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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"

38304 results found.

  1. GRB 250101A: MASTER earlier OT observations with SOSS emission features
  2. GRB 250101A: Nanshan/HMT optical observations
  3. GRB 250101A : GIT optical detection
  4. GRB 250101A: GMG Optical Observation
  5. GRB 250101A: Swift detection of a burst with an optical counterpart
  6. Swift GRB250101.56: Global MASTER-Net observations report
  7. GRB 241217a/EP241217b: ATCA Radio Detection
  8. GRB 241229B: Continued CrAO ZTSh observations
  9. GRB 241229A: EP-FXT X-ray afterglow confirmation
  10. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  11. GRB 241229B: SVOM/GRM observation
  12. GRB 241229B: SAO RAS optical upper limit
  13. GRB 241228B: SAO RAS optical observations
  14. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  15. GRB 241229A: SAO RAS optical observations
  16. GRB 241229B: SVOM/VT optical candidate
  17. GRB 241229A: Swift-XRT observations
  18. Konus-Wind detection of GRB 241228A
  19. GRB 241229A: EP-FXT afterglow candidates
  20. EP240702a: 7DT Optical upper limits
  21. GRB 240606B: 7DT Optical upper limits
  22. Fermi trigger No 757231333: Global MASTER-Net observations report
  23. GRB 241229B: Swift-BAT refined analysis
  24. Fermi Gamma-ray Burst Monitor trigger 757207662/241229978 (GRB 241229C) is not a GRB
  25. GRB241229B: UVOT upper limits
  26. GRB 241229C: Fermi GBM Final Real-time Localization
  27. GRB 241228B: D50 optical detection
  28. GRB 241228B: Fermi GBM Observation
  29. GRB 241228B: Swift-XRT afterglow detection
  30. GRB 241229B: Fermi GBM Observation
  31. GRB 241229A: Swift ToO observations
  32. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  33. GRB 241228A: Mondy optical afterglow observations
  34. GRB 241229B: Swift-XRT refined Analysis
  35. IceCube-241224A: No transient candidates from the Zwicky Transient Facility
  36. Swift GRB 241229B: Global MASTER-Net observations report
  37. GRB 241229A: GOTO optical upper limits
  38. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  39. GRB 241228A: NOT optical upper limits
  40. GRB 241228B: LCO optical observation
  41. GRB 241228A: Swift-BAT refined analysis
  42. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  43. GRB 241229B: Swift detection of a burst
  44. GRB 241229B: Fermi GBM Final Real-time Localization
  45. GRB 241229A: SVOM detection of a long burst
  46. Fermi GRB 241228B: Global MASTER-Net observations report
  47. GRB 241228A: Fermi GBM Observation
  48. GRB241228B: GROWTH-India Telescope optical observations
  49. Swift GRB 241228A: Global MASTER-Net observations report
  50. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  51. GRB 241228B: GOTO24jmz optical follow-up observations
  52. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  53. GRB 241228A: GROWTH-India telescope optical upper limit
  54. GRB 241228B: Swift ToO observations
  55. GRB 241228B: TRT optical counterpart confirmation
  56. GRB 241228A: Swift-XRT refined Analysis
  57. GRB 241228A: Swift/UVOT Upper Limits
  58. GRB 241228B: GOTO possible optical counterpart candidate
  59. GRB 241228A: Enhanced Swift-XRT position
  60. GRB 241228B: Fermi GBM Final Real-time Localization
  61. GRB 241228A: Swift detection of a burst
  62. LIGO/Virgo/KAGRA S241225c: Two counterpart neutrino candidates from IceCube neutrino searches
  63. GRB 241223A: GRBAlpha detection
  64. GRB 241212A: VZLUSAT-2 detection
  65. GRB 241217A/EP241217b: continued SOAR observations
  66. Fermi GRB 241226A: Global MASTER-Net observations report
  67. GRB 241226A: Fermi GBM Final Real-time Localization
  68. EP241223a: Mondy AZT-33IK optical observations
  69. GRB 241029A: LCO optical observation
  70. GRB 241223A: Swift-XRT observations
  71. GRB 241029A: AbAO AS-32 optical observations
  72. GRB 241223A: Fermi GBM Detection
  73. Fermi trigger No 756678579: Global MASTER-Net observations report
  74. EP241223a
  75. IceCube Alert 241224.30: Global MASTER-Net observations report
  76. GRB 241219A: SVOM/GRM observation
  77. EP241223a: Global MASTER-Net observations report
  78. GRB241113A: 7DT Optical upper limits
  79. Fermi Gamma-ray Burst Monitor trigger 756678579 / 241223854 is not a GRB
  80. Fermi GRB 241223A: Global MASTER-Net observations report
  81. GRB 241223A: GOTO optical observations summary
  82. GRB 241105A: JWST photometric observations of the host galaxy
  83. GRB 241223A: Swift ToO observations
  84. GRB 241223A: BALROG localization (Fermi Trigger 756648531 / GRB 241223506)
  85. GRB 241223A: Fermi GBM Final Real-time Localization
  86. GRB 241217A / EP241217b: Non-detection in ATCA Radio Follow-up Observations
  87. Fermi trigger No 756447119: Global MASTER-Net observations report
  88. GRB 241209B: host galaxy detection and GTC/OSIRIS+ spectroscopy
  89. Fermi Gamma-ray Burst Monitor trigger 756447119/241221175 is not a GRB
  90. Fermi GRB 241221A: Global MASTER-Net observations report
  91. GRB 241221A: Fermi GBM Final Real-time Localization
  92. GRB 241217A/EP241217b: SOAR afterglow detection
  93. GRB 241218A: Mondy AZT-33IK optical upper limit
  94. EP241217a : Leavitt Observatory optical upper limit
  95. GRB 241217A/EP241217b: tentative VLT spectroscopic redshift z=1.879
  96. EP241217a: 1.6m Mephisto multi-band optical observations
  97. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  98. GRB 241218A: Swift/UVOT Upper Limits
  99. GRB 241209B: EP-FXT afterglow detection
  100. Konus-Wind detection of GRB 241204A (short/hard)

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