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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"

43854 results found.

  1. GRB 251007A: Insight-HXMT detection
  2. GRB 251006A: CALET Gamma-Ray Burst Monitor detection
  3. GRB 251007B - SVOM/ECLAIRs refined analysis
  4. SVOM/sb25101004: SVOM detection of a stellar flare
  5. GRB 251009A: Fermi GBM Final Localization
  6. GRB 250916A: TERI Gamma-ray detection
  7. GRB 250919A: TERI gamma-ray detection
  8. EP251006a: Global MASTER-Net observations report
  9. GRB 251006A: Fermi GBM Observation
  10. GRB 251007A: 1.5m OSN and 2.2m CAHA optical follow-up
  11. GRB 251002A - SVOM/ECLAIRs refined analysis
  12. IceCube alert 141456_888784 retraction
  13. IceCube Alert 251008A: Global MASTER-Net observations report
  14. GRB 251003A: Fermi GBM Observation
  15. GRB 251006B: Fermi GBM Observation
  16. GRB 251007B: COLIBRÍ optical upper limit
  17. GRB 251007A: AstroSat CZTI detection
  18. GRB 251006B/EP251006a: EP-FXT afterglow detection
  19. GRB 250917B: iTelescope T-26 upper limit
  20. EP250911a: Koshka Zeiss-1000 Optical Upper Limit
  21. GRB 251007B: SVOM/VT optical candidate
  22. GRB 251007A: Swift-XRT refined Analysis
  23. GRB 251007A: Enhanced Swift-XRT position
  24. GRB 251007B: Swift-XRT refined Analysis
  25. GRB 251007B: Enhanced Swift-XRT position
  26. GRB 251007A: NOT optical observations
  27. GRB 251007A: AKO Optical Upper Limit
  28. GRB 251007A: CALET Gamma-Ray Burst Monitor detection
  29. GRB 251006B: Insight-HXMT detection
  30. GRB 251007A: SVOM/C-GFT optical observations
  31. GRB 251005C: PRIME J-band upper limit
  32. Swift GRB 251007B: Global MASTER-Net observations report
  33. GRB 251007A: Glowbug gamma-ray detection
  34. GRB 251007B: SVOM/C-GFT upper limit
  35. Swift GRB 251007A: Global MASTER-Net observations report
  36. GRB 251007B: SVOM detection of a faint burst
  37. GRB 251007B: Swift detection of a burst
  38. GRB 251007A: Swift detection of a burst with an optical counterpart
  39. GRB 250702B/EP250702a: JWST/NIRCam Observations
  40. GRB 251006A: Swift/BAT-GUANO subthreshold detection of a short burst
  41. GRB 251005B: Glowbug gamma-ray detection
  42. EP251003a: LCO and VST fading optical counterpart
  43. GRB 251006B/EP251006a: SVOM/VT optical candidate
  44. GRB 251006B/EP251006a: EP-FXT follow-up observation
  45. GRB 251006B: SVOM/GRM observation
  46. GRB 251006B: COLIBRÍ optical upper limit
  47. GRB 251006B/EP251006a: EP-WXT detection
  48. GRB 251005C: SVOM/VT optical fading
  49. GRB 251005C: SVOM/GRM observation of a likely short GRB
  50. LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate
  51. Fermi GRB 251006B: Global MASTER-Net observations report
  52. GRB 251006B: BALROG localization (Fermi Trigger 781473909 / GRB 251006837)
  53. GRB 251006B: Fermi GBM Final Real-time Localization
  54. GRB 251006A (short): Glowbug gamma-ray detection
  55. GRB 251005C: COLIBRÍ optical observations
  56. Fermi GRB 251006A: Global MASTER-Net observations report
  57. GRB 251005C: VLT/X-shooter Imaging
  58. GRB 251003A: LAST optical observations
  59. GRB 251002A: LAST optical observations
  60. GRB 251006A: Fermi GBM Final Real-time Localization
  61. GRB 251005C: SVOM/VT optical candidate
  62. GRB 251005C: AstroSat CZTI detection
  63. GRB 251005C: Swift/UVOT Upper Limits
  64. GRB 250902A: MSU cubesats detection
  65. GRB 251005C: Swift-XRT refined Analysis
  66. GRB 251005C: Fermi GBM Observation
  67. Swift GRB 251005A: Global MASTER-Net observations report
  68. GRB 251005C: Enhanced Swift-XRT position
  69. GRB 251005C: GOTO optical upper limits
  70. Fermi trigger No 781367244: Global MASTER-Net observations report
  71. GRB 251005C: Swift detection of a burst
  72. GRB 251005B: Fermi GBM Final Real-time Localization
  73. GRB 251005A: Fermi GBM Final Localization
  74. GRB 251002A: Mondy/AZT-33IK optical observations
  75. GRB 251002A: Insight-HXMT detection
  76. GRB 251002A: Insight-HXMT detection
  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 251003A: GOTO detection of the optical counterpart
  91. GRB 251002A: Fermi GBM Observation
  92. LIGO/Virgo/KAGRA S251003at: Retraction of GW compact binary merger candidate
  93. GRB 251002A: GOTO detection of optical counterpart
  94. GRB 251001C: SVOM/GRM observation
  95. EP250821a: iTelescope T-59 possible detection of the optical counterpart
  96. GRB 251003A: Enhanced Swift-XRT position
  97. GRB 251002A: AKO Early Optical Afterglow Detection
  98. GRB 251003A: GTC/OSIRIS+ spectroscopic redshift z = 4.412
  99. GRB 251003A: Kilonova-Catcher optical afterglow detection
  100. GRB 251002A: Swift-XRT afterglow detection

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