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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 200806A: CAHA optical afterglow confirmation
  2. GRB 200803A: Chilescope optical upper limit
  3. IceCube-200806A: Upper limits from a search for additional neutrino events in IceCube
  4. GRB 200806A: VIRT optical observations
  5. GRB 200806A: Swift-BAT refined analysis
  6. GRB 200806A: Swift/UVOT Possible Detection
  7. GRB 200806A: Swift-XRT refined Analysis
  8. Fermi-LAT Gamma-ray Observations of IceCube-200806A
  9. CGBM-SPI-ACS triangulation of short GRB 200805A
  10. GRB 200806A: AbAO optical upper limit
  11. GRB 200805A: CALET Gamma-Ray Burst Monitor detection of a short burst
  12. GRB 200806A: AstroSat CZTI detection
  13. GRB 200806A: MITSuME Akeno optical upper limits
  14. GRB 200806A: Enhanced Swift-XRT position
  15. IceCube-200806A: Upper limits from Fermi-GBM Observations
  16. Swift GRB 200806A: Global MASTER-Net observations report
  17. GRB 200806A: Swift detection of a burst
  18. IceCube-200806A: IceCube observation of a high-energy neutrino candidate event
  19. IceCube Alert 200806.58: Global MASTER-Net observations report
  20. GRB 200803B: MASTER possibly OT discovery
  21. GRB 200803A: AstroSat CZTI detection
  22. GRB 200803A: Fermi GBM detection
  23. GRB 200803A: Swift-XRT afterglow detection
  24. Fermi GRB 200803B: Global MASTER-Net observations report
  25. GRB 200803A: Fermi-LAT detection
  26. GRB 200803A: MASTER optical counterpart discovery
  27. GRB 200803B: Fermi GBM Final Real-time Localization
  28. GRB 200803A: Tiled Swift observations
  29. LAT GRB200803.15: Global MASTER-Net observations report
  30. Fermi GRB 200803A: Global MASTER-Net observations report
  31. GRB 200801B: AstroSat CZTI detection
  32. GRB 200803A: Fermi GBM Final Real-time Localization
  33. Fermi GRB 200801B: Global MASTER-Net observations report
  34. Fermi GRB 200802A: Global MASTER-Net observations report
  35. AX J1846.4-0258: Swift-BAT refined analysis
  36. Konus-Wind detection of GRB 200729A
  37. GRB 200802A: BALROG localization (Fermi Trigger 618061611 / GRB 200802491)
  38. GRB 200802A: Fermi GBM Final Real-time Localization
  39. GRB 200801C: BOOTES-1 and BOOTES-2 optical limits
  40. Fermi GRB 200801A: Global MASTER-Net observations report
  41. Swift Detection of an SGR-like flare from AX J1846.4-0258
  42. Swift GRB200801.84: Global MASTER-Net observations report
  43. GRB 200801B: BALROG localization (Fermi Trigger 617988951 / GRB 200801650)
  44. GRB 200801B: Fermi GBM Final Real-time Localization
  45. GRB 200801A: Fermi GBM Final Real-time Localization
  46. GRB 200729A: RT-22 observations at 36.8 GHz
  47. GRB 200729A: VLA Observations
  48. GRB 200729A: Nanshan/NEXT optical upper limit
  49. GRB 200729A: Swift-BAT refined analysis
  50. GRB 200729A: further analysis of the NOT data
  51. GRB 200729A: Swift/UVOT Upper Limits
  52. GRB 200729A: Swift-XRT refined Analysis
  53. GRB 200729A: HST imaging
  54. Fermi-GBM Sub-Threshold candidate for GRB 200729A
  55. GRB 200729A: IceCube neutrino search
  56. GRB 200729A: Pan-STARRS pre-explosion source detection
  57. GRB 200729A: Spitzer archival source detection
  58. GRB 200729A: TNG NIR upper limits
  59. GRB 200729A: NOT optical upper limits
  60. GRB 200729A: Enhanced Swift-XRT position
  61. GRB200729A: BOOTES-1 optical upper limit
  62. Swift GRB 200729A: Global MASTER-Net observations report
  63. GRB 200729A: Swift detection of a burst
  64. IceCube Alert 200728.35: Global MASTER-Net observations report
  65. IceCube GCN Notice 134327_10548129 retraction
  66. Baksan Neutrino Observatory Alert 200726.66: Global MASTER-Net observations report
  67. GRB 200723A: ATLAS observations of GOTO candidate AT2020qer
  68. GRB 200723A: Swift ToO observations
  69. GRB 200723A: GOTO candidate afterglow and host galaxy
  70. GRB 200724A: Fermi GBM Final Real-time Localization
  71. Fermi GRB 200723A: Global MASTER-Net observations report
  72. GRB 200723A: BALROG localization (Fermi Trigger 617214929 / GRB 200723691)
  73. GRB 200723A: Fermi GBM Final Real-time Localization
  74. GRB 200716C: Kitab optical observations
  75. GRB 200722A: BALROG localization (Fermi Trigger 617076900 / GRB 200722094)
  76. GRB 200716C: CAHA optical observation // Anomalous light curve behavior?
  77. GRB 200716C: CrAO, Terskol, Assy-Turgen optical observations
  78. GRB 200714E: Swift-XRT afterglow detection
  79. GRB 200716C: FRAM-ORM afterglow detection
  80. Konus-Wind observation of GRB 200716C: correction to GCN 28147
  81. Konus-Wind observation of GRB 200716C
  82. GRB 200716C: VIRT optical detection.
  83. GRB 200716C: Insight-HXMT/HE detection
  84. AMON IC_HAWC 170720: Correction to ANTARES GCN 28142
  85. Fermi GRB 200718A: Global MASTER-Net observations report
  86. AMON IC_HAWC 170720: No Neutrino Counterpart detected with ANTARES
  87. Fermi GBM trigger 616776657/200718619 is not a GRB
  88. GRB 200718A: Fermi GBM Final Real-time Localization
  89. GRB 200716C: CALET Gamma-Ray Burst Monitor detection
  90. GRB 200716C: Optical observations from HCT
  91. GRB 200716B: Insight-HXMT/HE detection
  92. GRB 200716C: Swift-BAT refined analysis
  93. GRB 200716C: Fermi GBM detection
  94. Fermi GRB 200716A: Global MASTER-Net observations report
  95. GRB 200716C: AGILE/MCAL detection
  96. GRB 200716C: possible host galaxy from the SDSS
  97. GRB 200716C: Swift-XRT refined analysis correction
  98. GRB 200716C: Fermi-LAT detection
  99. GRB 200716C: Swift-XRT refined Analysis
  100. GRB 200716C: Enhanced Swift-XRT position

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