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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. Fermi GRB 200803A: Global MASTER-Net observations report
  2. GRB 200801B: AstroSat CZTI detection
  3. GRB 200803A: Fermi GBM Final Real-time Localization
  4. Fermi GRB 200801B: Global MASTER-Net observations report
  5. Fermi GRB 200802A: Global MASTER-Net observations report
  6. AX J1846.4-0258: Swift-BAT refined analysis
  7. Konus-Wind detection of GRB 200729A
  8. GRB 200802A: BALROG localization (Fermi Trigger 618061611 / GRB 200802491)
  9. GRB 200802A: Fermi GBM Final Real-time Localization
  10. GRB 200801C: BOOTES-1 and BOOTES-2 optical limits
  11. Fermi GRB 200801A: Global MASTER-Net observations report
  12. Swift Detection of an SGR-like flare from AX J1846.4-0258
  13. Swift GRB200801.84: Global MASTER-Net observations report
  14. GRB 200801B: BALROG localization (Fermi Trigger 617988951 / GRB 200801650)
  15. GRB 200801B: Fermi GBM Final Real-time Localization
  16. GRB 200801A: Fermi GBM Final Real-time Localization
  17. GRB 200729A: RT-22 observations at 36.8 GHz
  18. GRB 200729A: VLA Observations
  19. GRB 200729A: Nanshan/NEXT optical upper limit
  20. GRB 200729A: Swift-BAT refined analysis
  21. GRB 200729A: further analysis of the NOT data
  22. GRB 200729A: Swift/UVOT Upper Limits
  23. GRB 200729A: Swift-XRT refined Analysis
  24. GRB 200729A: HST imaging
  25. Fermi-GBM Sub-Threshold candidate for GRB 200729A
  26. GRB 200729A: IceCube neutrino search
  27. GRB 200729A: Pan-STARRS pre-explosion source detection
  28. GRB 200729A: Spitzer archival source detection
  29. GRB 200729A: TNG NIR upper limits
  30. GRB 200729A: NOT optical upper limits
  31. GRB 200729A: Enhanced Swift-XRT position
  32. GRB200729A: BOOTES-1 optical upper limit
  33. Swift GRB 200729A: Global MASTER-Net observations report
  34. GRB 200729A: Swift detection of a burst
  35. IceCube Alert 200728.35: Global MASTER-Net observations report
  36. IceCube GCN Notice 134327_10548129 retraction
  37. Baksan Neutrino Observatory Alert 200726.66: Global MASTER-Net observations report
  38. GRB 200723A: ATLAS observations of GOTO candidate AT2020qer
  39. GRB 200723A: Swift ToO observations
  40. GRB 200723A: GOTO candidate afterglow and host galaxy
  41. GRB 200724A: Fermi GBM Final Real-time Localization
  42. Fermi GRB 200723A: Global MASTER-Net observations report
  43. GRB 200723A: BALROG localization (Fermi Trigger 617214929 / GRB 200723691)
  44. GRB 200723A: Fermi GBM Final Real-time Localization
  45. GRB 200716C: Kitab optical observations
  46. GRB 200722A: BALROG localization (Fermi Trigger 617076900 / GRB 200722094)
  47. GRB 200716C: CAHA optical observation // Anomalous light curve behavior?
  48. GRB 200716C: CrAO, Terskol, Assy-Turgen optical observations
  49. GRB 200714E: Swift-XRT afterglow detection
  50. GRB 200716C: FRAM-ORM afterglow detection
  51. Konus-Wind observation of GRB 200716C: correction to GCN 28147
  52. Konus-Wind observation of GRB 200716C
  53. GRB 200716C: VIRT optical detection.
  54. GRB 200716C: Insight-HXMT/HE detection
  55. AMON IC_HAWC 170720: Correction to ANTARES GCN 28142
  56. Fermi GRB 200718A: Global MASTER-Net observations report
  57. AMON IC_HAWC 170720: No Neutrino Counterpart detected with ANTARES
  58. Fermi GBM trigger 616776657/200718619 is not a GRB
  59. GRB 200718A: Fermi GBM Final Real-time Localization
  60. GRB 200716C: CALET Gamma-Ray Burst Monitor detection
  61. GRB 200716C: Optical observations from HCT
  62. GRB 200716B: Insight-HXMT/HE detection
  63. GRB 200716C: Swift-BAT refined analysis
  64. GRB 200716C: Fermi GBM detection
  65. Fermi GRB 200716A: Global MASTER-Net observations report
  66. GRB 200716C: AGILE/MCAL detection
  67. GRB 200716C: possible host galaxy from the SDSS
  68. GRB 200716C: Swift-XRT refined analysis correction
  69. GRB 200716C: Fermi-LAT detection
  70. GRB 200716C: Swift-XRT refined Analysis
  71. GRB 200716C: Enhanced Swift-XRT position
  72. GRB 200522A: HST NIR counterpart confirmation
  73. GRB200716C: BOOTES-1 optical afterglow detection
  74. Swift GRB200716C: Global MASTER-Net OT detection
  75. GRB 200716C: Swift detection of a burst with an optical counterpart
  76. GRB 200716C: Fermi GBM Final Real-time Localization
  77. Swift GRB200716.96: Global MASTER-Net observations report
  78. IPN triangulation of GRB 200716A
  79. GRB 200716A: Fermi GBM detection
  80. Fermi GRB 200716B: Global MASTER-Net observations report
  81. GRB 200716B: AstroSat CZTI detection
  82. GRB 200716A: AstroSat CZTI detection
  83. GRB 200716A: AGILE detection
  84. GRB 200715A: Swift-XRT afterglow detection
  85. GRB 200716B: BALROG localization (Fermi Trigger 616577673 / GRB 200716316)
  86. GRB 200716B: Fermi GBM Final Real-time Localization
  87. GRB 200716A: BALROG localization (Fermi Trigger 616555602 / GRB 200716060)
  88. GRB 200715A: Swift ToO observations
  89. GRB 200715A : A long GRB detected by INTEGRAL
  90. GRB 200716A: Fermi GBM Final Real-time Localization
  91. GRB 200714E: Fermi GBM observation
  92. GRB 200714E: Swift-XRT observations
  93. Fermi GRB 200714E: Global MASTER-Net observations report
  94. GRB 200714E: AGILE detection
  95. GRB 200714E: Swift ToO observations
  96. GRB 200714E: Swift/BAT-GUANO detection and arcminute localization
  97. Fermi GRB 200714D: Global MASTER-Net observations report
  98. Fermi GRB 200714A: Global MASTER-Net observations report
  99. GRB 200522A: Candidate Optical/nIR Counterpart from Gemini and HST Imaging
  100. GRB 200714E: BALROG localization (Fermi Trigger 616444510 / GRB 200714774)

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