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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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').
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16033 results found.

  1. GRB 250419A: Mondy and AbAO Optical Observations
  2. GRB 250419A: Liverpool Telescope observations
  3. GRB 250419A: AKO Optical Afterglow Detection
  4. GRB 250419A: MASTER optical afterglow observation
  5. GRB 250407A: GTC/OSIRIS+ spectroscopic redshift z = 1.36
  6. GRB 250419A: VLT/X-shooter spectroscopic redshift z = 0.845
  7. GRB 250419A: Swift-XRT refined Analysis
  8. GRB 250419A: GOTO optical counterpart detection
  9. GRB 250419A: KAIT optical afterglow observations
  10. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  11. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  12. GRB 250419A: SVOM detection of a soft burst
  13. EP250416a: Swift/XRT counterpart fading
  14. EP250416a: refined EP-WXT and EP-FXT analysis
  15. EP20250416a: Swift/XRT counterpart detection
  16. GRB 250403A: VLT/FORS2 spectroscopic redshift z = 1.847
  17. IceCube-250416A: DDOTI Optical Observations
  18. EP250416a: Gemini South-GMOS optical counterpart
  19. EP250225a: SVOM/VT optical brightening
  20. EP250416a: GSP optical upper limit
  21. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  22. IceCube 250414.324: DDOTI Optical Observations
  23. EP250304a: ATCA radio observations
  24. EP250404a: Nanshan 0.43m Telescope optical observatios
  25. GRB 250411A: DDOTI Optical Observations
  26. GRB 250407A: Continued KAIT/Nickel optical observations
  27. GRB 250407A: Mondy and AbAO Optical Observations
  28. EP250227a: Further NOT optical observations
  29. IceCube-250406A: Swift-XRT observations
  30. GRB 250407A: LCO detection of a fading optical counterpart
  31. GRB 250407A: SVOM/GRM observation of a bright long burst
  32. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  33. GRB 250407A: KAIT Optical Afterglow Candidate
  34. IceCube-250406A: No candidates from the Zwicky Transient Facility
  35. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  36. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  37. IceCube 250406.951: DDOTI Optical Observations
  38. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  39. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  40. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  41. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  42. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  43. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  44. GRB 250404A / EP250404a: Mondy optical observations
  45. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  46. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  47. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  48. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  49. EP250402a: Optical upper limit with PD 1.3m observations
  50. GRB 250404A / EP250404a: NOT optical observations
  51. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  52. EP250404a: REM optical/NIR observations
  53. EP250404a: Seimei/TriCCS optical counterpart detection
  54. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  55. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  56. EP250404a: LCO optical counterpart detection
  57. EP250404a: Xinglong decaying optical counterpart
  58. GRB 250403A: Montarrenti Observatory optical detection
  59. GRB 250403A: KAIT optical observations
  60. EP250404a: AKO Optical Afterglow Detection
  61. EP250404a: LAST detection of optical counterpart
  62. EP250404a: Xinglong-2.16m spectroscopic redshift
  63. GRB 250327B: VIRT Optical Upper Limit
  64. EP250404a: Mephisto multi-band optical detection
  65. EP250321A: J band upper limit by SYSU 80cm telescope
  66. EP250404a: BOOTES-4/JGT optical afterglow detection
  67. EP250404a: Nanshan/HMT optical counterpart detection
  68. GRB 250402A: Mondy optical observations
  69. GRB 250403A: Swift/UVOT Detection
  70. GRB 250402A: Swift/UVOT Upper Limits
  71. EP250402a: Optical upper limit with Kinder observations
  72. GRB 250403A: SVOM/VT optical observation
  73. GRB 250403A: REM NIR afterglow detection
  74. GRB 250403A: LCO optical counterpart detection
  75. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  76. GRB 250403A: JinShan optical observations
  77. GRB 250402A: EP-FXT afterglow detection
  78. GRB 250403A: Optical counterpart detection by LCO.
  79. GRB 250403A: Swift-XRT observations
  80. GRB 250403A: GOTO optical counterpart follow-up observations
  81. GRB 250402A: NUTTelA-TAO Early Optical Limits
  82. GRB 250403A: GMG Optical Observation
  83. GRB 250403A: 1.6m Mephisto multi-band optical detection
  84. GRB 250403A: SVOM/C-GFT optical observations
  85. GRB 250403A: GOTO detection of the optical afterglow
  86. GRB 250402A: Swift-XRT observations
  87. GRB 250225B: VLT host galaxy redshift z = 0.950
  88. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  89. GRB 250402A: REM optical/NIR upper limits
  90. GRB 250402A: LCO optical counterpart detection
  91. GRB 250402A: SVOM/VT optical counterpart
  92. GRB 250402A: SVOM detection of a burst
  93. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  94. GRB 250314A: ALMA detection
  95. GRB 250329A: Swift/UVOT Upper Limit
  96. GRB 250327B: Swift/UVOT Detection
  97. GRB 250327A: Swift/UVOT Upper Limits
  98. GRB 250331E: SVOM/GRM observation
  99. GRB 250327B: Kilonova-Catcher Observations
  100. GRB250331D: AbAO optical observations

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