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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').

18174 results found.

  1. GRB 241209A: Swift-XRT refined Analysis
  2. GRB 241209D: AstroSat CZTI detection
  3. GRB 241209A: EP-FXT follow-up observations
  4. GRB 241209B: SVOM/VT afterglow detection
  5. GRB 241207B: Fermi GBM Observation
  6. GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
  7. GRB 241209D: Swift-XRT refined Analysis
  8. GRB 241209D: Fermi GBM Observation
  9. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  10. GRB 241209D: COLIBRÍ detection of the afterglow
  11. GRB 241209A: COLIBRÍ Optical Upper Limit
  12. GRB 241209A: Fermi GBM Observation
  13. GRB 241209C: Swift/BAT-GUANO localization skymap of a burst
  14. GRB 241209A: GRANDMA/TAROT upper limit
  15. Swift GRB 241209D: Global MASTER-Net observations report
  16. GRB 241209B: Swift ToO observations
  17. GRB 241209A: REM optical/NIR observations
  18. GRB 241209D: Enhanced Swift-XRT position
  19. GRB 241209D: Swift detection of a burst
  20. GRB 241209A: Enhanced Swift-XRT position
  21. GRB 241209A: GOTO optical upper limits
  22. GRB 241209A: Prompt enhanced Swift-XRT position
  23. GRB 241209A: Swift detection of a short burst
  24. Swift GRB241209.23: Global MASTER-Net observations report
  25. GRB 241207B: Swift/BAT-GUANO localization skymap of a short burst
  26. GRB 241206A: DDOTI Upper Limit on the Afterglow
  27. GRB 241207C: Tiled Swift observations
  28. GRB 241206A: Fermi GBM observation
  29. GRB 241206A: Swift/BAT-GUANO localization skymap of a burst
  30. LIGO/Virgo/KAGRA S241125n: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  31. Fermi-GBM Sub-Threshold Detection of GRB 241128A
  32. GRB 241128A: Swift/UVOT Upper Limits
  33. GRB 241129A: Swift/BAT-GUANO localization skymap of a burst
  34. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  35. SVOM/GRM observation of a short burst from soft gamma repeater Kes 73
  36. GRB 241128A: Swift-BAT refined analysis
  37. GRB 241127A: Swift-BAT refined analysis
  38. GRB 241127A: PRIME near-infrared detection
  39. GRB 241128A: GRANDMA and Kilonova-Catcher Optical Afterglow Detections and Upperlimits
  40. Swift-XRT observations of IceCube -241127A
  41. Swift GRB 241128A: Global MASTER-Net observations report
  42. GRB 241128A: Swift-XRT refined Analysis
  43. GRB 241128A: Enhanced Swift-XRT position
  44. GRB 241128A: 1.5m OSN optical afterglow detection
  45. GRB 241128A: Swift-XRT afterglow detection
  46. GRB 241128A: Swift detection of a burst
  47. GRB 241127A: GRANDMA and Kilonova-Catcher optical afterglow detections
  48. GRB 241127A: Swift/UVOT Detection
  49. GRB 241127A: Swift-XRT refined Analysis
  50. GRB 241127A: SVOM/GRM observation
  51. GRB 241127A: Enhanced Swift-XRT position
  52. GRB 241127A: LCOGT (40-cm) optical counterpart detection
  53. Swift GRB241127.91: Global MASTER-Net OT detection
  54. LIGO/Virgo/KAGRA S241125n: Update on Coincidence False Alarm Method
  55. GRB 241127A: Swift detection of a burst with an optical counterpart
  56. Swift GRB241127.91: Global MASTER-Net observations report
  57. Swift GRB241127.91: Global MASTER-Net OT detection
  58. LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
  59. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  60. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  61. IPN triangulation of GRB 241114B
  62. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  63. LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
  64. Trigger_18947: Swift ToO observations (retracted)
  65. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
  66. LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
  67. LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
  68. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  69. EP241125a: EP detection of an X-ray transient
  70. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
  71. LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations
  72. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  73. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  74. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  75. LIGO/Virgo/KAGRA S241125n: No counterpart candidates in INTEGRAL SPI-ACS prompt observation, comparisong with Swift/BAT counterpart
  76. LIGO/Virgo/KAGRA S241125n: Updated Sky localization and Coincidence with External Event
  77. LIGO/Virgo/KAGRA S241125n: Swift/BAT-GUANO candidate counterpart
  78. Konus-Wind detection of GRB 241117A
  79. IPN triangulation of GRB 241117A
  80. GRB 241025A: VIRT Optical Upper Limit
  81. GRB 241115A: CALET Gamma-Ray Burst Monitor detection
  82. GRB 241115a: PRIME near-infrared upper limits
  83. GRB 241117A: Swift/BAT-GUANO localization skymap of a burst
  84. LIGO/Virgo/KAGRA S241116cq: Upper limits from Swift/BAT-GUANO
  85. GRB 241115B: Fermi GBM Observation
  86. GRB 241115B: Swift/BAT-GUANO localization skymap of a long burst
  87. GRB 241115C: Fermi GBM Observation
  88. GRB 241115A: Swift-XRT afterglow detection
  89. EP241115a/GRB 241115D: Optical upper limits with Kinder observations
  90. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  91. EP241113a: Swift XRT weak detection
  92. GRB 241115A: Fermi GBM Observation
  93. GRB 241115A: LCOGT Optical Upper Limits
  94. GRB 241115C: Swift/BAT-GUANO localization skymap of a burst
  95. Swift GRB 241115A: Global MASTER-Net observations report
  96. GRB 241115A: Swift detection of a burst
  97. GRB 241113A: Swift-BAT refined analysis
  98. GRB 241113A: PRIME near-infrared upper limits
  99. GRB 241113A: J-band observations with WINTER
  100. GRB 241113B: Swift-XRT observations

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