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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').
  1. Konus-Wind detection of GRB 241114B
  2. LIGO/Virgo/KAGRA S241130n: Updated Sky localization
  3. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  4. GRB 241128A: AbAO optical upper limit
  5. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  6. LIGO/Virgo/KAGRA S241130be: Identification of a GW compact binary merger candidate
  7. LIGO/Virgo/KAGRA S241129aa: Updated Sky localization
  8. LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
  9. SVOM/GRM observation of a short burst from soft gamma repeater Kes 73
  10. GRB 241128C: SVOM/GRM observation
  11. GRB 241128B: SVOM/GRM observation
  12. GRB 241128A: Swift-BAT refined analysis
  13. GRB 241127A: Swift-BAT refined analysis
  14. EP241126a: NOT optical observations
  15. GRB 241127A: PRIME near-infrared detection
  16. GRB 241128A: Mondy optical observations
  17. GRB 241128A: GRANDMA and Kilonova-Catcher Optical Afterglow Detections and Upperlimits
  18. Swift-XRT observations of IceCube -241127A
  19. Swift GRB 241128A: Global MASTER-Net observations report
  20. Fermi-LAT gamma-ray observations of IceCube-241127A
  21. EP241126a: SVOM/VT observations
  22. LIGO/Virgo/KAGRA S241129aa: Identification of a GW compact binary merger candidate
  23. GRB 241128A: Swift-XRT refined Analysis
  24. GRB 241129A: Fermi GBM Final Real-time Localization
  25. GRB 241128A: Enhanced Swift-XRT position
  26. GRB 241128A: NOT optical observations
  27. GRB 241128A: LCO optical detection
  28. GRB 241128A: 1.5m OSN optical afterglow detection
  29. LIGO/Virgo S241127aj: GRANDMA/FRAM-CTA-N Observations
  30. Fermi trigger No 754492985: Global MASTER-Net observations report
  31. GRB 241128A: Swift-XRT afterglow detection
  32. GRB 241128A: Swift detection of a burst
  33. GRB 241127A: GRANDMA and Kilonova-Catcher optical afterglow detections
  34. GRB 241127A: Swift/UVOT Detection
  35. GRB 241127A: Swift-XRT refined Analysis
  36. GRB 241127A: SVOM/GRM observation
  37. GRB 241127A: Enhanced Swift-XRT position
  38. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  39. The EP-WXT trigger 01709125191 is not a real source
  40. GRB 241127A: LCOGT (40-cm) optical counterpart detection
  41. Swift GRB241127.91: Global MASTER-Net OT detection
  42. EP241126a: WFST Observations
  43. LIGO/Virgo/KAGRA S241125n: Update on Coincidence False Alarm Method
  44. IceCube Alert 241127.59: Global MASTER-Net observations report
  45. GRB 241127A: Swift detection of a burst with an optical counterpart
  46. Swift GRB241127.91: Global MASTER-Net observations report
  47. Swift GRB241127.91: Global MASTER-Net OT detection
  48. LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
  49. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  50. IceCube-241127A: IceCube observation of a high-energy neutrino candidate track-like event
  51. LIGO/Virgo/KAGRA S241127aj: NED Galaxies in the Localization Volume
  52. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations (duplicate submission of 38345)
  53. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations (duplicate submission of 38345).
  54. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  55. EP241126a: Optical Upper limits with Kinder observations
  56. SVOM/GRM observation of GRB 241126B or a short burst from magnetar
  57. GRB 241126A: SVOM/GRM observation
  58. IPN triangulation of GRB 241114B
  59. EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations
  60. EP241126a: EP-FXT follow-up observation update
  61. EP241126a: GSP detects optical counterpart
  62. EP241126a: TRT optical counterpart detection
  63. LIGO/Virgo/KAGRA S241127aj: Identification of a GW compact binary merger candidate
  64. EP241126a: EP detection of a fast X-ray transient
  65. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  66. LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
  67. LIGO/Virgo/KAGRA S241126dm: Retraction of GW compact binary merger candidate
  68. Trigger_18947: Swift ToO observations (retracted)
  69. GRB 241113B: EP-FXT afterglow detection
  70. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
  71. LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
  72. SVOM/GRM detection of a short burst from SGR 1830
  73. GECAM detection of a short burst from SGR 1830
  74. LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
  75. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  76. Konus-Wind detection of GRB 241115D / EP 241115a
  77. LIGO/Virgo/KAGRA S241125n: HCT upper limit
  78. LIGO/Virgo/KAGRA S241125n: Upper limits from Konus-Wind observations
  79. GRB 241026A: radio detection with the VLA
  80. EP241125a: Optical upper limit with Kinder observations
  81. EP241125a: EP detection of an X-ray transient
  82. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
  83. LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations
  84. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  85. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  86. LIGO/Virgo/KAGRA S241125n: Updated Sky localization
  87. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  88. LIGO/Virgo/KAGRA S241125n: No counterpart candidates in INTEGRAL SPI-ACS prompt observation, comparisong with Swift/BAT counterpart
  89. LIGO/Virgo/KAGRA S241109bn: Upper limits from a two-week IceCube neutrino search
  90. LIGO/Virgo/KAGRA S241125n: Updated Sky localization and Coincidence with External Event
  91. LIGO/Virgo/KAGRA S241125n: Swift/BAT-GUANO candidate counterpart
  92. GRB 241120A: GRBAlpha detection
  93. GRB 241113B: SVOM/VT optical afterglow observations
  94. LIGO/Virgo/KAGRA S241125n: Identification of a GW compact binary merger candidate
  95. Konus-Wind detection of GRB 241117A
  96. LIGO/Virgo/KAGRA S241122a: Updated Sky localization and Source Classification
  97. GRB 241105A: ATCA radio detection
  98. LIGO/Virgo/KAGRA S241122a: Identification of a GW compact binary merger candidate
  99. IPN triangulation of GRB 241117A
  100. GRB 241026A: VIRT Optical Upper Limit

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