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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. LIGO/Virgo S200129m: Upper limits from Insight-HXMT/HE observations
  2. GRB 200120A: Fermi GBM observation
  3. LIGO/Virgo S200208q: Coverage and upper limits from MAXI/GSC observations
  4. LIGO/Virgo S200208q: no counterpart candidates in the Swift/BAT observations
  5. LIGO/Virgo S200208q: Upper limits from Fermi-GBM Observations
  6. LIGO/Virgo S200208q : upper limits from AGILE/GRID observations
  7. LIGO/Virgo S200208q: upper limits from AGILE/MCAL observations
  8. LIGO/Virgo S200208q: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  9. LIGO/Virgo S200208q: Global MASTER-Net observations report
  10. LIGO/Virgo S200208q: No counterpart candidates in HAWC observations
  11. LIGO/Virgo S200208q : no neutrino counterpart candidate in ANTARES search
  12. LIGO/Virgo S200208q: Upper limits from IceCube neutrino searches
  13. LIGO/Virgo S200208q: Identification of a GW compact binary merger candidate
  14. Fermi trigger No 602817262: Global MASTER-Net observations report
  15. GRB 200205B: Swift-BAT refined analysis
  16. GRB 200208A: Fermi GBM Final Real-time Localization
  17. Swift J0840.7-3516 (AKA GRB 200205A): Swift-BAT refined analysis
  18. Fermi trigger No 602731380: Global MASTER-Net observations report
  19. Swift Trigger 954840 is not a GRB
  20. Swift GRB200207.13: Global MASTER-Net observations report
  21. GRB 200205B: Swift/UVOT Detection
  22. GRB 200207A: Fermi GBM Final Real-time Localization
  23. GRB 200205B: ESO/NTT near-infrared imaging
  24. GRB 200205A = Swift J0840.7-3516: optical photometry in Chilescope observatory
  25. GRB 200206A: Fermi GBM Final Real-time Localization
  26. GRB 200205B: Swift-XRT refined Analysis
  27. GRB 200205A = Swift J0840.7-3516, A newly discovered transient X-ray Pulsar
  28. GRB 200205B: Enhanced Swift-XRT position
  29. GRB 200205B: VLT/X-shooter redshift
  30. Fermi trigger No 602626648: Global MASTER-Net observations report
  31. GRB 200205A: Enhanced Swift-XRT position
  32. GRB 200205B: LCO Optical Detection
  33. GRB 200205C: Fermi GBM Final Real-time Localization
  34. GRB 200205B: Swift detection of a burst with optical counterpart
  35. Swift GRB200205.81: Global MASTER-Net observations report
  36. Swift GRB200205.81: Global MASTER-Net OT detection
  37. MeerKAT observation of GRB 191221B
  38. GRB 200205A / Swift trigger 954304: VLT optical observations
  39. GRB200120A: SRG/eROSITA discovery of X-ray afterglow
  40. GRB 200205A: MAXI/GSC detection
  41. GRB 200205A: REM optical observations
  42. MAXI GRB200205.29: Global MASTER-Net observations report
  43. GRB 200205A: MASTER Ot detection
  44. Swift GRB 200205A: Global MASTER-Net observations report
  45. GRB 200205A: Swift detection of a burst with a possible UV counterpart
  46. Fermi trigger No 602455182: Global MASTER-Net observations report
  47. Re-classification of Fermi GBM triggers 200203137, 200203156/GRB200203A and 200203861
  48. LIGO/Virgo S200129m: Upper limits from Konus-Wind observations
  49. LIGO/Virgo S200128d: Upper limits from Konus-Wind observations
  50. GRB 200131A: Further RATIR Optical Observations
  51. AMON IceCube-HAWC_200202A : No neutrino counterpart seen with ANTARES
  52. Konus-Wind observation of GRB 200131A
  53. GRB200120A: SRG/ART-XC Upper Limit
  54. AMON IceCube-HAWC_200202A: MASTER optical inspect
  55. GRB 200131A: CALET Gamma-Ray Burst Monitor detection
  56. Fermi trigger No 602392636: Global MASTER-Net observations report
  57. ZTF20aajnksq: Occulted by Earth at the time of GRB 200128A
  58. GRB 200203A: Fermi GBM Final Real-time Localization
  59. ZTF20aajnksq: Gemini-North r-band photometry
  60. GRB 200131A: Swift-BAT refined analysis
  61. ZTF Discovery of ZTF20aajnksq: a Rapidly Fading Luminous Transient in the GRB 200128A Localiziation Region
  62. GRB 200131A: ISON-Castelgrande optical observations
  63. GRB 200131A: CDK700 optical observations
  64. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-200202A
  65. GRB 200131A: Swift/UVOT Detection
  66. GRB 200131A: Swift-XRT refined Analysis
  67. GRB 200131A: VIRT optical transient detection
  68. GRB 200131A: LCO Optical Detection
  69. GRB 200131A: KAIT Optical Upper Limit
  70. GRB 200131A: RATIR Optical Observations
  71. GRB 200131A: Enhanced Swift-XRT position
  72. GRB 200201A: Fermi GBM Final Real-time Localization
  73. GRB 200131A: MASTER optical transient detection
  74. GRB 200131A: Swift detection of a burst with an optical counterpart
  75. Swift GRB200131.95: Global MASTER-Net observations report
  76. Konus-Wind observation of GRB 200125B
  77. Konus-Wind observation of GRB 200130B
  78. IPN triangulation of GRB 200130B
  79. LIGO/Virgo S200128d: no counterpart candidate in SVOM/GWAC observations
  80. LIGO/Virgo S200128d : No significant candidates in FRAM - TAROT - GRANDMA observations
  81. Fermi trigger No 602071201: Global MASTER-Net observations report
  82. GRB 200130B: BALROG localization (Fermi Trigger 602071201 / GRB 200130417)
  83. GRB 200130B: Fermi GBM Final Real-time Localization
  84. Fermi trigger No 602056641: Global MASTER-Net observations report
  85. GRB 200130A: Fermi GBM Final Real-time Localization
  86. LIGO/Virgo S200129m: Upper limits from CALET observations.
  87. LIGO/Virgo S200129m: no counterpart candidates in the Swift/BAT observations
  88. GRB 200127A: Swift-BAT refined analysis
  89. LIGO/Virgo S200129m: NED Galaxies in the 50% Localization Volume
  90. LIGO/Virgo S200129m: No counterpart candidates in Fermi-LAT observations
  91. LIGO/Virgo S200129m: Not observable by Fermi-GBM
  92. Konus-Wind observation of GRB 200125A
  93. LIGO/Virgo S200128d: upper limits from AGILE/GRID observations
  94. LIGO/Virgo S200129m: Global MASTER-Net observations report
  95. GRB 200129A: Fermi GBM Final Real-time Localization
  96. LIGO/Virgo S200129m: upper limits from AGILE/GRID observations
  97. LIGO/Virgo S200129m: upper limits from AGILE/MCAL observations
  98. LIGO/Virgo S200129m: Coverage and upper limits from MAXI/GSC observations
  99. LIGO/Virgo S200129m: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  100. LIGO/Virgo S200129m: Upper limits from IceCube neutrino searches

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