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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"

21572 results found.

  1. GRB 230506B: MASTER optical observations
  2. Fermi trigger No 704837952: Global MASTER-Net observations report
  3. GRB 230427A: NOT optical upper limit
  4. GRB 230427A: Swift/UVOT Detection
  5. GRB 230427A: Gaoyazi/GOT optical upper limit
  6. GRB 230427A: OHP/T193 spectroscopy observations of WISEA J101316.01+481158.7
  7. GRB 230427A: Nanshan/HMT optical upper limit
  8. GRB 230427A: Osservatorio Astronomico Nastro verde upper limit
  9. GRB 230427A: OSIRIS+/GTC observations
  10. Fermi trigger No 704365743: Global MASTER-Net observations report
  11. GRB 230427A: GIT optical upper limit
  12. GRB 230427A: Bassano Bresciano Observatory upper limit
  13. Swift GRB230427.44: Global MASTER-Net observations report
  14. GRB 230426A: MASTER OT J023135.16-792104.8 optical counterpart discovery
  15. Fermi trigger No 704233744: Global MASTER-Net observations report
  16. GRB 230423A: Swift/UVOT Upper Limits
  17. GRB 230420A: Lowell Discovery Telescope Optical Detection
  18. GRB 221009A: Late-time JWST Observations and Detection of Supernova Emission
  19. GRB 230420A: Swift/UVOT Upper Limits
  20. GRB 230421: Swift/BAT-GUANO arcminute localization
  21. GRB 230420A: NOT optical afterglow confirmation
  22. GRB 230420A: Gaoyazi/GOT optical upper limit
  23. GRB 230418A: Swift/BAT-GUANO detection outside the coded FOV
  24. Fermi-LAT gamma-ray observations of IceCube-230416A
  25. GRB 230414B: Nickel and KAIT telescope optical observations
  26. GRB 230414B: Swift/UVOT Detection
  27. GRB 230414B: Osservatorio Astronomico Nastro Verde - Sorrento: optical observations
  28. GRB 230415A: Swift/BAT-GUANO detection
  29. GRB 230414B: 3.6m DOT Optical observations, slow decay at early epochs
  30. GRB 230307A: iTelescope optical upper limit (likely)
  31. GRB 230414B: Montarrenti Observatory late time optical afterglow detection
  32. Fermi trigger No 703284533: Global MASTER-Net observations report
  33. GRB 230414B: Lulin 40cm-SLT optical limit
  34. GRB 230414B: Bassano Bresciano Observatory optical observations
  35. GRB 230414B: Redshift from OSIRIS/GTC
  36. GRB 230414B: AbAO optical observations
  37. GRB 230409B: 3.6m DOT near-infrared detection, afterglow confirmation
  38. GRB 230414B: Dabancheng/GHOST optical observations
  39. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230414A
  40. GRB 230414B: SAO RAS optical observations
  41. GRB 230414B: 1.3m DFOT Optical observations
  42. Fermi GRB 230414A: Global MASTER-Net observations report
  43. GRB 230414B: Nanshan/HMT optical afterglow detection
  44. Swift GRB 230414B: Global MASTER-Net observations report
  45. Fermi GRB 230409C: Global MASTER-Net observations report
  46. Fermi GRB 230409A: Global MASTER-Net observations report
  47. Fermi trigger No 702745263: Global MASTER-Net observations report
  48. Swift GRB 230409B: Global MASTER-Net observations report
  49. GRB 230409B: Swift/UVOT Detection
  50. MAXI GRB230408.82: Global MASTER-Net observations report
  51. Fermi-LAT gamma-ray observations of IceCube-230405A
  52. GRB 230405B: MeerLICHT upper limits
  53. IceCube Alert 230405.56: Global MASTER-Net observations report
  54. GRB 230307A: JWST NIRSpec observations, possible higher redshift
  55. GRB 230307A: good match with kilonova models
  56. GRB 230405B: Swift/UVOT Upper Limits
  57. Swift GRB 230405B: Global MASTER-Net observations report
  58. GRB 230307A: JWST observations consistent with the presence of a kilonova
  59. Fermi GRB 230405A: Global MASTER-Net observations report
  60. Fermi-LAT gamma-ray observations of IceCube-230401A and detection of Fermi J0030.2+0005
  61. GRB 230307A: Chandra late-time detection of the X-ray afterglow
  62. GRB 230328B: Swift/UVOT Detection
  63. Fermi GRB 230402A: Global MASTER-Net observations report
  64. GRB 230328B : GRANDMA/Kilonova-Catcher optical detection
  65. GRB 230328B: CAHA 2.2m/CAFOS detection
  66. GRB 230328B: 3.6m DOT multiband optical observation
  67. Fermi trigger No 701883729: Global MASTER-Net observations report
  68. GRB 230328B NUTTelA-TAO / BSTI Early Measurements
  69. GRB 230328B: Liverpool Telescope afterglow detection
  70. GRB 230328B: OHP/T120 optical observations
  71. GRB 230328B: GIT optical follow-up
  72. GRB 230328B: OASDG optical observations
  73. GRB 230328B: Nanshan/NEXT optical upper limit
  74. GRB 230328B: Mondy, AbAO and Kitab optical observations
  75. Fermi GRB 230328A: Global MASTER-Net observations report
  76. GRB 230325A: Swift/UVOT Upper Limits
  77. Fermi trigger No 701313046: Global MASTER-Net observations report
  78. Fermi trigger No 701321709: Global MASTER-Net observations report
  79. GRB 230322B: Swift/UVOT Detection
  80. Konus-Wind detection of GRB 230309A
  81. Konus-Wind detection of GRB 230304B
  82. Swift GRB 230322B: Global MASTER-Net observations report
  83. Fermi trigger No 701071944: Global MASTER-Net observations report
  84. GRB 230320B: Swift/BAT-GUANO detection outside the coded FOV
  85. Fermi GRB 230320A: Global MASTER-Net observations report
  86. Fermi GRB 230321A: Global MASTER-Net observations report
  87. Fermi trigger No 701058254: Global MASTER-Net observations report
  88. Fermi trigger No 700976129: Global MASTER-Net observations report
  89. GRB 230307A: Continued Gemini-South observations confirm rapid optical fading
  90. Fermi GRB 230316A: Global MASTER-Net observations report
  91. GRB 230307A: Far off-axis NuSTAR detection of the GRB
  92. Fermi GRB 230314A: Global MASTER-Net observations report
  93. GRB 230307A: ATCA radio detection
  94. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  95. GRB 230307A: Swift/UVOT detection
  96. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-230313A
  97. Fermi GRB 230313A: Global MASTER-Net observations report
  98. GRB 230307A: soft X-ray detection with LEIA
  99. GRB 230307A: Swift-XRT afterglow detection
  100. Swift GRB230311.85: Global MASTER-Net observations report

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