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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"

3139 results found.

  1. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  2. GRB 250504A: MeerLICHT optical afterglow detection
  3. Fermi GRB 250504A: Global MASTER-Net observations report
  4. GRB 250502A: Montarrenti Observatory optical detection
  5. GRB 250502B: AstroSat CZTI detection
  6. EP250427a / GRB 250427A: OHP/T193 continued photometric observations
  7. Fermi trigger No 767623859: Global MASTER-Net observations report
  8. EP250427a: LT optical counterpart detection
  9. GRB 250407A: GRBAlpha detection
  10. GRB 250424A: AstroSat CZTI detection of a bright long burst
  11. GRB 250421A: AstroSat CZTI detection
  12. GRB 250419A: Mephisto Multi-band Optical Detection
  13. Fermi GRB 250421A: Global MASTER-Net observations report
  14. GRB 250421B: AstroSat CZTI detection of a bright long burst
  15. IceCube Alert 250421.71: Global MASTER-Net observations report
  16. GRB 250416B: Fermi GBM Final Real-time Localization
  17. GRB 250413A: AstroSat CZTI detection
  18. GRB 250412A: AstroSat CZTI detection
  19. EP250404a: Nanshan 0.43m Telescope optical observatios
  20. Fermi trigger No 766148493: Global MASTER-Net observations report
  21. Fermi trigger No 766173972: Global MASTER-Net observations report
  22. GRB 250407A: Mondy and AbAO Optical Observations
  23. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  24. Fermi GRB 250407A: Global MASTER-Net observations report
  25. GRB 250406A: AstroSat CZTI detection
  26. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  27. GRB 250404A / EP250404a: Mondy optical observations
  28. GRB 250404B: AstroSat CZTI detection of a short burst
  29. GRB 250403A: AstroSat CZTI detection
  30. Fermi GRB 250404A: Global MASTER-Net observations report
  31. EP250404a: Xinglong decaying optical counterpart
  32. GRB 250404A: Fermi GBM Detection
  33. GRB 250402B: AstroSat CZTI detection of a short burst
  34. GRB 250314A: ALMA detection
  35. GRB 250331D: Fermi GBM Final Real-time Localization
  36. GRB 250331A: MAXI/GSC detection
  37. Fermi GRB 250330A: Global MASTER-Net observations report
  38. IceCube Alert 250330.35: Global MASTER-Net observations report
  39. Fermi trigger No 764700395: Global MASTER-Net observations report
  40. EP250321a: Mondy AZT-33IK Continued Optical Observations
  41. GRB 250322A: AstroSat CZTI detection of a short burst
  42. GRB 250322B: AstroSat CZTI detection of a bright long burst
  43. EP250321a: Mondy AZT-33IK Optical Observations
  44. EP250321a: LCO optical counterpart detection
  45. EP250321A: COLIBRÍ Optical Observations
  46. GRB 250320B: AstroSat CZTI detection
  47. Fermi GRB 250320B: Global MASTER-Net observations report
  48. GRB 250321A: Fermi GBM Observation
  49. GRB 250321A: Swift detection of a burst
  50. GRB 250321A: Fermi GBM Final Real-time Localization
  51. GRB 250317C: AstroSat CZTI detection
  52. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  53. GRB 250314A: SVOM detection of a burst
  54. GRB 250313A: AstroSat CZTI detection of a bright long burst
  55. Fermi trigger No 763581136: Global MASTER-Net observations report
  56. EP250304a: Pan-STARRS r and i-band imaging and photometry
  57. Fermi GRB 250313A: Global MASTER-Net observations report
  58. The EP-WXT trigger 01709132425 is not a real source
  59. Fermi GRB 250309A: Global MASTER-Net observations report
  60. IceCube Alert 250309.32: Global MASTER-Net observations report
  61. GRB 250309A: Fermi GBM Final Real-time Localization
  62. GRB 250305A: AstroSat CZTI detection
  63. GRB 250306A: AstroSat CZTI detection
  64. Fermi trigger No 762963055: Global MASTER-Net observations report
  65. Swift GRB 250306A: Global MASTER-Net observations report
  66. Konus-Wind detection of GRB 250222A
  67. EP250304a: TRT optical counterpart detection
  68. EP250302a: NUTTelA-TAO Early Measurments
  69. EP250302a: Mondy Observations and Optical Light Curve
  70. EP250302a: Xinglong F60B optical observation
  71. EP250302a: Montarrenti Observatory optical detection
  72. Fermi GRB 250302A: Global MASTER-Net observations report
  73. EP250226a/GRB 250226A: 1.6m Mephisto observations
  74. GRB 250225B: Fermi GBM Observation
  75. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  76. Fermi GRB 250226A: Global MASTER-Net observations report
  77. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  78. EP250223a: Kinder optical follow-up observations
  79. EP250223a: LCO detection of the afterglow
  80. Fermi GRB 250223A: Global MASTER-Net observations report
  81. GRB 250219A: NOT optical observations
  82. GRB 250219A: SVOM/VT optical counterpart
  83. GRB 250219A: Swift-XRT observations
  84. IPN triangulation of GRB 250217C (short)
  85. GRB 250216A: AstroSat CZTI detection
  86. GRB 250217C: AstroSat CZTI detection of a short burst
  87. Fermi GRB 250217A: Global MASTER-Net observations report
  88. Fermi GRB 250216A: Global MASTER-Net observations report
  89. EP250215a / GRB 250215A: AstroSat CZTI detection
  90. EP250215a: Global MASTER-Net observations report
  91. Fermi GRB 250215A: Global MASTER-Net observations report
  92. GRB 250213A:SVOM/VT optical candidate
  93. Fermi GRB 250214A: Global MASTER-Net observations report
  94. EP250212a: Global MASTER-Net observations report
  95. GRB 250210A: AstroSat CZTI detection
  96. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  97. IceCube Alert 250207.09: Global MASTER-Net observations report
  98. GRB 250207A: 1.3m DFOT Optical observations
  99. GRB 250206A: Swift-XRT observations
  100. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet

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