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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"

44399 results found.

  1. GRB 241229B: SVOM/GRM observation
  2. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  3. EP241217A: J band upper limit by SYSU 80cm telescope
  4. LIGO/Virgo/KAGRA S241230ev: Identification of a GW compact binary merger candidate
  5. GRB 241229B: SAO RAS optical upper limit
  6. GRB 241228B: SAO RAS optical observations
  7. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  8. GRB 241229A: SAO RAS optical observations
  9. IceCube-Cascade 241228A: Upper limits from a search for additional neutrino events in IceCube
  10. GRB 241229B: SVOM/VT optical candidate
  11. GRB 241229A: Swift-XRT observations
  12. Konus-Wind detection of GRB 241228A
  13. GRB 241229A: EP-FXT afterglow candidates
  14. EP240702a: 7DT Optical upper limits
  15. GRB 240606B: 7DT Optical upper limits
  16. Fermi trigger No 757231333: Global MASTER-Net observations report
  17. LIGO/Virgo/KAGRA S241230bd: Identification of a GW compact binary merger candidate
  18. GRB 241229B: Swift-BAT refined analysis
  19. LIGO/Virgo/KAGRA S241225v: Updated Sky localization
  20. LIGO/Virgo/KAGRA S241225c: Updated Sky localization and EM Bright Classification
  21. Fermi Gamma-ray Burst Monitor trigger 757207662/241229978 (GRB 241229C) is not a GRB
  22. GRB241229B: UVOT upper limits
  23. GRB 241229C: Fermi GBM Final Real-time Localization
  24. GRB 241228B: D50 optical detection
  25. GRB 241228B: Fermi GBM Observation
  26. GRB 241228B: Swift-XRT afterglow detection
  27. GRB 241229B: Fermi GBM Observation
  28. GRB 241229A: Swift ToO observations
  29. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  30. GRB 241228A: Mondy optical afterglow observations
  31. GRB 241229B: Swift-XRT refined Analysis
  32. IceCube-241224A: No transient candidates from the Zwicky Transient Facility
  33. Swift GRB 241229B: Global MASTER-Net observations report
  34. GRB 241229A: GOTO optical upper limits
  35. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  36. GRB 241228A: NOT optical upper limits
  37. GRB 241228B: LCO optical observation
  38. GRB 241228A: Swift-BAT refined analysis
  39. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  40. GRB 241229B: Swift detection of a burst
  41. GRB 241229B: Fermi GBM Final Real-time Localization
  42. GRB 241229A: SVOM detection of a long burst
  43. Fermi GRB 241228B: Global MASTER-Net observations report
  44. GRB 241228A: Fermi GBM Observation
  45. GRB241228B: GROWTH-India Telescope optical observations
  46. Swift GRB 241228A: Global MASTER-Net observations report
  47. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  48. GRB 241228B: GOTO24jmz optical follow-up observations
  49. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  50. GRB 241228A: GROWTH-India telescope optical upper limit
  51. GRB 241228B: Swift ToO observations
  52. GRB 241228B: TRT optical counterpart confirmation
  53. GRB 241228A: Swift-XRT refined Analysis
  54. GRB 241228A: Swift/UVOT Upper Limits
  55. GRB 241228B: GOTO possible optical counterpart candidate
  56. GRB 241228A: Enhanced Swift-XRT position
  57. GRB 241228B: Fermi GBM Final Real-time Localization
  58. GRB 241228A: Swift detection of a burst
  59. IceCube-241224A: Upper limits from a search for additional neutrino events in IceCube
  60. LIGO/Virgo/KAGRA S241225c: Two counterpart neutrino candidates from IceCube neutrino searches
  61. GRB 241223A: GRBAlpha detection
  62. GRB 241212A: VZLUSAT-2 detection
  63. GRB 241217A/EP241217b: continued SOAR observations
  64. Fermi GRB 241226A: Global MASTER-Net observations report
  65. GRB 241226A: Fermi GBM Final Real-time Localization
  66. EP241223a: Mondy AZT-33IK optical observations
  67. GRB 241029A: LCO optical observation
  68. GRB 241223A: Swift-XRT observations
  69. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  70. GRB 241029A: AbAO AS-32 optical observations
  71. GRB 241223A: Fermi GBM Detection
  72. Fermi trigger No 756678579: Global MASTER-Net observations report
  73. LIGO/Virgo/KAGRA S241225c: Identification of a GW compact binary merger candidate
  74. EP241223a
  75. IceCube-241224A - IceCube observation of a high-energy neutrino candidate track-like event
  76. IceCube Alert 241224.30: Global MASTER-Net observations report
  77. GRB 241219A: SVOM/GRM observation
  78. EP241223a: Global MASTER-Net observations report
  79. EP241223a: EP-WXT detection of a fast X-ray transient
  80. EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
  81. GRB241113A: 7DT Optical upper limits
  82. Fermi Gamma-ray Burst Monitor trigger 756678579 / 241223854 is not a GRB
  83. Fermi GRB 241223A: Global MASTER-Net observations report
  84. GRB 241223A: GOTO optical observations summary
  85. GRB 241105A: JWST photometric observations of the host galaxy
  86. GRB 241223A: Swift ToO observations
  87. EP241217a: e-MERLIN radio observations
  88. GRB 241223A: BALROG localization (Fermi Trigger 756648531 / GRB 241223506)
  89. GRB 241223A: Fermi GBM Final Real-time Localization
  90. GRB 241217A / EP241217b: Non-detection in ATCA Radio Follow-up Observations
  91. The EP-WXT trigger 01709129287 is likely a flaring star
  92. Fermi trigger No 756447119: Global MASTER-Net observations report
  93. GRB 241209B: host galaxy detection and GTC/OSIRIS+ spectroscopy
  94. Fermi Gamma-ray Burst Monitor trigger 756447119/241221175 is not a GRB
  95. Fermi GRB 241221A: Global MASTER-Net observations report
  96. GRB 241221A: Fermi GBM Final Real-time Localization
  97. GRB 241217A/EP241217b: SOAR afterglow detection
  98. EP241217a: Liverpool Telescope optical upper limit
  99. EP241021a: VLA radio detection
  100. GRB 241218A: Mondy AZT-33IK optical upper limit

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