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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"

24571 results found.

  1. GRB 250430A: DDOTI Optical Observations
  2. GRB 250430A: Leavitt Observatory optical upper limit
  3. GRB 250430A: Bassano Bresciano Observatory upper limit
  4. GRB 250430A : MITSuME Akeno optical upper limits
  5. SVOM/sb25043004: EP-FXT observations
  6. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  7. GRB 250424A: CALET Gamma-Ray Burst Monitor detection
  8. IceCube-250429A: Upper limits from a search for additional neutrino events in IceCube
  9. IceCube-250426A: Upper limits from a search for additional neutrino events in IceCube
  10. GRB 250430A: AKO Optical Afterglow Detection
  11. GRB 250430A: Kanata optical upper limit
  12. EP 250427A: Optical counterpart detection by LCO.
  13. GRB 250430A: Swift detection of a burst with optical counterpart
  14. EP250427a/GRB250427A: HCT optical follow-up
  15. SVOM/sb25043004: SVOM detection of a X-ray transient
  16. EP250428b: GROWTH-India telescope optical upper limit
  17. EP250428b: SAO RAS optical upper limit
  18. EP250428b: LAST optical upper limit
  19. GRB 250427A: Swift/UVOT Detection
  20. EP250428b: Global MASTER-Net observations report
  21. EP250428b: Einstein Probe detection of a fast X-ray transient
  22. Fermi-LAT Gamma-ray Observations of IceCube-250426A
  23. EP250427a: Lesedi optical counterpart detection
  24. EP250427A: COLIBRÍ Continuing Optical Observations
  25. GRB250427A/EP250427a GIT optical afterglow detection:
  26. EP250427a: LT optical counterpart detection
  27. GRB 250427A: Swift-XRT refined Analysis
  28. EP250427a / GRB 250427A: LCO optical counterpart detection
  29. EP250427a: REM optical/NIR afterglow detection
  30. GRB 250424A: LCO optical observation
  31. GRB 250427A/ EP250427a: Fermi-GBM Sub-Threshold Detection
  32. EP250427A: COLIBRÍ Optical Detection
  33. EP250427a: TRT optical counterpart detection
  34. EP250427a: Einstein Probe detection of a fast X-ray transient
  35. GRB 250424A: Swift-BAT refined analysis
  36. GRB 250424A: SVOM/GRM observation of a long burst
  37. GRB 250424A: PRIME near-infrared detection
  38. GRB 250424A: WINTER J-band detection
  39. GRB 250424A: EIRSAT-1 GMOD Detection
  40. IceCube-250416A: Upper limits from a search for additional neutrino events in IceCube
  41. IceCube-250421A: Upper limits from a search for additional neutrino events in IceCube
  42. GRB 250419A: Mondy Optical Observations
  43. GRB 250424A: Swift/UVOT Detection
  44. Fermi-LAT gamma-ray observations of IceCube-250421A
  45. GRB 250424A: Skynet Optical Observations
  46. GRB 250424A: Kilonova-Catcher optical afterglow detection
  47. GRB 250330B: GRBAlpha detection
  48. GRB 250424A: Swift-XRT refined Analysis
  49. GRB 250424A: Enhanced Swift-XRT position
  50. GRB 250424A: AstroSat CZTI detection of a bright long burst
  51. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  52. GRB 250424A: BlackGEM optical afterglow detection
  53. GRB 250424A: DDOTI Afterglow Detection
  54. GRB 250424A: REM optical/NIR afterglow detection
  55. GRB 250424A: Swift detection of a burst with an optical counterpart
  56. Swift GRB250424A: Global MASTER-Net OT detection
  57. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  58. EP250421a: Nickel optical upper limit
  59. EP250421a: Upper limits from Fermi-GBM Observations
  60. SVOM/sb25042207: SVOM detection of an X-ray transient
  61. IceCube-250421A: DDOTI Detection of the LAST Candidate
  62. GRB 250419A: Mephisto Multi-band Optical Detection
  63. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  64. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  65. EP250421a: NOT optical observations
  66. GRB 250419A: Optical Observations via Virtual Telescope Project
  67. EP250421a: REM optical upper limit
  68. EP250421A: COLIBRÍ Optical Upper Limit
  69. GRB 250419A: Mondy Continued Optical Observations
  70. GRB 250421B: AstroSat CZTI detection of a bright long burst
  71. EP250421a: Einstein Probe detection of an X-ray transient
  72. EP250421a: Mephisto optical counterpart confirmation
  73. IceCube-Cascade 250414A: Upper limits from a search for additional neutrino events in IceCube
  74. EP250421a: JinShan likely optical counterpart
  75. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  76. GRB 250419A: LCO optical observation
  77. GRB 250419A: JinShan optical observations
  78. GRB 250419A: SVOM/C-GFT optical observations
  79. GRB 250419A: Swift/UVOT Follow up
  80. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  81. GRB 250419A: LCO optical afterglow multi-band observations
  82. GRB 250419A: Mondy and AbAO Optical Observations
  83. GRB 250419A: AKO Optical Afterglow Detection
  84. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  85. GRB 250419A: Swift-XRT refined Analysis
  86. GRB 250419A: KAIT optical afterglow observations
  87. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  88. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  89. GRB 250419A: SVOM detection of a soft burst
  90. EP250416a: Swift/XRT counterpart fading
  91. EP20250416a: Swift/XRT counterpart detection
  92. IceCube-250416A: DDOTI Optical Observations
  93. EP250416a: Gemini South-GMOS optical counterpart
  94. SVOM/sb25041603 is not a GRB
  95. EP250416a: GSP optical upper limit
  96. EP250416a: Einstein Probe detection of an X-ray transient
  97. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  98. SVOM/sb25041603: SVOM detection of an X-ray transient
  99. IceCube 250414.324: DDOTI Optical Observations
  100. GRB 250413A: AstroSat CZTI detection

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