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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. IceCube-210210A: Upper limits from a search for additional neutrino events in IceCube
  2. GRB 210212A: Swift/UVOT Upper Limits
  3. GRB 210212A: Swift-BAT refined analysis
  4. GRB 210204A: observations with the 3.6m Devasthal Optical Telescope and possible jet break
  5. GRB 210212A: Enhanced Swift-XRT position
  6. GRB 210210A : 1.3m DFOT optical observations
  7. GRB 210212A: Swift detection of a burst
  8. GRB 210207B: GECAM detection
  9. GRB 210211A: Swift/UVOT Detection
  10. GRB 210211A: Swift-XRT refined Analysis
  11. GRB 210211A: Swift-BAT refined analysis
  12. GRB 210211A: Fermi GBM observation
  13. GRB 210210A as a BdHN II
  14. Swift-XRT observations of IceCube-210210A
  15. GRB 210209A: Swift-BAT refined analysis
  16. GRB 210211A: Enhanced Swift-XRT position
  17. GRB 210211A: MASTER optical observation of REM OT
  18. GRB 210210A: CAHA detection and likely jet break
  19. IceCube-210210A: No neutrino counterpart in ANTARES
  20. GRB 210211A: REM optical/NIR afterglow detection
  21. Fermi-LAT Gamma-ray Observations of IceCube-210210A
  22. GRB 210211A: Swift detection of a burst
  23. Swift GRB210211.36: Global MASTER-Net observations report
  24. GRB 210211A: Fermi GBM Final Real-time Localization
  25. GRB 210210A: FRAM-ORM afterglow detection
  26. Fermi trigger No 634659312: Global MASTER-Net observations report
  27. GRB 210210A: Swift-BAT refined analysis
  28. IceCube Alert 210210.50: Global MASTER-Net observations report
  29. Fermi GRB 210210B: Global MASTER-Net observations report
  30. IceCube-210210A: Upper limits from Fermi-GBM Observations
  31. IceCube-210210A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  32. GRB 210210B: Fermi GBM Final Real-time Localization
  33. IceCube-210210A: Two Candidate Counterparts from the Zwicky Transient Facility
  34. GRB 210209A: BOOTES-4/MET optical upper limit
  35. GRB 210210A: LCO Optical Afterglow Detection
  36. Swift GRB 210209A: Global MASTER-Net observations report
  37. GRB 210210A: Swift/UVOT Detection
  38. GRB 210112A: LBT host detection and correction to GCN 29319 (CAHA observations)
  39. GRB 210209A: MITSuME Akeno optical upper limits
  40. IceCube-210210A: IceCube observation of a high-energy neutrino candidate event
  41. GRB 210209A: Swift/UVOT Upper Limits
  42. GRB 210210A: Swift-XRT refined Analysis
  43. GRB 210208A: GIT optical upper limit
  44. GRB 210210A: Redshift from OSIRIS/GTC
  45. GRB 210209A: Swift-XRT refined Analysis
  46. GRB 210210A: Enhanced Swift-XRT position
  47. GRB 210210A: MASTER afterglow observation
  48. ZTF21aahifke/AT2021clk: ZTF discovery of an optical fast transient (possible afterglow)
  49. Swift GRB 210210A: Global MASTER-Net observations report
  50. GRB 210210A: Swift detection of a burst with an optical counterpart
  51. GRB 210209A: Enhanced Swift-XRT position
  52. GRB 210209A: Swift detection of a burst
  53. GRB 210207B: Continued LCO Observations
  54. GRB 210104A: LBT observations
  55. GRB 210208A: BOOTES-2/TELMA optical upper limit
  56. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued Mondy optical observations
  57. GRB 210207B: AstroSat CZTI detection
  58. GRB 210207B: Swift/UVOT Detection
  59. GRB 210207B: Swift-BAT refined analysis
  60. GRB 210207B: Insight-HXMT/HE detection
  61. GRB 210204A: LBT observations and jet break
  62. GRB 210204A: redshift revision of ZTF21aagwbjr/AT2021buv (correction to GCN 29411)
  63. GRB 210207B: LCO Optical Afterglow Detection
  64. GRB 210207B: KAIT Optical Observations
  65. GRB 210208A: A long GRB detected by INTEGRAL
  66. GRB 210207B: AGILE observations
  67. GRB 210207B: Swift-XRT refined Analysis
  68. Konus-Wind detection of GRB 210207B
  69. SGR 1935+2154: MAXI/GSC detection
  70. Konus-Wind detection of GRB 210204A (correction to GCN 29415)
  71. GRB 210207B: AbAO optical upper limit
  72. GRB 210207B: Enhanced Swift-XRT position
  73. GRB 210207B: optical detection with 3.6m Devasthal Optical Telescope
  74. GRB 210207B: Swift detection of a burst with a bright optical counterpart
  75. Fermi GRB 210207A: Global MASTER-Net observations report
  76. GRB 210207A: BALROG localization (Fermi Trigger / GRB 210207603)
  77. GRB 210204A (ZTF21aagwbjr/AT2021buv): Mondy and AbAO optical observations
  78. GRB 210207A: Fermi GBM Final Real-time Localization
  79. Konus-Wind detection of GRB 210204A / ZTF21aagwbjr
  80. GRB 210204A: Optical Observations from HCT
  81. GRB 210204A / ZTF21aagwbjr: Swift-XRT observations
  82. GRB 210204A: Swift ToO observations
  83. VLT/X-shooter redshift of 1.466 for ZTF21aagwbjr/AT2021buv, strengthening its association with GRB 210204A
  84. GRB 210204A: AstroSat CZTI Detection
  85. GRB 210205A: Swift-BAT refined analysis
  86. IPN triangulation of GRB 210204A
  87. GRB 210205A: Swift-XRT refined Analysis
  88. GRB 210205A: MITSuME Ishigaki optical observation
  89. ZTF21aagwbjr/AT2021buv: ZTF discovery of a fast optical transient likely associated with GRB 210104A
  90. GRB 210205B: AGILE/MCAL detection of a burst
  91. GRB 210205A: Swift/UVOT Upper Limits
  92. Swift GRB 210205A: Global MASTER-Net observations report
  93. GRB 210205A: Nanshan/NEXT optical upper limit
  94. GRB 210205A: BOOTES-4/MET optical upper limit
  95. GRB 210205A: Enhanced Swift-XRT position
  96. GRB 210205A： GWAC-F60A optical upper limit
  97. GRB 210205A: Swift detection of a burst
  98. Fermi GRB 210204B: Global MASTER-Net observations report
  99. Fermi GRB 210204A: Global MASTER-Net observations report
  100. GRB 210204B: Fermi GBM Final Real-time Localization

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