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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"

3559 results found.

  1. GRB210702A: MeerLICHT multi-colour photometry
  2. GRB 210702A: Swift detection of a burst with a bright optical counterpart
  3. IceCube-210629A: Upper limits from a search for additional neutrino events in IceCube
  4. Fermi trigger No 646443989: Global MASTER-Net observations report
  5. Fermi GRB 210627B: Global MASTER-Net observations report
  6. Fermi GRB 210627A: Global MASTER-Net observations report
  7. GRB 210619B: ASIM observation
  8. Fermi trigger No 646189108: Global MASTER-Net observations report
  9. Fermi trigger No 646194855: Global MASTER-Net observations report
  10. GRB 210619B: Mini-MegaTORTORA early optical observations
  11. GRB 210619B: Ondrejov D50 detection
  12. GRB 210618A: DDOTI upper limit for the optical afterglow
  13. Swift GRB210618.07: Global MASTER-Net observations report
  14. Fermi GRB 210615A: Global MASTER-Net observations report
  15. GRB 210610B: Further SAO RAS optical observations
  16. GRB 201228B: Fermi GBM observation
  17. GRB 210610B: SAO RAS optical observations
  18. GRB 210610A: Swift-BAT refined analysis
  19. Fermi trigger No 645047470: Global MASTER-Net observations report
  20. GRB 210610A: Xinglong-2.16m optical afterglow observations
  21. GRB 210610A: Swift detection of a burst with an optical counterpart
  22. GRB 210607A/MAXI J1733-222: MAXI/GSC detection
  23. GRB 210605B: Swift/BAT-GUANO detection and arcminute localization
  24. Fermi trigger No 644359567: Global MASTER-Net observations report
  25. Fermi GRB 210601A: Global MASTER-Net observations report
  26. Fermi GRB 210529A: Global MASTER-Net observations report
  27. Fermi GRB 210529B: Global MASTER-Net observations report
  28. GRB 210528A: Fermi GBM detection
  29. GRB 210528A: AstroSat CZTI detection
  30. GRB 210528B: MAXI/GSC detection
  31. Fermi GRB 210528A: Global MASTER-Net observations report
  32. GRB 210528A: BALROG localization (Fermi Trigger 643903431 / GRB 210528586)
  33. GRB 210528A: Fermi GBM Final Real-time Localization
  34. GRB 210527A: MITSuME Akeno optical upper limits
  35. Fermi GRB 210518A: Global MASTER-Net observations report
  36. Fermi trigger No 642991619: Global MASTER-Net observations report
  37. GRB 210517A: AGILE detection
  38. GRB 210517A: Swift detection of a burst
  39. Fermi GRB 210515A: Global MASTER-Net observations report
  40. IPN triangulation of GRB 210427A
  41. Fermi GRB 210511A: Global MASTER-Net observations report
  42. Fermi GRB 210510A: Global MASTER-Net observations report
  43. GRB 201228B: Swift/BAT-GUANO archival detection and arcminute localization
  44. Fermi GRB 210507A: Global MASTER-Net observations report
  45. GRB 210504A: Swift detection of a burst
  46. Fermi GRB 210501A: Global MASTER-Net observations report
  47. IPN triangulation of GRB 210424B (short/hard)
  48. Fermi trigger No 640695289: Global MASTER-Net observations report
  49. Swift GRB 210421A: Global MASTER-Net observations report
  50. GRB 210421A: Swift detection of a burst
  51. Fermi GRB 210419B: Global MASTER-Net observations report
  52. GRB 210419B: Fermi GBM Final Real-time Localization
  53. Fermi GRB 210411B: Global MASTER-Net observations report
  54. Fermi GRB 210411A: Global MASTER-Net observations report
  55. GRB 210409A: GECAM detection
  56. Konus-Wind detection of GRB 210406A
  57. Integral GRB210406.72: Global MASTER-Net observations report
  58. Fermi trigger No 639199407: Global MASTER-Net observations report
  59. GRB 210328A: AstroSat CZTI detection
  60. Fermi trigger No 639093861: Global MASTER-Net observations report
  61. GRB 210328A: GECAM detection
  62. GRB 210328A: BALROG localization (Fermi Trigger / GRB 210328865)
  63. GRB 210328A: Fermi GBM Final Real-time Localization
  64. Fermi GRB 210324B: Global MASTER-Net observations report
  65. GRB 210324A: Fermi GBM Final Real-time Localization
  66. IceCube Alert 210322.11: Global MASTER-Net observations report
  67. GRB 210321A: Redshift from OSIRIS/GTC
  68. GRB 210320A: MAXI/GSC detection
  69. Fermi trigger No 637729731: Global MASTER-Net observations report
  70. Fermi trigger No 637521056: Global MASTER-Net observations report
  71. Fermi GRB 210312A: Global MASTER-Net observations report
  72. GRB 171205A: Continued ATCA observations
  73. Fermi trigger No 637027080: Global MASTER-Net observations report
  74. GRB 210308A: Swift/UVOT Detection
  75. GRB 210308A: Swift detection of a burst with an optical counterpart
  76. GRB 210307A: LCO Optical Upper Limits
  77. Fermi trigger No 636459103: Global MASTER-Net observations report
  78. Fermi trigger No 636187116: Global MASTER-Net observations report
  79. Fermi trigger No 636168178: Global MASTER-Net observations report
  80. GRB 210217A: Liverpool Telescope First Hour Observations
  81. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued CrAO and AbAO optical observations
  82. Fermi GRB 210207A: Global MASTER-Net observations report
  83. VLT/X-shooter redshift of 1.466 for ZTF21aagwbjr/AT2021buv, strengthening its association with GRB 210204A
  84. Recent activity of SGR 1935+2154 as observed by CGBM
  85. Konus-Wind detection of two bright bursts from SGR 1935+2154
  86. Fermi GRB 210120A: Global MASTER-Net observations report
  87. Konus-Wind detection of GRB 210112A
  88. GRB 201227A: ASIM observation
  89. GW170817: HST observations at 3.4 years from merger
  90. GRB 210104A: early ATLAS detections of the bright afterglow
  91. GRB 210104A: 1.3m DFOT Optical Afterglow Detection
  92. GRB 210104A: MITSuME Akeno optical observation
  93. GRB 210104A: GWAC-F60A optical afterglow observations
  94. GRB 210104A: Swift detection of a burst with a bright optical counterpart
  95. Fermi GRB 210102C: Global MASTER-Net observations report
  96. MAXI GRB210102.38: Global MASTER-Net observations report
  97. Fermi trigger No 631119348: Global MASTER-Net observations report
  98. Fermi trigger No 631113166: Global MASTER-Net observations report
  99. Fermi trigger No 631118376: Global MASTER-Net observations report
  100. GRB 201216C: TSHAO, Terskol, Mondy optical upper limits

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