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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"

36150 results found.

  1. GRB 240419B: Swift detection of a burst
  2. GRB 240411B: Swift/UVOT Detection
  3. GRB240418A: YAHPT Upper Limits
  4. GRB 240419A: VLT/UVES redshift of z = 5.178
  5. GRB 240419A: VLT optical afterglow detection
  6. GRB 240419A: Enhanced Swift-XRT position
  7. GRB 240419A: Prompt enhanced Swift-XRT position
  8. GRB 240419A: Swift detection of a burst
  9. GRB 240418A: TSHAO Zeiss-1000 optical upper limit
  10. GRB 240418A: NOT optical upper limits
  11. GRB 240418A: Enhanced Swift-XRT position
  12. GRB 240418A: AKO Upper Limit
  13. GRB 240411A: GOTO early optical upper limits
  14. GRB 240418A: Swift detection of a burst
  15. Fermi GRB 240417A: Global MASTER-Net observations report
  16. EP240416A: Terskol Zeiss-2000 optical upper limit
  17. EP240416A: Khureltogoot optical upper limit
  18. Improved IPN triangulation of GRB 240411A
  19. GRB 240417A: Fermi GBM Final Real-time Localization
  20. GRB 240415A: Glowbug gamma-ray detection
  21. GRB 240414A: Glowbug gamma-ray detection
  22. GRB 240415B: GECAM-B detection
  23. EP 240416a: Xinglong and NOT decaying optical counterpart
  24. GRB 240415A: Swift-BAT refined analysis
  25. GRB 240411A: Glowbug gamma-ray detection
  26. GRB 240414A: Swift-BAT refined analysis
  27. GRB 240414A: AbAO optical upprer limit
  28. GRB 240415A: Swift/UVOT Detection
  29. GRB 240415A: Fermi GBM Observation
  30. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  31. GRB 240415A: Earliest optical followup with the Kinder observations
  32. GRB 240414A: GMG observation
  33. GRB 240415A: Enhanced Swift-XRT position
  34. GRB 240415B: Swift ToO observations
  35. GRB 240415B: Swift/BAT-GUANO Correction
  36. GRB 240415B: Swift/BAT-GUANO arcminute localization of a short burst
  37. GRB 240415A: OHP/T193 optical observations
  38. GRB 240415A: optical afterglow detection from the INAF Asiago Observatory
  39. GRB 240415A: SAO RAS optical observations
  40. GRB 240415A: Mondy optical transient detection (photometry correction in GCN 36118 )
  41. GRB 240414A: Fermi GBM Observation
  42. Fermi GRB 240415A: Global MASTER-Net observations report
  43. GRB 240415A: Mondy optical transient detection
  44. GRB 240414A: Photometric observation from 2.2m CAHA
  45. IceCube-240412A: Upper limits from a search for additional neutrino events in IceCube
  46. GRB 240414A: Swift/UVOT Detection
  47. LXT 240402A/GRB 240402B: Swift follow-up observations
  48. GRB 240414A: Mondy optical observations
  49. GRB 240414B: Fermi GBM Final Real-time Localization
  50. GRB 240414A: AKO Optical Upper Limit
  51. GRB 240415A: Prompt Swift-XRT observations
  52. GRB 240415A: Swift detection of a burst
  53. GRB 240415A: Fermi GBM Final Real-time Localization
  54. EP240413a: Upper limits from GECAM-B Observation
  55. GRB 240414A: Swift-XRT refined Analysis
  56. GRB240414A : J-band upper limits from WINTER
  57. GRB 240414A: Enhanced Swift-XRT position
  58. GRB 240414A : OHP/T193 second epoch of optical follow-up and afterglow detection
  59. GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  60. GRB 240414A: Skynet Optical Afterglow Observations
  61. Swift GRB 240414A: Global MASTER-Net observations report
  62. IPN triangulation of GRB 240410A
  63. IPN triangulation of GRB 240411A
  64. GRB 240414A : MITSuME Akeno optical upper limits
  65. GRB 240414A: Redshift confirmation from GTC/OSIRIS+
  66. GRB 240414A : OHP/T193 redshift determination
  67. GRB 240414A : OHP/T193 optical counterpart detection
  68. GRB 240414A: Swift detection of a burst
  69. GRB 240411B: CrAO/ZTSh optical observations
  70. GRB 240411B: Kinder observations with Lulin observatory
  71. GRB 240411B: HiPERCAM/GTC observation
  72. GRB 240411B: Swift-BAT refined analysis
  73. GRB 240411B: Swift-XRT refined Analysis
  74. GRB 240411B: 1.3m DFOT Optical observations
  75. GRB 240411A: GRBAlpha detection
  76. GRB 240411B: OHP/T193 optical observations
  77. GRB 240405A: Glowbug gamma-ray detection
  78. GRB 240411B: Enhanced Swift-XRT position
  79. GRB 240411B: LCO optical afterglow detection
  80. GRB 240411B: Swift detection of a burst
  81. GRB 240408B: GRBAlpha detection
  82. GRB 240411A: Fermi GBM Final Real-time Localization
  83. EP240408a: Upper limits from GECAM-B Observation
  84. GRB 240405A: GRBAlpha detection
  85. GRB 240408B: AstroSat CZTI detection
  86. Fermi GRB 240408A: Global MASTER-Net observations report
  87. GRB 240408A: Fermi GBM Final Real-time Localization
  88. GRB 240407A: BALROG localization (Fermi Trigger 734144396 / GRB 240407042)
  89. GRB 240402C: CALET Gamma-Ray Burst Monitor detection
  90. Fermi GRB 240407A: Global MASTER-Net observations report
  91. GRB 240407A: Fermi GBM Final Real-time Localization
  92. LXT 240402A/GRB 240402B: rest-frame energetics from Konus-Wind observation
  93. Fermi GRB 240405B: Global MASTER-Net observations report
  94. GRB 240405B: Fermi GBM Final Real-time Localization
  95. GRB 240402C: Glowbug gamma-ray detection
  96. GRB 240405A: Fermi GBM Final Real-time Localization
  97. GRB 240402C: GRBAlpha detection
  98. GRB 240331A: GRBAlpha detection
  99. LXT 240402A/GRB 240402B: GECAM-C refined analysis
  100. GRB 240403B: Glowbug gamma-ray detection

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Download all Circulars as a .tar.gz archive (updated once a day):
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