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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"

12091 results found.

  1. Fermi trigger No 706317104: Global MASTER-Net observations report
  2. GRB 230520A: CALET Gamma-Ray Burst Monitor detection
  3. LIGO/Virgo/KAGRA S230520ae: Identification of a GW compact binary merger candidate: End-to-End Test
  4. GRB 230520B is not a GRB
  5. GRB 230520B: Fermi GBM Final Real-time Localization
  6. LIGO/Virgo/KAGRA S230520ae: Upper limits from IceCube neutrino search
  7. LIGO/Virgo/KAGRA S230518h: ATCA follow-up of candidate counterparts
  8. LIGO/Virgo/KAGRA S230518h: GECKO tiling observations with KMTNet
  9. GRB 230520A: MAXI/GSC detection
  10. LIGO/Virgo/KAGRA S230518h: Swope Search and Candidate Counterpart Identification
  11. LIGO/Virgo/KAGRA S230518h: Upper limits from Konus-Wind observations
  12. LIGO/Virgo S230518h: Swift XRT observations, 8 X-ray sources
  13. LIGO/Virgo/KAGRA S230518h: Coverage and upper limits from MAXI/GSC observations
  14. LIGO/Virgo/Kagra S230518h: NED Galaxies in the Localization Volume
  15. LIGO/Virgo/KAGRA S230518h: AstroSat CZTI non-detection and upper limits
  16. LIGO/Virgo S230518h: Global MASTER-Net observations report
  17. GRB 230510B: GRBAlpha detection
  18. Improved IPN triangulation of GRB 230512A
  19. GRB 230512A: GIT non detection of afterglow candidate
  20. GRB 230512A: Kitab possible afterglow candidate
  21. Fermi trigger No 705565670: Global MASTER-Net observations report
  22. Fermi-LAT gamma-ray observations of IceCube-230511A
  23. GRB 230430A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 704533643)
  24. GRB 230512A: Fermi-LAT detection
  25. GRB 230512A: AstroSat CZTI detection
  26. GRB 230510B: AstroSat CZTI detection
  27. GRB 230510B: MAXI/GSC detection
  28. Fermi trigger No 705413051: Global MASTER-Net observations report
  29. Fermi-LAT gamma-ray observations of IceCube-230506A
  30. GRB 230506C: Swift-XRT refined Analysis
  31. GRB 230506C: spectro-imaging observations of the optical afterglow with T193-OHP
  32. GRB 230506C: Swift-XRT analysis
  33. GRB 230506B: Swift/UVOT Detection
  34. GRB 230420A: Mondy optical afterglow detection, TSHAO, CrAO optical upper limit
  35. GRB 230427A: Swift-BAT refined analysis
  36. GRB 230503A: Fermi GBM Final Real-time Localization
  37. Konus-Wind detection of GRB 230430A
  38. GRB 230420A: AROMA-N Optical Upper Limit
  39. GRB 230430A: AstroSat CZTI detection
  40. GRB 230427A: Osservatorio Astronomico Nastro verde upper limit
  41. GRB 230427A: Swift-XRT refined Analysis
  42. GRB 230426A: VZLUSAT-2 detection
  43. GRB 230427A: GIT optical upper limit
  44. GRB 230427A : OHP/T193 optical upper limit
  45. GRB 230426A: MASTER OT J023135.16-792104.8 optical counterpart discovery
  46. GRB 230426A: Fermi GBM Detection
  47. GRB 230426A: AstroSat CZTI detection
  48. GRB 230426A: Fermi GBM Final Real-time Localization
  49. GRB 221009A: Late-time JWST Observations and Detection of Supernova Emission
  50. Konus-Wind detection of GRB 230418A
  51. GRB 230420A: Swift-XRT refined Analysis
  52. GRB 230420A: MITSuME Akeno optical observation
  53. GRB 230420A: Gaoyazi/GOT optical upper limit
  54. GRB 230420A: BOOTES-5/JGT optical afterglow detection
  55. GRB 230420A: LCOGT Optical Upper Limit
  56. IPN triangulation of GRB 230418A (short)
  57. GRB 230420A: Swift detection of a burst
  58. GRB 230418A: AstroSat CZTI detection
  59. GRB 230418A: Swift/BAT-GUANO detection outside the coded FOV
  60. IceCube-Cascade 230417A: Upper limits from a search for additional neutrino events in IceCube
  61. GRB 230402A: Fermi-LAT detection
  62. Fermi-LAT gamma-ray observations of IceCube-230416A
  63. GRB 230415A: Fermi GBM detection
  64. GRB 230414B: Osservatorio Astronomico Nastro Verde - Sorrento: optical observations
  65. GRB 230415A: Swift/BAT-GUANO detection
  66. New GCN Circulars Portal for Rapid Communications on Astronomical Transients is Online
  67. GRB 230307A: iTelescope optical upper limit (likely)
  68. GRB 230414B: Swift-XRT refined Analysis
  69. Fermi GRB 230414A: Global MASTER-Net observations report
  70. GRB 230414B: Nanshan/HMT optical afterglow detection
  71. GRB 230414B: Swift detection of a burst
  72. IceCube-230405A: BOOTES-4/MET Optical Upper Limits
  73. Fermi GRB 230409C: Global MASTER-Net observations report
  74. IceCube-230405A: Upper limits from a search for additional neutrino events in IceCube
  75. Fermi-LAT gamma-ray observations of IceCube-230405A
  76. Konus-Wind detection of GRB 230405B
  77. GRB 230405B: MeerLICHT upper limits
  78. IceCube Alert 230405.56: Global MASTER-Net observations report
  79. GRB 230307A: further analysis of the Konus-Wind detection and rest-frame energetics
  80. GRB 230405B: AstroSat CZTI detection
  81. IceCube-230405A: IceCube observation of a high-energy neutrino candidate
  82. GRB 230404A: AstroSat CZTI detection
  83. GRB 230402A: AstroSat CZTI detection
  84. Fermi-LAT gamma-ray observations of IceCube-230401A and detection of Fermi J0030.2+0005
  85. GRB 230307A: Chandra late-time detection of the X-ray afterglow
  86. GRB 230228A: detection by GTC of the potential host galaxy
  87. IceCube-Cascade 230329A: Upper limits from a search for additional neutrino events in IceCube
  88. GRB 230328B: 3.6m DOT multiband optical observation
  89. Fermi trigger No 701883729: Global MASTER-Net observations report
  90. Konus-Wind detection of GRB 230328B
  91. GRB 230328B: Liverpool Telescope afterglow detection
  92. GRB 230328B: OHP/T120 optical observations
  93. GRB 230328B: Swift-XRT refined Analysis
  94. GRB 230328B: AstroSat CZTI detection
  95. GRB 230328B: Mondy, AbAO and Kitab optical observations
  96. GRB 230328B: Swift detection of a burst with an optical afterglow
  97. GRB 230325A: Swift-XRT refined Analysis
  98. GRB 230325A: Swift detection of a burst
  99. GRB 230320B: Fermi GBM Observation
  100. Konus-Wind detection of GRB 230309A

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