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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

20549 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. GRB 250430A / EP250430a: VLT/X-shooter spectroscopic redshift z = 0.767
  8. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  9. IceCube-250429A: Upper limits from a search for additional neutrino events in IceCube
  10. IceCube-250426A: Upper limits from a search for additional neutrino events in IceCube
  11. GRB 250430A: AKO Optical Afterglow Detection
  12. GRB 250430A: Kanata optical upper limit
  13. EP 250427A: Optical counterpart detection by LCO.
  14. GRB 250430A: Swift detection of a burst with optical counterpart
  15. EP250427a/GRB250427A: HCT optical follow-up
  16. SVOM/sb25043004: SVOM detection of a X-ray transient
  17. EP250428b: GROWTH-India telescope optical upper limit
  18. EP250428b: SAO RAS optical upper limit
  19. EP250428b: LAST optical upper limit
  20. GRB 250427A: Swift/UVOT Detection
  21. EP250428b: Einstein Probe detection of a fast X-ray transient
  22. EP250427A: COLIBRÍ Continuing Optical Observations
  23. GRB250427A/EP250427a GIT optical afterglow detection:
  24. EP250427a: LT optical counterpart detection
  25. EP250427a / GRB 250427A: LCO optical counterpart detection
  26. EP250427a: REM optical/NIR afterglow detection
  27. GRB 250424A: LCO optical observation
  28. EP250427A: COLIBRÍ Optical Detection
  29. EP250427a: TRT optical counterpart detection
  30. EP 250427a: BOOTES-7 optical afterglow candidate
  31. EP250427a: Einstein Probe detection of a fast X-ray transient
  32. GRB 250424A: SVOM/GRM observation of a long burst
  33. GRB 250424A: PRIME near-infrared detection
  34. GRB 250424A: WINTER J-band detection
  35. IceCube-250416A: Upper limits from a search for additional neutrino events in IceCube
  36. IceCube-250421A: Upper limits from a search for additional neutrino events in IceCube
  37. GRB 250419A: Mondy Optical Observations
  38. GRB 250424A: Swift/UVOT Detection
  39. Konus-Wind detection of GRB 250424A
  40. Fermi-LAT gamma-ray observations of IceCube-250421A
  41. GRB 250424A: Skynet Optical Observations
  42. GRB 250424A: Kilonova-Catcher optical afterglow detection
  43. GRB 250419A: SVOM/ECLAIRs refined analysis
  44. GRB 250424A: Swift-XRT refined Analysis
  45. GRB 250424A: Enhanced Swift-XRT position
  46. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  47. GRB 250424A: BlackGEM optical afterglow detection
  48. GRB 250424A: DDOTI Afterglow Detection
  49. GRB 250424A: REM optical/NIR afterglow detection
  50. GRB 250424A: Swift detection of a burst with an optical counterpart
  51. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  52. EP250421a: Nickel optical upper limit
  53. EP250416a / GRB 250416C: Gemini GMOS-S likely host galaxy redshift z = 0.963
  54. SVOM/sb25042207: XRT observations
  55. GRB250419A: VLA radio detection
  56. IceCube-250421A: DDOTI Detection of the LAST Candidate
  57. GRB 250419A: Mephisto Multi-band Optical Detection
  58. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  59. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  60. EP250421a: NOT optical observations
  61. GRB 250419A: Optical Observations via Virtual Telescope Project
  62. EP250421a: REM optical upper limit
  63. EP250421A: COLIBRÍ Optical Upper Limit
  64. GRB 250419A: Mondy Continued Optical Observations
  65. GRB 250421B: AstroSat CZTI detection of a bright long burst
  66. EP250421a: Einstein Probe detection of an X-ray transient
  67. EP250421a: Mephisto optical counterpart confirmation
  68. IceCube-Cascade 250414A: Upper limits from a search for additional neutrino events in IceCube
  69. EP250421a: JinShan likely optical counterpart
  70. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  71. GRB 250419A: LCO optical observation
  72. GRB 250419A: JinShan optical observations
  73. GRB 250419A: SVOM/C-GFT optical observations
  74. GRB 250419A: Swift/UVOT Follow up
  75. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  76. GRB 250419A: LCO optical afterglow multi-band observations
  77. GRB 250419A: Mondy and AbAO Optical Observations
  78. GRB 250419A: AKO Optical Afterglow Detection
  79. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  80. GRB 250419A: VLT/X-shooter spectroscopic redshift z = 0.845
  81. GRB 250419A: KAIT optical afterglow observations
  82. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  83. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  84. GRB 250419A: SVOM detection of a soft burst
  85. EP250416a: refined EP-WXT and EP-FXT analysis
  86. EP20250416a: Swift/XRT counterpart detection
  87. GRB 250403A: VLT/FORS2 spectroscopic redshift z = 1.847
  88. IceCube-250416A: DDOTI Optical Observations
  89. EP250416a: Gemini South-GMOS optical counterpart
  90. SVOM/sb25041603 is not a GRB
  91. EP250416a: Einstein Probe detection of an X-ray transient
  92. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  93. IceCube 250414.324: DDOTI Optical Observations
  94. GRB 250413A: AstroSat CZTI detection
  95. GRB 250412A: AstroSat CZTI detection
  96. EP250404a: Nanshan 0.43m Telescope optical observatios
  97. GRB 250411A: DDOTI Optical Observations
  98. GRB 250314A: e-MERLIN observations
  99. GRB 250407A: Mondy and AbAO Optical Observations
  100. EP250227a: Further NOT optical observations

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