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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"

4046 results found.

  1. GRB 210610B: optical photometry of afterglow at INASAN/Simeiz
  2. GRB 210610A: CrAO/ZTSH optical observations
  3. GRB 210610B: Zwicky Transient Facility afterglow detection
  4. HAWC Transient Monitoring Alert: Significant Spot after 3 transits
  5. GRB210610B: MeerLICHT multi-colour photometry
  6. Fermi trigger No 645047470: Global MASTER-Net observations report
  7. Swift GRB 210610B: Global MASTER-Net observations report
  8. GRB 210610B: Swift detection of a burst with bright optical afterglow
  9. GRB 210610A: MITSuME Akeno optical observation
  10. GECAM Sub-Threshold Detection of new magnetar Swift SGR J1555.2-5402
  11. GRB 210606B: GECAM detection
  12. Fermi GBM Sub-Threshold Detection of new Swift SGR J1555.2-5402
  13. SGR J1555.2-5402: Swift-BAT refined analysis
  14. Fermi trigger No 644449593: Global MASTER-Net observations report
  15. Swift J1555.2-5402: Swift XRT refined analysis of the new SGR
  16. NICER discovery of 3.86 s pulsations from a new magnetar: SGR J1555.2-5402
  17. Swift Detection of probable new Swift SGR J1555.2-5402
  18. GRB 210602B: GECAM detection
  19. GRB 210529A: GECAM detection
  20. Fermi trigger No 644359567: Global MASTER-Net observations report
  21. Fermi GRB 210529A: Global MASTER-Net observations report
  22. Fermi GRB 210529B: Global MASTER-Net observations report
  23. GRB 210529B: Fermi GBM Final Real-time Localization
  24. GRB 210529A: Fermi GBM Final Real-time Localization
  25. GRB 210528B: DDOTI Upper Limits on the Afterglow
  26. GRB 210528B: MITSuME Akeno optical upper limits
  27. MAXI GRB210528.95: Global MASTER-Net observations report
  28. GRB 210528B: MAXI/GSC detection
  29. Fermi trigger No 643548039: Global MASTER-Net observations report
  30. GRB 210522A: GECAM detection
  31. GRB 210521A: MAXI/GSC detection
  32. GRB 210520A: GECAM detection
  33. Fermi GRB 210520A: Global MASTER-Net observations report
  34. Fermi GBM observation of a bright burst from magneta
  35. IPN triangulation of GRB 210518A
  36. Fermi trigger No 643065622: Global MASTER-Net observations report
  37. Fermi trigger No 642991619: Global MASTER-Net observations report
  38. GRB 210517A: Swift detection of a burst
  39. Fermi GRB 210515B: Global MASTER-Net observations report
  40. Fermi GRB 210515A: Global MASTER-Net observations report
  41. Fermi GRB 210511A: Global MASTER-Net observations report
  42. GRB 210511B: GECAM detection
  43. IceCube Alert 210510.20: Global MASTER-Net observations report
  44. Fermi GRB 210507A: Global MASTER-Net observations report
  45. ZTF21aayokph (AT2021lfa): MASTER OT detection 3h befor ZTF
  46. ZTF and LT observations of ZTF21aayokph (AT2021lfa), a fast-fading red transient
  47. Swift Detection of MAXI J1803-298 including an optical counterpart
  48. MAXI GRB210501.83: Global MASTER-Net observations report
  49. Fermi GRB 210501A: Global MASTER-Net observations report
  50. GRB 210424B: MITSuME Akeno optical upper limits
  51. Swift GRB210430.45: Global MASTER-Net observations report
  52. Swift Trigger 1045571 is not a GRB
  53. GRB 210427A: GECAM detection
  54. GRB 210425A: GECAM detection
  55. GRB 210420B: follow-up photometry of optical afterglow at INASAN/Simeiz
  56. GRB 210421A: GECAM detection
  57. Fermi GRB 210421C: Global MASTER-Net observations report
  58. GRB 210420B: Montarrenti Observatory follow-up observations
  59. GRB 210420B: Montarrenti Observatory optical afterglow detection
  60. GRB 210420A: Fermi GBM Final Real-time Localization
  61. GRB 210413A: GECAM detection
  62. Fermi GRB 210411B: Global MASTER-Net observations report
  63. Fermi GRB 210411A: Global MASTER-Net observations report
  64. GRB 210409A: GECAM detection
  65. Fermi GRB 210410A: Global MASTER-Net observations report
  66. GRB 210401A: GECAM detection
  67. GRB 210328A: GECAM detection
  68. GRB 210330A: GECAM detection
  69. Fermi trigger No 638414549: Global MASTER-Net observations report
  70. Fermi GRB 210324B: Global MASTER-Net observations report
  71. Fermi trigger No 637729731: Global MASTER-Net observations report
  72. GRB 210317A: GECAM detection
  73. GRB 210317A: Fermi GBM Final Real-time Localization
  74. Fermi trigger No 637521056: Global MASTER-Net observations report
  75. Fermi GRB 210312A: Global MASTER-Net observations report
  76. Fermi trigger No 637027080: Global MASTER-Net observations report
  77. GRB 210308A: Nanshan/NEXT optical upper limits
  78. GRB 210307B: GECAM detection
  79. GRB 210306A: Tautenburg observations
  80. GRB 210228A: GECAM detection
  81. GRB 210226A: Fermi GBM detection
  82. GRB 210222A: MAXI/GSC detection
  83. GRB 210205A: observations with the 3.6m DOT, a potential dark burst?
  84. Fermi/GBM observation of a burst from SGR 1830-0645
  85. GRB 210212A: Mondy optical observations
  86. GRB 210210A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
  87. Swift Trigger 1033144: Detection of SGR 1830-0645
  88. Swift Trigger 1032350: Detection of SGR 1830-0645
  89. GRB 210204A: observations with the 3.6m Devasthal Optical Telescope and possible jet break
  90. GRB 210207B: GECAM detection
  91. GRB 210211A: Fermi GBM observation
  92. Swift-XRT observations of IceCube-210210A
  93. Fermi trigger No 634659312: Global MASTER-Net observations report
  94. SGR 1935+2154: MAXI/GSC detection
  95. GRB 210207B: optical detection with 3.6m Devasthal Optical Telescope
  96. Fermi GRB 210207A: Global MASTER-Net observations report
  97. GRB 210204A: Optical Observations from HCT
  98. IPN triangulation of GRB 210204A
  99. GRB 210205A: MITSuME Ishigaki optical observation
  100. GRB 210204: Fermi GBM observation

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