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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.

Lucene Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

24573 results found.

  1. IceCube 250414.324: DDOTI Optical Observations
  2. GRB 250413A: AstroSat CZTI detection
  3. EP250304a: ATCA radio observations
  4. EP250404a: Nanshan 0.43m Telescope optical observatios
  5. GRB 250411A: DDOTI Optical Observations
  6. Fermi GRB 250411A: Global MASTER-Net observations report
  7. GRB 250407A: Continued KAIT/Nickel optical observations
  8. GRB 250314A: e-MERLIN observations
  9. GRB 250407A: Mondy and AbAO Optical Observations
  10. EP250227a: Further NOT optical observations
  11. GRB 250320B: cubesat Avion detection
  12. IceCube-250406A: Swift-XRT observations
  13. GRB 250407A: LCO detection of a fading optical counterpart
  14. Fermi-LAT gamma-ray observations of IceCube-250406A
  15. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  16. GRB 250407A: SVOM/GRM observation of a bright long burst
  17. GRB 250407A: EP-WXT afterglow detection
  18. EP250407a: EP-WXT detection of a fast X-ray transient
  19. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  20. GRB 250407A: KAIT Optical Afterglow Candidate
  21. IceCube-250406A: No candidates from the Zwicky Transient Facility
  22. GRB 250407A: Fermi GBM Detection
  23. GRB 250407A: Swift-XRT afterglow detection
  24. GRB 250407A: SRG/ART-XC afterglow detection
  25. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  26. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  27. IPN triangulation of GRB 250406B (short/hard)
  28. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  29. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  30. IceCube 250406.951: DDOTI Optical Observations
  31. GRB 250406A: AstroSat CZTI detection
  32. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  33. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  34. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  35. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  36. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  37. Konus-Wind detection of GRB 250404A / EP250404a
  38. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  39. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  40. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  41. EP250402a: Optical upper limit with PD 1.3m observations
  42. GRB 250404A / EP250404a: NOT optical observations
  43. GRB 250331D: Swift-XRT afterglow detection
  44. GRB 250404B: AstroSat CZTI detection of a short burst
  45. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  46. EP250404a: REM optical/NIR observations
  47. EP250404a: Seimei/TriCCS optical counterpart detection
  48. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  49. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  50. EP250404a: LCO optical counterpart detection
  51. EP250404a: Xinglong decaying optical counterpart
  52. GRB 250403A: Montarrenti Observatory optical detection
  53. GRB 250404A: Fermi GBM Detection
  54. GRB 250403A: KAIT optical observations
  55. EP250404a: AKO Optical Afterglow Detection
  56. EP250404a: LAST detection of optical counterpart
  57. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  58. GRB 250403A: Fermi GBM observations
  59. GRB 250327B: VIRT Optical Upper Limit
  60. EP250404a: Mephisto multi-band optical detection
  61. GRB 250331C Swift-BAT refined analysis
  62. GRB 250331B Swift-BAT refined analysis
  63. GRB 250330A Swift-BAT refined analysis
  64. EP250321A: J band upper limit by SYSU 80cm telescope
  65. EP250404a: Nanshan/HMT optical counterpart detection
  66. EP250404a: Einstein Probe detection of an X-ray transient
  67. GRB 250403A: Swift/UVOT Detection
  68. GRB 250402A: Swift/UVOT Upper Limits
  69. EP250402a: Optical upper limit with Kinder observations
  70. GRB 250403A: REM NIR afterglow detection
  71. GRB 250403A: LCO optical counterpart detection
  72. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  73. GRB 250403A: JinShan optical observations
  74. GRB 250403A: Optical counterpart detection by LCO.
  75. EP250402a: EP-FXT follow-up observations
  76. GRB 250403A: Swift-XRT observations
  77. GRB 250322A: 10 GHz VLA radio upper limits
  78. GRB 250403A: GMG Optical Observation
  79. GRB 250403A: 1.6m Mephisto multi-band optical detection
  80. GRB 250402A: Fermi GBM Observation
  81. GRB 250403A: SVOM/C-GFT optical observations
  82. GRB 250402A: Swift-XRT observations
  83. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  84. GRB 250402A: REM optical/NIR upper limits
  85. GRB 250402A: LCO optical counterpart detection
  86. EP250402a: Einstein Probe detection of a fast X-ray transient
  87. GRB 250402B: AstroSat CZTI detection of a short burst
  88. GRB 250402A: SVOM/VT optical counterpart
  89. GRB 250402A: SVOM detection of a burst
  90. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  91. GRB 250329B: Swift/UVOT Upper Limit
  92. GRB 250329A: Swift/UVOT Upper Limit
  93. GRB 250327B: Swift/UVOT Detection
  94. GRB 250327A: Swift/UVOT Upper Limits
  95. GRB 250331E: SVOM/GRM observation
  96. GRB 250327B: Kilonova-Catcher Observations
  97. GRB250331D: AbAO optical observations
  98. GRB 250331D: Fermi GBM observation
  99. GRB 250331C: Swift/UVOT Upper Limits
  100. GRB 250331B: Swift/UVOT Upper Limits

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