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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').

18187 results found.

  1. Swift GRB 250103B: Global MASTER-Net observations report
  2. GRB 250103A: Swift ToO observations
  3. GRB 250101a: Liverpool Telescope optical follow-up
  4. GRB 250103B: SVOM detection of a long burst
  5. GRB 250103B: Swift detection of a burst
  6. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  7. GRB 250101A: Swift-BAT refined analysis
  8. GRB 250101A: further SAO RAS optical observations
  9. GRB 250101A: LCO optical counterpart detection
  10. GRB 250101A: GMG spectroscopic redshift at z ~ 2.481
  11. GRB 250101A: Swift/UVOT Detection
  12. GRB 250101A: 1.6m Mephisto multi-band optical followup
  13. GRB 250101A: Swift-XRT refined Analysis
  14. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  15. GRB 250101A: LCOGT optical afterglow detection
  16. GRB 250101A: OASDG optical observations
  17. GRB 250101A: BOOTES-4/MET optical afterglow detection
  18. GRB 250101A: SAO RAS optical observations
  19. GRB 250101A: Enhanced Swift-XRT position
  20. GRB 250101A: Xinglong-2.16m spectroscopic redshift
  21. GRB 250101A: SVOM/C-GFT early optical observations
  22. GRB 250101A: MASTER earlier OT observations with SOSS emission features
  23. GRB 250101A: Nanshan/HMT optical observations
  24. GRB 250101A : GIT optical detection
  25. GRB 250101A: Swift detection of a burst with an optical counterpart
  26. Swift GRB250101.56: Global MASTER-Net observations report
  27. EP241217a: VLA Radio Detection

  28. GRB 241229A: EP-FXT X-ray afterglow confirmation
  29. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  30. GRB 241229B: SVOM/GRM observation
  31. EP241217A: J band upper limit by SYSU 80cm telescope
  32. GRB 241228B: SAO RAS optical observations
  33. GRB 241229B: SVOM/VT optical candidate
  34. GRB 241229A: Swift-XRT observations
  35. Konus-Wind detection of GRB 241228A
  36. GRB 241229A: EP-FXT afterglow candidates
  37. GRB 240606B: 7DT Optical upper limits
  38. GRB 241229B: Swift-BAT refined analysis
  39. GRB241229B: UVOT upper limits
  40. GRB 241228B: D50 optical detection
  41. GRB 241228B: Fermi GBM Observation
  42. GRB 241228B: Swift-XRT afterglow detection
  43. GRB 241229B: Fermi GBM Observation
  44. GRB 241229A: Swift ToO observations
  45. GRB 241229B: Swift-XRT refined Analysis
  46. Swift GRB 241229B: Global MASTER-Net observations report
  47. GRB 241228A: NOT optical upper limits
  48. GRB 241228A: Swift-BAT refined analysis
  49. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  50. GRB 241229B: Swift detection of a burst
  51. GRB 241228A: Fermi GBM Observation
  52. Swift GRB 241228A: Global MASTER-Net observations report
  53. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  54. GRB 241228A: GROWTH-India telescope optical upper limit
  55. GRB 241228B: Swift ToO observations
  56. GRB 241228A: Swift-XRT refined Analysis
  57. GRB 241228A: Swift/UVOT Upper Limits
  58. GRB 241228A: Enhanced Swift-XRT position
  59. GRB 241228A: Swift detection of a burst
  60. GRB 241223A: Swift-XRT observations
  61. GRB241113A: 7DT Optical upper limits
  62. GRB 241223A: GOTO optical observations summary
  63. GRB 241223A: Swift ToO observations
  64. GRB 241218A: Mondy AZT-33IK optical upper limit
  65. GRB 241218A: Swift/UVOT Upper Limits
  66. EP241217a: optical upper limit with the Liverpool Telescope
  67. GRB 241209B: EP-FXT afterglow detection
  68. GRB 241218A: NOT optical upper limits
  69. GRB 241218A: Swift-BAT refined analysis
  70. EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
  71. GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission.
  72. GRB 241218A: REM optical upper limit
  73. GRB 241217A/EP241217b: REM optical/NIR upper limits
  74. EP241217a: REM optical/NIR upper limits
  75. GRB 241218a: Liverpool Telescope optical follow-up
  76. GRB 241217a: Liverpool Telescope optical follow-up
  77. GRB 241218A: Swift-XRT refined Analysis
  78. GRB 241209A: ATCA radio follow-up observations
  79. GRB 241218A: LCOGT Optical Upper Limit
  80. GRB 241218A: Enhanced Swift-XRT position
  81. GRB 241218A: Swift detection of a burst
  82. GRB 241217A : SVOM/VT optical afterglow detection
  83. GRB 241217A: Swift-XRT afterglow detection
  84. EP241217a: Swift-XRT Detection
  85. GRB 241214A: GRBAlpha detection
  86. GRB 241213A (EP241213a): GRBAlpha detection
  87. GRB 241209D: GRBAlpha detection
  88. GRB 241213A: Swift-BAT refined analysis
  89. GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
  90. Konus-Wind detection of GRB 241213A (EP 241213a)
  91. GRB 241212A: Swift-XRT observations
  92. GRB 241213B: Swift-XRT observations
  93. GRB 241209D: CALET Gamma-Ray Burst Monitor detection
  94. GRB 241213A: SVOM/VT optical candidate
  95. GRB 241213B: Tiled Swift observations
  96. GRB 241213A: Swift/UVOT Upper Limits
  97. GRB 241213A: Swift-XRT refined Analysis
  98. GRB 241212A: Swift ToO observations
  99. GRB 241213A: LCOGT Optical Upper Limits
  100. EP241213a: EP detection of An X-ray Transient

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