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

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