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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').

773 results found.

  1. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  2. SVOM/sb25041603: SVOM detection of an X-ray transient
  3. GRB 250314A: e-MERLIN observations
  4. GRB 250320B: cubesat Avion detection
  5. IPN triangulation of GRB 250407A
  6. GRB 250407A: LCO detection of a fading optical counterpart
  7. Konus-Wind detection of GRB 250407A
  8. GRB 250407A: SVOM/GRM observation of a bright long burst
  9. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  10. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  11. GRB 250403A: AstroSat CZTI detection
  12. GRB 250403A: Montarrenti Observatory optical detection
  13. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  14. GRB 250403A: Fermi GBM observations
  15. GRB 250327B: VIRT Optical Upper Limit
  16. GRB 250403A: Swift/UVOT Detection
  17. GRB 250402A: Swift/UVOT Upper Limits
  18. GRB 250403A: SVOM/VT optical observation
  19. GRB 250403A: REM NIR afterglow detection
  20. GRB 250403A: LCO optical counterpart detection
  21. GRB 250403A: JinShan optical observations
  22. GRB 250402A: EP-FXT afterglow detection
  23. GRB 250403A: Swift-XRT observations
  24. GRB 250402A: NUTTelA-TAO Early Optical Limits
  25. GRB 250403A: 1.6m Mephisto multi-band optical detection
  26. GRB 250402A: Fermi GBM Observation
  27. GRB 250403A: SVOM/C-GFT optical observations
  28. GRB 250403A: GOTO detection of the optical afterglow
  29. GRB 250402A: Swift-XRT observations
  30. GRB 250403A : SVOM detection of a burst
  31. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  32. GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
  33. GRB 250402A: REM optical/NIR upper limits
  34. GRB 250402A: LCO optical counterpart detection
  35. GRB 250402A: refined SVOM/MXT data analysis
  36. GRB 250402A: SVOM/VT optical counterpart
  37. GRB 250402A: SVOM detection of a burst
  38. GRB 250314A: ALMA detection
  39. GRB 250329B: Swift/UVOT Upper Limit
  40. GRB 250329A: Swift/UVOT Upper Limit
  41. GRB 250327B: Swift/UVOT Detection
  42. GRB 250331E: SVOM/GRM observation
  43. GRB 250327B: Kilonova-Catcher Observations
  44. GRB 250330B: SVOM/GRM observation of a short burst
  45. GRB 250329B: CAHA 2.2m telescope optical limit
  46. Konus-Wind detection of GRB 250327B
  47. GRB 250320C : SVOM detection of a burst through offline search
  48. GRB20250327B: 45th Parallel Observatory upper limit
  49. GRB 250328A: Swift/UVOT Detection
  50. GRB 250328A: Swift-XRT refined Analysis
  51. SVOM/sb25033102 is a false trigger
  52. GRB 250330A: SVOM/VT optical upper limit
  53. SVOM/sb25033102: SVOM detection of an X-ray transient
  54. GRB 250314A: VLA detection
  55. GRB 250328A: 1.6m Mephisto optical observations
  56. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  57. GRB 250329B: Swift-XRT afterglow detection
  58. GRB 250328A: A fading optical afterglow confirmed by SVOM/VT
  59. GRB 250329B: SVOM/C-GFT optical upper limit
  60. GRB 250329B: SVOM/VT optical upper limit
  61. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  62. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  63. GRB250329A: REM optical afterglow detection
  64. GRB 250329B: GWAC-F50A optical upper limit
  65. GRB 250329B: SVOM detection of a faint transient
  66. GRB 250329A: Swift-XRT afterglow detection
  67. GRB 250328A: SVOM/VT optical observation
  68. GRB 250329A: Fading optical counterpart detection by LCO.
  69. GRB 250328A: SVOM/C-GFT optical upper limit
  70. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  71. GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate
  72. GRB 250329A: VLT/X-shooter redshift z = 2.921
  73. GRB 250329A: SVOM/VT optical counterpart confirmation
  74. GRB 250329A: SVOM detection of a burst
  75. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  76. GRB 250327B: MASTER detection of OT rebrightening
  77. GRB 250327B: LCO optical counterpart detection
  78. GRB 250328A: GWAC-F50A optical upper limit
  79. GRB 250328A: SVOM detection of a burst
  80. GRB 250327B: OHP/T193 spectroscopic observations and redshift confirmation
  81. GRB 250327B: further optical observations by LCOGT
  82. GRB 250327A: SVOM/VT upper limits on the XRT position
  83. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  84. GRB 250327B: Las Cumbres optical counterpart detection
  85. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  86. GRB 250327B: 1.6m Mephisto optical observations
  87. GRB 250327B: NOT spectroscopic redshift z = 3.035
  88. GRB 250327B: GOTO optical counterpart detection
  89. GRB 250327B: SVOM/VT optically bright counterpart
  90. GRB 250327B: SAO RAS optical candidate
  91. GRB 250327B: SVOM detection of a burst
  92. GRB 250327A: J-band observations with WINTER
  93. GRB 250327A: SVOM/VT optical candidate
  94. GRB 250321B: Swift-XRT observations
  95. SVOM/sb25032302: SVOM detection of a long X-ray transient
  96. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  97. GRB 250225B: GECAM-A detection
  98. GRB 250321B: Swift ToO observations
  99. GRB 250320B: NuSTAR detection of the prompt emission from two broad bursts and preliminary analysis
  100. GRB 250320B: Fermi GBM Observation

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