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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. EP241201a: EP detection of a fast X-ray transient
  2. The EP-WXT trigger 01709126243 is not a real source
  3. GRB 241127B: detection of a long GRB by SVOM/ECLAIRs
  4. GRB241201B: Fermi GBM Final Localization
  5. GRB241201B: Fermi GBM Final Localization
  6. LIGO/Virgo/KAGRA S241201ac: Updated Sky localization
  7. EP241126a: SOAR observations of the optical counterpart
  8. Fermi GRB 241201A: Global MASTER-Net observations report
  9. GRB 241201A: BALROG localization (Fermi Trigger 754757764 / GRB 241201622)
  10. GRB 241130A: Fermi GBM Final Real-time Localization
  11. GRB 241130A: Fermi GBM Final Real-time Localization
  12. EP241126a: 1.6m Mephisto Optical Upper Limits
  13. GRB 241201A: Fermi GBM Final Real-time Localization
  14. LIGO/Virgo/KAGRA S241201ac: Identification of a GW compact binary merger candidate
  15. LIGO/Virgo/KAGRA S241130be: Updated Sky localization
  16. Fermi trigger No 754701230: Global MASTER-Net observations report
  17. IPN triangulation of GRB 241128B
  18. Konus-Wind detection of GRB 241114B
  19. LIGO/Virgo/KAGRA S241130n: Updated Sky localization
  20. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  21. GRB 241128A: AbAO optical upper limit
  22. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  23. LIGO/Virgo/KAGRA S241130be: Identification of a GW compact binary merger candidate
  24. LIGO/Virgo/KAGRA S241129aa: Updated Sky localization
  25. LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
  26. SVOM/GRM observation of a short burst from soft gamma repeater Kes 73
  27. GRB 241128C: SVOM/GRM observation
  28. GRB 241128B: SVOM/GRM observation
  29. GRB 241128A: Swift-BAT refined analysis
  30. GRB 241127A: Swift-BAT refined analysis
  31. EP241126a: NOT optical observations
  32. GRB 241127A: PRIME near-infrared detection
  33. GRB 241128A: Mondy optical observations
  34. GRB 241128A: GRANDMA and Kilonova-Catcher Optical Afterglow Detections and Upperlimits
  35. Swift-XRT observations of IceCube -241127A
  36. Swift GRB 241128A: Global MASTER-Net observations report
  37. Fermi-LAT gamma-ray observations of IceCube-241127A
  38. EP241126a: SVOM/VT observations
  39. LIGO/Virgo/KAGRA S241129aa: Identification of a GW compact binary merger candidate
  40. GRB 241128A: Swift-XRT refined Analysis
  41. GRB 241129A: Fermi GBM Final Real-time Localization
  42. GRB 241128A: Enhanced Swift-XRT position
  43. GRB 241128A: NOT optical observations
  44. GRB 241128A: LCO optical detection
  45. GRB 241128A: 1.5m OSN optical afterglow detection
  46. LIGO/Virgo S241127aj: GRANDMA/FRAM-CTA-N Observations
  47. Fermi trigger No 754492985: Global MASTER-Net observations report
  48. GRB 241128A: Swift-XRT afterglow detection
  49. GRB 241128A: Swift detection of a burst
  50. GRB 241127A: GRANDMA and Kilonova-Catcher optical afterglow detections
  51. GRB 241127A: Swift/UVOT Detection
  52. GRB 241127A: Swift-XRT refined Analysis
  53. GRB 241127A: SVOM/GRM observation
  54. GRB 241127A: Enhanced Swift-XRT position
  55. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  56. The EP-WXT trigger 01709125191 is not a real source
  57. GRB 241127A: LCOGT (40-cm) optical counterpart detection
  58. Swift GRB241127.91: Global MASTER-Net OT detection
  59. EP241126a: WFST Observations
  60. LIGO/Virgo/KAGRA S241125n: Update on Coincidence False Alarm Method
  61. IceCube Alert 241127.59: Global MASTER-Net observations report
  62. GRB 241127A: Swift detection of a burst with an optical counterpart
  63. Swift GRB241127.91: Global MASTER-Net observations report
  64. Swift GRB241127.91: Global MASTER-Net OT detection
  65. LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
  66. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  67. IceCube-241127A: IceCube observation of a high-energy neutrino candidate track-like event
  68. LIGO/Virgo/KAGRA S241127aj: NED Galaxies in the Localization Volume
  69. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations (duplicate submission of 38345)
  70. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations (duplicate submission of 38345).
  71. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  72. EP241126a: Optical Upper limits with Kinder observations
  73. SVOM/GRM observation of GRB 241126B or a short burst from magnetar
  74. GRB 241126A: SVOM/GRM observation
  75. IPN triangulation of GRB 241114B
  76. EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations
  77. EP241126a: EP-FXT follow-up observation update
  78. EP241126a: GSP detects optical counterpart
  79. EP241126a: TRT optical counterpart detection
  80. LIGO/Virgo/KAGRA S241127aj: Identification of a GW compact binary merger candidate
  81. EP241126a: EP detection of a fast X-ray transient
  82. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  83. LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
  84. LIGO/Virgo/KAGRA S241126dm: Retraction of GW compact binary merger candidate
  85. Trigger_18947: Swift ToO observations (retracted)
  86. GRB 241113B: EP-FXT afterglow detection
  87. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
  88. LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
  89. SVOM/GRM detection of a short burst from SGR 1830
  90. GECAM detection of a short burst from SGR 1830
  91. LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
  92. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  93. Konus-Wind detection of GRB 241115D / EP 241115a
  94. LIGO/Virgo/KAGRA S241125n: HCT upper limit
  95. LIGO/Virgo/KAGRA S241125n: Upper limits from Konus-Wind observations
  96. GRB 241026A: radio detection with the VLA
  97. EP241125a: Optical upper limit with Kinder observations
  98. EP241125a: EP detection of an X-ray transient
  99. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
  100. LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations

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