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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"

5055 results found.

  1. GRB 210803A: Fermi GBM observation
  2. GRB 210731A: Swift-XRT refined Analysis
  3. Fermi trigger No 649519043: Global MASTER-Net observations report
  4. GRB 210731A: Swift detection of a burst
  5. Trigger 1062273: Swift detection of 4U 1700-377
  6. Fermi trigger No 649390368: Global MASTER-Net observations report
  7. GRB 210730A: Swift-XRT refined Analysis
  8. GRB 210724A: Early CAHA 2.2m limit
  9. Fermi trigger No 649072251: Global MASTER-Net observations report
  10. Fermi trigger No 648959581: Global MASTER-Net observations report
  11. GRB 210724A: Zeiss-1000 of Koshka observatory, optical upper limit
  12. GRB 210725A: Swift-XRT refined Analysis
  13. GRB 210725A: MITSuME Akeno optical upper limits
  14. GRB 210722A: continued Assy optical observations
  15. GRB 210722A: Nanshan/NEXT further optical observations
  16. Fermi trigger No 648868114: Global MASTER-Net observations report
  17. GRB210724A: MeerLICHT upper limits
  18. Swift GRB210724.84: Global MASTER-Net observations report
  19. GRB 210723A: Swift-XRT refined Analysis
  20. GRB 210722A: D50 optical detection
  21. GRB 210722A: Swift-XRT refined Analysis
  22. Fermi trigger No 648602917: Global MASTER-Net observations report
  23. GRB 210719A: GECAM detection
  24. Fermi trigger No 648278666: Global MASTER-Net observations report
  25. GRB 210704A: Zeiss-1000/SAO-RAS optical observations
  26. Fermi trigger No 648033323: Global MASTER-Net observations report
  27. Fermi trigger No 648024201: Global MASTER-Net observations report
  28. Fermi trigger No 647942198: Global MASTER-Net observations report
  29. GRB 210712A: Swift-XRT refined Analysis
  30. Fermi trigger No 647805873: Global MASTER-Net observations report
  31. Fermi trigger No 647653174: Global MASTER-Net observations report
  32. Fermi trigger No 647624281: Global MASTER-Net observations report
  33. Fermi GRB 210709A: Global MASTER-Net observations report
  34. GRB 210708B: Swift detection of a possible burst
  35. GRB 210708A: Swift-XRT refined Analysis
  36. Fermi trigger No 647365516: Global MASTER-Net observations report
  37. Konus-Wind detection of GRB 210704A
  38. GRB 210704A: BALROG localization (Fermi Trigger 647120009 / GRB 210704815)
  39. GRB 210702A: Swift-XRT refined Analysis
  40. Fermi trigger No 646443989: Global MASTER-Net observations report
  41. Fermi GRB 210627B: Global MASTER-Net observations report
  42. Fermi GRB 210627A: Global MASTER-Net observations report
  43. GRB 210618A: 1.5m OSN optical upper limit
  44. Fermi trigger No 646189108: Global MASTER-Net observations report
  45. Fermi GBM observation of a bright burst in the direction of SGR 1935+2154
  46. Fermi trigger No 646194855: Global MASTER-Net observations report
  47. GRB 210619B: Swift-XRT refined Analysis
  48. Fermi trigger No 645857659: Global MASTER-Net observations report
  49. GRB 210618A: DDOTI upper limit for the optical afterglow
  50. Fermi GRB 210615A: Global MASTER-Net observations report
  51. Swift-BAT Trigger 1055000/GRB210612.54: MASTER optical source observation
  52. Follow-up on HAWC Transient Monitoring Alert J0020+3108
  53. GRB 210610B: iTelescope optical afterglow observations
  54. GRB 210610B: optical observations from Burke-Gaffney Observatory and Abbey Ridge Observatory
  55. Swift-BAT Trigger 1055000: Swift detection of an outburst from 4U 1543-47
  56. GRB 210610B: MITSuME Akeno optical observation
  57. GRB 210610B: CrAO/ZTSH optical observations and light curve
  58. GRB 210610B: Swift-BAT refined analysis
  59. Konus-Wind detection of GRB 210610B
  60. GRB 210610A: Swift-XRT refined Analysis
  61. HAWC Transient Monitoring Alert: Significant Spot after 3 transits
  62. Fermi trigger No 645047470: Global MASTER-Net observations report
  63. GRB 210610B: CrAO/ZTSh optical afterglow photometry
  64. GRB 210610B: CrAO/ZTSh optical observations
  65. Swift GRB210610.83: Global MASTER-Net OT detection
  66. GRB 210610A: MITSuME Akeno optical observation
  67. GRB 210606B: Fermi GBM detection
  68. Fermi GRB 210605A: Global MASTER-Net observations report
  69. Fermi trigger No 644449593: Global MASTER-Net observations report
  70. Fermi trigger No 644359567: Global MASTER-Net observations report
  71. Fermi GRB 210601A: Global MASTER-Net observations report
  72. Fermi GRB 210529B: Global MASTER-Net observations report
  73. GRB 210529A: Fermi GBM Final Real-time Localization
  74. GRB 210528B: MITSuME Akeno optical upper limits
  75. GRB 210528B: MAXI/GSC detection
  76. Fermi GRB 210528A: Global MASTER-Net observations report
  77. GRB 210527A: MITSuME Akeno optical upper limits
  78. GRB 210527A: Swift-XRT refined Analysis
  79. Fermi GRB 210524B: DDOTI Upper Limits on the Afterglow
  80. Fermi trigger No 643548039: Global MASTER-Net observations report
  81. GRB 210524B: Fermi GBM Final Real-time Localization
  82. GRB 210524A: BALROG localization (Fermi Trigger 643525204 / GRB 210524208)
  83. Fermi GRB 210524A: Global MASTER-Net observations report
  84. GRB 210524A: Fermi GBM Final Real-time Localization
  85. GRB 210517A: KCT optical upper limit
  86. Fermi trigger No 643065622: Global MASTER-Net observations report
  87. Konus-Wind detection of GRB 210514A
  88. Fermi trigger No 642991619: Global MASTER-Net observations report
  89. GRB 210517A: Swift-XRT refined Analysis
  90. GRB 210515C: Swift-XRT refined Analysis
  91. Fermi GRB 210515B: Global MASTER-Net observations report
  92. Fermi GRB 210515A: Global MASTER-Net observations report
  93. Fermi trigger No 642538568: Global MASTER-Net observations report
  94. Fermi GRB 210511A: Global MASTER-Net observations report
  95. Fermi GRB 210510A: DDOTI Upper Limits on the Afterglow
  96. Fermi GRB 210510A: Global MASTER-Net observations report
  97. Swift trigger 1047857 is 4U 1700-377
  98. GRB 210509A: Swift-XRT refined Analysis
  99. HAWC-210507A: No neutrino counterpart candidates in ANTARES search
  100. Fermi GRB 210507A: Global MASTER-Net observations report

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