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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"

45423 results found.

  1. LIGO/Virgo/KAGRA S241009an: Updated Sky localization
  2. Fermi GRB 241010B: Global MASTER-Net observations report
  3. GRB 241010B: Fermi GBM Final Real-time Localization
  4. IceCube-241006A: Upper limits from a search for additional neutrino events in IceCube
  5. GRB 241010A: Enhanced Swift-XRT position
  6. GRB 241010A: LCO optical observations
  7. GRB 241010A: Swift detection of a burst with an optical counterpart
  8. Fermi-LAT Gamma-ray Observations of IceCube-241006A
  9. GRB 241006A: Swift-BAT refined analysis
  10. GRB 241009A: Swift ToO observations
  11. LIGO/Virgo/KAGRA S241009l: Updated Sky localization
  12. LIGO/Virgo/KAGRA S241009em: Identification of a GW compact binary merger candidate
  13. GRB 241009A : Detection of a long duration GRB by SVOM/ECLAIRs
  14. GRB 241008A: Fermi GBM Observation
  15. GRB 241008A: Fermi-LAT detection
  16. GRB 241002B: Swift-XRT afterglow detection
  17. LIGO/Virgo/KAGRA S241009an: Identification of a GW compact binary merger candidate
  18. GRB 241002A: NOT optical upper limits
  19. LIGO/Virgo/KAGRA S241009l: Identification of a GW compact binary merger candidate
  20. Fermi GRB 241008A: Global MASTER-Net observations report
  21. GRB 241008A: BALROG localization (Fermi Trigger 750117609 / GRB 241008917)
  22. GRB 241008A: Fermi GBM Final Real-time Localization
  23. IceCube-241006A: No candidates from the Zwicky Transient Facility
  24. GRB 241006A: GRANDMA optical upper limits
  25. EP240930a / GRB 240930B: CrAO ZTSH optical upper limit
  26. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  27. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  28. GRB 240910A: LBT optical observations
  29. EP trigger ID 01709065118: KAIT confirmation of the stellar flare
  30. GRB 241006A: Swift-XRT refined Analysis
  31. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  32. GRB 241006A: PRIME near-infrared upper limits
  33. GRB 241006A: Swift/UVOT Upper Limits
  34. GRB 241006A: SVOM/VT follow-up and optical upper limit
  35. LIGO/Virgo/KAGRA S241007bw: Identification of a GW compact binary merger candidate
  36. IceCube Alert 241006.94: Global MASTER-Net observations report
  37. GRB 241001A: Swift-XRT afterglow detection
  38. GRB 241006A: Enhanced Swift-XRT position
  39. IceCube-241006A - IceCube observation of a high-energy neutrino candidate track-like event
  40. GRB 241006A: Swift detection of a burst
  41. Swift GRB241006.91: Global MASTER-Net observations report
  42. GRB 240930B: SVOM/C-GFT optical upper limit
  43. LIGO/Virgo/KAGRA S241006k: Identification of a GW compact binary merger candidate
  44. LIGO/Virgo/KAGRA S241005bo: Retraction of GW compact binary merger candidate
  45. Fermi trigger No 749721670: Global MASTER-Net observations report
  46. GRB 241004A: SVOM/GRM observation
  47. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  48. GRB 240930B / EP 240930a: SVOM/GRM observation
  49. GRB 241001A : ECLAIRs spectral analysis and XRF classification
  50. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  51. GRB 241002B: Fermi GBM Observation
  52. Fermi trigger No 749735279: Global MASTER-Net observations report
  53. Fermi trigger No 749630753: Global MASTER-Net observations report
  54. Fermi trigger No 749693019: Global MASTER-Net observations report
  55. GRB 241002B: Swift-XRT observations
  56. GRB 241002C: SVOM/C-GFT optical upper limit
  57. GRB 241002A: Swift-BAT refined analysis
  58. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  59. GRB 241002B: Swift ToO observations
  60. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  61. Konus-Wind detection of GRB 240926A
  62. GRB 241002B: PRIME near-infrared detection
  63. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  64. GRB 241002C: Swift ToO observations
  65. Fermi-GBM Sub-Threshold Detection of GRB 241002D
  66. IPN triangulation of GRB 240930B / EP 240930a
  67. GRB 241001A : SVOM/VT optical detection
  68. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  69. GRB 241002D: SVOM/GRM observation
  70. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  71. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  72. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  73. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  74. GRB 241002C : MITSuME Akeno optical upper limits
  75. LIGO/Virgo/KAGRA S240925n: Updated Sky localization
  76. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  77. GRB241001A: REM optical/NIR upper limits
  78. LIGO/Virgo/KAGRA S241002e: Updated Sky localization
  79. GRB 241002A: Swift/UVOT Upper Limits
  80. EP240930a: Liverpool Telescope observations
  81. GRB 241002A: Swift-XRT refined Analysis
  82. GRB 241002A: LCOGT Optical Upper Limits
  83. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  84. GRB 241001A: Swift/UVOT Detection
  85. GRB 241001A: VLT/X-shooter redshift
  86. GRB 241002B: GOTO optical counterpart candidate
  87. EP trigger ID 01709064214: GOTO confirms detection as a flare star
  88. GRB 241002C : Detection of a long soft transient by SVOM/ECLAIRs
  89. GRB 241001A: correction to GCN 37667
  90. Fermi GRB 241002B: Global MASTER-Net observations report
  91. GRB 241001A: Swift-XRT observations
  92. EP trigger ID 01709064214: the X-ray transient is most likely a stellar flare event
  93. GRB 241002B: Fermi GBM Final Real-time Localization
  94. GRB241001A: optical afterglow candidate
  95. GRB 241002A: 1.5m OSN optical upper limit
  96. GRB 241002A: Enhanced Swift-XRT position
  97. GRB 241001A: BOOTES-6/DPRT optical upper limit
  98. LIGO/Virgo/KAGRA S241002e: Identification of a GW compact binary merger candidate
  99. GRB 241002A: Swift detection of a burst
  100. LIGO/Virgo/KAGRA S240930du: Updated Sky localization

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