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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"

32533 results found.

  1. X-ray transient EP240315a: second epoch e-MERLIN radio observations
  2. GRB 240405A: GRBAlpha detection
  3. IceCube-240327B: GRANDMA/Kilonova-Catcher observations of 4FGL J0555.9+0030 and optical upper limits
  4. Fermi GRB 240408A: Global MASTER-Net observations report
  5. GRB 240402C: CALET Gamma-Ray Burst Monitor detection
  6. Fermi GRB 240407A: Global MASTER-Net observations report
  7. Fermi-LAT gamma-ray observations of IceCube-240327B
  8. Fermi-LAT gamma-ray observations of IceCube-240327A
  9. LXT 240402A/GRB 240402B: rest-frame energetics from Konus-Wind observation
  10. Fermi GRB 240405B: Global MASTER-Net observations report
  11. GRB 240402C: Glowbug gamma-ray detection
  12. GRB 240331A: GRBAlpha detection
  13. LXT 240402A/GRB 240402B: GECAM-C refined analysis
  14. Swift satellite resumes pointed science observations
  15. GRB 240403A: Glowbug gamma-ray detection
  16. LXT 240402A/GRB 240402B: Glowbug gamma-ray detection
  17. X-ray transient LXT 240402A: WFST optical upper limits​
  18. Konus-Wind detection of LXT 240402A/GRB 240402B
  19. GRB/FXT 240402B: Kinder optical counterpart candidate
  20. IceCube-240327B: GRANDMA observations of 4FGL J0555.9+0030
  21. GRB/FXT 240402B: VLT/FORS2 optical afterglow candidate
  22. X-ray transient LXT240402A: AST3-3 optical upper limits
  23. LXT 240402A: EP-FXT detection of the X-ray afterglow
  24. Fermi GRB 240404A: Global MASTER-Net observations report
  25. LXT 240402A: MASTER optical observations with AGN in error-box
  26. GRB 240402B: GWAC-F50A optical upper limit
  27. GRB 240402B: GECAM-C detection
  28. Fermi GRB 240402A: Global MASTER-Net observations report
  29. X-ray transient EP240331a: Kinder optical upper limits
  30. X-ray transient EP240331A: GRANDMA-Kilonova catcher optical upper limit
  31. EP240331A: MASTER optical observations
  32. Transient EP240315a: J-band observations of AT2024eju with WIRC
  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. GRB 240329A: Glowbug gamma-ray detection
  36. GRB 240331A: AstroSat CZTI detection
  37. GRB 240329A: AstroSat CZTI detection
  38. GRB 240329A: GRBAlpha detection
  39. Fermi GRB 240329A: Global MASTER-Net observations report
  40. Fermi GRB 240328B: Global MASTER-Net observations report
  41. Fermi GRB 240328A: Global MASTER-Net observations report
  42. X-ray transient EP240315a: continued ATCA monitoring
  43. IceCube-240327B: No candidates from the Zwicky Transient Facility
  44. X-ray transient EP 240315a: Second epoch Chandra observations
  45. X-ray transient EP240315a: e-MERLIN radio observations
  46. X-ray transient EP240315a: Ondrejov D50 optical limit
  47. Transient EPW20240219aa: REM optical/NIR further observations
  48. GRB 240320A: Glowbug gamma-ray detection
  49. GRB 240318A: Fermi GBM Observation
  50. Fermi GRB 240320A: Global MASTER-Net observations report
  51. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  52. GRB 240315C / X-ray transient EP240315a: Swift/BAT detection
  53. IPN triangulation of GRB 240315C (consistent with a fast X-ray transient EP240315a)
  54. GRB 240317B: Swift/BAT-GUANO Angular Error Correction
  55. X-ray transient EP 240315a: Chandra observations
  56. X-ray transient EP240315a: GTC/HiPERCAM photometry
  57. X-ray transient EP240315a: MeerKAT radio detection
  58. X-ray transient EP240315a: GTC/OSIRIS spectroscopic redshift confirmation
  59. GRB 240318A: Glowbug gamma-ray detection
  60. X-ray transient EP240315a: PRIME near infrared detection
  61. GRB 240317B: Fermi GBM Observation
  62. X-ray transient EP240315a: 3.6 m TNG NIR detection
  63. Swift satellite in safe mode
  64. X-ray transient EP240315a/AT2024eju: TShAO (Zeiss-1000) observatory optical upper limit
  65. X-ray transient EP240315a: EP-FXT detection of the X-ray afterglow
  66. Fermi GRB 240318A: Global MASTER-Net observations report
  67. GRB 240317A: AstroSat CZTI detection
  68. X-ray transient EP240315a: Kitab observatory optical upper limitns
  69. X-ray transient EP240315a: Montarrenti Observatory optical upper limit
  70. Fermi GRB 240317B: Global MASTER-Net observations report
  71. Fermi GRB 240317A: Global MASTER-Net observations report
  72. X-ray transient EP240315a: orphan FXT?
  73. X-ray transient EP240315a: Kinder follow-up observations for AT 2024eju with Lulin observatory
  74. X-ray transient EP240315a: GROND J-band detection
  75. X-ray transient EP240315a: VLT/X-shooter spectroscopic redshift of z = 4.859
  76. X-ray transient EP240315a: Nanshan/HMT optical upper limit
  77. AT2024eju: followup observations with Liverpool Telescope suggest a fading transient
  78. X-ray transient EP240315a: ATLAS detection of a possible optical counterpart AT2024eju
  79. GRID detection of GRB 240306A
  80. Changes to the Fermi-GBM Triggering Thresholds
  81. Fermi GRB 240314A: Global MASTER-Net observations report
  82. GRB240204A: VIRT optical upper limit
  83. GRB 240312A: Glowbug gamma-ray detection
  84. GRB 240310A: MASTER OT J200702.72-263928.7 inside 3sigma
  85. Fermi-LAT gamma-ray observations of IceCube-240307A
  86. Fermi GRB 240310A: Global MASTER-Net observations report
  87. IceCube-240307A: Upper limits from a search for additional neutrino events in IceCube
  88. GRID detection of GRB 240229A (Updated Report)
  89. GRID detection of GRB 240229A
  90. GRB 231215A: further radio observations with the VLA
  91. GRB 240306A: Fermi GBM observation
  92. GRB 240229A: Glowbug gamma-ray detection
  93. GRB 240227A (short): Glowbug gamma-ray detection
  94. GRB 240229A: GRBAlpha detection
  95. Konus-Wind detection of GRB 231118A
  96. GRB 240306A: AstroSat CZTI detection
  97. Fermi GRB 240306A: Global MASTER-Net observations report
  98. Fermi GRB 240305A: Global MASTER-Net observations report
  99. GRB 240305A: Fermi GBM observation
  100. Fermi-LAT gamma-ray observations of IceCube-240229A

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