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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"

3136 results found.

  1. GRB 250502A: Montarrenti Observatory optical detection
  2. GRB 250502B: AstroSat CZTI detection
  3. EP250427a / GRB 250427A: OHP/T193 continued photometric observations
  4. Fermi trigger No 767623859: Global MASTER-Net observations report
  5. EP250427a: LT optical counterpart detection
  6. GRB 250407A: GRBAlpha detection
  7. GRB 250424A: AstroSat CZTI detection of a bright long burst
  8. GRB 250421A: AstroSat CZTI detection
  9. GRB 250419A: Mephisto Multi-band Optical Detection
  10. Fermi GRB 250421A: Global MASTER-Net observations report
  11. GRB 250421B: AstroSat CZTI detection of a bright long burst
  12. IceCube Alert 250421.71: Global MASTER-Net observations report
  13. GRB 250416B: Fermi GBM Final Real-time Localization
  14. GRB 250413A: AstroSat CZTI detection
  15. GRB 250412A: AstroSat CZTI detection
  16. EP250404a: Nanshan 0.43m Telescope optical observatios
  17. Fermi trigger No 766148493: Global MASTER-Net observations report
  18. Fermi trigger No 766173972: Global MASTER-Net observations report
  19. GRB 250407A: Mondy and AbAO Optical Observations
  20. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  21. Fermi GRB 250407A: Global MASTER-Net observations report
  22. GRB 250406A: AstroSat CZTI detection
  23. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  24. GRB 250404A / EP250404a: Mondy optical observations
  25. GRB 250404B: AstroSat CZTI detection of a short burst
  26. GRB 250403A: AstroSat CZTI detection
  27. Fermi GRB 250404A: Global MASTER-Net observations report
  28. EP250404a: Xinglong decaying optical counterpart
  29. GRB 250404A: Fermi GBM Detection
  30. GRB 250402B: AstroSat CZTI detection of a short burst
  31. GRB 250314A: ALMA detection
  32. GRB 250331D: Fermi GBM Final Real-time Localization
  33. GRB 250331A: MAXI/GSC detection
  34. Fermi GRB 250330A: Global MASTER-Net observations report
  35. IceCube Alert 250330.35: Global MASTER-Net observations report
  36. Fermi trigger No 764700395: Global MASTER-Net observations report
  37. EP250321a: Mondy AZT-33IK Continued Optical Observations
  38. GRB 250322A: AstroSat CZTI detection of a short burst
  39. GRB 250322B: AstroSat CZTI detection of a bright long burst
  40. EP250321a: Mondy AZT-33IK Optical Observations
  41. EP250321a: LCO optical counterpart detection
  42. EP250321A: COLIBRÍ Optical Observations
  43. GRB 250320B: AstroSat CZTI detection
  44. Fermi GRB 250320B: Global MASTER-Net observations report
  45. GRB 250321A: Fermi GBM Observation
  46. GRB 250321A: Swift detection of a burst
  47. GRB 250321A: Fermi GBM Final Real-time Localization
  48. GRB 250317C: AstroSat CZTI detection
  49. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  50. GRB 250314A: SVOM detection of a burst
  51. GRB 250313A: AstroSat CZTI detection of a bright long burst
  52. Fermi trigger No 763581136: Global MASTER-Net observations report
  53. EP250304a: Pan-STARRS r and i-band imaging and photometry
  54. Fermi GRB 250313A: Global MASTER-Net observations report
  55. The EP-WXT trigger 01709132425 is not a real source
  56. Fermi GRB 250309A: Global MASTER-Net observations report
  57. IceCube Alert 250309.32: Global MASTER-Net observations report
  58. GRB 250309A: Fermi GBM Final Real-time Localization
  59. GRB 250305A: AstroSat CZTI detection
  60. GRB 250306A: AstroSat CZTI detection
  61. Fermi trigger No 762963055: Global MASTER-Net observations report
  62. Swift GRB 250306A: Global MASTER-Net observations report
  63. Konus-Wind detection of GRB 250222A
  64. EP250304a: TRT optical counterpart detection
  65. EP250302a: NUTTelA-TAO Early Measurments
  66. EP250302a: Mondy Observations and Optical Light Curve
  67. EP250302a: Xinglong F60B optical observation
  68. EP250302a: Montarrenti Observatory optical detection
  69. Fermi GRB 250302A: Global MASTER-Net observations report
  70. EP250226a/GRB 250226A: 1.6m Mephisto observations
  71. GRB 250225B: Fermi GBM Observation
  72. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  73. Fermi GRB 250226A: Global MASTER-Net observations report
  74. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  75. EP250223a: Kinder optical follow-up observations
  76. EP250223a: LCO detection of the afterglow
  77. Fermi GRB 250223A: Global MASTER-Net observations report
  78. GRB 250219A: NOT optical observations
  79. GRB 250219A: SVOM/VT optical counterpart
  80. GRB 250219A: Swift-XRT observations
  81. IPN triangulation of GRB 250217C (short)
  82. GRB 250216A: AstroSat CZTI detection
  83. GRB 250217C: AstroSat CZTI detection of a short burst
  84. Fermi GRB 250217A: Global MASTER-Net observations report
  85. Fermi GRB 250216A: Global MASTER-Net observations report
  86. EP250215a / GRB 250215A: AstroSat CZTI detection
  87. EP250215a: Global MASTER-Net observations report
  88. Fermi GRB 250215A: Global MASTER-Net observations report
  89. GRB 250213A:SVOM/VT optical candidate
  90. Fermi GRB 250214A: Global MASTER-Net observations report
  91. EP250212a: Global MASTER-Net observations report
  92. GRB 250210A: AstroSat CZTI detection
  93. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  94. IceCube Alert 250207.09: Global MASTER-Net observations report
  95. GRB 250207A: 1.3m DFOT Optical observations
  96. GRB 250206A: Swift-XRT observations
  97. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  98. EP250205a/GRB 250205A: Einstein Probe observation
  99. GRB 250205A: OHP/T193 optical counterpart candidate
  100. GRB 250204B: AstroSat CZTI detection of a short burst

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