250128B: Swift-XRT refined Analysis
  81. Swift GRB 250128B: Global MASTER-Net observations report
  82. EP250125a: Upper limits from Swift/BAT-GUANO
  83. GRB 250128B: Swift detection of a short burst
  84. GRB 250127B: DDOTI Upper Limit on the Afterglow
  85. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  86. GRB 250127A: EP-FXT afterglow detection
  87. GRB 250117A: Fermi GBM Observation
  88. Fermi GRB 250127B: Global MASTER-Net observations report
  89. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  90. GRB 250126A: MAXI/GSC detection
  91. EP250108a / SN 2025kg: Refined Analysis of EP-WXT Detection
  92. EP250125a: a new X-ray transient detected by Einstein Probe
  93. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  94. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  95. IPN triangulation of a bright burst from SGR 1E1841-045
  96. EP250108a: AbAO, CMO and Terskol optical upper limits
  97. Konus-Wind detection of GRB 250118B
  98. GRB 250121A: Fermi GBM Observation
  99. IPN triangulation of GRB 250118B
  100. Konus-Wind detection of GRB 250119B

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