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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. SGR 1935+2154: MAXI/GSC detection
  2. Fermi GBM observation of a bright flare from magnetar SGR 1935+2154
  3. IceCube-200425A: No significant detection in HAWC
  4. Swift detection of multiple bursts from SGR 1935+2154
  5. IceCube-200425A: Upper limits from a search for additional neutrino events in IceCube
  6. IceCube-200425A: Upper limits from Fermi-GBM Observations
  7. Fermi-LAT Gamma-ray Observations of IceCube-200425A
  8. Gagarin-day GRB 200412B: observations with the 3.6m Devasthal Optical Telescope
  9. IceCube-200425A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  10. IceCube-200425A - IceCube observation of a high-energy neutrino candidate event
  11. GRB 200425A: Swift-BAT refined analysis
  12. IceCube Alert 200425.98: Global MASTER-Net observations report
  13. GRB 200424A: Swift/UVOT Upper Limits
  14. IPN triangulation of GRB 200423A (short)
  15. GRB 200425A: LCO Optical Upper Limits
  16. Swift GRB 200425A: Global MASTER-Net observations report
  17. GRB 200425B: Fermi GBM Final Real-time Localization
  18. GRB 200425A: Swift/UVOT Upper Limits
  19. GRB 200424A: AstroSat CZTI detection
  20. GRB 200425A: Swift-XRT refined Analysis
  21. GRB 200424A: Swift-XRT observations
  22. GRB 200425A: Enhanced Swift-XRT position
  23. GRB 200425A: Swift detection of a burst
  24. GRB 200424A: LCO Optical Upper Limit
  25. GRB 200424A: Swift ToO observations
  26. Konus-Wind observation of GRB 200422A
  27. GRB 200424A: a long GRB detected by INTEGRAL
  28. Fermi GRB 200423A: Global MASTER-Net observations report
  29. GRB 200423A: Fermi GBM Final Real-time Localization
  30. Konus-Wind observation of a bright burst from SGR 1935+2154
  31. GRB 200422A: AstroSat CZTI detection
  32. GRB 200415A correction to GCN 27627 (possible magnetar Giant Flare in Sculptor Galaxy): INTEGRAL observations
  33. GRB 200422A: MASTER optical observations
  34. GRB 200415A (possible magnetar Giant Flare in Sculptor Galaxy): INTEGRAL observations
  35. IPN triangulation of GRB 200422A (long/very bright)
  36. IPN Triangulation of a bright burst from SGR 1935+2154
  37. IceCube-200421A: Upper limits from a search for additional neutrino events in IceCube
  38. bright SGR burst detected by CALET Gamma-Ray Burst Monitor
  39. GRB 200415A: ASIM observation
  40. GRB 200410A: Liverpool Telescope First Hour Observations
  41. Fermi-LAT Gamma-ray Observations of IceCube-200421A
  42. IceCube-200421A: No Neutrino Counterpart in ANTARES data
  43. Fermi GRB 200421A: Global MASTER-Net observations report
  44. IceCube-200421A: No significant detection in HAWC
  45. GRB 200421A: Fermi GBM Final Real-time Localization
  46. IceCube-200421A: not observable by Fermi-GBM
  47. IceCube Alert 200421.02: Global MASTER-Net observations report
  48. IceCube-200421A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  49. IceCube-200421A - IceCube observation of a high-energy neutrino candidate event
  50. IceCube Alert 200420.97: Global MASTER-Net observations report
  51. GRB 200412B: continued Mondy and Terskol optical observations
  52. GRB 200420: Fermi GBM Final Localization Correction
  53. Fermi GRB 200420A: Global MASTER-Net observations report
  54. GRB 200420A: Fermi GBM Final Real-time Localization
  55. Fermi trigger No 608935505: Global MASTER-Net observations report
  56. GRB 200412B: continued Terskol optical observations
  57. GRB 200412B: continued AbAO, Mondy, TSHAO, Terskol optical observations
  58. GRB 200410A: Optical upper limit
  59. GRB 200416A: Swift/UVOT Detection
  60. GRB 200416A: Swift-BAT refined analysis
  61. GRB 200412B: Swift XRT confirmation of afterglow and UVOT upper limits
  62. GRB 200415A: MASTER imspection and possible localisation
  63. GRB200412B: GROWTH India detection of afterglow
  64. GRB 200415A: Fermi-LAT localization update
  65. Konus-Wind observation of GRB 200415A (a magnetar Giant Flare in Sculptor Galaxy?)
  66. Improved IPN error box for GRB 200415A (consistent with the Sculptor Galaxy)
  67. GRB 200416A: Swift-XRT refined Analysis
  68. GRB 200412B: continued Tautenburg observations
  69. GRB 200416A: Fermi GBM observation
  70. GRB 200416A: Swift detection of a burst with an optical afterglow
  71. Fermi GRB 200415A: Global MASTER-Net observations report
  72. GRB 200411A: Chandra observations indicative of temporal steepening
  73. GRB 200412A : AstroSat CZTI detection
  74. GRB 200415A: Fermi GBM observation
  75. GRB 200415A: Fermi-LAT detection
  76. IPN triangulation of GRB 200415A (possible Magnetar Giant Flare in Sculptor Galaxy?)
  77. GRB 200410A: CALET Gamma-Ray Burst Monitor detection
  78. GRB 200412B: Mondy optical observations
  79. GRB 200412B: continued Tautenburg observations
  80. Konus-Wind observation of GRB 200412B
  81. GRB 200415A: BALROG localization (Fermi Trigger 608633290 / GRB 200415367)
  82. GRB 200415A: Fermi GBM Final Real-time Localization
  83. GRB 200410A: Swift-BAT refined analysis
  84. Konus-Wind observation of GRB 200412A
  85. GRB 200412B: MITSuME Akeno optical observation
  86. GRB 200412B: Tautenburg observations
  87. GRB 200412B: contunued AbAO optical observations
  88. GRB 200411A: ATCA 5/9 GHz radio observations
  89. GRB 200412B: CALET Gamma-Ray Burst Monitor detection
  90. GRB 200412B: Xinglong TNT optical observations
  91. GRB 200412B: SAO RAS observations of OT
  92. IceCube-200410A: No significant detection in HAWC
  93. GRB 200405B: Further Swift-XRT observations
  94. GRB 200412B: Tautenburg observations
  95. GRB 200412B: AbAO optical observations
  96. GRB 200412B: Insight-HXMT/HE detection
  97. GRB 200412B: Optical afterglow detection with 1.3m DFOT
  98. GRB 200412B : AstroSat CZTI detection
  99. IceCube-200410A : Upper limits from Insight-HXMT/HE observations
  100. GRB 200412B: Swift-XRT afterglow detection

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