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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. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  2. GRB241001A: REM optical/NIR upper limits
  3. LIGO/Virgo/KAGRA S241002e: Updated Sky localization
  4. GRB 241002A: Swift/UVOT Upper Limits
  5. EP240930a: Liverpool Telescope observations
  6. GRB 241002A: Swift-XRT refined Analysis
  7. GRB 241002A: LCOGT Optical Upper Limits
  8. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  9. GRB 241001A: Swift/UVOT Detection
  10. GRB 241001A: VLT/X-shooter redshift
  11. GRB 241002B: GOTO optical counterpart candidate
  12. EP trigger ID 01709064214: GOTO confirms detection as a flare star
  13. GRB 241002C : Detection of a long soft transient by SVOM/ECLAIRs
  14. GRB 241001A: correction to GCN 37667
  15. GRB 240929A: Liverpool Telescope prompt followup observations
  16. Fermi GRB 241002B: Global MASTER-Net observations report
  17. GRB 241001A: Swift-XRT observations
  18. EP trigger ID 01709064214: the X-ray transient is most likely a stellar flare event
  19. GRB 241002B: Fermi GBM Final Real-time Localization
  20. GRB241001A: optical afterglow candidate
  21. GRB 241002A: 1.5m OSN optical upper limit
  22. GRB 241002A: Enhanced Swift-XRT position
  23. GRB 241001A: BOOTES-6/DPRT optical upper limit
  24. LIGO/Virgo/KAGRA S241002e: Identification of a GW compact binary merger candidate
  25. GRB 241002A: Swift detection of a burst
  26. LIGO/Virgo/KAGRA S240930du: Updated Sky localization
  27. GRB 240930B: Fermi GBM Observation
  28. GRB 241001A: Swift ToO observations
  29. GRB 240930B: GRBAlpha detection
  30. GRB 240929A: GRBAlpha detection
  31. EP240930a : KAIT optical upper limit
  32. GRB 241001A : Detection of a soft transient by ECLAIRs onboard SVOM
  33. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  34. EP240930a: EP-FXT follow-up observation update
  35. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  36. EP240930a: GOTO optical upper limits
  37. GRB 240929A: SVOM/GRM observation
  38. EP EP240930a: Global MASTER-Net observations report
  39. EP240930a: EP-WXT detection of a fast X-ray transient
  40. SVOM/GRM detection of a burst from SGR Swift J1818.0-1607
  41. LIGO/Virgo/KAGRA S240930du: Identification of a GW compact binary merger candidate
  42. IceCube-240929A: Upper limits from a search for additional neutrino events in IceCube
  43. LIGO/Virgo/KAGRA S240930df: 1 counterpart neutrino candidate event from an IceCube neutrino search
  44. AMON NuEM 240926A: Swift XRT Follow-up
  45. GRB 240929A : Leavitt Observatory optical upper limit
  46. Fermi GRB 240930B: Global MASTER-Net observations report
  47. GRB 240930B: Fermi GBM Final Real-time Localization
  48. IPN triangulation of GRB 240926A
  49. GRB 240825A: LBT optical observations
  50. GRB 240928A: SVOM/GRM observation
  51. Fermi GRB 240930A: Global MASTER-Net observations report
  52. Fermi Gamma-ray Burst Monitor trigger 749362078/240930172 (GRB 240930A) is not a GRB
  53. LIGO/Virgo/KAGRA S240930aa: Identification of a GW compact binary merger candidate
  54. GRB 240930A: Fermi GBM Final Real-time Localization
  55. Fermi trigger No 749339671: Global MASTER-Net observations report
  56. Fermi Gamma-ray Burst Monitor trigger 749339671/240929913 is not a GRB
  57. GRB 240929A long GRB detected by INTEGRAL
  58. GRB 240929A: BALROG localization (Fermi Trigger 749332209 / GRB 240929826)
  59. Fermi GRB 240929A: Global MASTER-Net observations report
  60. GRB 240929A: Fermi GBM Final Real-time Localization
  61. Integral GRB240929.83: Global MASTER-Net observations report
  62. IceCube-240929A - IceCube observation of a high-energy neutrino candidate track-like event
  63. Konus-Wind detection of GRB 240912A
  64. Swift Trigger 1256950 is probably not a GRB
  65. Fermi Gamma-ray Burst Monitor trigger 749191601/240928199 is not a GRB
  66. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  67. LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO
  68. LIGO/Virgo/KAGRA S240919bn: Upper limits from Swift/BAT-GUANO
  69. EP trigger ID 01709059262: Lick/Kast spectroscopy with 3 m Shane telescope
  70. NuEm-240926A / IC240926A: BZQJ0955+4532 ~0.6m optical decay and rebrightening detection by MASTER
  71. GRB 240926A: SVOM/GRM observation
  72. EP trigger ID 01709061302: the X-ray transient is likely a stellar flare event
  73. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-240926A
  74. Konus-Wind detection of GRB 240905B
  75. GRB 240529A: FRAM-ORM early optical afterglow observations reveal plateau and rebrightening
  76. GW S240915b and S240919bn : Swift UVOT follow-up
  77. EP240919a / GRB 240919A: SVOM/VT upper limit
  78. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  79. EP240918b and EP240918c: EP-FXT follow-up observations
  80. LIGO/Virgo/KAGRA S240925n: Updated Sky localization and Source Classification
  81. Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
  82. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  83. LIGO/Virgo/KAGRA S240925n: Identification of a GW compact binary merger candidate
  84. Konus-Wind detection of GRB 240918B
  85. IPN triangulation of GRB 240918B
  86. GRB 240905B: VZLUSAT-2 detection
  87. LIGO/Virgo/KAGRA S240922df: Updated Sky localization
  88. LIGO/Virgo/KAGRA S240920dw: Updated Sky localization
  89. LIGO/Virgo/KAGRA S240921cw: Updated Sky localization
  90. LIGO/Virgo/KAGRA S240924a: Updated Sky localization
  91. LIGO/Virgo/KAGRA S240920bz: Updated Sky localization and Source Classification
  92. LIGO/Virgo/KAGRA S240923ct: Updated Sky localization and Source Classification
  93. EP trigger ID 01709059262: correction to the observation start time and source localization
  94. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  95. LIGO/Virgo/KAGRA S240924a: Identification of a GW compact binary merger candidate
  96. LIGO/Virgo/KAGRA S240923ct: Identification of a GW compact binary merger candidate
  97. LIGO/Virgo S240919bn: GOTO optical upper limits
  98. LIGO/Virgo S240919bn: Swift XRT observations, 10 X-ray sources
  99. GRB 240918B: AstroSat CZTI detection
  100. LIGO/Virgo/KAGRA S240922df: Identification of a GW compact binary merger candidate

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