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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. GRB 241006A: Swift-BAT refined analysis
  2. GRB 241009A: Swift ToO observations
  3. LIGO/Virgo/KAGRA S241009l: Updated Sky localization
  4. LIGO/Virgo/KAGRA S241009em: Identification of a GW compact binary merger candidate
  5. GRB 241009A : Detection of a long duration GRB by SVOM/ECLAIRs
  6. GRB 241008A: Fermi GBM Observation
  7. GRB 241008A: Fermi-LAT detection
  8. GRB 241002B: Swift-XRT afterglow detection
  9. LIGO/Virgo/KAGRA S241009an: Identification of a GW compact binary merger candidate
  10. GRB 241002A: NOT optical upper limits
  11. LIGO/Virgo/KAGRA S241009l: Identification of a GW compact binary merger candidate
  12. Fermi GRB 241008A: Global MASTER-Net observations report
  13. GRB 241008A: BALROG localization (Fermi Trigger 750117609 / GRB 241008917)
  14. GRB 241008A: Fermi GBM Final Real-time Localization
  15. IceCube-241006A: No candidates from the Zwicky Transient Facility
  16. GRB 241006A: GRANDMA optical upper limits
  17. EP240930a / GRB 240930B: CrAO ZTSH optical upper limit
  18. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  19. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  20. GRB 240910A: LBT optical observations
  21. EP trigger ID 01709065118: KAIT confirmation of the stellar flare
  22. GRB 241006A: Swift-XRT refined Analysis
  23. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  24. GRB 241006A: PRIME near-infrared upper limits
  25. GRB 241006A: Swift/UVOT Upper Limits
  26. GRB 241006A: SVOM/VT follow-up and optical upper limit
  27. LIGO/Virgo/KAGRA S241007bw: Identification of a GW compact binary merger candidate
  28. IceCube Alert 241006.94: Global MASTER-Net observations report
  29. GRB 241001A: Swift-XRT afterglow detection
  30. GRB 241006A: Enhanced Swift-XRT position
  31. IceCube-241006A - IceCube observation of a high-energy neutrino candidate track-like event
  32. GRB 241006A: Swift detection of a burst
  33. Swift GRB241006.91: Global MASTER-Net observations report
  34. GRB 240930B: SVOM/C-GFT optical upper limit
  35. LIGO/Virgo/KAGRA S241006k: Identification of a GW compact binary merger candidate
  36. LIGO/Virgo/KAGRA S241005bo: Retraction of GW compact binary merger candidate
  37. Fermi trigger No 749721670: Global MASTER-Net observations report
  38. GRB 241004A: SVOM/GRM observation
  39. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  40. GRB 240930B / EP 240930a: SVOM/GRM observation
  41. GRB 241001A : ECLAIRs spectral analysis and XRF classification
  42. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  43. GRB 241002B: Fermi GBM Observation
  44. Fermi trigger No 749735279: Global MASTER-Net observations report
  45. Fermi trigger No 749630753: Global MASTER-Net observations report
  46. Fermi trigger No 749693019: Global MASTER-Net observations report
  47. GRB 241002B: Swift-XRT observations
  48. GRB 241002C: SVOM/C-GFT optical upper limit
  49. GRB 241002A: Swift-BAT refined analysis
  50. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  51. GRB 241002B: Swift ToO observations
  52. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  53. Konus-Wind detection of GRB 240926A
  54. GRB 241002B: PRIME near-infrared detection
  55. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  56. GRB 241002C: Swift ToO observations
  57. Fermi-GBM Sub-Threshold Detection of GRB 241002D
  58. IPN triangulation of GRB 240930B / EP 240930a
  59. GRB 241001A : SVOM/VT optical detection
  60. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  61. GRB 241002D: SVOM/GRM observation
  62. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  63. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  64. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  65. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  66. GRB 241002C : MITSuME Akeno optical upper limits
  67. LIGO/Virgo/KAGRA S240925n: Updated Sky localization
  68. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  69. GRB241001A: REM optical/NIR upper limits
  70. LIGO/Virgo/KAGRA S241002e: Updated Sky localization
  71. GRB 241002A: Swift/UVOT Upper Limits
  72. EP240930a: Liverpool Telescope observations
  73. GRB 241002A: Swift-XRT refined Analysis
  74. GRB 241002A: LCOGT Optical Upper Limits
  75. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  76. GRB 241001A: Swift/UVOT Detection
  77. GRB 241001A: VLT/X-shooter redshift
  78. GRB 241002B: GOTO optical counterpart candidate
  79. EP trigger ID 01709064214: GOTO confirms detection as a flare star
  80. GRB 241002C : Detection of a long soft transient by SVOM/ECLAIRs
  81. GRB 241001A: correction to GCN 37667
  82. GRB 240929A: Liverpool Telescope prompt followup observations
  83. Fermi GRB 241002B: Global MASTER-Net observations report
  84. GRB 241001A: Swift-XRT observations
  85. EP trigger ID 01709064214: the X-ray transient is most likely a stellar flare event
  86. GRB 241002B: Fermi GBM Final Real-time Localization
  87. GRB241001A: optical afterglow candidate
  88. GRB 241002A: 1.5m OSN optical upper limit
  89. GRB 241002A: Enhanced Swift-XRT position
  90. GRB 241001A: BOOTES-6/DPRT optical upper limit
  91. LIGO/Virgo/KAGRA S241002e: Identification of a GW compact binary merger candidate
  92. GRB 241002A: Swift detection of a burst
  93. LIGO/Virgo/KAGRA S240930du: Updated Sky localization
  94. GRB 240930B: Fermi GBM Observation
  95. GRB 241001A: Swift ToO observations
  96. GRB 240930B: GRBAlpha detection
  97. GRB 240929A: GRBAlpha detection
  98. EP240930a : KAIT optical upper limit
  99. GRB 241001A : Detection of a soft transient by ECLAIRs onboard SVOM
  100. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst

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