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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"

22081 results found.

  1. GRB 241018A: SVOM/VT follow-up and optical candidate
  2. GRB 241018A: Swift ToO observations
  3. GRB 241018A: X-ray afterglow candidate observed by MXT
  4. GRB 241016B: Fermi GBM Observations
  5. GRB 241017A: Swift-XRT observations
  6. GRB241017a: Liverpool Telescope observations of XRT uncatalogued sources
  7. GRB241017A: TOO Observations by SVOM/MXT
  8. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  9. GRB 241017A: J-band upper limit from WINTER
  10. Fermi trigger No 750788395: Global MASTER-Net observations report
  11. GRB 241017A: Swift ToO observations
  12. Fermi GRB 241016B: Global MASTER-Net observations report
  13. Fermi GRB 241016A: Global MASTER-Net observations report
  14. IceCube Alert 241016.04: Global MASTER-Net observations report
  15. GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
  16. GRB 240916A: radio detection with the VLA
  17. GRB241013A: REM observations
  18. Fermi GRB 241013B: Global MASTER-Net observations report
  19. Integral GRB241013.04: Global MASTER-Net observations report
  20. LIGO/Virgo/KAGRA S241011k: NED Galaxies in the Localization Volume
  21. GRB 241009A: GRANDMA optical upper limits
  22. GRB 241009A: Swift-XRT afterglow detection
  23. GRB 241010A: JinShan optical observations and potential host galaxy
  24. GRB 241006A: ATCA Radio Upper Limits
  25. Fermi trigger No 750211959: Global MASTER-Net observations report
  26. Swift GRB 241010A: Global MASTER-Net observations report
  27. Fermi trigger No 750291012: Global MASTER-Net observations report
  28. GRB 241010A: J-band observations with WINTER
  29. Fermi GRB 241010B: Global MASTER-Net observations report
  30. GRB 241010A: LCO optical observations
  31. Fermi-LAT Gamma-ray Observations of IceCube-241006A
  32. GRB 241009A: Swift ToO observations
  33. LIGO/Virgo/KAGRA S241009em: Identification of a GW compact binary merger candidate
  34. GRB 241002B: Swift-XRT afterglow detection
  35. GRB 241002A: NOT optical upper limits
  36. Fermi GRB 241008A: Global MASTER-Net observations report
  37. IceCube-241006A: No candidates from the Zwicky Transient Facility
  38. GRB 241006A: GRANDMA optical upper limits
  39. EP240930a / GRB 240930B: CrAO ZTSH optical upper limit
  40. GRB 241002B: PRIME near-infrared detection in 3rd epoch
  41. Fermi-LAT Gamma-ray Observations of NuEm-240926A
  42. GRB 240910A: LBT optical observations
  43. EP trigger ID 01709065118: KAIT confirmation of the stellar flare
  44. GRB 240821A: Host galaxy redshift from VLT/X-shooter
  45. GRB 241006A: PRIME near-infrared upper limits
  46. GRB 241006A: Swift/UVOT Upper Limits
  47. GRB 241006A: SVOM/VT follow-up and optical upper limit
  48. IceCube Alert 241006.94: Global MASTER-Net observations report
  49. GRB 241001A: Swift-XRT afterglow detection
  50. Swift GRB241006.91: Global MASTER-Net observations report
  51. Fermi trigger No 749721670: Global MASTER-Net observations report
  52. GRB 241002B: PRIME near-infrared detection in 2nd epoch
  53. GRB 241002B: Fermi GBM Observation
  54. Fermi trigger No 749735279: Global MASTER-Net observations report
  55. Fermi trigger No 749630753: Global MASTER-Net observations report
  56. Fermi trigger No 749693019: Global MASTER-Net observations report
  57. GRB 241002B: Swift-XRT observations
  58. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  59. GRB 241002B: Swift ToO observations
  60. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  61. Konus-Wind detection of GRB 240926A
  62. GRB 241002B: PRIME near-infrared detection
  63. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  64. GRB 241002C: Swift ToO observations
  65. GRB 241001A : SVOM/VT optical detection
  66. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  67. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  68. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  69. GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
  70. GRB241001A: REM optical/NIR upper limits
  71. GRB 241002A: Swift/UVOT Upper Limits
  72. EP240930a: Liverpool Telescope observations
  73. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  74. GRB 241001A: Swift/UVOT Detection
  75. GRB 241001A: VLT/X-shooter redshift
  76. GRB 241002B: GOTO optical counterpart candidate
  77. EP trigger ID 01709064214: GOTO confirms detection as a flare star
  78. GRB 240929A: Liverpool Telescope prompt followup observations
  79. Fermi GRB 241002B: Global MASTER-Net observations report
  80. GRB 241001A: Swift-XRT observations
  81. GRB241001A: optical afterglow candidate
  82. GRB 241002A: 1.5m OSN optical upper limit
  83. GRB 241001A: Swift ToO observations
  84. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  85. Fermi-LAT Gamma-ray Observations of IceCube-240929A
  86. EP240930a: GOTO optical upper limits
  87. EP EP240930a: Global MASTER-Net observations report
  88. EP240930a: EP-WXT detection of a fast X-ray transient
  89. AMON NuEM 240926A: Swift XRT Follow-up
  90. GRB 240929A : Leavitt Observatory optical upper limit
  91. Fermi GRB 240930B: Global MASTER-Net observations report
  92. GRB 240825A: LBT optical observations
  93. Fermi GRB 240930A: Global MASTER-Net observations report
  94. Fermi trigger No 749339671: Global MASTER-Net observations report
  95. Fermi GRB 240929A: Global MASTER-Net observations report
  96. Integral GRB240929.83: Global MASTER-Net observations report
  97. Konus-Wind detection of GRB 240912A
  98. Swift Trigger 1256950 is probably not a GRB
  99. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  100. LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO

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