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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. GRB 200205A = Swift J0840.7-3516: optical photometry in Chilescope observatory
  2. GRB 200206A: Fermi GBM Final Real-time Localization
  3. GRB 200205B: Swift-XRT refined Analysis
  4. GRB 200205A = Swift J0840.7-3516, A newly discovered transient X-ray Pulsar
  5. GRB 200205B: Enhanced Swift-XRT position
  6. GRB 200205B: VLT/X-shooter redshift
  7. Fermi trigger No 602626648: Global MASTER-Net observations report
  8. GRB 200205A: Enhanced Swift-XRT position
  9. GRB 200205B: LCO Optical Detection
  10. GRB 200205C: Fermi GBM Final Real-time Localization
  11. GRB 200205B: Swift detection of a burst with optical counterpart
  12. Swift GRB200205.81: Global MASTER-Net observations report
  13. Swift GRB200205.81: Global MASTER-Net OT detection
  14. MeerKAT observation of GRB 191221B
  15. GRB 200205A / Swift trigger 954304: VLT optical observations
  16. GRB200120A: SRG/eROSITA discovery of X-ray afterglow
  17. GRB 200205A: MAXI/GSC detection
  18. GRB 200205A: REM optical observations
  19. MAXI GRB200205.29: Global MASTER-Net observations report
  20. GRB 200205A: MASTER Ot detection
  21. Swift GRB 200205A: Global MASTER-Net observations report
  22. GRB 200205A: Swift detection of a burst with a possible UV counterpart
  23. Fermi trigger No 602455182: Global MASTER-Net observations report
  24. Re-classification of Fermi GBM triggers 200203137, 200203156/GRB200203A and 200203861
  25. LIGO/Virgo S200129m: Upper limits from Konus-Wind observations
  26. LIGO/Virgo S200128d: Upper limits from Konus-Wind observations
  27. GRB 200131A: Further RATIR Optical Observations
  28. AMON IceCube-HAWC_200202A : No neutrino counterpart seen with ANTARES
  29. Konus-Wind observation of GRB 200131A
  30. GRB200120A: SRG/ART-XC Upper Limit
  31. AMON IceCube-HAWC_200202A: MASTER optical inspect
  32. GRB 200131A: CALET Gamma-Ray Burst Monitor detection
  33. Fermi trigger No 602392636: Global MASTER-Net observations report
  34. ZTF20aajnksq: Occulted by Earth at the time of GRB 200128A
  35. GRB 200203A: Fermi GBM Final Real-time Localization
  36. ZTF20aajnksq: Gemini-North r-band photometry
  37. GRB 200131A: Swift-BAT refined analysis
  38. ZTF Discovery of ZTF20aajnksq: a Rapidly Fading Luminous Transient in the GRB 200128A Localiziation Region
  39. GRB 200131A: ISON-Castelgrande optical observations
  40. GRB 200131A: CDK700 optical observations
  41. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-200202A
  42. GRB 200131A: Swift/UVOT Detection
  43. GRB 200131A: Swift-XRT refined Analysis
  44. GRB 200131A: VIRT optical transient detection
  45. GRB 200131A: LCO Optical Detection
  46. GRB 200131A: KAIT Optical Upper Limit
  47. GRB 200131A: RATIR Optical Observations
  48. GRB 200131A: Enhanced Swift-XRT position
  49. GRB 200201A: Fermi GBM Final Real-time Localization
  50. GRB 200131A: MASTER optical transient detection
  51. GRB 200131A: Swift detection of a burst with an optical counterpart
  52. Swift GRB200131.95: Global MASTER-Net observations report
  53. Konus-Wind observation of GRB 200125B
  54. Konus-Wind observation of GRB 200130B
  55. IPN triangulation of GRB 200130B
  56. LIGO/Virgo S200128d: no counterpart candidate in SVOM/GWAC observations
  57. LIGO/Virgo S200128d : No significant candidates in FRAM - TAROT - GRANDMA observations
  58. Fermi trigger No 602071201: Global MASTER-Net observations report
  59. GRB 200130B: BALROG localization (Fermi Trigger 602071201 / GRB 200130417)
  60. GRB 200130B: Fermi GBM Final Real-time Localization
  61. Fermi trigger No 602056641: Global MASTER-Net observations report
  62. GRB 200130A: Fermi GBM Final Real-time Localization
  63. LIGO/Virgo S200129m: Upper limits from CALET observations.
  64. LIGO/Virgo S200129m: no counterpart candidates in the Swift/BAT observations
  65. GRB 200127A: Swift-BAT refined analysis
  66. LIGO/Virgo S200129m: NED Galaxies in the 50% Localization Volume
  67. LIGO/Virgo S200129m: No counterpart candidates in Fermi-LAT observations
  68. LIGO/Virgo S200129m: Not observable by Fermi-GBM
  69. Konus-Wind observation of GRB 200125A
  70. LIGO/Virgo S200128d: upper limits from AGILE/GRID observations
  71. LIGO/Virgo S200129m: Global MASTER-Net observations report
  72. GRB 200129A: Fermi GBM Final Real-time Localization
  73. LIGO/Virgo S200129m: upper limits from AGILE/GRID observations
  74. LIGO/Virgo S200129m: upper limits from AGILE/MCAL observations
  75. LIGO/Virgo S200129m: Coverage and upper limits from MAXI/GSC observations
  76. LIGO/Virgo S200129m: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  77. LIGO/Virgo S200129m: Upper limits from IceCube neutrino searches
  78. LIGO/Virgo S200129m: Identification of a GW compact binary merger candidate
  79. LIGO/Virgo S200128d: No counterpart candidates in Fermi-LAT observations
  80. LIGO/Virgo S200128d: Upper limits from CALET observations
  81. LIGO/Virgo S200128d: No counterpart candidates in KAIT observations
  82. Fermi-LAT ANTARES coincidence: IceCube neutrino search
  83. LIGO/Virgo S200128d: no counterpart candidates in the Swift/BAT observations
  84. Fermi-LAT ANTARES 200127.79 coincidence: MASTER alert observation and presence of young pulsar close to error-box
  85. GRB 200127A: Swift/UVOT Upper Limits
  86. IPN triangulation of GRB 200125B
  87. GRB 200128B: AGILE/MCAL detection of a burst
  88. LIGO/Virgo S200128d: Upper limits from Fermi-GBM Observations
  89. Fermi-LAT-ANTARES coincidence
  90. GRB 200127A: Mondy optical upper limit
  91. GRB200127A: Nordic Optical telecope optical upper limit
  92. LIGO/Virgo S200128d : no neutrino counterpart candidate in ANTARES search
  93. GRB 200125B: DDOTI/OAN optical observations report
  94. LIGO/Virgo S200128d: Coverage and upper limits from MAXI/GSC observations
  95. GRB 200128A: Fermi GBM Final Real-time Localization
  96. LIGO/Virgo S200128d: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  97. LIGO/Virgo S200128d: No counterpart candidates in HAWC observations
  98. LIGO/Virgo S200128d: Identification of a GW compact binary merger candidate
  99. LIGO/Virgo S200128d: Upper limits from IceCube neutrino searches
  100. GRB 200127A: Nanshan-0.6m optical upper limit

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