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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').
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"

36319 results found.

  1. GRB 250103B: Swift-XRT refined Analysis
  2. GRB 250103B: LCO/1m optical afterglow candidate detection
  3. GRB 250103A: Bassano Bresciano Observatory upper limit
  4. GRB 250103B: VLT/X-shooter spectroscopic redshift z = 1.416
  5. GRB 250103A: Swift-XRT observations
  6. GRB 250101A: 1.3m DFOT optical afterglow detection
  7. GRB 241229A: 1.3m DFOT upper limit
  8. GRB 241228B: 1.3m DFOT Optical observations
  9. GRB 241228A: 1.3m DFOT upper limit
  10. GRB 250103A: NOT spectroscopic redshift
  11. GRB 250103B：SVOM/VT optical counterpart
  12. GRB 250103A: Montarrenti Observatory optical detection
  13. GRB 250101A: further LCOGT optical afterglow observations
  14. GRB 250103A: Redshift 4.01 from OSIRIS+/GTC
  15. GRB 250103A: NOT optical observations
  16. GRB 250103A: TSHAO optical upper limit
  17. GRB 250103A: Fermi GBM Observation
  18. GRB 250103B: LCOGT Optical Upper Limit
  19. IceCube-250102A: Upper limits from a search for additional neutrino events in IceCube
  20. Swift GRB 250103B: Global MASTER-Net observations report
  21. GRB 250103A: SVOM/VT optical counterpart confirmation
  22. GRB 250103A: Swift ToO observations
  23. IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
  24. GRB 250101a: Liverpool Telescope optical follow-up
  25. GRB 250103B: SVOM detection of a long burst
  26. GRB 250103B: Swift detection of a burst
  27. GRB 250103A: Xinglong 2.16m Optical Candidate
  28. Fermi GRB 250102A: Global MASTER-Net observations report
  29. GRB 250101B: SVOM/GRM observation
  30. GRB 250103A: GOTO optical upper limit
  31. GRB 250103A: SVOM/C-GFT optical upper limit
  32. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  33. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  34. GRB 250103A: SVOM detection of a long burst
  35. GRB 250102A: Fermi GBM Final Real-time Localization
  36. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  37. GRB 250101A: Swift-BAT refined analysis
  38. GRB 250101A: further SAO RAS optical observations
  39. GRB 250101A: LCO optical counterpart detection
  40. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  41. GRB 250101A: GMG spectroscopic redshift at z ~ 2.481
  42. GRB 250101A: Swift/UVOT Detection
  43. GRB 250101A: 1.6m Mephisto multi-band optical followup
  44. GRB 250101A: Swift-XRT refined Analysis
  45. Fermi Gamma-ray Burst Monitor trigger 757464861/250101954 is not a GRB
  46. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  47. GRB 250101A: LCOGT optical afterglow detection
  48. GRB 250101A: OASDG optical observations
  49. Fermi GRB 250101B: Global MASTER-Net observations report
  50. GRB 250101B: Fermi GBM Final Real-time Localization
  51. GRB 250101A: SAO RAS observations of optical brightening
  52. GRB 250101A: BOOTES-4/MET optical afterglow detection
  53. GRB 250101A: AKO Optical Afterglow Detection
  54. GRB 250101A: SAO RAS optical observations
  55. GRB 250101A: Enhanced Swift-XRT position
  56. GRB 250101A: Xinglong-2.16m spectroscopic redshift
  57. GRB 250101A: SVOM/C-GFT early optical observations
  58. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  59. GRB 250101A: MASTER earlier OT observations with SOSS emission features
  60. GRB 250101A: Nanshan/HMT optical observations
  61. GRB 250101A : GIT optical detection
  62. GRB 250101A: GMG Optical Observation
  63. GRB 250101A: Swift detection of a burst with an optical counterpart
  64. GRB 241217a/EP241217b: ATCA Radio Detection
  65. GRB 241229B: Continued CrAO ZTSh observations
  66. GRB 241229A: EP-FXT X-ray afterglow confirmation
  67. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  68. GRB 241229B: SVOM/GRM observation
  69. GRB 241229B: SAO RAS optical upper limit
  70. GRB 241228B: SAO RAS optical observations
  71. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  72. GRB 241229A: SAO RAS optical observations
  73. GRB 241229B: SVOM/VT optical candidate
  74. GRB 241229A: Swift-XRT observations
  75. Konus-Wind detection of GRB 241228A
  76. GRB 241229A: EP-FXT afterglow candidates
  77. GRB 240606B: 7DT Optical upper limits
  78. GRB 241229B: Swift-BAT refined analysis
  79. Fermi Gamma-ray Burst Monitor trigger 757207662/241229978 (GRB 241229C) is not a GRB
  80. GRB241229B: UVOT upper limits
  81. GRB 241229C: Fermi GBM Final Real-time Localization
  82. GRB 241228B: D50 optical detection
  83. GRB 241228B: Fermi GBM Observation
  84. GRB 241228B: Swift-XRT afterglow detection
  85. GRB 241229B: Fermi GBM Observation
  86. GRB 241229A: Swift ToO observations
  87. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  88. GRB 241228A: Mondy optical afterglow observations
  89. GRB 241229B: Swift-XRT refined Analysis
  90. Swift GRB 241229B: Global MASTER-Net observations report
  91. GRB 241229A: GOTO optical upper limits
  92. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  93. GRB 241228A: NOT optical upper limits
  94. GRB 241228B: LCO optical observation
  95. GRB 241228A: Swift-BAT refined analysis
  96. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  97. GRB 241229B: Swift detection of a burst
  98. GRB 241229B: Fermi GBM Final Real-time Localization
  99. GRB 241229A: SVOM detection of a long burst
  100. Fermi GRB 241228B: Global MASTER-Net observations report

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