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

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