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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: Swift-BAT refined analysis
  2. GRB 200806A: Swift/UVOT Possible Detection
  3. GRB 200806A: Swift-XRT refined Analysis
  4. Fermi-LAT Gamma-ray Observations of IceCube-200806A
  5. CGBM-SPI-ACS triangulation of short GRB 200805A
  6. GRB 200806A: AbAO optical upper limit
  7. GRB 200805A: CALET Gamma-Ray Burst Monitor detection of a short burst
  8. GRB 200806A: AstroSat CZTI detection
  9. GRB 200806A: MITSuME Akeno optical upper limits
  10. GRB 200806A: Enhanced Swift-XRT position
  11. IceCube-200806A: Upper limits from Fermi-GBM Observations
  12. Swift GRB 200806A: Global MASTER-Net observations report
  13. GRB 200806A: Swift detection of a burst
  14. IceCube-200806A: IceCube observation of a high-energy neutrino candidate event
  15. IceCube Alert 200806.58: Global MASTER-Net observations report
  16. GRB 200803B: MASTER possibly OT discovery
  17. GRB 200803A: AstroSat CZTI detection
  18. GRB 200803A: Fermi GBM detection
  19. GRB 200803A: Swift-XRT afterglow detection
  20. Fermi GRB 200803B: Global MASTER-Net observations report
  21. GRB 200803A: Fermi-LAT detection
  22. GRB 200803A: MASTER optical counterpart discovery
  23. GRB 200803B: Fermi GBM Final Real-time Localization
  24. GRB 200803A: Tiled Swift observations
  25. LAT GRB200803.15: Global MASTER-Net observations report
  26. Fermi GRB 200803A: Global MASTER-Net observations report
  27. GRB 200801B: AstroSat CZTI detection
  28. GRB 200803A: Fermi GBM Final Real-time Localization
  29. Fermi GRB 200801B: Global MASTER-Net observations report
  30. Fermi GRB 200802A: Global MASTER-Net observations report
  31. AX J1846.4-0258: Swift-BAT refined analysis
  32. Konus-Wind detection of GRB 200729A
  33. GRB 200802A: BALROG localization (Fermi Trigger 618061611 / GRB 200802491)
  34. GRB 200802A: Fermi GBM Final Real-time Localization
  35. GRB 200801C: BOOTES-1 and BOOTES-2 optical limits
  36. Fermi GRB 200801A: Global MASTER-Net observations report
  37. Swift Detection of an SGR-like flare from AX J1846.4-0258
  38. Swift GRB200801.84: Global MASTER-Net observations report
  39. GRB 200801B: BALROG localization (Fermi Trigger 617988951 / GRB 200801650)
  40. GRB 200801B: Fermi GBM Final Real-time Localization
  41. GRB 200801A: Fermi GBM Final Real-time Localization
  42. GRB 200729A: RT-22 observations at 36.8 GHz
  43. GRB 200729A: VLA Observations
  44. GRB 200729A: Nanshan/NEXT optical upper limit
  45. GRB 200729A: Swift-BAT refined analysis
  46. GRB 200729A: further analysis of the NOT data
  47. GRB 200729A: Swift/UVOT Upper Limits
  48. GRB 200729A: Swift-XRT refined Analysis
  49. GRB 200729A: HST imaging
  50. Fermi-GBM Sub-Threshold candidate for GRB 200729A
  51. GRB 200729A: IceCube neutrino search
  52. GRB 200729A: Pan-STARRS pre-explosion source detection
  53. GRB 200729A: Spitzer archival source detection
  54. GRB 200729A: TNG NIR upper limits
  55. GRB 200729A: NOT optical upper limits
  56. GRB 200729A: Enhanced Swift-XRT position
  57. GRB200729A: BOOTES-1 optical upper limit
  58. Swift GRB 200729A: Global MASTER-Net observations report
  59. GRB 200729A: Swift detection of a burst
  60. IceCube Alert 200728.35: Global MASTER-Net observations report
  61. IceCube GCN Notice 134327_10548129 retraction
  62. Baksan Neutrino Observatory Alert 200726.66: Global MASTER-Net observations report
  63. GRB 200723A: ATLAS observations of GOTO candidate AT2020qer
  64. GRB 200723A: Swift ToO observations
  65. GRB 200723A: GOTO candidate afterglow and host galaxy
  66. GRB 200724A: Fermi GBM Final Real-time Localization
  67. Fermi GRB 200723A: Global MASTER-Net observations report
  68. GRB 200723A: BALROG localization (Fermi Trigger 617214929 / GRB 200723691)
  69. GRB 200723A: Fermi GBM Final Real-time Localization
  70. GRB 200716C: Kitab optical observations
  71. GRB 200722A: BALROG localization (Fermi Trigger 617076900 / GRB 200722094)
  72. GRB 200716C: CAHA optical observation // Anomalous light curve behavior?
  73. GRB 200716C: CrAO, Terskol, Assy-Turgen optical observations
  74. GRB 200714E: Swift-XRT afterglow detection
  75. GRB 200716C: FRAM-ORM afterglow detection
  76. Konus-Wind observation of GRB 200716C: correction to GCN 28147
  77. Konus-Wind observation of GRB 200716C
  78. GRB 200716C: VIRT optical detection.
  79. GRB 200716C: Insight-HXMT/HE detection
  80. AMON IC_HAWC 170720: Correction to ANTARES GCN 28142
  81. Fermi GRB 200718A: Global MASTER-Net observations report
  82. AMON IC_HAWC 170720: No Neutrino Counterpart detected with ANTARES
  83. Fermi GBM trigger 616776657/200718619 is not a GRB
  84. GRB 200718A: Fermi GBM Final Real-time Localization
  85. GRB 200716C: CALET Gamma-Ray Burst Monitor detection
  86. GRB 200716C: Optical observations from HCT
  87. GRB 200716B: Insight-HXMT/HE detection
  88. GRB 200716C: Swift-BAT refined analysis
  89. GRB 200716C: Fermi GBM detection
  90. Fermi GRB 200716A: Global MASTER-Net observations report
  91. GRB 200716C: AGILE/MCAL detection
  92. GRB 200716C: possible host galaxy from the SDSS
  93. GRB 200716C: Swift-XRT refined analysis correction
  94. GRB 200716C: Fermi-LAT detection
  95. GRB 200716C: Swift-XRT refined Analysis
  96. GRB 200716C: Enhanced Swift-XRT position
  97. GRB 200522A: HST NIR counterpart confirmation
  98. GRB200716C: BOOTES-1 optical afterglow detection
  99. Swift GRB200716C: Global MASTER-Net OT detection
  100. GRB 200716C: Swift detection of a burst with an optical counterpart

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