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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"

12090 results found.

  1. GRB 230520A: CALET Gamma-Ray Burst Monitor detection
  2. LIGO/Virgo/KAGRA S230520ae: Identification of a GW compact binary merger candidate: End-to-End Test
  3. GRB 230520B is not a GRB
  4. GRB 230520B: Fermi GBM Final Real-time Localization
  5. LIGO/Virgo/KAGRA S230520ae: Upper limits from IceCube neutrino search
  6. LIGO/Virgo/KAGRA S230518h: ATCA follow-up of candidate counterparts
  7. LIGO/Virgo/KAGRA S230518h: GECKO tiling observations with KMTNet
  8. GRB 230520A: MAXI/GSC detection
  9. LIGO/Virgo/KAGRA S230518h: Swope Search and Candidate Counterpart Identification
  10. LIGO/Virgo/KAGRA S230518h: Upper limits from Konus-Wind observations
  11. LIGO/Virgo S230518h: Swift XRT observations, 8 X-ray sources
  12. LIGO/Virgo/KAGRA S230518h: Coverage and upper limits from MAXI/GSC observations
  13. LIGO/Virgo/Kagra S230518h: NED Galaxies in the Localization Volume
  14. LIGO/Virgo/KAGRA S230518h: AstroSat CZTI non-detection and upper limits
  15. LIGO/Virgo S230518h: Global MASTER-Net observations report
  16. GRB 230510B: GRBAlpha detection
  17. Improved IPN triangulation of GRB 230512A
  18. GRB 230512A: GIT non detection of afterglow candidate
  19. GRB 230512A: Kitab possible afterglow candidate
  20. Fermi trigger No 705565670: Global MASTER-Net observations report
  21. Fermi-LAT gamma-ray observations of IceCube-230511A
  22. GRB 230430A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 704533643)
  23. GRB 230512A: Fermi-LAT detection
  24. GRB 230512A: AstroSat CZTI detection
  25. GRB 230510B: AstroSat CZTI detection
  26. GRB 230510B: MAXI/GSC detection
  27. Fermi trigger No 705413051: Global MASTER-Net observations report
  28. Fermi-LAT gamma-ray observations of IceCube-230506A
  29. GRB 230506C: Swift-XRT refined Analysis
  30. GRB 230506C: spectro-imaging observations of the optical afterglow with T193-OHP
  31. GRB 230506C: Swift-XRT analysis
  32. GRB 230506B: Swift/UVOT Detection
  33. GRB 230420A: Mondy optical afterglow detection, TSHAO, CrAO optical upper limit
  34. GRB 230427A: Swift-BAT refined analysis
  35. GRB 230503A: Fermi GBM Final Real-time Localization
  36. Konus-Wind detection of GRB 230430A
  37. GRB 230420A: AROMA-N Optical Upper Limit
  38. GRB 230430A: AstroSat CZTI detection
  39. GRB 230427A: Osservatorio Astronomico Nastro verde upper limit
  40. GRB 230427A: Swift-XRT refined Analysis
  41. GRB 230426A: VZLUSAT-2 detection
  42. GRB 230427A: GIT optical upper limit
  43. GRB 230427A : OHP/T193 optical upper limit
  44. GRB 230426A: MASTER OT J023135.16-792104.8 optical counterpart discovery
  45. GRB 230426A: Fermi GBM Detection
  46. GRB 230426A: AstroSat CZTI detection
  47. GRB 230426A: Fermi GBM Final Real-time Localization
  48. GRB 221009A: Late-time JWST Observations and Detection of Supernova Emission
  49. Konus-Wind detection of GRB 230418A
  50. GRB 230420A: Swift-XRT refined Analysis
  51. GRB 230420A: MITSuME Akeno optical observation
  52. GRB 230420A: Gaoyazi/GOT optical upper limit
  53. GRB 230420A: BOOTES-5/JGT optical afterglow detection
  54. GRB 230420A: LCOGT Optical Upper Limit
  55. IPN triangulation of GRB 230418A (short)
  56. GRB 230420A: Swift detection of a burst
  57. GRB 230418A: AstroSat CZTI detection
  58. GRB 230418A: Swift/BAT-GUANO detection outside the coded FOV
  59. IceCube-Cascade 230417A: Upper limits from a search for additional neutrino events in IceCube
  60. GRB 230402A: Fermi-LAT detection
  61. Fermi-LAT gamma-ray observations of IceCube-230416A
  62. GRB 230415A: Fermi GBM detection
  63. GRB 230414B: Osservatorio Astronomico Nastro Verde - Sorrento: optical observations
  64. GRB 230415A: Swift/BAT-GUANO detection
  65. New GCN Circulars Portal for Rapid Communications on Astronomical Transients is Online
  66. GRB 230307A: iTelescope optical upper limit (likely)
  67. GRB 230414B: Swift-XRT refined Analysis
  68. Fermi GRB 230414A: Global MASTER-Net observations report
  69. GRB 230414B: Nanshan/HMT optical afterglow detection
  70. GRB 230414B: Swift detection of a burst
  71. IceCube-230405A: BOOTES-4/MET Optical Upper Limits
  72. Fermi GRB 230409C: Global MASTER-Net observations report
  73. IceCube-230405A: Upper limits from a search for additional neutrino events in IceCube
  74. Fermi-LAT gamma-ray observations of IceCube-230405A
  75. Konus-Wind detection of GRB 230405B
  76. GRB 230405B: MeerLICHT upper limits
  77. IceCube Alert 230405.56: Global MASTER-Net observations report
  78. GRB 230307A: further analysis of the Konus-Wind detection and rest-frame energetics
  79. GRB 230405B: AstroSat CZTI detection
  80. IceCube-230405A: IceCube observation of a high-energy neutrino candidate
  81. GRB 230404A: AstroSat CZTI detection
  82. GRB 230402A: AstroSat CZTI detection
  83. Fermi-LAT gamma-ray observations of IceCube-230401A and detection of Fermi J0030.2+0005
  84. GRB 230307A: Chandra late-time detection of the X-ray afterglow
  85. GRB 230228A: detection by GTC of the potential host galaxy
  86. IceCube-Cascade 230329A: Upper limits from a search for additional neutrino events in IceCube
  87. GRB 230328B: 3.6m DOT multiband optical observation
  88. Fermi trigger No 701883729: Global MASTER-Net observations report
  89. Konus-Wind detection of GRB 230328B
  90. GRB 230328B: Liverpool Telescope afterglow detection
  91. GRB 230328B: OHP/T120 optical observations
  92. GRB 230328B: Swift-XRT refined Analysis
  93. GRB 230328B: AstroSat CZTI detection
  94. GRB 230328B: Mondy, AbAO and Kitab optical observations
  95. GRB 230328B: Swift detection of a burst with an optical afterglow
  96. GRB 230325A: Swift-XRT refined Analysis
  97. GRB 230325A: Swift detection of a burst
  98. GRB 230320B: Fermi GBM Observation
  99. Konus-Wind detection of GRB 230309A
  100. Konus-Wind detection of GRB 230308A

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