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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').

10636 results found.

  1. EP250227a: Einstein Probe detected of a fast X-ray transient
  2. EP250223a: J band upper limit by SYSU 80cm telescope
  3. EP250228a: Einstein Probe detection of an X-ray transient
  4. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  5. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  6. Konus-Wind detection of GRB 250225B
  7. GRB 250225B: VLT/FORS2 candidate optical afterglow
  8. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  9. EP250226a / GRB 250226A: TRT optical counterpart observation
  10. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  11. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  12. Fermi GRB 250226A: Global MASTER-Net observations report
  13. EP250225a: Einstein Probe detected of a fast X-ray transient
  14. Fermi GRB 250225A: Global MASTER-Net observations report
  15. EP250215A: J band upper limit by SYSU 80cm telescope
  16. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  17. GRB 250223C: Fermi GBM Final Real-time Localization
  18. GRB 250202B: VZLUSAT-2 detection
  19. GRB 250219A: EP-FXT afterglow detection
  20. EP250223a: 1.6m Mephisto and 50cm array observations
  21. 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
  22. EP250223a: NOT optical afterglow candidate
  23. Fermi GRB 250223A: Global MASTER-Net observations report
  24. EP250223a: Einstein Probe detection of an X-ray transient
  25. LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
  26. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  27. Konus-Wind detection of GRB 250221A
  28. GRB 250221A: Assy optical observations
  29. EP250220a: FTW optical and NIR observations and upper limits
  30. EP250220a: EP-FXT follow-up observations
  31. GRB 250221A: Swift-XRT refined Analysis
  32. EP250220a: Liverpool Telescope upper limits
  33. EP250220a: 1.6m Mephisto observations
  34. EP250220a: Liverpool Telescope optical upper limits
  35. GRB 250221A: Swift detection of a burst with an optical counterpart
  36. Swift GRB250221.15: Global MASTER-Net OT detection
  37. Swift GRB250221.15: Global MASTER-Net observations report
  38. Fermi Gamma-ray Burst Monitor trigger 761788229/250220993 is not a GRB
  39. GRB 250220B: Fermi GBM Final Real-time Localization
  40. Fermi Gamma-ray Burst Monitor trigger 761782146/250220923 is not a GRB
  41. GRB 250220A: Fermi GBM Final Real-time Localization
  42. EP250220a: Global MASTER-Net observations report
  43. EP250220a: EP-WXT detection of a fast X-ray transient
  44. Konus-Wind detection of GRB 250217C (short)
  45. GRB 250219A: OHP/T193 optical upper limit
  46. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  47. Konus-Wind detection of GRB 250215A / EP250215a
  48. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  49. GRB 250217C: SVOM/GRM observation
  50. SVOM/sb25021804: SVOM detection of a long X-ray transient
  51. GRB 250213A: Swift-XRT observations
  52. GRB 250216A: AstroSat CZTI detection
  53. GRB 250217C: AstroSat CZTI detection of a short burst
  54. Fermi GRB 250217A: Global MASTER-Net observations report
  55. GRB 250216A: Fermi GBM Final Real-time Localization
  56. GRB 250215A: Swift-XRT refined Analysis
  57. EP250215a / GRB 250215A: AstroSat CZTI detection
  58. EP250215a: Global MASTER-Net observations report
  59. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  60. Fermi GRB 250215A: Global MASTER-Net observations report
  61. Fermi trigger No 761206993: Global MASTER-Net observations report
  62. EP250212a: Liverpool Telescope optical upper limits
  63. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  64. Fermi GRB 250212A: Global MASTER-Net observations report
  65. Fermi trigger No 760945500: Global MASTER-Net observations report
  66. GRB 250211B: A long GRB detected by INTEGRAL
  67. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  68. GRB 250207A: Fermi GBM Observation
  69. Konus-Wind detection of GRB 250207A
  70. Konus-Wind detection of GRB 250206A
  71. EP250207b: Global MASTER-Net observations report
  72. GRB 250207A: Skynet optical afterglow observations
  73. GRB 250210A: AstroSat CZTI detection
  74. EP250207b: a new X-ray transient detected by Einstein Probe
  75. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  76. Fermi GRB 250210A: Global MASTER-Net observations report
  77. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  78. IceCube Alert 250207.09: Global MASTER-Net observations report
  79. Fermi-LAT Gamma-ray Observations of IceCube-250207A
  80. LIGO/Virgo/KAGRA S250207bg: Updated NED Galaxies in the Localization Volume
  81. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  82. LIGO/Virgo/KAGRA S250206dm: (Update-7) NED Galaxies in the Localization Volume
  83. GRB 250206A: Fermi-LAT detection
  84. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of the DDOTI optical candidates
  85. GRB 250207A: Swift-XRT refined Analysis
  86. LIGO/Virgo/KAGRA S250207bg: NED Galaxies in the Localization Volume
  87. Konus-Wind detection of GRB 250204B
  88. GRB 250129A: Continued AbAO and Mondy optical observations
  89. GRB 250207B: MAXI/GSC detection
  90. The EP-WXT trigger 01709131332 is likely a flaring star
  91. LIGO/Virgo/KAGRA S250206dm: Updated-6 NED Galaxies in the Localization Volume
  92. Fermi-LAT Gamma-ray Observations of IceCube-250203A
  93. LIGO/Virgo/KAGRA S250206dm: Coverage and upper limits from MAXI/GSC observations
  94. LIGO/Virgo/KAGRA S250206dm: Updated NED Galaxies in the Localization Volume
  95. LIGO/Virgo/KAGRA S250206dm: NED Galaxies in the Localization Volume
  96. EP250205a/GRB 250205A: Einstein Probe observation
  97. LIGO/Virgo/KAGRA S250205bk: NED Galaxies in the Localization Volume
  98. Konus-Wind detection of GRB 250201A
  99. Konus-Wind detection of GRB 250202B
  100. GRB 250204B: AstroSat CZTI detection of a short burst

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