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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"

32167 results found.

  1. GRB 241008A: Fermi GBM Observation
  2. GRB 241008A: Fermi-LAT detection
  3. GRB 241002B: Swift-XRT afterglow detection
  4. GRB 241002A: NOT optical upper limits
  5. Fermi GRB 241008A: Global MASTER-Net observations report
  6. GRB 241008A: BALROG localization (Fermi Trigger 750117609 / GRB 241008917)
  7. GRB 241008A: Fermi GBM Final Real-time Localization
  8. GRB 241006A: GRANDMA optical upper limits
  9. EP240930a / GRB 240930B: CrAO ZTSH optical upper limit
  10. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  11. GRB 240910A: LBT optical observations
  12. EP trigger ID 01709065118: KAIT confirmation of the stellar flare
  13. GRB 241006A: Swift-XRT refined Analysis
  14. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  15. GRB 241006A: PRIME near-infrared upper limits
  16. GRB 241006A: Swift/UVOT Upper Limits
  17. GRB 241006A: SVOM/VT follow-up and optical upper limit
  18. GRB 241001A: Swift-XRT afterglow detection
  19. GRB 241006A: Enhanced Swift-XRT position
  20. GRB 241006A: Swift detection of a burst
  21. GRB 240930B: SVOM/C-GFT optical upper limit
  22. GRB 241004A: SVOM/GRM observation
  23. GRB 240930B / EP 240930a: SVOM/GRM observation
  24. GRB 241001A : ECLAIRs spectral analysis and XRF classification
  25. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  26. GRB 241002B: Fermi GBM Observation
  27. GRB 241002B: Swift-XRT observations
  28. GRB 241002C: SVOM/C-GFT optical upper limit
  29. GRB 241002A: Swift-BAT refined analysis
  30. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  31. GRB 241002B: Swift ToO observations
  32. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  33. Konus-Wind detection of GRB 240926A
  34. GRB 241002B: PRIME near-infrared detection
  35. GRB 241002C: Swift ToO observations
  36. Fermi-GBM Sub-Threshold Detection of GRB 241002D
  37. IPN triangulation of GRB 240930B / EP 240930a
  38. GRB 241001A : SVOM/VT optical detection
  39. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  40. GRB 241002D: SVOM/GRM observation
  41. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  42. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  43. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  44. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  45. GRB 241002C : MITSuME Akeno optical upper limits
  46. GRB241001A: REM optical/NIR upper limits
  47. GRB 241002A: Swift/UVOT Upper Limits
  48. GRB 241002A: Swift-XRT refined Analysis
  49. GRB 241002A: LCOGT Optical Upper Limits
  50. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  51. GRB 241001A: Swift/UVOT Detection
  52. GRB 241001A: VLT/X-shooter redshift
  53. GRB 241002B: GOTO optical counterpart candidate
  54. GRB 241002C : Detection of a long soft transient by SVOM/ECLAIRs
  55. GRB 241001A: correction to GCN 37667
  56. GRB 240929A: Liverpool Telescope prompt followup observations
  57. Fermi GRB 241002B: Global MASTER-Net observations report
  58. GRB 241001A: Swift-XRT observations
  59. GRB 241002B: Fermi GBM Final Real-time Localization
  60. GRB241001A: optical afterglow candidate
  61. GRB 241002A: 1.5m OSN optical upper limit
  62. GRB 241002A: Enhanced Swift-XRT position
  63. GRB 241001A: BOOTES-6/DPRT optical upper limit
  64. GRB 241002A: Swift detection of a burst
  65. GRB 240930B: Fermi GBM Observation
  66. GRB 241001A: Swift ToO observations
  67. GRB 240930B: GRBAlpha detection
  68. GRB 240929A: GRBAlpha detection
  69. EP240930a : KAIT optical upper limit
  70. GRB 241001A : Detection of a soft transient by ECLAIRs onboard SVOM
  71. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  72. EP240930a: EP-FXT follow-up observation update
  73. EP240930a: GOTO optical upper limits
  74. GRB 240929A: SVOM/GRM observation
  75. EP240930a: EP-WXT detection of a fast X-ray transient
  76. GRB 240929A : Leavitt Observatory optical upper limit
  77. Fermi GRB 240930B: Global MASTER-Net observations report
  78. GRB 240930B: Fermi GBM Final Real-time Localization
  79. IPN triangulation of GRB 240926A
  80. GRB 240825A: LBT optical observations
  81. GRB 240928A: SVOM/GRM observation
  82. Fermi GRB 240930A: Global MASTER-Net observations report
  83. Fermi Gamma-ray Burst Monitor trigger 749362078/240930172 (GRB 240930A) is not a GRB
  84. GRB 240930A: Fermi GBM Final Real-time Localization
  85. Fermi Gamma-ray Burst Monitor trigger 749339671/240929913 is not a GRB
  86. GRB 240929A long GRB detected by INTEGRAL
  87. GRB 240929A: BALROG localization (Fermi Trigger 749332209 / GRB 240929826)
  88. Fermi GRB 240929A: Global MASTER-Net observations report
  89. GRB 240929A: Fermi GBM Final Real-time Localization
  90. Konus-Wind detection of GRB 240912A
  91. Swift Trigger 1256950 is probably not a GRB
  92. Fermi Gamma-ray Burst Monitor trigger 749191601/240928199 is not a GRB
  93. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  94. LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO
  95. LIGO/Virgo/KAGRA S240919bn: Upper limits from Swift/BAT-GUANO
  96. EP trigger ID 01709059262: Lick/Kast spectroscopy with 3 m Shane telescope
  97. GRB 240926A: SVOM/GRM observation
  98. Konus-Wind detection of GRB 240905B
  99. GRB 240529A: FRAM-ORM early optical afterglow observations reveal plateau and rebrightening
  100. EP240919a / GRB 240919A: SVOM/VT upper limit

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