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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"

11774 results found.

  1. IPN triangulation of GRB 250119B
  2. GRB 250121A: Fermi-LAT detection
  3. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  4. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  5. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  6. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  7. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  8. Konus-Wind detection of GRB 250117A
  9. IPN triangulation of GRB 250117A (short)
  10. LIGO/Virgo/KAGRA S250119cv: Updated NED Galaxies in the Localization Volume
  11. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  12. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  13. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  14. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  15. GRB 250117A: GECAM observation of a short burst
  16. Konus-Wind detection of GRB 250116A
  17. GRB 250116A: GECAM-B detection of a long burst
  18. GRB 250116A: Fermi-LAT detection
  19. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  20. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  21. Konus-Wind detection of GRB 250113A
  22. IPN triangulation of GRB 250113A
  23. GRB 250114A: Swift-XRT refined Analysis
  24. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  25. GRB 250114A: Swift detection of a burst with an optical counterpart
  26. GRB 250101A: Terskol Zeiss-2000 optical observations
  27. GRB 250106A: Swift-XRT afterglow detection
  28. Fermi trigger No 758442826: Global MASTER-Net observations report
  29. EP250108a / AT 2025kg: LCO optical observations
  30. EP250111a: Global MASTER-Net observations report
  31. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  32. EP250111a: a new X-ray transient detected by Einstein Probe
  33. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  34. Konus-Wind detection of GRB 250107C
  35. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  36. Konus-Wind detection of GRB 250107D (short/hard)
  37. IPN triangulation of GRB 250107D (short/hard)
  38. EP250109a: EP-WXT detection of an X-ray transient
  39. EP250108a: EP-WXT detection of an X-ray transient
  40. GRB 250108B: Swift-XRT refined Analysis
  41. Swift GRB 250108B: Global MASTER-Net observations report
  42. Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
  43. GRB 250103A: Swift-XRT afterglow detection
  44. GRB 250108B: Swift detection of a burst
  45. GRB 241228B: Fermi-LAT detection
  46. GRB 250101A: J band upper limit by SYSU 80cm telescope
  47. The EP-WXT trigger 01709129925 is likely a flaring star
  48. Fermi trigger No 757753930: Global MASTER-Net observations report
  49. GRB 250103B: Swift-XRT refined Analysis
  50. GRB 250103A: Bassano Bresciano Observatory upper limit
  51. IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
  52. IceCube Alert 250102.58: Global MASTER-Net observations report
  53. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  54. GRB 250103A: SVOM detection of a long burst
  55. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  56. GRB 250101A: further SAO RAS optical observations
  57. GRB 250101A: SAO RAS optical observations
  58. Swift GRB250101.56: Global MASTER-Net observations report
  59. GRB 241217a/EP241217b: ATCA Radio Detection
  60. EP241217a: VLA Radio Detection

  61. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  62. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  63. LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
  64. GRB 241229A: EP-FXT X-ray afterglow confirmation
  65. EP241217A: J band upper limit by SYSU 80cm telescope
  66. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  67. Konus-Wind detection of GRB 241228A
  68. EP240702a: 7DT Optical upper limits
  69. GRB 240606B: 7DT Optical upper limits
  70. GRB 241228B: Swift-XRT afterglow detection
  71. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  72. Fermi GRB 241228B: Global MASTER-Net observations report
  73. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  74. GRB 241228A: Swift-XRT refined Analysis
  75. GRB 241228A: Swift detection of a burst
  76. GRB 241217A/EP241217b: continued SOAR observations
  77. Fermi GRB 241226A: Global MASTER-Net observations report
  78. Fermi trigger No 756678579: Global MASTER-Net observations report
  79. IceCube Alert 241224.30: Global MASTER-Net observations report
  80. EP241223a: Global MASTER-Net observations report
  81. EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
  82. GRB241113A: 7DT Optical upper limits
  83. Fermi Gamma-ray Burst Monitor trigger 756678579 / 241223854 is not a GRB
  84. Fermi GRB 241223A: Global MASTER-Net observations report
  85. GRB 241223A: GOTO optical observations summary
  86. EP241217a: e-MERLIN radio observations
  87. GRB 241217A / EP241217b: Non-detection in ATCA Radio Follow-up Observations
  88. Fermi trigger No 756447119: Global MASTER-Net observations report
  89. GRB 241217A/EP241217b: SOAR afterglow detection
  90. EP241217a: Liverpool Telescope optical upper limit
  91. GRB 241218A: Mondy AZT-33IK optical upper limit
  92. Konus-Wind detection of GRB 241204A (short/hard)
  93. EP 241217a: NIR detection with P200/WIRC
  94. GRB 241217A / EP241217b: NOT optical upper limits
  95. GRB 241218A: Swift-XRT refined Analysis
  96. EP241119a: 7DT Optical upper limits
  97. EP241217b/GRB 241217A: EP detection of the prompt X-ray emssion
  98. EP241217a: Global MASTER-Net observations report
  99. GRB 241218A: Swift detection of a burst
  100. EP241217a: Swift-XRT Detection

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