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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"
  1. IceCube Alert 200421.02: Global MASTER-Net observations report
  2. IceCube-200421A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  3. IceCube-200421A - IceCube observation of a high-energy neutrino candidate event
  4. IceCube Alert 200420.97: Global MASTER-Net observations report
  5. GRB 200412B: continued Mondy and Terskol optical observations
  6. GRB 200420: Fermi GBM Final Localization Correction
  7. Fermi GRB 200420A: Global MASTER-Net observations report
  8. GRB 200420A: Fermi GBM Final Real-time Localization
  9. Fermi trigger No 608935505: Global MASTER-Net observations report
  10. GRB 200412B: continued Terskol optical observations
  11. GRB 200412B: continued AbAO, Mondy, TSHAO, Terskol optical observations
  12. GRB 200410A: Optical upper limit
  13. GRB 200416A: Swift/UVOT Detection
  14. GRB 200416A: Swift-BAT refined analysis
  15. GRB 200412B: Swift XRT confirmation of afterglow and UVOT upper limits
  16. GRB 200415A: MASTER imspection and possible localisation
  17. GRB200412B: GROWTH India detection of afterglow
  18. GRB 200415A: Fermi-LAT localization update
  19. Konus-Wind observation of GRB 200415A (a magnetar Giant Flare in Sculptor Galaxy?)
  20. Improved IPN error box for GRB 200415A (consistent with the Sculptor Galaxy)
  21. GRB 200416A: Swift-XRT refined Analysis
  22. GRB 200412B: continued Tautenburg observations
  23. GRB 200416A: Fermi GBM observation
  24. GRB 200416A: Swift detection of a burst with an optical afterglow
  25. Fermi GRB 200415A: Global MASTER-Net observations report
  26. GRB 200411A: Chandra observations indicative of temporal steepening
  27. GRB 200412A : AstroSat CZTI detection
  28. GRB 200415A: Fermi GBM observation
  29. GRB 200415A: Fermi-LAT detection
  30. IPN triangulation of GRB 200415A (possible Magnetar Giant Flare in Sculptor Galaxy?)
  31. GRB 200410A: CALET Gamma-Ray Burst Monitor detection
  32. GRB 200412B: Mondy optical observations
  33. GRB 200412B: continued Tautenburg observations
  34. Konus-Wind observation of GRB 200412B
  35. GRB 200415A: BALROG localization (Fermi Trigger 608633290 / GRB 200415367)
  36. GRB 200415A: Fermi GBM Final Real-time Localization
  37. GRB 200410A: Swift-BAT refined analysis
  38. Konus-Wind observation of GRB 200412A
  39. GRB 200412B: MITSuME Akeno optical observation
  40. GRB 200412B: Tautenburg observations
  41. GRB 200412B: contunued AbAO optical observations
  42. GRB 200411A: ATCA 5/9 GHz radio observations
  43. GRB 200412B: CALET Gamma-Ray Burst Monitor detection
  44. GRB 200412B: Xinglong TNT optical observations
  45. GRB 200412B: SAO RAS observations of OT
  46. IceCube-200410A: No significant detection in HAWC
  47. GRB 200405B: Further Swift-XRT observations
  48. GRB 200412B: Tautenburg observations
  49. GRB 200412B: AbAO optical observations
  50. GRB 200412B: Insight-HXMT/HE detection
  51. GRB 200412B: Optical afterglow detection with 1.3m DFOT
  52. GRB 200412B : AstroSat CZTI detection
  53. IceCube-200410A : Upper limits from Insight-HXMT/HE observations
  54. GRB 200412B: Swift-XRT afterglow detection
  55. IPN triangulation of GRB 200412A
  56. Fermi GRB 200412A: Global MASTER-Net observations report
  57. GRB 200412B: Fermi GBM detection
  58. GRB 200412B: Fermi-LAT detection
  59. GRB 200412B: MASTER-Amur Optical Couterpart in Gagarin day!
  60. GRB 200412B: MASTER Optical Couterpart in Gagarin day!
  61. Konus-Wind observation of a bright burst from SGR 1935+2154
  62. Correction to GCN 27551 - Swift is observing GRB 200412*B*
  63. IceCube-200410A: Upper limits from a search for additional neutrino events in IceCube
  64. GRB 200412B: Tiled Swift observations
  65. GRB 200412A: Fermi GBM detection
  66. Fermi GRB 200412B: Global MASTER-Net observations report
  67. GRB 200412B: BALROG localization (Fermi Trigger 608375325 / GRB 200412381)
  68. GRB 200412B: Fermi GBM Final Real-time Localization
  69. GRB 200412A: BALROG localization (Fermi Trigger 608367436 / GRB 200412290)
  70. GRB 200411A: Swift-BAT refined analysis
  71. Fermi-LAT Gamma-ray Observations of IceCube-200410A
  72. GRB 200411A: Fermi GBM observation
  73. Swift GRB 200411A: Global MASTER-Net observations report
  74. IceCube-200410A: Upper limits from Fermi-GBM Observations
  75. GRB 200411A: Swift-XRT refined Analysis
  76. GRB 200411A: Swift/UVOT Upper Limits
  77. GRB 200411A: Enhanced Swift-XRT position
  78. IceCube-200410A: Possible associated excess in INTEGRAL SPI-ACS prompt observation
  79. GRB 200411A: Swift detection of a short burst
  80. GRB 200411A: Fermi GBM Final Real-time Localization
  81. IceCube-200410A - IceCube observation of a high-energy neutrino candidate event
  82. IceCube Alert 200410.97: Global MASTER-Net observations report
  83. GRB 200410A: Swift/UVOT Detection
  84. SGR 1935+2154: Fermi GBM observation
  85. Baksan Neutrino Observatory Alert 200410.82: Global MASTER-Net observations report
  86. Fermi trigger No 608204639: Global MASTER-Net observations report
  87. Baksan Neutrino Observatory Alert 200409.81: Global MASTER-Net observations report
  88. IPN Triangulation of a bright burst from SGR 1935+2154
  89. LIGO/Virgo S200225q: Swift XRT observations, 1 X-ray sources
  90. Konus-Wind observation of GRB 200327A
  91. LIGO/Virgo S200224ca: Swift XRT observations, 8 X-ray sources
  92. GRB 200410A: Swift-XRT refined Analysis
  93. GRB 200410A: Enhanced Swift-XRT position
  94. GRB 200409A: No detection of radio emission 5 hours post-burst
  95. GRB 200410A: Ondrejov D50 afterglow confirmation
  96. GRB 200409A: Swift-BAT refined analysis
  97. GRB 200410A: Swift detection of a burst with a possible optical counterpart
  98. Swift GRB200410.10: Global MASTER-Net observations report
  99. GRB 200405B: ATCA follow-up and ASKAP limits on pre-burst radio emission
  100. Baksan Neutrino Observatory Alert 200408.26: Global MASTER-Net observations report

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