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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"

27774 results found.

  1. IceCube-241006A - IceCube observation of a high-energy neutrino candidate track-like event
  2. GRB 241006A: Swift detection of a burst
  3. Swift GRB241006.91: Global MASTER-Net observations report
  4. GRB 240930B: SVOM/C-GFT optical upper limit
  5. LIGO/Virgo/KAGRA S241005bo: Retraction of GW compact binary merger candidate
  6. GRB 240930B / EP 240930a: SVOM/GRM observation
  7. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  8. GRB 241002B: Fermi GBM Observation
  9. GRB 241002B: Swift-XRT observations
  10. GRB 241002A: Swift-BAT refined analysis
  11. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  12. GRB 241002B: Swift ToO observations
  13. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  14. Konus-Wind detection of GRB 240926A
  15. GRB 241002B: PRIME near-infrared detection
  16. GRB 241002C: Swift ToO observations
  17. Fermi-GBM Sub-Threshold Detection of GRB 241002D
  18. IPN triangulation of GRB 240930B / EP 240930a
  19. GRB 241001A : SVOM/VT optical detection
  20. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  21. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  22. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  23. GRB 241002A: Swift/UVOT Upper Limits
  24. GRB 241002A: Swift-XRT refined Analysis
  25. GRB 241002A: LCOGT Optical Upper Limits
  26. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  27. GRB 241001A: Swift/UVOT Detection
  28. GRB 241001A: VLT/X-shooter redshift
  29. EP trigger ID 01709064214: GOTO confirms detection as a flare star
  30. GRB 241002C : Detection of a long soft transient by SVOM/ECLAIRs
  31. GRB 241001A: Swift-XRT observations
  32. EP trigger ID 01709064214: the X-ray transient is most likely a stellar flare event
  33. GRB 241002B: Fermi GBM Final Real-time Localization
  34. GRB241001A: optical afterglow candidate
  35. GRB 241002A: 1.5m OSN optical upper limit
  36. GRB 241002A: Enhanced Swift-XRT position
  37. GRB 241001A: BOOTES-6/DPRT optical upper limit
  38. GRB 241002A: Swift detection of a burst
  39. GRB 240930B: Fermi GBM Observation
  40. GRB 241001A: Swift ToO observations
  41. GRB 240930B: GRBAlpha detection
  42. GRB 240929A: GRBAlpha detection
  43. GRB 241001A : Detection of a soft transient by ECLAIRs onboard SVOM
  44. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  45. EP240930a: EP-FXT follow-up observation update
  46. EP240930a: EP-WXT detection of a fast X-ray transient
  47. SVOM/GRM detection of a burst from SGR Swift J1818.0-1607
  48. AMON NuEM 240926A: Swift XRT Follow-up
  49. GRB 240930B: Fermi GBM Final Real-time Localization
  50. IPN triangulation of GRB 240926A
  51. GRB 240930A: Fermi GBM Final Real-time Localization
  52. GRB 240929A: Fermi GBM Final Real-time Localization
  53. IceCube-240929A - IceCube observation of a high-energy neutrino candidate track-like event
  54. Konus-Wind detection of GRB 240912A
  55. Swift Trigger 1256950 is probably not a GRB
  56. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  57. LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO
  58. LIGO/Virgo/KAGRA S240919bn: Upper limits from Swift/BAT-GUANO
  59. NuEm-240926A / IC240926A: BZQJ0955+4532 ~0.6m optical decay and rebrightening detection by MASTER
  60. Konus-Wind detection of GRB 240905B
  61. GRB 240529A: FRAM-ORM early optical afterglow observations reveal plateau and rebrightening
  62. GW S240915b and S240919bn : Swift UVOT follow-up
  63. EP240918b and EP240918c: EP-FXT follow-up observations
  64. Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
  65. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  66. Konus-Wind detection of GRB 240918B
  67. IPN triangulation of GRB 240918B
  68. GRB 240905B: VZLUSAT-2 detection
  69. LIGO/Virgo S240919bn: GOTO optical upper limits
  70. LIGO/Virgo S240919bn: Swift XRT observations, 10 X-ray sources
  71. GRB 240918B: AstroSat CZTI detection
  72. EP240919a: EP-FXT follow-up observation update
  73. EP240913A/GRB 240913C: AbAO optical upper limit
  74. EP240913a/GRB 240913C: 1.6m Mephisto observations
  75. EP240918a: SVOM/VT upper limit
  76. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  77. EP240918b and EP240918c: Optical upper limits with Kinder observations
  78. EP240919a: Optical upper limit with Kinder observations
  79. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  80. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  81. GRB 240910A: radio detection with the VLA
  82. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  83. EP240919a: GOTO optical upper limits
  84. EP240919a: EP-WXT detection of a fast X-ray transient
  85. GRB 240918B: Fermi GBM Detection
  86. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  87. EP240918a: EP observation update
  88. GRB 240910A: further Swift observations and confirmation of afterglow
  89. EP240918a: Swift-XRT observation
  90. GRB 240918A: Fermi GBM Final Real-time Localization
  91. EP240918a: YAHPT Optical Upper Limit
  92. GRB 240916A: GRBAlpha detection
  93. GRB 240914B: GRBAlpha detection
  94. EP240918a: an X-ray transient detected by Einstein Probe
  95. GRB 240912A: Swift-BAT refined analysis
  96. IPN triangulation of GRB 240913C / EP 240913a
  97. GRB 240825A: INTEGRAL SPI ACS LIGHT CURVE
  98. GRB 240825A: The nature of the afterglow motivates the search of the associated supernova
  99. GRB 240916A: Fermi GBM Observation
  100. GRB 240916A (AT 2024vlp / GOTO24fzn): VLT/X-shooter redshift

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