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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 200803A: Swift-XRT afterglow detection
  2. Fermi GRB 200803B: Global MASTER-Net observations report
  3. GRB 200803A: Fermi-LAT detection
  4. GRB 200803A: MASTER optical counterpart discovery
  5. GRB 200803B: Fermi GBM Final Real-time Localization
  6. GRB 200803A: Tiled Swift observations
  7. LAT GRB200803.15: Global MASTER-Net observations report
  8. Fermi GRB 200803A: Global MASTER-Net observations report
  9. GRB 200801B: AstroSat CZTI detection
  10. GRB 200803A: Fermi GBM Final Real-time Localization
  11. Fermi GRB 200801B: Global MASTER-Net observations report
  12. Fermi GRB 200802A: Global MASTER-Net observations report
  13. AX J1846.4-0258: Swift-BAT refined analysis
  14. Konus-Wind detection of GRB 200729A
  15. GRB 200802A: BALROG localization (Fermi Trigger 618061611 / GRB 200802491)
  16. GRB 200802A: Fermi GBM Final Real-time Localization
  17. GRB 200801C: BOOTES-1 and BOOTES-2 optical limits
  18. Fermi GRB 200801A: Global MASTER-Net observations report
  19. Swift Detection of an SGR-like flare from AX J1846.4-0258
  20. Swift GRB200801.84: Global MASTER-Net observations report
  21. GRB 200801B: BALROG localization (Fermi Trigger 617988951 / GRB 200801650)
  22. GRB 200801B: Fermi GBM Final Real-time Localization
  23. GRB 200801A: Fermi GBM Final Real-time Localization
  24. GRB 200729A: RT-22 observations at 36.8 GHz
  25. GRB 200729A: VLA Observations
  26. GRB 200729A: Nanshan/NEXT optical upper limit
  27. GRB 200729A: Swift-BAT refined analysis
  28. GRB 200729A: further analysis of the NOT data
  29. GRB 200729A: Swift/UVOT Upper Limits
  30. GRB 200729A: Swift-XRT refined Analysis
  31. GRB 200729A: HST imaging
  32. Fermi-GBM Sub-Threshold candidate for GRB 200729A
  33. GRB 200729A: IceCube neutrino search
  34. GRB 200729A: Pan-STARRS pre-explosion source detection
  35. GRB 200729A: Spitzer archival source detection
  36. GRB 200729A: TNG NIR upper limits
  37. GRB 200729A: NOT optical upper limits
  38. GRB 200729A: Enhanced Swift-XRT position
  39. GRB200729A: BOOTES-1 optical upper limit
  40. Swift GRB 200729A: Global MASTER-Net observations report
  41. GRB 200729A: Swift detection of a burst
  42. IceCube Alert 200728.35: Global MASTER-Net observations report
  43. IceCube GCN Notice 134327_10548129 retraction
  44. Baksan Neutrino Observatory Alert 200726.66: Global MASTER-Net observations report
  45. GRB 200723A: ATLAS observations of GOTO candidate AT2020qer
  46. GRB 200723A: Swift ToO observations
  47. GRB 200723A: GOTO candidate afterglow and host galaxy
  48. GRB 200724A: Fermi GBM Final Real-time Localization
  49. Fermi GRB 200723A: Global MASTER-Net observations report
  50. GRB 200723A: BALROG localization (Fermi Trigger 617214929 / GRB 200723691)
  51. GRB 200723A: Fermi GBM Final Real-time Localization
  52. GRB 200716C: Kitab optical observations
  53. GRB 200722A: BALROG localization (Fermi Trigger 617076900 / GRB 200722094)
  54. GRB 200716C: CAHA optical observation // Anomalous light curve behavior?
  55. GRB 200716C: CrAO, Terskol, Assy-Turgen optical observations
  56. GRB 200714E: Swift-XRT afterglow detection
  57. GRB 200716C: FRAM-ORM afterglow detection
  58. Konus-Wind observation of GRB 200716C: correction to GCN 28147
  59. Konus-Wind observation of GRB 200716C
  60. GRB 200716C: VIRT optical detection.
  61. GRB 200716C: Insight-HXMT/HE detection
  62. AMON IC_HAWC 170720: Correction to ANTARES GCN 28142
  63. Fermi GRB 200718A: Global MASTER-Net observations report
  64. AMON IC_HAWC 170720: No Neutrino Counterpart detected with ANTARES
  65. Fermi GBM trigger 616776657/200718619 is not a GRB
  66. GRB 200718A: Fermi GBM Final Real-time Localization
  67. GRB 200716C: CALET Gamma-Ray Burst Monitor detection
  68. GRB 200716C: Optical observations from HCT
  69. GRB 200716B: Insight-HXMT/HE detection
  70. GRB 200716C: Swift-BAT refined analysis
  71. GRB 200716C: Fermi GBM detection
  72. Fermi GRB 200716A: Global MASTER-Net observations report
  73. GRB 200716C: AGILE/MCAL detection
  74. GRB 200716C: possible host galaxy from the SDSS
  75. GRB 200716C: Swift-XRT refined analysis correction
  76. GRB 200716C: Fermi-LAT detection
  77. GRB 200716C: Swift-XRT refined Analysis
  78. GRB 200716C: Enhanced Swift-XRT position
  79. GRB 200522A: HST NIR counterpart confirmation
  80. GRB200716C: BOOTES-1 optical afterglow detection
  81. Swift GRB200716C: Global MASTER-Net OT detection
  82. GRB 200716C: Swift detection of a burst with an optical counterpart
  83. GRB 200716C: Fermi GBM Final Real-time Localization
  84. Swift GRB200716.96: Global MASTER-Net observations report
  85. IPN triangulation of GRB 200716A
  86. GRB 200716A: Fermi GBM detection
  87. Fermi GRB 200716B: Global MASTER-Net observations report
  88. GRB 200716B: AstroSat CZTI detection
  89. GRB 200716A: AstroSat CZTI detection
  90. GRB 200716A: AGILE detection
  91. GRB 200715A: Swift-XRT afterglow detection
  92. GRB 200716B: BALROG localization (Fermi Trigger 616577673 / GRB 200716316)
  93. GRB 200716B: Fermi GBM Final Real-time Localization
  94. GRB 200716A: BALROG localization (Fermi Trigger 616555602 / GRB 200716060)
  95. GRB 200715A: Swift ToO observations
  96. GRB 200715A : A long GRB detected by INTEGRAL
  97. GRB 200716A: Fermi GBM Final Real-time Localization
  98. GRB 200714E: Fermi GBM observation
  99. GRB 200714E: Swift-XRT observations
  100. Fermi GRB 200714E: Global MASTER-Net observations report

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