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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"

27351 results found.

  1. GRB 251013C: LCO optical afterglow detection
  2. GRB 251013C: Optical Observations via Virtual Telescope Project, Italy
  3. GRB 251013C: LAST detection of optical counterpart
  4. GRB 251013C: SVOM/VT optical observation
  5. GRB 251013C: SVOM detection of a burst
  6. LIGO/Virgo/KAGRA S251013x: Updated Sky localization and Source Classification
  7. GRB 251013B: SVOM/GRM observation
  8. GRB 251013A: SVOM/GRM observation
  9. GRB 251003A: Mondy optical upper limit
  10. MASTER OT J011025.98-583210.6 : SVOM/VT optical observation
  11. LIGO/Virgo/KAGRA S251013x: Identification of a GW compact binary merger candidate
  12. GRB 251011B inspection: MASTER orphan GRB detection
  13. GRB 251011B: Swift/UVOT Upper Limits
  14. Fermi GRB 251011A: Global MASTER-Net observations report
  15. GRB 251011B: SVOM/GRM observation
  16. GRB 251011B: Swift-XRT refined Analysis
  17. GRB 251011B: Fermi GBM Observation
  18. GRB 251011B : MASTER optical observations
  19. GRB 251011B: Enhanced Swift-XRT position
  20. GRB 251011B: Swift detection of a burst
  21. GRB 251007B: Swift/UVOT Upper Limits
  22. GRB251007A: Swift/UVOT Detection
  23. GRB 251009A: GECAM-B detection of a short burst
  24. GRB 251009B (short): Glowbug gamma-ray detection
  25. GRB 251007A: Swift-BAT refined analysis
  26. GRB 251007A: SVOM/GRM observation
  27. SVOM/sb25101004: SVOM detection of a stellar flare
  28. GRB 250916A: TERI Gamma-ray detection
  29. GRB 250919A: TERI gamma-ray detection
  30. EP251006a: Global MASTER-Net observations report
  31. GRB 251006A: Fermi GBM Observation
  32. GRB 251003A: Fermi GBM Observation
  33. GRB 251006B: Fermi GBM Observation
  34. GRB 251007B: COLIBRÍ optical upper limit
  35. GRB 251007A: AstroSat CZTI detection
  36. GRB 250917B: iTelescope T-26 upper limit
  37. EP250911a: Koshka Zeiss-1000 Optical Upper Limit
  38. GRB 251007A: Swift-XRT refined Analysis
  39. GRB 251007A: Enhanced Swift-XRT position
  40. GRB 251007B: Swift-XRT refined Analysis
  41. GRB 251007B: Enhanced Swift-XRT position
  42. GRB 251007A: AKO Optical Upper Limit
  43. GRB 251007A: SVOM/C-GFT optical observations
  44. GRB 251005C: PRIME J-band upper limit
  45. GRB 251007A: Glowbug gamma-ray detection
  46. GRB 251007B: SVOM/C-GFT upper limit
  47. GRB 251007B: Swift detection of a burst
  48. GRB 251007A: Swift detection of a burst with an optical counterpart
  49. GRB 250702B/EP250702a: JWST/NIRCam Observations
  50. GRB 251006A: Swift/BAT-GUANO subthreshold detection of a short burst
  51. GRB 251005B: Glowbug gamma-ray detection
  52. EP251003a: LCO and VST fading optical counterpart
  53. GRB 251006B/EP251006a: EP-FXT follow-up observation
  54. GRB 251006B: SVOM/GRM observation
  55. GRB 251006B: COLIBRÍ optical upper limit
  56. GRB 251006B/EP251006a: EP-WXT detection
  57. GRB 251005C: SVOM/VT optical fading
  58. GRB 251005C: SVOM/GRM observation of a likely short GRB
  59. LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate
  60. GRB 251006B: BALROG localization (Fermi Trigger 781473909 / GRB 251006837)
  61. GRB 251006A (short): Glowbug gamma-ray detection
  62. GRB 251005C: COLIBRÍ optical observations
  63. GRB 251005C: VLT/X-shooter Imaging
  64. GRB 251003A: LAST optical observations
  65. GRB 251002A: LAST optical observations
  66. GRB 251005C: Swift/UVOT Upper Limits
  67. GRB 250902A: MSU cubesats detection
  68. GRB 251005C: Swift-XRT refined Analysis
  69. GRB 251005C: Enhanced Swift-XRT position
  70. GRB 251005C: Swift detection of a burst
  71. GRB 251002A: Mondy/AZT-33IK optical observations
  72. EP251003a: Einstein Probe detection of an X-ray transient
  73. GRB 251003A: J-band detection with WINTER
  74. GRB 251002A: NIR observations with WINTER
  75. Fermi GBM Sub-Threshold Detection of GRB 250910A
  76. GRB 251003A: Swift-BAT refined analysis
  77. GRB 251001B: NIR observations with WINTER
  78. GRB 251002A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  79. GRB 251003A: Swift/UVOT Upper Limits
  80. GRB 251002A: Swift/UVOT detection
  81. GRB 251001A: AstroSat CZTI detection
  82. GRB 251001B: COLIBRÍ further observations and evidence of a multi-wavelength shallow decay
  83. GRB 251003A: Swift-XRT refined Analysis
  84. GRB 251003A: COLIBRÍ photometric redshift
  85. GRB 251002A: Fermi GBM Observation
  86. GRB 251002A: GOTO detection of optical counterpart
  87. GRB 251001C: SVOM/GRM observation
  88. EP250821a: iTelescope T-59 possible detection of the optical counterpart
  89. GRB 251003A: Enhanced Swift-XRT position
  90. GRB 251002A: AKO Early Optical Afterglow Detection
  91. GRB 251003A: Kilonova-Catcher optical afterglow detection
  92. GRB 251002A: Swift-XRT afterglow detection
  93. GRB 251001B: AbAO optical upper limit
  94. GRB 251002A: Kilonova-Catcher optical afterglow detection
  95. GRB 251002A: AbAO optical observations
  96. GRB 251002A: SVOM/COLIBRÍ (FM-GFT) optical observations
  97. GRB 251001C: CALET Gamma-Ray Burst Monitor detection
  98. GRB 251002A: J band observations by SYSU 80cm infrared telescope
  99. GRB 251002A: OHP/T193 MISTRAL optical afterglow detection
  100. GRB 251002A: EP-FXT counterpart detection

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