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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"

39150 results found.

  1. GRB 250103A: Montarrenti Observatory optical detection
  2. GRB 250101A: further LCOGT optical afterglow observations
  3. GRB 250103A: Redshift 4.01 from OSIRIS+/GTC
  4. GRB 250103A: NOT optical observations
  5. GRB 250103A: TSHAO optical upper limit
  6. GRB 250103A: Fermi GBM Observation
  7. GRB 250103B: LCOGT Optical Upper Limit
  8. Swift GRB 250103B: Global MASTER-Net observations report
  9. GRB 250103A: SVOM/VT optical counterpart confirmation
  10. GRB 250103A: Swift ToO observations
  11. GRB 250101a: Liverpool Telescope optical follow-up
  12. GRB 250103B: SVOM detection of a long burst
  13. GRB 250103B: Swift detection of a burst
  14. GRB 250103A: Xinglong 2.16m Optical Candidate
  15. Fermi GRB 250102A: Global MASTER-Net observations report
  16. GRB 250101B: SVOM/GRM observation
  17. GRB 250103A: GOTO optical upper limit
  18. GRB 250103A: SVOM/C-GFT optical upper limit
  19. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  20. IceCube Alert 250102.58: Global MASTER-Net observations report
  21. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  22. GRB 250103A: SVOM detection of a long burst
  23. GRB 250102A: Fermi GBM Final Real-time Localization
  24. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  25. GRB 250101A: Swift-BAT refined analysis
  26. GRB 250101A: further SAO RAS optical observations
  27. GRB 250101A: LCO optical counterpart detection
  28. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  29. GRB 250101A: GMG spectroscopic redshift at z ~ 2.481
  30. GRB 250101A: Swift/UVOT Detection
  31. GRB 250101A: 1.6m Mephisto multi-band optical followup
  32. GRB 250101A: Swift-XRT refined Analysis
  33. Fermi Gamma-ray Burst Monitor trigger 757464861/250101954 is not a GRB
  34. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  35. GRB 250101A: LCOGT optical afterglow detection
  36. GRB 250101A: OASDG optical observations
  37. Fermi GRB 250101B: Global MASTER-Net observations report
  38. GRB 250101B: Fermi GBM Final Real-time Localization
  39. GRB 250101A: SAO RAS observations of optical brightening
  40. GRB 250101A: BOOTES-4/MET optical afterglow detection
  41. GRB 250101A: AKO Optical Afterglow Detection
  42. GRB 250101A: SAO RAS optical observations
  43. GRB 250101A: Enhanced Swift-XRT position
  44. GRB 250101A: Xinglong-2.16m spectroscopic redshift
  45. GRB 250101A: SVOM/C-GFT early optical observations
  46. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  47. GRB 250101A: MASTER earlier OT observations with SOSS emission features
  48. GRB 250101A: Nanshan/HMT optical observations
  49. GRB 250101A : GIT optical detection
  50. GRB 250101A: GMG Optical Observation
  51. GRB 250101A: Swift detection of a burst with an optical counterpart
  52. Swift GRB250101.56: Global MASTER-Net observations report
  53. GRB 241217a/EP241217b: ATCA Radio Detection
  54. GRB 241229B: Continued CrAO ZTSh observations
  55. GRB 241229A: EP-FXT X-ray afterglow confirmation
  56. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  57. GRB 241229B: SVOM/GRM observation
  58. GRB 241229B: SAO RAS optical upper limit
  59. GRB 241228B: SAO RAS optical observations
  60. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  61. GRB 241229A: SAO RAS optical observations
  62. GRB 241229B: SVOM/VT optical candidate
  63. GRB 241229A: Swift-XRT observations
  64. Konus-Wind detection of GRB 241228A
  65. GRB 241229A: EP-FXT afterglow candidates
  66. EP240702a: 7DT Optical upper limits
  67. GRB 240606B: 7DT Optical upper limits
  68. Fermi trigger No 757231333: Global MASTER-Net observations report
  69. GRB 241229B: Swift-BAT refined analysis
  70. Fermi Gamma-ray Burst Monitor trigger 757207662/241229978 (GRB 241229C) is not a GRB
  71. GRB241229B: UVOT upper limits
  72. GRB 241229C: Fermi GBM Final Real-time Localization
  73. GRB 241228B: D50 optical detection
  74. GRB 241228B: Fermi GBM Observation
  75. GRB 241228B: Swift-XRT afterglow detection
  76. GRB 241229B: Fermi GBM Observation
  77. GRB 241229A: Swift ToO observations
  78. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  79. GRB 241228A: Mondy optical afterglow observations
  80. GRB 241229B: Swift-XRT refined Analysis
  81. IceCube-241224A: No transient candidates from the Zwicky Transient Facility
  82. Swift GRB 241229B: Global MASTER-Net observations report
  83. GRB 241229A: GOTO optical upper limits
  84. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  85. GRB 241228A: NOT optical upper limits
  86. GRB 241228B: LCO optical observation
  87. GRB 241228A: Swift-BAT refined analysis
  88. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  89. GRB 241229B: Swift detection of a burst
  90. GRB 241229B: Fermi GBM Final Real-time Localization
  91. GRB 241229A: SVOM detection of a long burst
  92. Fermi GRB 241228B: Global MASTER-Net observations report
  93. GRB 241228A: Fermi GBM Observation
  94. GRB241228B: GROWTH-India Telescope optical observations
  95. Swift GRB 241228A: Global MASTER-Net observations report
  96. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  97. GRB 241228B: GOTO24jmz optical follow-up observations
  98. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  99. GRB 241228A: GROWTH-India telescope optical upper limit
  100. GRB 241228B: Swift ToO observations

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