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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"

38169 results found.

  1. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  2. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  3. GRB 241002C : MITSuME Akeno optical upper limits
  4. GRB241001A: REM optical/NIR upper limits
  5. GRB 241002A: Swift/UVOT Upper Limits
  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. GRB 241002C : Detection of a long soft transient by SVOM/ECLAIRs
  13. GRB 241001A: correction to GCN 37667
  14. GRB 240929A: Liverpool Telescope prompt followup observations
  15. Fermi GRB 241002B: Global MASTER-Net observations report
  16. GRB 241001A: Swift-XRT observations
  17. EP trigger ID 01709064214: the X-ray transient is most likely a stellar flare event
  18. GRB 241002B: Fermi GBM Final Real-time Localization
  19. GRB241001A: optical afterglow candidate
  20. GRB 241002A: 1.5m OSN optical upper limit
  21. GRB 241002A: Enhanced Swift-XRT position
  22. GRB 241001A: BOOTES-6/DPRT optical upper limit
  23. GRB 241002A: Swift detection of a burst
  24. GRB 240930B: Fermi GBM Observation
  25. GRB 241001A: Swift ToO observations
  26. GRB 240930B: GRBAlpha detection
  27. GRB 240929A: GRBAlpha detection
  28. EP240930a : KAIT optical upper limit
  29. GRB 241001A : Detection of a soft transient by ECLAIRs onboard SVOM
  30. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  31. EP240930a: EP-FXT follow-up observation update
  32. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  33. EP240930a: GOTO optical upper limits
  34. GRB 240929A: SVOM/GRM observation
  35. EP EP240930a: Global MASTER-Net observations report
  36. EP240930a: EP-WXT detection of a fast X-ray transient
  37. SVOM/GRM detection of a burst from SGR Swift J1818.0-1607
  38. AMON NuEM 240926A: Swift XRT Follow-up
  39. GRB 240929A : Leavitt Observatory optical upper limit
  40. Fermi GRB 240930B: Global MASTER-Net observations report
  41. GRB 240930B: Fermi GBM Final Real-time Localization
  42. IPN triangulation of GRB 240926A
  43. GRB 240825A: LBT optical observations
  44. GRB 240928A: SVOM/GRM observation
  45. Fermi GRB 240930A: Global MASTER-Net observations report
  46. Fermi Gamma-ray Burst Monitor trigger 749362078/240930172 (GRB 240930A) is not a GRB
  47. GRB 240930A: Fermi GBM Final Real-time Localization
  48. Fermi trigger No 749339671: Global MASTER-Net observations report
  49. Fermi Gamma-ray Burst Monitor trigger 749339671/240929913 is not a GRB
  50. GRB 240929A long GRB detected by INTEGRAL
  51. GRB 240929A: BALROG localization (Fermi Trigger 749332209 / GRB 240929826)
  52. Fermi GRB 240929A: Global MASTER-Net observations report
  53. GRB 240929A: Fermi GBM Final Real-time Localization
  54. Integral GRB240929.83: Global MASTER-Net observations report
  55. Konus-Wind detection of GRB 240912A
  56. Swift Trigger 1256950 is probably not a GRB
  57. Fermi Gamma-ray Burst Monitor trigger 749191601/240928199 is not a GRB
  58. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  59. LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO
  60. LIGO/Virgo/KAGRA S240919bn: Upper limits from Swift/BAT-GUANO
  61. EP trigger ID 01709059262: Lick/Kast spectroscopy with 3 m Shane telescope
  62. GRB 240926A: SVOM/GRM observation
  63. EP trigger ID 01709061302: the X-ray transient is likely a stellar flare event
  64. Konus-Wind detection of GRB 240905B
  65. GRB 240529A: FRAM-ORM early optical afterglow observations reveal plateau and rebrightening
  66. EP240919a / GRB 240919A: SVOM/VT upper limit
  67. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  68. Konus-Wind detection of GRB 240918B
  69. IPN triangulation of GRB 240918B
  70. GRB 240905B: VZLUSAT-2 detection
  71. GRB 240918B: AstroSat CZTI detection
  72. EP240913A/GRB 240913C: AbAO optical upper limit
  73. EP240919a / GRB 240919A: Mondy optical upper limit
  74. EP240913a/GRB 240913C: 1.6m Mephisto observations
  75. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  76. EP240919a / GRB 240919A: REM optical and NIR upper limits
  77. EP240919a / GRB 240919A: KAIT optical upper limit
  78. GRB 240414A: further radio observations with the VLA
  79. GRB 240919A / EP240919a: SVOM/GRM observation
  80. EP EP240919a: Global MASTER-Net observations report
  81. GRB 240910A: radio detection with the VLA
  82. EP240919a: NOT and Gemini optical observations
  83. EP240919a: JinShan optical upper limits
  84. EP240919a is likely a GRB event (duplicate submission of 37563)
  85. EP240919a is likely a GRB event
  86. GRB 240918A and GRB 240918B : INTEGRAL SPI ACS LIGHT CURVE
  87. GRB 240918B: Fermi GBM Detection
  88. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  89. EP240918a: EP observation update
  90. GRB 240910A: further Swift observations and confirmation of afterglow
  91. Fermi GRB 240918A: Global MASTER-Net observations report
  92. GRB 240918A: Fermi GBM Final Real-time Localization
  93. EP EP240918a: Global MASTER-Net observations report
  94. EP240918a: JinShan optical upper limits
  95. GRB 240916A: GRBAlpha detection
  96. GRB 240914B: GRBAlpha detection
  97. GRB 240916A: NOT optical observation
  98. GRB 240912A: Swift-BAT refined analysis
  99. IPN triangulation of GRB 240913C / EP 240913a
  100. GRB 240825A: INTEGRAL SPI ACS LIGHT CURVE

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