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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"

44271 results found.

  1. Fermi trigger No 749630753: Global MASTER-Net observations report
  2. Fermi trigger No 749693019: Global MASTER-Net observations report
  3. GRB 241002B: Swift-XRT observations
  4. GRB 241002C: SVOM/C-GFT optical upper limit
  5. GRB 241002A: Swift-BAT refined analysis
  6. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  7. GRB 241002B: Swift ToO observations
  8. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  9. Konus-Wind detection of GRB 240926A
  10. GRB 241002B: PRIME near-infrared detection
  11. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  12. GRB 241002C: Swift ToO observations
  13. Fermi-GBM Sub-Threshold Detection of GRB 241002D
  14. IPN triangulation of GRB 240930B / EP 240930a
  15. GRB 241001A : SVOM/VT optical detection
  16. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  17. GRB 241002D: SVOM/GRM observation
  18. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  19. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  20. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  21. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  22. GRB 241002C : MITSuME Akeno optical upper limits
  23. LIGO/Virgo/KAGRA S240925n: Updated Sky localization
  24. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  25. GRB241001A: REM optical/NIR upper limits
  26. LIGO/Virgo/KAGRA S241002e: Updated Sky localization
  27. GRB 241002A: Swift/UVOT Upper Limits
  28. EP240930a: Liverpool Telescope observations
  29. GRB 241002A: Swift-XRT refined Analysis
  30. GRB 241002A: LCOGT Optical Upper Limits
  31. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  32. GRB 241001A: Swift/UVOT Detection
  33. GRB 241001A: VLT/X-shooter redshift
  34. GRB 241002B: GOTO optical counterpart candidate
  35. EP trigger ID 01709064214: GOTO confirms detection as a flare star
  36. GRB 241002C : Detection of a long soft transient by SVOM/ECLAIRs
  37. GRB 241001A: correction to GCN 37667
  38. Fermi GRB 241002B: Global MASTER-Net observations report
  39. GRB 241001A: Swift-XRT observations
  40. EP trigger ID 01709064214: the X-ray transient is most likely a stellar flare event
  41. GRB 241002B: Fermi GBM Final Real-time Localization
  42. GRB241001A: optical afterglow candidate
  43. GRB 241002A: 1.5m OSN optical upper limit
  44. GRB 241002A: Enhanced Swift-XRT position
  45. GRB 241001A: BOOTES-6/DPRT optical upper limit
  46. LIGO/Virgo/KAGRA S241002e: Identification of a GW compact binary merger candidate
  47. GRB 241002A: Swift detection of a burst
  48. LIGO/Virgo/KAGRA S240930du: Updated Sky localization
  49. GRB 240930B: Fermi GBM Observation
  50. GRB 241001A: Swift ToO observations
  51. GRB 240930B: GRBAlpha detection
  52. GRB 240929A: GRBAlpha detection
  53. EP240930a : KAIT optical upper limit
  54. GRB 241001A : Detection of a soft transient by ECLAIRs onboard SVOM
  55. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  56. EP240930a: EP-FXT follow-up observation update
  57. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  58. EP240930a: GOTO optical upper limits
  59. GRB 240929A: SVOM/GRM observation
  60. EP EP240930a: Global MASTER-Net observations report
  61. EP240930a: EP-WXT detection of a fast X-ray transient
  62. SVOM/GRM detection of a burst from SGR Swift J1818.0-1607
  63. LIGO/Virgo/KAGRA S240930du: Identification of a GW compact binary merger candidate
  64. IceCube-240929A: Upper limits from a search for additional neutrino events in IceCube
  65. LIGO/Virgo/KAGRA S240930df: 1 counterpart neutrino candidate event from an IceCube neutrino search
  66. AMON NuEM 240926A: Swift XRT Follow-up
  67. GRB 240929A : Leavitt Observatory optical upper limit
  68. Fermi GRB 240930B: Global MASTER-Net observations report
  69. GRB 240930B: Fermi GBM Final Real-time Localization
  70. IPN triangulation of GRB 240926A
  71. GRB 240825A: LBT optical observations
  72. GRB 240928A: SVOM/GRM observation
  73. Fermi GRB 240930A: Global MASTER-Net observations report
  74. Fermi Gamma-ray Burst Monitor trigger 749362078/240930172 (GRB 240930A) is not a GRB
  75. LIGO/Virgo/KAGRA S240930aa: Identification of a GW compact binary merger candidate
  76. GRB 240930A: Fermi GBM Final Real-time Localization
  77. Fermi trigger No 749339671: Global MASTER-Net observations report
  78. Fermi Gamma-ray Burst Monitor trigger 749339671/240929913 is not a GRB
  79. GRB 240929A long GRB detected by INTEGRAL
  80. GRB 240929A: BALROG localization (Fermi Trigger 749332209 / GRB 240929826)
  81. Fermi GRB 240929A: Global MASTER-Net observations report
  82. GRB 240929A: Fermi GBM Final Real-time Localization
  83. Integral GRB240929.83: Global MASTER-Net observations report
  84. IceCube-240929A - IceCube observation of a high-energy neutrino candidate track-like event
  85. Konus-Wind detection of GRB 240912A
  86. Swift Trigger 1256950 is probably not a GRB
  87. Fermi Gamma-ray Burst Monitor trigger 749191601/240928199 is not a GRB
  88. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  89. LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO
  90. LIGO/Virgo/KAGRA S240919bn: Upper limits from Swift/BAT-GUANO
  91. EP trigger ID 01709059262: Lick/Kast spectroscopy with 3 m Shane telescope
  92. NuEm-240926A / IC240926A: BZQJ0955+4532 ~0.6m optical decay and rebrightening detection by MASTER
  93. GRB 240926A: SVOM/GRM observation
  94. EP trigger ID 01709061302: the X-ray transient is likely a stellar flare event
  95. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-240926A
  96. Konus-Wind detection of GRB 240905B
  97. GRB 240529A: FRAM-ORM early optical afterglow observations reveal plateau and rebrightening
  98. GW S240915b and S240919bn : Swift UVOT follow-up
  99. EP240919a / GRB 240919A: SVOM/VT upper limit
  100. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume

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