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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"

35325 results found.

  1. GRB 241018A: SVOM/VT follow-up and optical candidate
  2. GRB 241018A: LCO/0.4m optical upper limits
  3. GRB 241018A: Swift ToO observations
  4. GRB 241006A: VIRT Optical Upper Limit
  5. GRB 240727A: VIRT Optical Upper Limit
  6. GRB 241018A: X-ray afterglow candidate observed by MXT
  7. GRB 241016B: Fermi GBM Observations
  8. GRB 241018A: Detection of a bright long GRB by SVOM
  9. GRB 241017A: Swift-XRT observations
  10. GRB 241001A: EP-FXT afterglow detection
  11. GRB 241017A: GROWTH-India Telescope optical upper limit
  12. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  13. GRB 241017A: J-band upper limit from WINTER
  14. GRB 241016B: SVOM/GRM observation
  15. GRB241016C: Fermi GBM Final Localization
  16. Fermi Gamma-ray Burst Monitor trigger 750792698/241016730 is not a GRB
  17. GRB 241017A: Swift ToO observations
  18. GRB 241017A : Detection of a weak and soft long duration GRB by SVOM/ECLAIRs
  19. Fermi GRB 241016B: Global MASTER-Net observations report
  20. GRB 241016B: Fermi GBM Final Localization
  21. Fermi GRB 241016A: Global MASTER-Net observations report
  22. GRB 241016A: Fermi GBM Final Real-time Localization
  23. GRB 241010A: Swift-BAT refined analysis
  24. GRB 241013B: Fermi GBM Observation
  25. GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
  26. GRB 241013A: Fermi GBM Observation
  27. GRB 240916A: radio detection with the VLA
  28. GRB241013A: REM observations
  29. GRB 241009A: LCO optical upper limits
  30. GRB 241013B: SVOM/GRM observation
  31. Fermi GRB 241013B: Global MASTER-Net observations report
  32. GRB 241013B: Fermi GBM Final Real-time Localization
  33. GRB 241013A: a long GRB detected by INTEGRAL
  34. GRB 241013A: Fermi GBM Final Real-time Localization
  35. Fermi Gamma-ray Burst Monitor GRB trigger 750372658/241011869 (GRB 241011A) is not a GRB
  36. GRB 241011A: Fermi GBM Final Real-time Localization
  37. GRB 241009A: GRANDMA optical upper limits
  38. GRB 241009A: Swift-XRT afterglow detection
  39. GRB 241010A: JinShan optical observations and potential host galaxy
  40. GRB 241006A: ATCA Radio Upper Limits
  41. GRB 241010A: Swift-XRT refined Analysis
  42. Fermi Gamma-ray Burst Monitor trigger 750303285/241011066 is not a GRB
  43. Fermi Gamma-ray Burst Monitor trigger 750291012/241010924 is not a GRB
  44. Swift GRB 241010A: Global MASTER-Net observations report
  45. GRB 241010A: J-band observations with WINTER
  46. Fermi GRB 241010B: Global MASTER-Net observations report
  47. GRB 241010B: Fermi GBM Final Real-time Localization
  48. IceCube-241006A: Upper limits from a search for additional neutrino events in IceCube
  49. GRB 241010A: Enhanced Swift-XRT position
  50. GRB 241010A: LCO optical observations
  51. GRB 241010A: Swift detection of a burst with an optical counterpart
  52. GRB 241006A: Swift-BAT refined analysis
  53. GRB 241009A: Swift ToO observations
  54. GRB 241009A : Detection of a long duration GRB by SVOM/ECLAIRs
  55. GRB 241008A: Fermi GBM Observation
  56. GRB 241008A: Fermi-LAT detection
  57. GRB 241002B: Swift-XRT afterglow detection
  58. GRB 241002A: NOT optical upper limits
  59. Fermi GRB 241008A: Global MASTER-Net observations report
  60. GRB 241008A: BALROG localization (Fermi Trigger 750117609 / GRB 241008917)
  61. GRB 241008A: Fermi GBM Final Real-time Localization
  62. GRB 241006A: GRANDMA optical upper limits
  63. EP240930a / GRB 240930B: CrAO ZTSH optical upper limit
  64. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  65. GRB 240910A: LBT optical observations
  66. EP trigger ID 01709065118: KAIT confirmation of the stellar flare
  67. GRB 241006A: Swift-XRT refined Analysis
  68. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  69. GRB 241006A: PRIME near-infrared upper limits
  70. GRB 241006A: Swift/UVOT Upper Limits
  71. GRB 241006A: SVOM/VT follow-up and optical upper limit
  72. GRB 241001A: Swift-XRT afterglow detection
  73. GRB 241006A: Enhanced Swift-XRT position
  74. GRB 241006A: Swift detection of a burst
  75. GRB 240930B: SVOM/C-GFT optical upper limit
  76. GRB 241004A: SVOM/GRM observation
  77. GRB 240930B / EP 240930a: SVOM/GRM observation
  78. GRB 241001A : ECLAIRs spectral analysis and XRF classification
  79. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  80. GRB 241002B: Fermi GBM Observation
  81. GRB 241002B: Swift-XRT observations
  82. GRB 241002C: SVOM/C-GFT optical upper limit
  83. GRB 241002A: Swift-BAT refined analysis
  84. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  85. GRB 241002B: Swift ToO observations
  86. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  87. Konus-Wind detection of GRB 240926A
  88. GRB 241002B: PRIME near-infrared detection
  89. GRB 241002C: Swift ToO observations
  90. Fermi-GBM Sub-Threshold Detection of GRB 241002D
  91. IPN triangulation of GRB 240930B / EP 240930a
  92. GRB 241001A : SVOM/VT optical detection
  93. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  94. GRB 241002D: SVOM/GRM observation
  95. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  96. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  97. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  98. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  99. GRB 241002C : MITSuME Akeno optical upper limits
  100. LIGO/Virgo/KAGRA S240925n: Updated Sky localization

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