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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"

24373 results found.

  1. GRB 250407A: EP-WXT afterglow detection
  2. IceCube-250406A: No candidates from the Zwicky Transient Facility
  3. GRB 250407A: Fermi GBM Detection
  4. Fermi GRB 250407A: Global MASTER-Net observations report
  5. GRB 250407A: SRG/ART-XC afterglow detection
  6. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  7. Konus-Wind detection of GRB 250406B (short/hard)
  8. IPN triangulation of GRB 250406B (short/hard)
  9. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  10. GRB 250407A: Fermi GBM Final Real-time Localization
  11. IceCube-250406A - IceCube observation of a high-energy neutrino candidate track-like event
  12. IceCube Alert 250406.95: Global MASTER-Net observations report
  13. Fermi trigger No 765663719: Global MASTER-Net observations report
  14. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  15. Fermi GRB 250406A: Global MASTER-Net observations report
  16. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  17. GRB 250406A: Fermi GBM Final Real-time Localization
  18. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  19. Fermi trigger No 765619921: Global MASTER-Net observations report
  20. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  21. Konus-Wind detection of GRB 250404A / EP250404a
  22. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  23. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  24. EP250402a: Optical upper limit with PD 1.3m observations
  25. GRB 250331D: Swift-XRT afterglow detection
  26. EP250404a: REM optical/NIR observations
  27. EP250404a: LCO optical counterpart detection
  28. Fermi GRB 250404A: Global MASTER-Net observations report
  29. EP250404a: Xinglong decaying optical counterpart
  30. GRB 250403A: Montarrenti Observatory optical detection
  31. GRB 250404A: Fermi GBM Detection
  32. EP250404a: Global MASTER-Net observations report
  33. GRB 250403A: KAIT optical observations
  34. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  35. GRB 250403A: Fermi GBM observations
  36. EP250404a: Mephisto multi-band optical detection
  37. GRB 250331C Swift-BAT refined analysis
  38. GRB 250331B Swift-BAT refined analysis
  39. GRB 250330A Swift-BAT refined analysis
  40. EP250404a: Nanshan/HMT optical counterpart detection
  41. GRB 250404A: Fermi GBM Final Real-time Localization
  42. EP250402a: Optical upper limit with Kinder observations
  43. GRB 250403A: SVOM/VT optical observation
  44. GRB 250403A: REM NIR afterglow detection
  45. GRB 250403A: LCO optical counterpart detection
  46. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  47. EP250402a: EP-FXT follow-up observations
  48. GRB 250322A: 10 GHz VLA radio upper limits
  49. Fermi GRB 250403A: Global MASTER-Net observations report
  50. GRB 250403A: GOTO optical counterpart follow-up observations
  51. GRB 250402A: NUTTelA-TAO Early Optical Limits
  52. GRB 250403A: 1.6m Mephisto multi-band optical detection
  53. GRB 250402A: Fermi GBM Observation
  54. GRB 250403A: SVOM/C-GFT optical observations
  55. GRB 250403A: GOTO detection of the optical afterglow
  56. GRB 250403A : SVOM detection of a burst
  57. GRB 250403A: Fermi GBM Final Real-time Localization
  58. GRB 250402A: REM optical/NIR upper limits
  59. GRB 250402A: LCO optical counterpart detection
  60. GRB 250402A: refined SVOM/MXT data analysis
  61. The EP-WXT trigger 01709133862 is a flaring star
  62. GRB 250402A: SVOM/VT optical counterpart
  63. GRB 250402A: SVOM detection of a burst
  64. GRB 250331D: Fermi GBM observation
  65. GRB 250322B: GRBAlpha detection
  66. GRB 250331D: Swift-XRT observations
  67. GRB 250322B possible detection by the AstroSat Satellite
  68. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  69. Fermi GRB 250331E: Global MASTER-Net observations report
  70. Fermi GRB 250331D: Global MASTER-Net observations report
  71. GRB 250330B: EIRSAT-1 GMOD Detection
  72. GRB 250331E: Fermi GBM Final Real-time Localization
  73. GRB 250327A Swift-BAT refined analysis
  74. LIGO/Virgo/KAGRA S250331o: Updated Sky localization
  75. Fermi trigger No 765078057: Global MASTER-Net observations report
  76. Swift GRB 250331C: Global MASTER-Net observations report
  77. Swift GRB 250331B: Global MASTER-Net observations report
  78. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  79. Konus-Wind detection of GRB 250327B
  80. IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube
  81. LIGO/Virgo/KAGRA S250331o: NED Galaxies in the 3-Initial Localization Volume
  82. GRB 250320C : SVOM detection of a burst through offline search
  83. GRB20250327B: 45th Parallel Observatory upper limit
  84. Fermi-LAT gamma-ray observations of IceCube-250330A
  85. SVOM/sb25033102 is a false trigger
  86. GRB 250330A: Fermi GBM Observation
  87. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  88. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  89. GRB 250331D: Fermi GBM Final Real-time Localization
  90. GRB 250331B: Swift detection of a burst
  91. GRB 250330A: SVOM/VT optical upper limit
  92. SVOM/sb25033102: SVOM detection of an X-ray transient
  93. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  94. Fermi GRB 250330B: Global MASTER-Net observations report
  95. GRB 250330B: Fermi GBM Final Real-time Localization
  96. Fermi GRB 250330A: Global MASTER-Net observations report
  97. GRB 250330A: BOOTES-7 early optical upper limit
  98. GRB 250328A: 1.6m Mephisto optical observations
  99. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  100. GRB 250330A: Fermi GBM Final Localization

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