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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').

2964 results found.

  1. Fermi GRB 240428A: Global MASTER-Net observations report
  2. GRB 240428A: Fermi GBM Final Real-time Localization
  3. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  4. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  5. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  6. S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4
  7. LIGO/Virgo/KAGRA S240422ed: Second night Pan-STARRS observations of the skymap
  8. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  9. Fermi trigger No 735697285: Global MASTER-Net observations report
  10. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  11. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  12. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  13. IceCube Alert 240424.08: Global MASTER-Net observations report
  14. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  15. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  16. Fermi GRB 240421B: Global MASTER-Net observations report
  17. Fermi trigger No 735280430: Global MASTER-Net observations report
  18. IceCube Alert 240419.98: Global MASTER-Net observations report
  19. EP240420a: EP-WXT detection of a fast X-ray transient
  20. Fermi GRB 240417A: Global MASTER-Net observations report
  21. LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
  22. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  23. Fermi GRB 240415A: Global MASTER-Net observations report
  24. GRB 240414A: Photometric observation from 2.2m CAHA
  25. Fermi trigger No 734754044: Global MASTER-Net observations report
  26. LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
  27. GRB 240411B: 1.3m DFOT Optical observations
  28. X-ray transient EP240315a: second epoch e-MERLIN radio observations
  29. Fermi GRB 240407A: Global MASTER-Net observations report
  30. X-ray transient LXT 240402A: WFST optical upper limits​
  31. X-ray transient LXT240402A: AST3-3 optical upper limits
  32. LXT 240402A: MASTER optical observations with AGN in error-box
  33. IceCube-240327B: Upper limits from a search for additional neutrino events in IceCube
  34. IceCube-240327A: Upper limits from a search for additional neutrino events in IceCube
  35. Fermi GRB 240329A: Global MASTER-Net observations report
  36. IceCube-240327B: No candidates from the Zwicky Transient Facility
  37. GRB 240328C: Glowbug gamma-ray detection
  38. GRB 240328B: Fermi GBM Final Real-time Localization
  39. GRB 240328A: Fermi GBM Final Real-time Localization
  40. IceCube Alert 240327.68: Global MASTER-Net observations report
  41. Fermi GRB 240320A: Global MASTER-Net observations report
  42. GRB 240315B: AstroSat CZTI detection
  43. Fermi trigger No 732299243: Global MASTER-Net observations report
  44. Fermi trigger No 731839490: Global MASTER-Net observations report
  45. Fermi trigger No 731571927: Global MASTER-Net observations report
  46. GRB 231215A: further radio observations with the VLA
  47. GRB 231028C: Glowbug gamma-ray confirmation of a prior burst
  48. Swift detection of Swift J151857.0-572147
  49. Fermi trigger No 731161136: Global MASTER-Net observations report
  50. IceCube-240229A: Upper limits from a search for additional neutrino events in IceCube
  51. Fermi GRB 240229A: Global MASTER-Net observations report
  52. IceCube Alert 240229.66: Global MASTER-Net observations report
  53. GRB 240225B: 3.6m DOT observation
  54. GRB 240225B: SAO RAS optical observations
  55. Fermi GRB 240227A: Global MASTER-Net observations report
  56. GRB 240225B: MAXI/GSC detection
  57. Fermi trigger No 729914426: Global MASTER-Net observations report
  58. Gamma-ray flaring activity from the blazar 1ES 1959+650 observed by the Fermi-LAT
  59. GRB 240213A: GRBAlpha detection
  60. Fermi trigger No 729703985: Global MASTER-Net observations report
  61. Fermi GRB 240213A: Global MASTER-Net observations report
  62. Fermi trigger No 729152364: Global MASTER-Net observations report
  63. Fermi trigger No 729012023: Global MASTER-Net observations report
  64. Konus-Wind detection of GRB 240205B (long / very soft)
  65. Fermi trigger No 728749569: Global MASTER-Net observations report
  66. Fermi trigger No 728796365: Global MASTER-Net observations report
  67. Fermi GRB 240204A: Global MASTER-Net observations report
  68. Fermi trigger No 728706420: Global MASTER-Net observations report
  69. IceCube Alert 240204.38: Global MASTER-Net observations report
  70. GRB 240129A: Fermi GBM Observation
  71. GRB 240128A: Glowbug gamma-ray detection
  72. GRB 240128A: GRBAlpha detection
  73. GRB 240128A: CALET Gamma-Ray Burst Monitor detection
  74. GRB 240128A: MAXI/GSC detection
  75. GRB 240122A: MAXI/GSC detection
  76. Fermi GRB 240115B: Global MASTER-Net observations report
  77. GRB 240114A: MAXI/GSC detection
  78. Fermi trigger No 726774492: Global MASTER-Net observations report
  79. GRB 230818A: further radio observations with the VLA
  80. IceCube Alert 240105.52: Global MASTER-Net observations report
  81. GRB 240101B: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  82. GRB 231230A: GOTO optical upper limits
  83. Fermi trigger No 725592555: Global MASTER-Net observations report
  84. Swift Triggers 1205103, 1205104, 1205107 and 1205110 are not astrophysical events
  85. LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate
  86. Fermi trigger No 724781422: Global MASTER-Net observations report
  87. GRB 231215A: Osservatorio Astronomico Nastro Verde upper limit
  88. GRB 231216A: BOOTES-2/TELMA optical upper limit
  89. GRB 231214A: AstroSat CZTI detection
  90. Fermi trigger No 724278269: Global MASTER-Net observations report
  91. Fermi trigger No 724233240: Global MASTER-Net observations report
  92. GRB 231214A: Swift detection of a burst
  93. GRB 231210B: detection of the optical counterpart with the LCOGT 40cm telescope at Sutherland Observatory
  94. GRB 231129C: ASIM MXGS observation and localization
  95. Fermi trigger No 723435916: Global MASTER-Net observations report
  96. Fermi trigger No 723326169: Global MASTER-Net observations report
  97. Fermi trigger No 723149952: Global MASTER-Net observations report
  98. GRB 231128A: VZLUSAT-2 detection
  99. GRB 231129C: MAXI/GSC detection
  100. GRB 231128A: Fermi GBM Final Real-time Localization

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