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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"

24376 results found.

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

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