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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"

36180 results found.

  1. GRB 250101A: LCO optical counterpart detection
  2. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  3. GRB 250101A: GMG spectroscopic redshift at z ~ 2.481
  4. GRB 250101A: Swift/UVOT Detection
  5. GRB 250101A: 1.6m Mephisto multi-band optical followup
  6. GRB 250101A: Swift-XRT refined Analysis
  7. Fermi Gamma-ray Burst Monitor trigger 757464861/250101954 is not a GRB
  8. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  9. GRB 250101A: LCOGT optical afterglow detection
  10. GRB 250101A: OASDG optical observations
  11. Fermi GRB 250101B: Global MASTER-Net observations report
  12. GRB 250101B: Fermi GBM Final Real-time Localization
  13. GRB 250101A: SAO RAS observations of optical brightening
  14. GRB 250101A: BOOTES-4/MET optical afterglow detection
  15. GRB 250101A: AKO Optical Afterglow Detection
  16. GRB 250101A: SAO RAS optical observations
  17. GRB 250101A: Enhanced Swift-XRT position
  18. GRB 250101A: Xinglong-2.16m spectroscopic redshift
  19. GRB 250101A: SVOM/C-GFT early optical observations
  20. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  21. GRB 250101A: MASTER earlier OT observations with SOSS emission features
  22. GRB 250101A: Nanshan/HMT optical observations
  23. GRB 250101A : GIT optical detection
  24. GRB 250101A: GMG Optical Observation
  25. GRB 250101A: Swift detection of a burst with an optical counterpart
  26. GRB 241217a/EP241217b: ATCA Radio Detection
  27. GRB 241229B: Continued CrAO ZTSh observations
  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. GRB 241229B: SAO RAS optical upper limit
  32. GRB 241228B: SAO RAS optical observations
  33. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  34. GRB 241229A: SAO RAS optical observations
  35. GRB 241229B: SVOM/VT optical candidate
  36. GRB 241229A: Swift-XRT observations
  37. Konus-Wind detection of GRB 241228A
  38. GRB 241229A: EP-FXT afterglow candidates
  39. GRB 240606B: 7DT Optical upper limits
  40. GRB 241229B: Swift-BAT refined analysis
  41. Fermi Gamma-ray Burst Monitor trigger 757207662/241229978 (GRB 241229C) is not a GRB
  42. GRB241229B: UVOT upper limits
  43. GRB 241229C: Fermi GBM Final Real-time Localization
  44. GRB 241228B: D50 optical detection
  45. GRB 241228B: Fermi GBM Observation
  46. GRB 241228B: Swift-XRT afterglow detection
  47. GRB 241229B: Fermi GBM Observation
  48. GRB 241229A: Swift ToO observations
  49. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  50. GRB 241228A: Mondy optical afterglow observations
  51. GRB 241229B: Swift-XRT refined Analysis
  52. Swift GRB 241229B: Global MASTER-Net observations report
  53. GRB 241229A: GOTO optical upper limits
  54. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  55. GRB 241228A: NOT optical upper limits
  56. GRB 241228B: LCO optical observation
  57. GRB 241228A: Swift-BAT refined analysis
  58. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  59. GRB 241229B: Swift detection of a burst
  60. GRB 241229B: Fermi GBM Final Real-time Localization
  61. GRB 241229A: SVOM detection of a long burst
  62. Fermi GRB 241228B: Global MASTER-Net observations report
  63. GRB 241228A: Fermi GBM Observation
  64. GRB241228B: GROWTH-India Telescope optical observations
  65. Swift GRB 241228A: Global MASTER-Net observations report
  66. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  67. GRB 241228B: GOTO24jmz optical follow-up observations
  68. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  69. GRB 241228A: GROWTH-India telescope optical upper limit
  70. GRB 241228B: Swift ToO observations
  71. GRB 241228B: TRT optical counterpart confirmation
  72. GRB 241228A: Swift-XRT refined Analysis
  73. GRB 241228A: Swift/UVOT Upper Limits
  74. GRB 241228B: GOTO possible optical counterpart candidate
  75. GRB 241228A: Enhanced Swift-XRT position
  76. GRB 241228B: Fermi GBM Final Real-time Localization
  77. GRB 241228A: Swift detection of a burst
  78. IceCube-241224A: Upper limits from a search for additional neutrino events in IceCube
  79. GRB 241223A: GRBAlpha detection
  80. GRB 241212A: VZLUSAT-2 detection
  81. GRB 241217A/EP241217b: continued SOAR observations
  82. Fermi GRB 241226A: Global MASTER-Net observations report
  83. GRB 241226A: Fermi GBM Final Real-time Localization
  84. EP241223a: Mondy AZT-33IK optical observations
  85. GRB 241029A: LCO optical observation
  86. GRB 241223A: Swift-XRT observations
  87. GRB 241029A: AbAO AS-32 optical observations
  88. GRB 241223A: Fermi GBM Detection
  89. GRB 241219A: SVOM/GRM observation
  90. GRB241113A: 7DT Optical upper limits
  91. Fermi Gamma-ray Burst Monitor trigger 756678579 / 241223854 is not a GRB
  92. Fermi GRB 241223A: Global MASTER-Net observations report
  93. GRB 241223A: GOTO optical observations summary
  94. GRB 241105A: JWST photometric observations of the host galaxy
  95. GRB 241223A: Swift ToO observations
  96. GRB 241223A: BALROG localization (Fermi Trigger 756648531 / GRB 241223506)
  97. GRB 241223A: Fermi GBM Final Real-time Localization
  98. GRB 241217A / EP241217b: Non-detection in ATCA Radio Follow-up Observations
  99. GRB 241209B: host galaxy detection and GTC/OSIRIS+ spectroscopy
  100. Fermi Gamma-ray Burst Monitor trigger 756447119/241221175 is not a GRB

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