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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"
  1. Baksan Neutrino Observatory Alert 200601.42: Global MASTER-Net observations report
  2. Fermi-LAT Gamma-ray Observations of IceCube-200530A
  3. GRB 200529A: MITSuME Akeno optical upper limits
  4. Fermi GRB 200601A: Global MASTER-Net observations report
  5. GRB 200601A: Fermi GBM Final Real-time Localization
  6. IceCube-200530A: not observable by Fermi-GBM
  7. Fermi GRB 200531A: Global MASTER-Net observations report
  8. IceCube-200530A: No significant detection in HAWC
  9. IceCube-200530A: Candidate Counterparts from the Zwicky Transient Facility
  10. IceCube-200530A: No ANTARES neutrino counterpart
  11. GRB 200531A: Fermi GBM Final Real-time Localization
  12. IceCube Alert 200530.33: Global MASTER-Net observations report
  13. GRB 200529A: Swift-BAT refined analysis
  14. Konus-Wind observation of GRB 200524A
  15. IceCube-200530A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  16. IceCube-200530A - IceCube observation of a high-energy neutrino candidate event
  17. GRB 200530A: AstroSat CZTI detection
  18. GRB 200529A: Swift-XRT refined Analysis
  19. Fermi GRB 200530A: Global MASTER-Net observations report
  20. GRB 200530A: Fermi GBM Final Real-time Localization
  21. GRB 200528A: CAHA Upper Limit
  22. GRB 200529A: Fermi GBM Detection
  23. GRB 200529A: LCO Optical Afterglow Detection
  24. Fermi GRB 200529B: Global MASTER-Net observations report
  25. Fermi trigger No 612429771: Global MASTER-Net observations report
  26. GRB 200528A: CALET Gamma-Ray Burst Monitor detection
  27. GRB 200529B: Fermi GBM Final Real-time Localization
  28. GRB 200529A: BOOTES-2/TELMA early optical upper limit
  29. GRB 200528A: Swift-XRT refined Analysis
  30. GRB 200524A: SAO RAS optical observations
  31. GRB 200524A: Assy continued optical observations
  32. GRB 200528A: Assy optical upper limit
  33. GRB 200529A: Enhanced Swift-XRT position
  34. GRB 200529A: KAIT Optical Afterglow Confirmation
  35. GRB 200529A: NOT optical afterglow
  36. GRB 200529A: Swift detection of a burst
  37. GRB 200529A: Fermi GBM Final Real-time Localization
  38. Swift GRB200529.04: Global MASTER-Net observations report
  39. GRB 200528A: NOT optical upper limits
  40. GRB 200528A: Fermi GBM Observation
  41. GRB 200528A: Swift/UVOT Upper Limits
  42. GRB 200528A: Swift-BAT refined analysis
  43. GRB 200528A: 1.3m DFOT Optical Upper Limits
  44. GRB 200528A: Nanshan/NEXT optical upper limit
  45. GRB 200528A: Enhanced Swift-XRT position
  46. Swift GRB 200528A: Global MASTER-Net observations report
  47. GRB 200528A: MITSuME Akeno optical upper limits
  48. GRB 200528A: Potential host galaxy in PanSTARRS, SDSS and WISE
  49. GRB 200528A: Swift detection of a burst
  50. GRB 200528A: Fermi GBM Final Real-time Localization
  51. GRB 200524A: Assy optical observations
  52. Baksan Neutrino Observatory Alert 200526.85: Global MASTER-Net observations report
  53. IceCube-200523A: Upper limits from a search for additional neutrino events in IceCube
  54. GRB 200522A: HST F125W new point source detection
  55. GRB 200522A: Hubble Space Telescope Near-IR F160W Observations
  56. GRB200524A: UVOT detection
  57. GRB 200524A: optical upper limits from further MITSuME Akeno observation
  58. Fermi GRB 200525A: Global MASTER-Net observations report
  59. GRB 200522A: Gemini North optical imaging
  60. GRB 200524A: CrAO optical observations
  61. GRB 200524A: Kitab observatory afterglow observations
  62. GRB 200525A: Fermi GBM Final Real-time Localization
  63. GRB 200524A: AstroSat CZTI detection
  64. GRB 200524A: Further Liverpool Telescope observations
  65. Fermi-LAT Gamma-ray Observations of IceCube-190523A
  66. GRB200521A: ASIM observation
  67. GRB 200524A: KAIT Optical Observations
  68. GRB 200524A: MITSuME Akeno optical observation
  69. GRB 171205A: ATCA observations of late-time radio emission
  70. GRB 200524A: Swift-XRT afterglow detection
  71. GRB 200524A: OAJ multicolor afterglow detection
  72. GRB 200524A: Fermi GBM detection
  73. GRB 200524: Swift/UVOT observations missed the ZTF20abbiixp position
  74. GRB 200524A: CAHA multicolor afterglow detection
  75. GRB 200524A: 1.3m DFOT Optical Observation of ZTF20abbiixp
  76. GRB 200524A: Liverpool Telescope observations
  77. GRB 200524A: Correction to the GCN 27800
  78. GRB 200524A: 3.6m DOT observations of the afterglow candidate ZTF20abbiixp
  79. GRB 200524A: CrAO observations of ZTF20abbiixp
  80. Fermi GRB 200524A: Global MASTER-Net observations report
  81. GRB 200524A: GROWTH-India confirmation of optical afterglow
  82. ZTF Discovery of ZTF20abbiixp: The Likely Optical Afterglow to GRB 200524A
  83. GRB 200524A: Swift ToO observations
  84. GRB 200524A: Fermi-LAT detection
  85. Konus-Wind detection of short/hard GRB 200521A
  86. IPN triangulation of GRB 200521A (short)
  87. GRB 200522A: Correction to GCN 27792
  88. GRB 200522A: Swift-BAT refined analysis
  89. GRB 200522A: LCO Optical Afterglow Detection
  90. IceCube-200523A: Upper limits from Fermi-GBM Observations
  91. CGBM-SPI-ACS triangulation of short GRB 200521A
  92. Swift GRB 200522A: Global MASTER-Net observations report
  93. IceCube Alert 200523.10: Global MASTER-Net observations report
  94. IceCube-200523A - IceCube observation of a high-energy neutrino candidate event
  95. GRB 200522A: 6 GHz VLA radio source detection
  96. GRB 200522A: Swift-XRT refined Analysis
  97. GRB 200522A: BOOTES-3/YA optical upper limit
  98. GRB 200522A: Swift/UVOT Upper Limits
  99. Fermi GRB 200522B: Global MASTER-Net observations report
  100. GRB 200522B: Fermi GBM Final Real-time Localization

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