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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"

45440 results found.

  1. LIGO/Virgo/KAGRA S241011k: Updated Sky localization
  2. LIGO/Virgo/KAGRA S241011k: NED Galaxies in the Localization Volume
  3. LIGO/Virgo/KAGRA S241011k: Identification of a GW compact binary merger candidate
  4. Fermi Gamma-ray Burst Monitor GRB trigger 750372658/241011869 (GRB 241011A) is not a GRB
  5. GRB 241011A: Fermi GBM Final Real-time Localization
  6. GRB 241009A: GRANDMA optical upper limits
  7. GRB 241009A: Swift-XRT afterglow detection
  8. GRB 241010A: JinShan optical observations and potential host galaxy
  9. GRB 241006A: ATCA Radio Upper Limits
  10. GRB 241010A: Swift-XRT refined Analysis
  11. LIGO/Virgo/KAGRA S241007bw: Updated Sky localization
  12. Fermi trigger No 750211959: Global MASTER-Net observations report
  13. Fermi Gamma-ray Burst Monitor trigger 750303285/241011066 is not a GRB
  14. Fermi Gamma-ray Burst Monitor trigger 750291012/241010924 is not a GRB
  15. Swift GRB 241010A: Global MASTER-Net observations report
  16. Fermi trigger No 750291012: Global MASTER-Net observations report
  17. GRB 241010A: J-band observations with WINTER
  18. LIGO/Virgo/KAGRA S241009an: Updated Sky localization
  19. Fermi GRB 241010B: Global MASTER-Net observations report
  20. GRB 241010B: Fermi GBM Final Real-time Localization
  21. IceCube-241006A: Upper limits from a search for additional neutrino events in IceCube
  22. GRB 241010A: Enhanced Swift-XRT position
  23. GRB 241010A: LCO optical observations
  24. GRB 241010A: Swift detection of a burst with an optical counterpart
  25. Fermi-LAT Gamma-ray Observations of IceCube-241006A
  26. GRB 241006A: Swift-BAT refined analysis
  27. GRB 241009A: Swift ToO observations
  28. LIGO/Virgo/KAGRA S241009l: Updated Sky localization
  29. LIGO/Virgo/KAGRA S241009em: Identification of a GW compact binary merger candidate
  30. GRB 241009A : Detection of a long duration GRB by SVOM/ECLAIRs
  31. GRB 241008A: Fermi GBM Observation
  32. GRB 241008A: Fermi-LAT detection
  33. GRB 241002B: Swift-XRT afterglow detection
  34. LIGO/Virgo/KAGRA S241009an: Identification of a GW compact binary merger candidate
  35. GRB 241002A: NOT optical upper limits
  36. LIGO/Virgo/KAGRA S241009l: Identification of a GW compact binary merger candidate
  37. Fermi GRB 241008A: Global MASTER-Net observations report
  38. GRB 241008A: BALROG localization (Fermi Trigger 750117609 / GRB 241008917)
  39. GRB 241008A: Fermi GBM Final Real-time Localization
  40. IceCube-241006A: No candidates from the Zwicky Transient Facility
  41. GRB 241006A: GRANDMA optical upper limits
  42. EP240930a / GRB 240930B: CrAO ZTSH optical upper limit
  43. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  44. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  45. GRB 240910A: LBT optical observations
  46. EP trigger ID 01709065118: KAIT confirmation of the stellar flare
  47. GRB 241006A: Swift-XRT refined Analysis
  48. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  49. GRB 241006A: PRIME near-infrared upper limits
  50. GRB 241006A: Swift/UVOT Upper Limits
  51. GRB 241006A: SVOM/VT follow-up and optical upper limit
  52. LIGO/Virgo/KAGRA S241007bw: Identification of a GW compact binary merger candidate
  53. IceCube Alert 241006.94: Global MASTER-Net observations report
  54. GRB 241001A: Swift-XRT afterglow detection
  55. GRB 241006A: Enhanced Swift-XRT position
  56. IceCube-241006A - IceCube observation of a high-energy neutrino candidate track-like event
  57. GRB 241006A: Swift detection of a burst
  58. Swift GRB241006.91: Global MASTER-Net observations report
  59. GRB 240930B: SVOM/C-GFT optical upper limit
  60. LIGO/Virgo/KAGRA S241006k: Identification of a GW compact binary merger candidate
  61. LIGO/Virgo/KAGRA S241005bo: Retraction of GW compact binary merger candidate
  62. Fermi trigger No 749721670: Global MASTER-Net observations report
  63. GRB 241004A: SVOM/GRM observation
  64. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  65. GRB 240930B / EP 240930a: SVOM/GRM observation
  66. GRB 241001A : ECLAIRs spectral analysis and XRF classification
  67. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  68. GRB 241002B: Fermi GBM Observation
  69. Fermi trigger No 749735279: Global MASTER-Net observations report
  70. Fermi trigger No 749630753: Global MASTER-Net observations report
  71. Fermi trigger No 749693019: Global MASTER-Net observations report
  72. GRB 241002B: Swift-XRT observations
  73. GRB 241002C: SVOM/C-GFT optical upper limit
  74. GRB 241002A: Swift-BAT refined analysis
  75. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  76. GRB 241002B: Swift ToO observations
  77. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  78. Konus-Wind detection of GRB 240926A
  79. GRB 241002B: PRIME near-infrared detection
  80. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  81. GRB 241002C: Swift ToO observations
  82. Fermi-GBM Sub-Threshold Detection of GRB 241002D
  83. IPN triangulation of GRB 240930B / EP 240930a
  84. GRB 241001A : SVOM/VT optical detection
  85. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  86. GRB 241002D: SVOM/GRM observation
  87. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  88. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  89. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  90. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  91. GRB 241002C : MITSuME Akeno optical upper limits
  92. LIGO/Virgo/KAGRA S240925n: Updated Sky localization
  93. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  94. GRB241001A: REM optical/NIR upper limits
  95. LIGO/Virgo/KAGRA S241002e: Updated Sky localization
  96. GRB 241002A: Swift/UVOT Upper Limits
  97. EP240930a: Liverpool Telescope observations
  98. GRB 241002A: Swift-XRT refined Analysis
  99. GRB 241002A: LCOGT Optical Upper Limits
  100. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits

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