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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"

11468 results found.

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

  55. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  56. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  57. LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
  58. GRB 241229A: EP-FXT X-ray afterglow confirmation
  59. EP241217A: J band upper limit by SYSU 80cm telescope
  60. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  61. Konus-Wind detection of GRB 241228A
  62. EP240702a: 7DT Optical upper limits
  63. GRB 240606B: 7DT Optical upper limits
  64. GRB 241228B: Swift-XRT afterglow detection
  65. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  66. Fermi GRB 241228B: Global MASTER-Net observations report
  67. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  68. GRB 241228A: Swift-XRT refined Analysis
  69. GRB 241228A: Swift detection of a burst
  70. GRB 241217A/EP241217b: continued SOAR observations
  71. Fermi GRB 241226A: Global MASTER-Net observations report
  72. Fermi trigger No 756678579: Global MASTER-Net observations report
  73. IceCube Alert 241224.30: Global MASTER-Net observations report
  74. EP241223a: Global MASTER-Net observations report
  75. EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
  76. GRB241113A: 7DT Optical upper limits
  77. Fermi Gamma-ray Burst Monitor trigger 756678579 / 241223854 is not a GRB
  78. Fermi GRB 241223A: Global MASTER-Net observations report
  79. GRB 241223A: GOTO optical observations summary
  80. EP241217a: e-MERLIN radio observations
  81. GRB 241217A / EP241217b: Non-detection in ATCA Radio Follow-up Observations
  82. Fermi trigger No 756447119: Global MASTER-Net observations report
  83. GRB 241217A/EP241217b: SOAR afterglow detection
  84. EP241217a: Liverpool Telescope optical upper limit
  85. GRB 241218A: Mondy AZT-33IK optical upper limit
  86. Konus-Wind detection of GRB 241204A (short/hard)
  87. EP 241217a: NIR detection with P200/WIRC
  88. GRB 241217A / EP241217b: NOT optical upper limits
  89. GRB 241218A: Swift-XRT refined Analysis
  90. EP241119a: 7DT Optical upper limits
  91. EP241217b/GRB 241217A: EP detection of the prompt X-ray emssion
  92. EP241217a: Global MASTER-Net observations report
  93. GRB 241218A: Swift detection of a burst
  94. EP241217a: Swift-XRT Detection
  95. EP241217a: EP detection of an X-ray transient
  96. GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
  97. Konus-Wind detection of GRB 241213A (EP 241213a)
  98. The EP-WXT trigger 01709128948 is likely a flaring star
  99. GRB 241215A: A long GRB detected by INTEGRAL
  100. GRB 241213A: Swift-XRT refined Analysis

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