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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

5859 results found.

  1. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEM-210515A and 210515B
  2. GRB 210512.786: DDOTI Upper Limits on the Afterglow
  3. IceCube-210510A: Upper limits from a search for additional neutrino events in IceCube
  4. IceCube-210510A: No candidate counterparts from the Zwicky Transient Facility
  5. Fermi GRB 210511A: Global MASTER-Net observations report
  6. Fermi GRB 210510A: Global MASTER-Net observations report
  7. Swift trigger 1047857 is 4U 1700-377
  8. Swift GRB 210509A: Global MASTER-Net observations report
  9. Fermi GRB 210503A: Global MASTER-Net observations report
  10. GRB 210503A: Fermi GBM Final Real-time Localization
  11. Fermi GRB 210501A: Global MASTER-Net observations report
  12. Fermi trigger No 641601187: Global MASTER-Net observations report
  13. IPN triangulation of GRB 210424B (short/hard)
  14. GRB 210421A: MITSuME Akeno optical upper limits
  15. GRB 210421B: Fermi GBM Final Localization
  16. Fermi trigger No 640695289: Global MASTER-Net observations report
  17. GRB 210420A: Fermi GBM Final Real-time Localization
  18. GRB 210419A: Swift detection of a burst
  19. Fermi GRB 210411B: Global MASTER-Net observations report
  20. Fermi GRB 210401A: Global MASTER-Net observations report
  21. GRB 210323A: MASTER optical observation
  22. Fermi GRB 210324B: Global MASTER-Net observations report
  23. GRB 210321A: Swift detection of a burst
  24. GRB 210317A: Fermi GBM Final Real-time Localization
  25. Fermi trigger No 637521056: Global MASTER-Net observations report
  26. Fermi GRB 210312A: Global MASTER-Net observations report
  27. GRB 210306B: Fermi GBM detection
  28. Fermi trigger No 636926765: Global MASTER-Net observations report
  29. GRB 210307A: LCO Optical Upper Limits
  30. GRB 210306B: Swift-BAT refined analysis
  31. GRB 210306A: MITSuME Akeno optical observation
  32. GRB 210306A: iTelescope T24 optical observations
  33. GRB 210306B: Swift detection of a burst
  34. Trigger 1035744: Swift detection of Sco X-1 due to Star Tracker loss of lock
  35. Fermi trigger No 636187116: Global MASTER-Net observations report
  36. Fermi trigger No 636168178: Global MASTER-Net observations report
  37. Integral GRB210227.20: Global MASTER-Net observations report
  38. GRB 210218A: Swift-XRT observations
  39. GRB 210217A: 1.3m DFOT optical detection
  40. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued Assy and Mondy optical observations
  41. IceCube-210210A: Two Additional Optical Candidate Counterparts Found by DECam
  42. GRB 210212A: 1.3m DFOT Optical upper limit
  43. IceCube-210210A: Four Candidate Optical Counterparts from DECam Observations
  44. GRB 210204A (ZTF21aagwbjr/AT2021buv): continued CrAO and AbAO optical observations
  45. IceCube-210210A: Upper limits from a search for additional neutrino events in IceCube
  46. GRB 210209A: MITSuME Akeno optical upper limits
  47. ZTF21aahifke/AT2021clk: ZTF discovery of an optical fast transient (possible afterglow)
  48. GRB 210209A: Swift detection of a burst
  49. ZTF21aagwbjr/AT2021buv: ZTF discovery of a fast optical transient likely associated with GRB 210104A
  50. GRB 210205A: Nanshan/NEXT optical upper limit
  51. Fermi trigger No 633879387: Global MASTER-Net observations report
  52. GRB 140320B: Swift-XRT refined Analysis
  53. GRB 140104B: Swift-XRT refined Analysis
  54. GECAM detection of a burst possibly from the X-ray burster 4U 0614+09 or GRB 210124A
  55. Swift detection of a new SGR Swift J1851.2-6148 or a short GRB 210119A
  56. GRB 210119A: Fermi GBM Final Real-time Localization
  57. NuEm-210111A: MAXI/GSC upper limit
  58. GRB 210104A: Mondy optical observations, light curve
  59. GRB 210104A: Assy continued optical observations, correction to GCN circ. 29265
  60. GRB 210109A: MAXI/GSC detection
  61. GRB 210104A: SARA-KP 0.9m Optical Afterglow Detection
  62. GRB 210104A: Swift detection of a burst with a bright optical counterpart
  63. Fermi GRB 210102C: Global MASTER-Net observations report
  64. Fermi trigger No 631104264: Global MASTER-Net observations report
  65. GRB 201104B: Maidanak and CrAO optical observations
  66. IPN triangulation of GRB 201227A (short)
  67. GRB 201223A: AROMA-N Optical Observation
  68. Fermi trigger No 630681391: Global MASTER-Net observations report
  69. GRB 201221A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
  70. Fermi GRB 201222B: Global MASTER-Net observations report
  71. GRB 201221D: Swift-BAT refined analysis
  72. GRB 201221D: Lowell Discovery Telescope afterglow observations
  73. Fermi GRB 201221E: Global MASTER-Net observations report
  74. Fermi GBM Sub-Threshold Detection of GRB 201221A
  75. GRB 201221A: Swift detection of a burst
  76. GRB 201209A: Mondy optical observations, afterglow confirmation
  77. IPN triangulation of GRB 201218A
  78. GRB 201218B: Fermi GBM Final Real-time Localization
  79. IceCube-201209A : MAXI/GSC upper limit
  80. GRB 201214B: Swift-XRT observations
  81. Fermi GRB 201215A: Global MASTER-Net observations report
  82. IceCube-201209A: Upper limits from Insight-HXMT/HE observations
  83. IceCube-201209: No significant detection in HAWC
  84. Long-lasting X-ray emission from GW170817 detected by Chandra
  85. GRB 200826A: GMOS-N detected source magnitude (Correction)
  86. IceCube-201209A: Upper limits from a search for additional neutrino events in IceCube
  87. Fermi-LAT Gamma-ray Observations of IceCube-201209A
  88. IceCube-201209A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  89. GRB 201208A: LCO observations
  90. GRB 201209A: Xinglong-2.16m likely optical afterglow detection
  91. IceCube-201209A: IceCube observation of a high-energy neutrino candidate event
  92. GRB 201209A: AstroSat CZTI detection
  93. IceCube-201130A: Optical and NIR Imaging Follow-up by Kanata Telescope
  94. GRB 201209A: KAIT Optical Upper Limit
  95. Swift GRB201209.24: Global MASTER-Net observations report
  96. Fermi GRB 201208A: Global MASTER-Net observations report
  97. Fermi GRB 201201A: Global MASTER-Net observations report
  98. IceCube Alert 201130.85: Global MASTER-Net observations report
  99. GRB 201130A: DDOTI Observations
  100. IceCube-201120A in the Cygnus region: No enhanced TeV gamma-ray flux detected by HAWC

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