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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"

27354 results found.

  1. GRB 251013D: Swift/BAT-GUANO arcminute localization of a burst
  2. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) detection of the optical counterpart
  3. GRB 251013C: DDOTI detection of the optical afterglow
  4. GRB 251013C: Swift-XRT counterpart detection
  5. GRB 251013C: SAO RAS optical observations
  6. GRB 251013C: LCO optical afterglow detection
  7. GRB 251013C: Optical Observations via Virtual Telescope Project, Italy
  8. GRB 251013C: LAST detection of optical counterpart
  9. GRB 251013C: SVOM/VT optical observation
  10. GRB 251013C: SVOM detection of a burst
  11. LIGO/Virgo/KAGRA S251013x: Updated Sky localization and Source Classification
  12. GRB 251013B: SVOM/GRM observation
  13. GRB 251013A: SVOM/GRM observation
  14. GRB 251003A: Mondy optical upper limit
  15. MASTER OT J011025.98-583210.6 : SVOM/VT optical observation
  16. LIGO/Virgo/KAGRA S251013x: Identification of a GW compact binary merger candidate
  17. GRB 251011B inspection: MASTER orphan GRB detection
  18. GRB 251011B: Swift/UVOT Upper Limits
  19. Fermi GRB 251011A: Global MASTER-Net observations report
  20. GRB 251011B: SVOM/GRM observation
  21. GRB 251011B: Swift-XRT refined Analysis
  22. GRB 251011B: Fermi GBM Observation
  23. GRB 251011B : MASTER optical observations
  24. GRB 251011B: Enhanced Swift-XRT position
  25. GRB 251011B: Swift detection of a burst
  26. GRB 251007B: Swift/UVOT Upper Limits
  27. GRB251007A: Swift/UVOT Detection
  28. GRB 251009A: GECAM-B detection of a short burst
  29. GRB 251009B (short): Glowbug gamma-ray detection
  30. GRB 251007A: Swift-BAT refined analysis
  31. GRB 251007A: SVOM/GRM observation
  32. SVOM/sb25101004: SVOM detection of a stellar flare
  33. GRB 250916A: TERI Gamma-ray detection
  34. GRB 250919A: TERI gamma-ray detection
  35. EP251006a: Global MASTER-Net observations report
  36. GRB 251006A: Fermi GBM Observation
  37. GRB 251003A: Fermi GBM Observation
  38. GRB 251006B: Fermi GBM Observation
  39. GRB 251007B: COLIBRÍ optical upper limit
  40. GRB 251007A: AstroSat CZTI detection
  41. GRB 250917B: iTelescope T-26 upper limit
  42. EP250911a: Koshka Zeiss-1000 Optical Upper Limit
  43. GRB 251007A: Swift-XRT refined Analysis
  44. GRB 251007A: Enhanced Swift-XRT position
  45. GRB 251007B: Swift-XRT refined Analysis
  46. GRB 251007B: Enhanced Swift-XRT position
  47. GRB 251007A: AKO Optical Upper Limit
  48. GRB 251007A: SVOM/C-GFT optical observations
  49. GRB 251005C: PRIME J-band upper limit
  50. GRB 251007A: Glowbug gamma-ray detection
  51. GRB 251007B: SVOM/C-GFT upper limit
  52. GRB 251007B: Swift detection of a burst
  53. GRB 251007A: Swift detection of a burst with an optical counterpart
  54. GRB 250702B/EP250702a: JWST/NIRCam Observations
  55. GRB 251006A: Swift/BAT-GUANO subthreshold detection of a short burst
  56. GRB 251005B: Glowbug gamma-ray detection
  57. EP251003a: LCO and VST fading optical counterpart
  58. GRB 251006B/EP251006a: EP-FXT follow-up observation
  59. GRB 251006B: SVOM/GRM observation
  60. GRB 251006B: COLIBRÍ optical upper limit
  61. GRB 251006B/EP251006a: EP-WXT detection
  62. GRB 251005C: SVOM/VT optical fading
  63. GRB 251005C: SVOM/GRM observation of a likely short GRB
  64. LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate
  65. GRB 251006B: BALROG localization (Fermi Trigger 781473909 / GRB 251006837)
  66. GRB 251006A (short): Glowbug gamma-ray detection
  67. GRB 251005C: COLIBRÍ optical observations
  68. GRB 251005C: VLT/X-shooter Imaging
  69. GRB 251003A: LAST optical observations
  70. GRB 251002A: LAST optical observations
  71. GRB 251005C: Swift/UVOT Upper Limits
  72. GRB 250902A: MSU cubesats detection
  73. GRB 251005C: Swift-XRT refined Analysis
  74. GRB 251005C: Enhanced Swift-XRT position
  75. GRB 251005C: Swift detection of a burst
  76. GRB 251002A: Mondy/AZT-33IK optical observations
  77. EP251003a: Einstein Probe detection of an X-ray transient
  78. GRB 251003A: J-band detection with WINTER
  79. GRB 251002A: NIR observations with WINTER
  80. Fermi GBM Sub-Threshold Detection of GRB 250910A
  81. GRB 251003A: Swift-BAT refined analysis
  82. GRB 251001B: NIR observations with WINTER
  83. GRB 251002A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  84. GRB 251003A: Swift/UVOT Upper Limits
  85. GRB 251002A: Swift/UVOT detection
  86. GRB 251001A: AstroSat CZTI detection
  87. GRB 251001B: COLIBRÍ further observations and evidence of a multi-wavelength shallow decay
  88. GRB 251003A: Swift-XRT refined Analysis
  89. GRB 251003A: COLIBRÍ photometric redshift
  90. GRB 251002A: Fermi GBM Observation
  91. GRB 251002A: GOTO detection of optical counterpart
  92. GRB 251001C: SVOM/GRM observation
  93. EP250821a: iTelescope T-59 possible detection of the optical counterpart
  94. GRB 251003A: Enhanced Swift-XRT position
  95. GRB 251002A: AKO Early Optical Afterglow Detection
  96. GRB 251003A: Kilonova-Catcher optical afterglow detection
  97. GRB 251002A: Swift-XRT afterglow detection
  98. GRB 251001B: AbAO optical upper limit
  99. GRB 251002A: Kilonova-Catcher optical afterglow detection
  100. GRB 251002A: AbAO optical observations

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