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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"

39039 results found.

  1. GRB 250103B: SVOM detection of a long burst
  2. GRB 250103B: Swift detection of a burst
  3. GRB 250103A: Xinglong 2.16m Optical Candidate
  4. Fermi GRB 250102A: Global MASTER-Net observations report
  5. GRB 250101B: SVOM/GRM observation
  6. GRB 250103A: GOTO optical upper limit
  7. GRB 250103A: SVOM/C-GFT optical upper limit
  8. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  9. IceCube Alert 250102.58: Global MASTER-Net observations report
  10. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  11. GRB 250103A: SVOM detection of a long burst
  12. GRB 250102A: Fermi GBM Final Real-time Localization
  13. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  14. GRB 250101A: Swift-BAT refined analysis
  15. GRB 250101A: further SAO RAS optical observations
  16. GRB 250101A: LCO optical counterpart detection
  17. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  18. GRB 250101A: GMG spectroscopic redshift at z ~ 2.481
  19. GRB 250101A: Swift/UVOT Detection
  20. GRB 250101A: 1.6m Mephisto multi-band optical followup
  21. GRB 250101A: Swift-XRT refined Analysis
  22. Fermi Gamma-ray Burst Monitor trigger 757464861/250101954 is not a GRB
  23. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  24. GRB 250101A: LCOGT optical afterglow detection
  25. GRB 250101A: OASDG optical observations
  26. Fermi GRB 250101B: Global MASTER-Net observations report
  27. GRB 250101B: Fermi GBM Final Real-time Localization
  28. GRB 250101A: SAO RAS observations of optical brightening
  29. GRB 250101A: BOOTES-4/MET optical afterglow detection
  30. GRB 250101A: AKO Optical Afterglow Detection
  31. GRB 250101A: SAO RAS optical observations
  32. GRB 250101A: Enhanced Swift-XRT position
  33. GRB 250101A: Xinglong-2.16m spectroscopic redshift
  34. GRB 250101A: SVOM/C-GFT early optical observations
  35. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  36. GRB 250101A: MASTER earlier OT observations with SOSS emission features
  37. GRB 250101A: Nanshan/HMT optical observations
  38. GRB 250101A : GIT optical detection
  39. GRB 250101A: GMG Optical Observation
  40. GRB 250101A: Swift detection of a burst with an optical counterpart
  41. Swift GRB250101.56: Global MASTER-Net observations report
  42. GRB 241217a/EP241217b: ATCA Radio Detection
  43. GRB 241229B: Continued CrAO ZTSh observations
  44. GRB 241229A: EP-FXT X-ray afterglow confirmation
  45. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  46. GRB 241229B: SVOM/GRM observation
  47. GRB 241229B: SAO RAS optical upper limit
  48. GRB 241228B: SAO RAS optical observations
  49. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  50. GRB 241229A: SAO RAS optical observations
  51. GRB 241229B: SVOM/VT optical candidate
  52. GRB 241229A: Swift-XRT observations
  53. Konus-Wind detection of GRB 241228A
  54. GRB 241229A: EP-FXT afterglow candidates
  55. EP240702a: 7DT Optical upper limits
  56. GRB 240606B: 7DT Optical upper limits
  57. Fermi trigger No 757231333: Global MASTER-Net observations report
  58. GRB 241229B: Swift-BAT refined analysis
  59. Fermi Gamma-ray Burst Monitor trigger 757207662/241229978 (GRB 241229C) is not a GRB
  60. GRB241229B: UVOT upper limits
  61. GRB 241229C: Fermi GBM Final Real-time Localization
  62. GRB 241228B: D50 optical detection
  63. GRB 241228B: Fermi GBM Observation
  64. GRB 241228B: Swift-XRT afterglow detection
  65. GRB 241229B: Fermi GBM Observation
  66. GRB 241229A: Swift ToO observations
  67. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  68. GRB 241228A: Mondy optical afterglow observations
  69. GRB 241229B: Swift-XRT refined Analysis
  70. IceCube-241224A: No transient candidates from the Zwicky Transient Facility
  71. Swift GRB 241229B: Global MASTER-Net observations report
  72. GRB 241229A: GOTO optical upper limits
  73. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  74. GRB 241228A: NOT optical upper limits
  75. GRB 241228B: LCO optical observation
  76. GRB 241228A: Swift-BAT refined analysis
  77. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  78. GRB 241229B: Swift detection of a burst
  79. GRB 241229B: Fermi GBM Final Real-time Localization
  80. GRB 241229A: SVOM detection of a long burst
  81. Fermi GRB 241228B: Global MASTER-Net observations report
  82. GRB 241228A: Fermi GBM Observation
  83. GRB241228B: GROWTH-India Telescope optical observations
  84. Swift GRB 241228A: Global MASTER-Net observations report
  85. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  86. GRB 241228B: GOTO24jmz optical follow-up observations
  87. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  88. GRB 241228A: GROWTH-India telescope optical upper limit
  89. GRB 241228B: Swift ToO observations
  90. GRB 241228B: TRT optical counterpart confirmation
  91. GRB 241228A: Swift-XRT refined Analysis
  92. GRB 241228A: Swift/UVOT Upper Limits
  93. GRB 241228B: GOTO possible optical counterpart candidate
  94. GRB 241228A: Enhanced Swift-XRT position
  95. GRB 241228B: Fermi GBM Final Real-time Localization
  96. GRB 241228A: Swift detection of a burst
  97. LIGO/Virgo/KAGRA S241225c: Two counterpart neutrino candidates from IceCube neutrino searches
  98. GRB 241223A: GRBAlpha detection
  99. GRB 241212A: VZLUSAT-2 detection
  100. GRB 241217A/EP241217b: continued SOAR observations

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