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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"

36183 results found.

  1. Swift GRB 241010A: Global MASTER-Net observations report
  2. GRB 241010A: J-band observations with WINTER
  3. Fermi GRB 241010B: Global MASTER-Net observations report
  4. GRB 241010B: Fermi GBM Final Real-time Localization
  5. IceCube-241006A: Upper limits from a search for additional neutrino events in IceCube
  6. GRB 241010A: Enhanced Swift-XRT position
  7. GRB 241010A: LCO optical observations
  8. GRB 241010A: Swift detection of a burst with an optical counterpart
  9. GRB 241006A: Swift-BAT refined analysis
  10. GRB 241009A: Swift ToO observations
  11. GRB 241009A : Detection of a long duration GRB by SVOM/ECLAIRs
  12. GRB 241008A: Fermi GBM Observation
  13. GRB 241008A: Fermi-LAT detection
  14. GRB 241002B: Swift-XRT afterglow detection
  15. GRB 241002A: NOT optical upper limits
  16. Fermi GRB 241008A: Global MASTER-Net observations report
  17. GRB 241008A: BALROG localization (Fermi Trigger 750117609 / GRB 241008917)
  18. GRB 241008A: Fermi GBM Final Real-time Localization
  19. GRB 241006A: GRANDMA optical upper limits
  20. EP240930a / GRB 240930B: CrAO ZTSH optical upper limit
  21. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  22. GRB 240910A: LBT optical observations
  23. EP trigger ID 01709065118: KAIT confirmation of the stellar flare
  24. GRB 241006A: Swift-XRT refined Analysis
  25. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  26. GRB 241006A: PRIME near-infrared upper limits
  27. GRB 241006A: Swift/UVOT Upper Limits
  28. GRB 241006A: SVOM/VT follow-up and optical upper limit
  29. GRB 241001A: Swift-XRT afterglow detection
  30. GRB 241006A: Enhanced Swift-XRT position
  31. GRB 241006A: Swift detection of a burst
  32. GRB 240930B: SVOM/C-GFT optical upper limit
  33. GRB 241004A: SVOM/GRM observation
  34. GRB 240930B / EP 240930a: SVOM/GRM observation
  35. GRB 241001A : ECLAIRs spectral analysis and XRF classification
  36. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  37. GRB 241002B: Fermi GBM Observation
  38. GRB 241002B: Swift-XRT observations
  39. GRB 241002C: SVOM/C-GFT optical upper limit
  40. GRB 241002A: Swift-BAT refined analysis
  41. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  42. GRB 241002B: Swift ToO observations
  43. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  44. Konus-Wind detection of GRB 240926A
  45. GRB 241002B: PRIME near-infrared detection
  46. GRB 241002C: Swift ToO observations
  47. Fermi-GBM Sub-Threshold Detection of GRB 241002D
  48. IPN triangulation of GRB 240930B / EP 240930a
  49. GRB 241001A : SVOM/VT optical detection
  50. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  51. GRB 241002D: SVOM/GRM observation
  52. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  53. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  54. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  55. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  56. GRB 241002C : MITSuME Akeno optical upper limits
  57. LIGO/Virgo/KAGRA S240925n: Updated Sky localization
  58. NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
  59. GRB241001A: REM optical/NIR upper limits
  60. GRB 241002A: Swift/UVOT Upper Limits
  61. GRB 241002A: Swift-XRT refined Analysis
  62. GRB 241002A: LCOGT Optical Upper Limits
  63. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  64. GRB 241001A: Swift/UVOT Detection
  65. GRB 241001A: VLT/X-shooter redshift
  66. GRB 241002B: GOTO optical counterpart candidate
  67. GRB 241002C : Detection of a long soft transient by SVOM/ECLAIRs
  68. GRB 241001A: correction to GCN 37667
  69. GRB 240929A: Liverpool Telescope prompt followup observations
  70. Fermi GRB 241002B: Global MASTER-Net observations report
  71. GRB 241001A: Swift-XRT observations
  72. GRB 241002B: Fermi GBM Final Real-time Localization
  73. GRB241001A: optical afterglow candidate
  74. GRB 241002A: 1.5m OSN optical upper limit
  75. GRB 241002A: Enhanced Swift-XRT position
  76. GRB 241001A: BOOTES-6/DPRT optical upper limit
  77. GRB 241002A: Swift detection of a burst
  78. GRB 240930B: Fermi GBM Observation
  79. GRB 241001A: Swift ToO observations
  80. GRB 240930B: GRBAlpha detection
  81. GRB 240929A: GRBAlpha detection
  82. EP240930a : KAIT optical upper limit
  83. GRB 241001A : Detection of a soft transient by ECLAIRs onboard SVOM
  84. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  85. EP240930a: EP-FXT follow-up observation update
  86. EP240930a: GOTO optical upper limits
  87. GRB 240929A: SVOM/GRM observation
  88. EP240930a: EP-WXT detection of a fast X-ray transient
  89. IceCube-240929A: Upper limits from a search for additional neutrino events in IceCube
  90. GRB 240929A : Leavitt Observatory optical upper limit
  91. Fermi GRB 240930B: Global MASTER-Net observations report
  92. GRB 240930B: Fermi GBM Final Real-time Localization
  93. IPN triangulation of GRB 240926A
  94. GRB 240825A: LBT optical observations
  95. GRB 240928A: SVOM/GRM observation
  96. Fermi GRB 240930A: Global MASTER-Net observations report
  97. Fermi Gamma-ray Burst Monitor trigger 749362078/240930172 (GRB 240930A) is not a GRB
  98. GRB 240930A: Fermi GBM Final Real-time Localization
  99. Fermi Gamma-ray Burst Monitor trigger 749339671/240929913 is not a GRB
  100. GRB 240929A long GRB detected by INTEGRAL

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