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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"

45431 results found.

  1. GRB 241002B: Fermi GBM Final Real-time Localization
  2. GRB241001A: optical afterglow candidate
  3. GRB 241002A: 1.5m OSN optical upper limit
  4. GRB 241002A: Enhanced Swift-XRT position
  5. GRB 241001A: BOOTES-6/DPRT optical upper limit
  6. LIGO/Virgo/KAGRA S241002e: Identification of a GW compact binary merger candidate
  7. GRB 241002A: Swift detection of a burst
  8. LIGO/Virgo/KAGRA S240930du: Updated Sky localization
  9. GRB 240930B: Fermi GBM Observation
  10. GRB 241001A: Swift ToO observations
  11. GRB 240930B: GRBAlpha detection
  12. GRB 240929A: GRBAlpha detection
  13. EP240930a : KAIT optical upper limit
  14. GRB 241001A : Detection of a soft transient by ECLAIRs onboard SVOM
  15. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  16. EP240930a: EP-FXT follow-up observation update
  17. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  18. EP240930a: GOTO optical upper limits
  19. GRB 240929A: SVOM/GRM observation
  20. EP EP240930a: Global MASTER-Net observations report
  21. EP240930a: EP-WXT detection of a fast X-ray transient
  22. SVOM/GRM detection of a burst from SGR Swift J1818.0-1607
  23. LIGO/Virgo/KAGRA S240930du: Identification of a GW compact binary merger candidate
  24. IceCube-240929A: Upper limits from a search for additional neutrino events in IceCube
  25. LIGO/Virgo/KAGRA S240930df: 1 counterpart neutrino candidate event from an IceCube neutrino search
  26. AMON NuEM 240926A: Swift XRT Follow-up
  27. GRB 240929A : Leavitt Observatory optical upper limit
  28. Fermi GRB 240930B: Global MASTER-Net observations report
  29. GRB 240930B: Fermi GBM Final Real-time Localization
  30. IPN triangulation of GRB 240926A
  31. GRB 240825A: LBT optical observations
  32. GRB 240928A: SVOM/GRM observation
  33. Fermi GRB 240930A: Global MASTER-Net observations report
  34. Fermi Gamma-ray Burst Monitor trigger 749362078/240930172 (GRB 240930A) is not a GRB
  35. LIGO/Virgo/KAGRA S240930aa: Identification of a GW compact binary merger candidate
  36. GRB 240930A: Fermi GBM Final Real-time Localization
  37. Fermi trigger No 749339671: Global MASTER-Net observations report
  38. Fermi Gamma-ray Burst Monitor trigger 749339671/240929913 is not a GRB
  39. GRB 240929A long GRB detected by INTEGRAL
  40. GRB 240929A: BALROG localization (Fermi Trigger 749332209 / GRB 240929826)
  41. Fermi GRB 240929A: Global MASTER-Net observations report
  42. GRB 240929A: Fermi GBM Final Real-time Localization
  43. Integral GRB240929.83: Global MASTER-Net observations report
  44. IceCube-240929A - IceCube observation of a high-energy neutrino candidate track-like event
  45. Konus-Wind detection of GRB 240912A
  46. Swift Trigger 1256950 is probably not a GRB
  47. Fermi Gamma-ray Burst Monitor trigger 749191601/240928199 is not a GRB
  48. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  49. LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO
  50. LIGO/Virgo/KAGRA S240919bn: Upper limits from Swift/BAT-GUANO
  51. EP trigger ID 01709059262: Lick/Kast spectroscopy with 3 m Shane telescope
  52. NuEm-240926A / IC240926A: BZQJ0955+4532 ~0.6m optical decay and rebrightening detection by MASTER
  53. GRB 240926A: SVOM/GRM observation
  54. EP trigger ID 01709061302: the X-ray transient is likely a stellar flare event
  55. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-240926A
  56. Konus-Wind detection of GRB 240905B
  57. GRB 240529A: FRAM-ORM early optical afterglow observations reveal plateau and rebrightening
  58. GW S240915b and S240919bn : Swift UVOT follow-up
  59. EP240919a / GRB 240919A: SVOM/VT upper limit
  60. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  61. EP240918b and EP240918c: EP-FXT follow-up observations
  62. LIGO/Virgo/KAGRA S240925n: Updated Sky localization and Source Classification
  63. Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
  64. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  65. LIGO/Virgo/KAGRA S240925n: Identification of a GW compact binary merger candidate
  66. Konus-Wind detection of GRB 240918B
  67. IPN triangulation of GRB 240918B
  68. GRB 240905B: VZLUSAT-2 detection
  69. LIGO/Virgo/KAGRA S240922df: Updated Sky localization
  70. LIGO/Virgo/KAGRA S240920dw: Updated Sky localization
  71. LIGO/Virgo/KAGRA S240921cw: Updated Sky localization
  72. LIGO/Virgo/KAGRA S240924a: Updated Sky localization
  73. LIGO/Virgo/KAGRA S240920bz: Updated Sky localization and Source Classification
  74. LIGO/Virgo/KAGRA S240923ct: Updated Sky localization and Source Classification
  75. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  76. LIGO/Virgo/KAGRA S240924a: Identification of a GW compact binary merger candidate
  77. LIGO/Virgo/KAGRA S240923ct: Identification of a GW compact binary merger candidate
  78. LIGO/Virgo S240919bn: GOTO optical upper limits
  79. LIGO/Virgo S240919bn: Swift XRT observations, 10 X-ray sources
  80. GRB 240918B: AstroSat CZTI detection
  81. LIGO/Virgo/KAGRA S240922df: Identification of a GW compact binary merger candidate
  82. LIGO/Virgo/KAGRA S240921cw: Identification of a GW compact binary merger candidate
  83. EP240919a: EP-FXT follow-up observation update
  84. EP240913A/GRB 240913C: AbAO optical upper limit
  85. EP240919a / GRB 240919A: Mondy optical upper limit
  86. EP240913a/GRB 240913C: 1.6m Mephisto observations
  87. EP240918a: SVOM/VT upper limit
  88. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  89. EP240919a / GRB 240919A: REM optical and NIR upper limits
  90. EP240919a / GRB 240919A: KAIT optical upper limit
  91. EP240918b and EP240918c: Optical upper limits with Kinder observations
  92. GRB 240414A: further radio observations with the VLA
  93. EP240919a: Optical upper limit with Kinder observations
  94. GRB 240919A / EP240919a: SVOM/GRM observation
  95. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  96. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  97. LIGO/Virgo/KAGRA S240920dw: Identification of a GW compact binary merger candidate
  98. EP EP240919a: Global MASTER-Net observations report
  99. GRB 240910A: radio detection with the VLA
  100. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit

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