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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').
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"

12172 results found.

  1. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  2. GRB 250309B: Swift-XRT refined Analysis
  3. GRB 250309B / AT2025dws: Swift-UVOT detection
  4. Fermi GRB 250309A: Global MASTER-Net observations report
  5. Fermi-LAT gamma-ray observations of IceCube-250309A
  6. IceCube Alert 250309.32: Global MASTER-Net observations report
  7. EP250308a: Einstein Probe detection of an X-ray transient
  8. The EP-WXT trigger 01709132387 is likely a flaring star
  9. Fermi GRB 250307A: Global MASTER-Net observations report
  10. Konus-Wind detection of GRB 250306A
  11. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  12. GRB 250305A: AstroSat CZTI detection
  13. GRB 250306A: AstroSat CZTI detection
  14. Fermi trigger No 762963055: Global MASTER-Net observations report
  15. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  16. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  17. EP 250304A: Optical counterpart detection by LCO
  18. EP250302A: 1.3m DFOT optical afterglow detection
  19. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  20. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  21. Konus-Wind detection of GRB 250222A
  22. EP250304a: Einstein Probe detection of an X-ray transient
  23. EP250302a: SAO RAS optical observations
  24. EP250302a : GIT optical follow-up
  25. EP250302a: optical observation from the INAF Asiago Observatory
  26. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  27. EP250302A: VLT near-infrared observations
  28. EP250302a: OHP/T193 optical and spectroscopic observations
  29. EP250302a: Einstein Probe detection of an X-ray transient
  30. EP250302a: Montarrenti Observatory optical detection
  31. Fermi GRB 250302A: Global MASTER-Net observations report
  32. EP250302a: FTW optical and NIR detection
  33. IceCube-250302A - IceCube observation of a high-energy neutrino candidate track-like event
  34. EP250228a: Optical observations with Kinder and Swift/UVOT
  35. Konus-Wind detection of GRB 250226A
  36. GRB 250225B: VLT/HAWKI near-infrared observations
  37. EP250227a: Einstein Probe detected of a fast X-ray transient
  38. EP250223a: J band upper limit by SYSU 80cm telescope
  39. EP250228a: Einstein Probe detection of an X-ray transient
  40. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  41. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  42. Konus-Wind detection of GRB 250225B
  43. GRB 250225B: VLT/FORS2 candidate optical afterglow
  44. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  45. EP250226a / GRB 250226A: TRT optical counterpart observation
  46. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  47. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  48. Fermi GRB 250226A: Global MASTER-Net observations report
  49. EP250225a: Einstein Probe detected of a fast X-ray transient
  50. Fermi GRB 250225A: Global MASTER-Net observations report
  51. EP250215A: J band upper limit by SYSU 80cm telescope
  52. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  53. GRB 250223C: Fermi GBM Final Real-time Localization
  54. GRB 250202B: VZLUSAT-2 detection
  55. GRB 250219A: EP-FXT afterglow detection
  56. EP250223a: 1.6m Mephisto and 50cm array observations
  57. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO trigger with ID 762004910: Identification of a GW compact binary merger candidate possibly associated with a sub-threshold Swift/BAT-GUANO trigger
  58. EP250223a: NOT optical afterglow candidate
  59. Fermi GRB 250223A: Global MASTER-Net observations report
  60. EP250223a: Einstein Probe detection of an X-ray transient
  61. LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
  62. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  63. Konus-Wind detection of GRB 250221A
  64. GRB 250221A: Assy optical observations
  65. EP250220a: FTW optical and NIR observations and upper limits
  66. EP250220a: EP-FXT follow-up observations
  67. GRB 250221A: Swift-XRT refined Analysis
  68. EP250220a: Liverpool Telescope upper limits
  69. EP250220a: 1.6m Mephisto observations
  70. EP250220a: Liverpool Telescope optical upper limits
  71. GRB 250221A: Swift detection of a burst with an optical counterpart
  72. Swift GRB250221.15: Global MASTER-Net OT detection
  73. Swift GRB250221.15: Global MASTER-Net observations report
  74. Fermi Gamma-ray Burst Monitor trigger 761788229/250220993 is not a GRB
  75. GRB 250220B: Fermi GBM Final Real-time Localization
  76. Fermi Gamma-ray Burst Monitor trigger 761782146/250220923 is not a GRB
  77. GRB 250220A: Fermi GBM Final Real-time Localization
  78. EP250220a: Global MASTER-Net observations report
  79. EP250220a: EP-WXT detection of a fast X-ray transient
  80. Konus-Wind detection of GRB 250217C (short)
  81. GRB 250219A: OHP/T193 optical upper limit
  82. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  83. Konus-Wind detection of GRB 250215A / EP250215a
  84. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  85. GRB 250217C: SVOM/GRM observation
  86. SVOM/sb25021804: SVOM detection of a long X-ray transient
  87. GRB 250213A: Swift-XRT observations
  88. GRB 250216A: AstroSat CZTI detection
  89. GRB 250217C: AstroSat CZTI detection of a short burst
  90. Fermi GRB 250217A: Global MASTER-Net observations report
  91. GRB 250216A: Fermi GBM Final Real-time Localization
  92. GRB 250215A: Swift-XRT refined Analysis
  93. EP250215a / GRB 250215A: AstroSat CZTI detection
  94. EP250215a: Global MASTER-Net observations report
  95. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  96. Fermi GRB 250215A: Global MASTER-Net observations report
  97. Fermi trigger No 761206993: Global MASTER-Net observations report
  98. EP250212a: Liverpool Telescope optical upper limits
  99. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  100. Fermi GRB 250212A: Global MASTER-Net observations report

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