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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"
  1. GRB 241002B: Swift-XRT afterglow detection
  2. LIGO/Virgo/KAGRA S241009an: Identification of a GW compact binary merger candidate
  3. GRB 241002A: NOT optical upper limits
  4. LIGO/Virgo/KAGRA S241009l: Identification of a GW compact binary merger candidate
  5. Fermi GRB 241008A: Global MASTER-Net observations report
  6. GRB 241008A: BALROG localization (Fermi Trigger 750117609 / GRB 241008917)
  7. GRB 241008A: Fermi GBM Final Real-time Localization
  8. IceCube-241006A: No candidates from the Zwicky Transient Facility
  9. GRB 241006A: GRANDMA optical upper limits
  10. EP240930a / GRB 240930B: CrAO ZTSH optical upper limit
  11. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  12. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  13. GRB 240910A: LBT optical observations
  14. EP trigger ID 01709065118: KAIT confirmation of the stellar flare
  15. GRB 241006A: Swift-XRT refined Analysis
  16. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  17. GRB 241006A: PRIME near-infrared upper limits
  18. GRB 241006A: Swift/UVOT Upper Limits
  19. GRB 241006A: SVOM/VT follow-up and optical upper limit
  20. LIGO/Virgo/KAGRA S241007bw: Identification of a GW compact binary merger candidate
  21. IceCube Alert 241006.94: Global MASTER-Net observations report
  22. GRB 241001A: Swift-XRT afterglow detection
  23. GRB 241006A: Enhanced Swift-XRT position
  24. IceCube-241006A - IceCube observation of a high-energy neutrino candidate track-like event
  25. GRB 241006A: Swift detection of a burst
  26. Swift GRB241006.91: Global MASTER-Net observations report
  27. GRB 240930B: SVOM/C-GFT optical upper limit
  28. LIGO/Virgo/KAGRA S241006k: Identification of a GW compact binary merger candidate
  29. LIGO/Virgo/KAGRA S241005bo: Retraction of GW compact binary merger candidate
  30. Fermi trigger No 749721670: Global MASTER-Net observations report
  31. GRB 241004A: SVOM/GRM observation
  32. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  33. GRB 240930B / EP 240930a: SVOM/GRM observation
  34. GRB 241001A : ECLAIRs spectral analysis and XRF classification
  35. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  36. GRB 241002B: Fermi GBM Observation
  37. Fermi trigger No 749735279: Global MASTER-Net observations report
  38. Fermi trigger No 749630753: Global MASTER-Net observations report
  39. Fermi trigger No 749693019: Global MASTER-Net observations report
  40. GRB 241002B: Swift-XRT observations
  41. GRB 241002C: SVOM/C-GFT optical upper limit
  42. GRB 241002A: Swift-BAT refined analysis
  43. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  44. GRB 241002B: Swift ToO observations
  45. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  46. Konus-Wind detection of GRB 240926A
  47. GRB 241002B: PRIME near-infrared detection
  48. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  49. GRB 241002C: Swift ToO observations
  50. Fermi-GBM Sub-Threshold Detection of GRB 241002D
  51. IPN triangulation of GRB 240930B / EP 240930a
  52. GRB 241001A : SVOM/VT optical detection
  53. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  54. GRB 241002D: SVOM/GRM observation
  55. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  56. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  57. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  58. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  59. GRB 241002C : MITSuME Akeno optical upper limits
  60. LIGO/Virgo/KAGRA S240925n: Updated Sky localization
  61. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  62. GRB241001A: REM optical/NIR upper limits
  63. LIGO/Virgo/KAGRA S241002e: Updated Sky localization
  64. GRB 241002A: Swift/UVOT Upper Limits
  65. EP240930a: Liverpool Telescope observations
  66. GRB 241002A: Swift-XRT refined Analysis
  67. GRB 241002A: LCOGT Optical Upper Limits
  68. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  69. GRB 241001A: Swift/UVOT Detection
  70. GRB 241001A: VLT/X-shooter redshift
  71. GRB 241002B: GOTO optical counterpart candidate
  72. EP trigger ID 01709064214: GOTO confirms detection as a flare star
  73. GRB 241002C : Detection of a long soft transient by SVOM/ECLAIRs
  74. GRB 241001A: correction to GCN 37667
  75. GRB 240929A: Liverpool Telescope prompt followup observations
  76. Fermi GRB 241002B: Global MASTER-Net observations report
  77. GRB 241001A: Swift-XRT observations
  78. EP trigger ID 01709064214: the X-ray transient is most likely a stellar flare event
  79. GRB 241002B: Fermi GBM Final Real-time Localization
  80. GRB241001A: optical afterglow candidate
  81. GRB 241002A: 1.5m OSN optical upper limit
  82. GRB 241002A: Enhanced Swift-XRT position
  83. GRB 241001A: BOOTES-6/DPRT optical upper limit
  84. LIGO/Virgo/KAGRA S241002e: Identification of a GW compact binary merger candidate
  85. GRB 241002A: Swift detection of a burst
  86. LIGO/Virgo/KAGRA S240930du: Updated Sky localization
  87. GRB 240930B: Fermi GBM Observation
  88. GRB 241001A: Swift ToO observations
  89. GRB 240930B: GRBAlpha detection
  90. GRB 240929A: GRBAlpha detection
  91. EP240930a : KAIT optical upper limit
  92. GRB 241001A : Detection of a soft transient by ECLAIRs onboard SVOM
  93. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  94. EP240930a: EP-FXT follow-up observation update
  95. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  96. EP240930a: GOTO optical upper limits
  97. GRB 240929A: SVOM/GRM observation
  98. EP EP240930a: Global MASTER-Net observations report
  99. EP240930a: EP-WXT detection of a fast X-ray transient
  100. SVOM/GRM detection of a burst from SGR Swift J1818.0-1607

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