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

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