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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"

45423 results found.

  1. Fermi GRB 241024B: Global MASTER-Net observations report
  2. GRB 241025A: Fermi GBM Final Real-time Localization
  3. GRB 241025A: Swift detection of a burst with an optical counterpart
  4. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  5. GRB 241001A: ATCA radio observations
  6. GRB 241024B: Fermi GBM Final Localization
  7. EP241021a: No Detection in Fermi-GBM Observation
  8. GRB 241010A: VIRT Optical Upper Limit
  9. GRB 241024A: Fermi GBM Final Localisation
  10. EP241021a: VLT/FORS2 redshift z = 0.75
  11. Fermi trigger No 751449953: Global MASTER-Net observations report
  12. EP241021a: SAO RAS optical observations
  13. EP241021a: KAIT optical observations
  14. EP241021a: EP-FXT follow-up observation update
  15. IPN triangulation of GRB 241021A (long)
  16. EP241021a: Optical counterpart observations with the Liverpool Telescope
  17. EP241021a: 1.3m DFOT Optical observations
  18. EP241021a: GSP detects optical candidate counterpart
  19. EP241021a: Optical upper limits with Kinder observations
  20. EP241021a: TRT optical observations
  21. GRB 241018A: SVOM/C-GFT optical observations
  22. EP241021a: NOT likely optical counterpart
  23. EP EP241021a: Global MASTER-Net observations report
  24. GRB241017A: 1.3m DFOT optical upper limit
  25. GRB 241018A: 1.3m DFOT Optical upper limit
  26. GRB 241018A: EP-FXT afterglow detection
  27. EP241021a: GOTO optical upper limits
  28. EP241021a: EP detection of a fast X-ray transient
  29. IceCube-Cascade 241019A: Upper limits from a search for additional neutrino events in IceCube
  30. Konus-Wind detection of GRB 241018A
  31. GRB 241018A: SVOM/GRM observation
  32. GRB 241018A/sb24101802: Mephisto optical upper limit
  33. GRB 241017A/sb24101702: Mephisto optical upper limit
  34. GRB 241018A: BOOTES-4/MET optical upper limit
  35. GRB 241018A: Mondy optical upper limit
  36. GRB 241018A: SVOM/VT further analysis and counterpart confirmed
  37. GRB 241018A: GROWTH-India telescope optical upper limit
  38. GRB241018A: XingLong Optical Upper Limit
  39. GRB 241018A: Swift-XRT observations
  40. GRB 241018A: REM optical/NIR upper limits
  41. GRB 241018A: NOT optical observations
  42. GRB 241017A: SVOM/VT follow-up and optical upper limit
  43. GRB 241018A: SVOM/VT follow-up and optical candidate
  44. GRB 241018A: LCO/0.4m optical upper limits
  45. GRB 241018A: Swift ToO observations
  46. GRB 241006A: VIRT Optical Upper Limit
  47. GRB 240727A: VIRT Optical Upper Limit
  48. GRB 241018A: X-ray afterglow candidate observed by MXT
  49. GRB 241016B: Fermi GBM Observations
  50. GRB 241018A: Detection of a bright long GRB by SVOM
  51. GRB 241017A: Swift-XRT observations
  52. GRB241017a: Liverpool Telescope observations of XRT uncatalogued sources
  53. GRB 241001A: EP-FXT afterglow detection
  54. GRB 241017A: GROWTH-India Telescope optical upper limit
  55. GRB241017A: TOO Observations by SVOM/MXT
  56. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  57. GRB 241017A: J-band upper limit from WINTER
  58. Fermi trigger No 750788395: Global MASTER-Net observations report
  59. GRB 241016B: SVOM/GRM observation
  60. GRB241016C: Fermi GBM Final Localization
  61. Fermi Gamma-ray Burst Monitor trigger 750792698/241016730 is not a GRB
  62. GRB 241017A: Swift ToO observations
  63. GRB 241017A : Detection of a weak and soft long duration GRB by SVOM/ECLAIRs
  64. Fermi GRB 241016B: Global MASTER-Net observations report
  65. GRB 241016B: Fermi GBM Final Localization
  66. Fermi GRB 241016A: Global MASTER-Net observations report
  67. GRB 241016A: Fermi GBM Final Real-time Localization
  68. IceCube alert 139977_2910365 retraction
  69. IceCube Alert 241016.04: Global MASTER-Net observations report
  70. GRB 241010A: Swift-BAT refined analysis
  71. GRB 241013B: Fermi GBM Observation
  72. GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
  73. GRB 241013A: Fermi GBM Observation
  74. GRB 240916A: radio detection with the VLA
  75. GRB241013A: REM observations
  76. GRB 241009A: LCO optical upper limits
  77. GRB 241013B: SVOM/GRM observation
  78. Fermi GRB 241013B: Global MASTER-Net observations report
  79. Integral GRB241013.04: Global MASTER-Net observations report
  80. GRB 241013B: Fermi GBM Final Real-time Localization
  81. GRB 241013A: a long GRB detected by INTEGRAL
  82. GRB 241013A: Fermi GBM Final Real-time Localization
  83. LIGO/Virgo/KAGRA S241009em: Updated Sky localization
  84. LIGO/Virgo/KAGRA S241011k: Updated Sky localization
  85. LIGO/Virgo/KAGRA S241011k: NED Galaxies in the Localization Volume
  86. LIGO/Virgo/KAGRA S241011k: Identification of a GW compact binary merger candidate
  87. Fermi Gamma-ray Burst Monitor GRB trigger 750372658/241011869 (GRB 241011A) is not a GRB
  88. GRB 241011A: Fermi GBM Final Real-time Localization
  89. GRB 241009A: GRANDMA optical upper limits
  90. GRB 241009A: Swift-XRT afterglow detection
  91. GRB 241010A: JinShan optical observations and potential host galaxy
  92. GRB 241006A: ATCA Radio Upper Limits
  93. GRB 241010A: Swift-XRT refined Analysis
  94. LIGO/Virgo/KAGRA S241007bw: Updated Sky localization
  95. Fermi trigger No 750211959: Global MASTER-Net observations report
  96. Fermi Gamma-ray Burst Monitor trigger 750303285/241011066 is not a GRB
  97. Fermi Gamma-ray Burst Monitor trigger 750291012/241010924 is not a GRB
  98. Swift GRB 241010A: Global MASTER-Net observations report
  99. Fermi trigger No 750291012: Global MASTER-Net observations report
  100. GRB 241010A: J-band observations with WINTER

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