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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"

45415 results found.

  1. GRB 250101A : GIT optical detection
  2. GRB 250101A: GMG Optical Observation
  3. GRB 250101A: Swift detection of a burst with an optical counterpart
  4. Swift GRB250101.56: Global MASTER-Net observations report
  5. GRB 241217a/EP241217b: ATCA Radio Detection
  6. EP241217a: VLA Radio Detection

  7. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  8. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  9. GRB 241229B: Continued CrAO ZTSh observations
  10. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  11. LIGO/Virgo/KAGRA S241231bg: Updated Sky localization and EM Bright Classification
  12. LIGO/Virgo/KAGRA S241230ev: Updated Sky localization
  13. LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
  14. LIGO/Virgo/KAGRA S241230bd: Updated Sky localization
  15. GRB 241229A: EP-FXT X-ray afterglow confirmation
  16. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  17. GRB 241229B: SVOM/GRM observation
  18. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  19. EP241217A: J band upper limit by SYSU 80cm telescope
  20. LIGO/Virgo/KAGRA S241230ev: Identification of a GW compact binary merger candidate
  21. GRB 241229B: SAO RAS optical upper limit
  22. GRB 241228B: SAO RAS optical observations
  23. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  24. GRB 241229A: SAO RAS optical observations
  25. IceCube-Cascade 241228A: Upper limits from a search for additional neutrino events in IceCube
  26. GRB 241229B: SVOM/VT optical candidate
  27. GRB 241229A: Swift-XRT observations
  28. Konus-Wind detection of GRB 241228A
  29. GRB 241229A: EP-FXT afterglow candidates
  30. EP240702a: 7DT Optical upper limits
  31. GRB 240606B: 7DT Optical upper limits
  32. Fermi trigger No 757231333: Global MASTER-Net observations report
  33. LIGO/Virgo/KAGRA S241230bd: Identification of a GW compact binary merger candidate
  34. GRB 241229B: Swift-BAT refined analysis
  35. LIGO/Virgo/KAGRA S241225v: Updated Sky localization
  36. LIGO/Virgo/KAGRA S241225c: Updated Sky localization and EM Bright Classification
  37. Fermi Gamma-ray Burst Monitor trigger 757207662/241229978 (GRB 241229C) is not a GRB
  38. GRB241229B: UVOT upper limits
  39. GRB 241229C: Fermi GBM Final Real-time Localization
  40. GRB 241228B: D50 optical detection
  41. GRB 241228B: Fermi GBM Observation
  42. GRB 241228B: Swift-XRT afterglow detection
  43. GRB 241229B: Fermi GBM Observation
  44. GRB 241229A: Swift ToO observations
  45. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  46. GRB 241228A: Mondy optical afterglow observations
  47. GRB 241229B: Swift-XRT refined Analysis
  48. IceCube-241224A: No transient candidates from the Zwicky Transient Facility
  49. Swift GRB 241229B: Global MASTER-Net observations report
  50. GRB 241229A: GOTO optical upper limits
  51. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  52. GRB 241228A: NOT optical upper limits
  53. GRB 241228B: LCO optical observation
  54. GRB 241228A: Swift-BAT refined analysis
  55. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  56. GRB 241229B: Swift detection of a burst
  57. GRB 241229B: Fermi GBM Final Real-time Localization
  58. GRB 241229A: SVOM detection of a long burst
  59. Fermi GRB 241228B: Global MASTER-Net observations report
  60. GRB 241228A: Fermi GBM Observation
  61. GRB241228B: GROWTH-India Telescope optical observations
  62. Swift GRB 241228A: Global MASTER-Net observations report
  63. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  64. GRB 241228B: GOTO24jmz optical follow-up observations
  65. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  66. GRB 241228A: GROWTH-India telescope optical upper limit
  67. GRB 241228B: Swift ToO observations
  68. GRB 241228B: TRT optical counterpart confirmation
  69. GRB 241228A: Swift-XRT refined Analysis
  70. GRB 241228A: Swift/UVOT Upper Limits
  71. GRB 241228B: GOTO possible optical counterpart candidate
  72. GRB 241228A: Enhanced Swift-XRT position
  73. GRB 241228B: Fermi GBM Final Real-time Localization
  74. GRB 241228A: Swift detection of a burst
  75. IceCube-241224A: Upper limits from a search for additional neutrino events in IceCube
  76. LIGO/Virgo/KAGRA S241225c: Two counterpart neutrino candidates from IceCube neutrino searches
  77. GRB 241223A: GRBAlpha detection
  78. GRB 241212A: VZLUSAT-2 detection
  79. GRB 241217A/EP241217b: continued SOAR observations
  80. Fermi GRB 241226A: Global MASTER-Net observations report
  81. GRB 241226A: Fermi GBM Final Real-time Localization
  82. EP241223a: Mondy AZT-33IK optical observations
  83. GRB 241029A: LCO optical observation
  84. GRB 241223A: Swift-XRT observations
  85. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  86. GRB 241029A: AbAO AS-32 optical observations
  87. GRB 241223A: Fermi GBM Detection
  88. Fermi trigger No 756678579: Global MASTER-Net observations report
  89. LIGO/Virgo/KAGRA S241225c: Identification of a GW compact binary merger candidate
  90. EP241223a
  91. IceCube-241224A - IceCube observation of a high-energy neutrino candidate track-like event
  92. IceCube Alert 241224.30: Global MASTER-Net observations report
  93. GRB 241219A: SVOM/GRM observation
  94. EP241223a: Global MASTER-Net observations report
  95. EP241223a: EP-WXT detection of a fast X-ray transient
  96. EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
  97. GRB241113A: 7DT Optical upper limits
  98. Fermi Gamma-ray Burst Monitor trigger 756678579 / 241223854 is not a GRB
  99. Fermi GRB 241223A: Global MASTER-Net observations report
  100. GRB 241223A: GOTO optical observations summary

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