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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 S200316bj: No Counterparts in DDOTI/OAN Optical Observations
  2. LIGO/Virgo S200316bj: no counterpart candidates in the Swift/BAT observations
  3. LIGO/Virgo S200213t: Continued Swift UVOT and XRT observations of ZTF20aamvmzj (AT2020cja)
  4. Konus-Wind observation of GRB 200313A
  5. Konus-Wind observation of GRB 200311A
  6. LIGO/Virgo S200316bj: No counterpart candidates in INTEGRAL SPI-ACS, and IBIS prompt observation
  7. LIGO/Virgo S200316bj: upper limits from AGILE/GRID observations
  8. LIGO/Virgo S200316bj: upper limits from AGILE/MCAL observations
  9. LIGO/Virgo S200316bj: Upper limits from Fermi-GBM Observations
  10. Fermi trigger No 606098435: Global MASTER-Net observations report
  11. GRB 200317A: Fermi GBM Final Real-time Localization
  12. LIGO/Virgo S200316bj: Coverage and upper limits from MAXI/GSC observations
  13. LIGO/Virgo S200316bj : no neutrino counterpart candidate in ANTARES search
  14. LIGO/Virgo S200316bj: Upper limits from IceCube neutrino searches
  15. LIGO/Virgo S200316bj: Identification of a GW compact binary merger candidate
  16. LIGO/Virgo S200316bj: Global MASTER-Net observations report
  17. IPN triangulation of GRB 200313B (short)
  18. IPN triangulation of GRB 200313A
  19. SGR Swift J1818.0-1607: Swift-BAT refined analysis
  20. GRB 200313A: Fermi GBM detection
  21. LIGO/Virgo S200311bg: Updated Sky Localization and EM Bright Classification
  22. IPN triangulation of GRB 200311A
  23. Fermi trigger No 605789837: Global MASTER-Net observations report
  24. GRB 200313B: Fermi GBM Final Real-time Localization
  25. SGR Swift J1818.0-1607: BOOTES-4/MET optical limit
  26. GRB 200313A: BALROG localization (Fermi Trigger 605756501 / GRB 200313071)
  27. Fermi trigger No 605756501: Global MASTER-Net observations report
  28. Swift GRB200312.89: Global MASTER-Net observations report
  29. GRB 200313A: Fermi GBM Final Real-time Localization
  30. Swift-BAT trigger 960986: Swift detection of a new SGR Swift J1818.0-1607
  31. LIGO/Virgo S200311bg: Not observable by CALET
  32. GRB 200311A: AstroSat CZTI detection
  33. Fermi trigger No 605632577: Global MASTER-Net observations report
  34. LIGO/Virgo S200311bg: Swift/BAT in the South Atlantic Anomaly
  35. LIGO/Virgo S200311bg: No significant counterpart candidates in Fermi-LAT observations
  36. IPN triangulation of GRB 200307A (short)
  37. LIGO/Virgo S200224ca: DESGW Summary of DECam Observations
  38. GRB 200311A: AGILE/MCAL and scientific ratemeters observations
  39. LIGO/Virgo S200311bg: not observable by Fermi GBM
  40. GRB 200311A: Fermi GBM Final Real-time Localization
  41. LIGO/Virgo S200311bg: Coverage and upper limits from MAXI/GSC observations
  42. LIGO/Virgo S200311bg: not observable by AGILE at the event time
  43. LIGO/Virgo S200311bg: No counterpart candidates in INTEGRAL SPI-ACS,prompt observation
  44. LIGO/Virgo S200311bg: Upper limits from IceCube neutrino searches
  45. LIGO/Virgo S200311bg: Identification of a GW compact binary merger candidate
  46. Chandra observations of GW170817 ~ 2.5 years since merger (epoch 1 of 4)
  47. GRB 200307A: Updated localization from Fermi/GBM and Swift/BAT-GUANO
  48. GRB 200310A: MAXI/GSC detection
  49. GRB 200306C: ALMA 3mm upper limit
  50. GRB 200306C: Swift-BAT refined analysis
  51. GRB 200306C: Swift/UVOT Detection
  52. GRB 200306A: Swift/UVOT Upper Limits
  53. GRB 200308A: Fermi GBM Final Real-time Localization
  54. Fermi trigger No 605309224: Global MASTER-Net observations report
  55. GRB 200306C: Calar Alto 2.2m upper limit
  56. LIGO/Virgo S200308e: Retraction of GW compact binary merger candidate
  57. GRB 200306A: Swift-BAT refined analysis
  58. GRB 200306C: Swift-XRT refined Analysis
  59. GRB 200307A: Fermi GBM Final Real-time Localization
  60. GRB 200306A: RATIR Optical Observations
  61. GRB 200306C: Enhanced Swift-XRT position
  62. GRB 200306C: VIRT optical upper limits
  63. GRB 200306A: AstroSat CZTI detection
  64. GRB 200306C: KCT upper limit of the optical afterglow
  65. GRB200306C: First Hour Liverpool Telescope Observations
  66. GRB 200306C: LCO Optical Upper Limits
  67. GRB 200306B: Fermi GBM Final Localization Correction
  68. GRB 200306C: OSN 1.5m afterglow detection
  69. GRB 200306C: Liverpool Telescope observations
  70. GRB 200306C: SAO RAS observations of OT
  71. GRB 200306C: GOTO upper limits
  72. GRB 200306A: Swift-XRT refined Analysis
  73. LIGO/Virgo S200302c: No notable candidates in GOTO imaging
  74. GRB 200306C: BOOTES-1 detection of the optical afterglow
  75. GRB 200306C: FRAM-ORM afterglow detection
  76. Swift GRB200306.95: Global MASTER-Net observations report
  77. GRB 200306C: Swift detection of a burst with an optical counterpart
  78. Swift GRB200306.95: Global MASTER-Net OT detection
  79. Swift GRB200306.95: Global MASTER-Net OT detection
  80. GRB 200306B: Fermi GBM Final Real-time Localization
  81. LIGO/Virgo S200302c : No significant candidates in FRAM - TAROT - GRANDMA observations.
  82. GRB 200306A: Potential LCO Optical Afterglow Detection
  83. GRB 200306A: Swift detection of a burst
  84. Swift GRB200306.01: Global MASTER-Net observations report
  85. GRB 200228B: continued optical observations
  86. LIGO/Virgo S200225q: No notable candidates in GOTO imaging
  87. Konus-Wind observation of GRB200303A
  88. LIGO/Virgo S200302c: AstroSat CZTI upper limits
  89. GRB 200303A: Fermi GBM observation
  90. GRB200210A AstroSat observations
  91. GRB 200303A: Swift-XRT refined Analysis
  92. GRB 200303A: Swift-BAT refined analysis
  93. LIGO/Virgo S200302c: Upper limits from Insight-HXMT/HE observations
  94. GRB 200303A: NOT optical observations
  95. GRB 200303A: Swift/UVOT Upper Limits
  96. GRB 200303A: FRAM-ORM optical limit
  97. LIGO/Virgo S200303ba: Retraction of GW compact binary merger candidate
  98. GRB 200219A: AstroSat CZTI detection
  99. GRB 200303A: GOTO observations upper limit
  100. GRB 200303A: Optical limit from CAHA

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