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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"

28054 results found.

  1. ZTF21aayokph (AT2021lfa): LBT optical observations
  2. Fermi GRB 210524B: DDOTI Upper Limits on the Afterglow
  3. Konus-Wind detection of GRB 210524A
  4. IPN triangulation of GRB 210524A
  5. GRB 210524A: BALROG localization (Fermi Trigger 643525204 / GRB 210524208)
  6. GRB 210522A: GECAM detection
  7. GRB 210520A: Swift-XRT observations
  8. MAXI GRB210521.54: Global MASTER-Net observations report
  9. GRB 210521A: MAXI/GSC detection
  10. GRB210413B: further Swift-XRT observations
  11. GRB 210520A: Fermi GBM detection
  12. ZTF21aayokph (AT2021lfa): continued Assy optical observations
  13. GRB 210520A: GECAM detection
  14. GRB 210517A: KCT optical upper limit
  15. GRB 210518.889: DDOTI Upper Limits on the Afterglow
  16. Fermi-LAT Gamma-ray Observations of IceCube-210516A
  17. IceCube Alert 210515.01: Global MASTER-Net observations report
  18. GRB 210517A: Swift-BAT refined analysis
  19. GRB 210517A: Swift-XRT refined Analysis
  20. IceCube-210516A: No significant detection in HAWC
  21. GRB 210517A: Swift/UVOT Upper Limits
  22. GRB 210515C: Swift/UVOT Upper Limits
  23. IceCube-210516A: Upper limits from a search for additional neutrino events in IceCube
  24. GRB 210517A: VLT/X-shooter optical afterglow and redshift
  25. GRB 210517A: Enhanced Swift-XRT position
  26. GRB 210517A: Swift detection of a burst
  27. GRB 210515C: LCO Optical Upper Limit
  28. GRB 210504A: LCO Optical Afterglow Detection
  29. GRB 210514A: Swift/UVOT Upper Limits
  30. AMON IC_HAWC NuEm-210515A / NuEm-210515B : No neutrino counterpart detected with ANTARES
  31. GRB 210515C: Swift-XRT refined Analysis
  32. GRB 210515C: Swift-BAT refined analysis
  33. GRB 210514A: Swift-BAT refined analysis
  34. Fermi GRB 210515A: Global MASTER-Net observations report
  35. GRB 210514A: Swift-XRT refined Analysis
  36. GRB 210514A: Enhanced Swift-XRT position
  37. GRB 210512.786: DDOTI Upper Limits on the Afterglow
  38. IceCube-210510A: Upper limits from a search for additional neutrino events in IceCube
  39. Short GRB 210323A: likely host galaxy detection
  40. GRB 210511B: DDOTI Upper Limits on the Afterglow
  41. IPN triangulation of GRB 210427A
  42. GRB 210511B: Fermi GBM observation
  43. Fermi-LAT Gamma-ray Observations of IceCube-210510A
  44. Fermi GRB 210510A: DDOTI Upper Limits on the Afterglow
  45. GRB 210511B: GECAM detection
  46. GRB 210511B: BALROG localization (Fermi Trigger 642425204 / GRB 210511477)
  47. GRB 201228B: Swift/BAT-GUANO archival detection and arcminute localization
  48. GRB 200716A: Swift/BAT-GUANO archival detection and arcminute localization
  49. IceCube-210510A: DDOTI Upper Limits
  50. GRB 210509A: RATIR Optical and NIR Upper Limits
  51. GRB 210509A: Swift/UVOT Upper Limits
  52. GRB 210509A: Swift-XRT refined Analysis
  53. GRB 210509A: Swift-BAT refined analysis
  54. GRB 210509A: Enhanced Swift-XRT position
  55. GRB 210509A: Swift-XRT observations
  56. GRB 210506A: Swift/BAT-GUANO position retraction
  57. HAWC-210507A: No neutrino counterpart candidates in ANTARES search
  58. Fermi-LAT Gamma-ray Observations of IceCube-210503A and detection of a new gamma-ray source, Fermi J0931.9+3633
  59. GRB 210506A: Swift-XRT observations
  60. ZTF21aayokph (AT2021lfa): MASTER OT detection 3h befor ZTF
  61. Alert from the HAWC Burst Monitor HAWC-210507A
  62. HAWC GRB 210507.443: DDOTI Upper Limit
  63. GRB 210506A: Nanshan/NEXT optical upper limit
  64. GRB 210506A: TNG NIR upper limits
  65. ZTF21aayokph (AT2021lfa): Mondy and Koshka observatory optical observations
  66. ZTF21aayokph (AT2021lfa): X-ray Detection with Swift/XRT
  67. Lowell Discovery Telescope Observations of ZTF21aayokph (AT2021lfa)
  68. ZTF21aayokph (AT2021lfa): Assy optical observations
  69. ZTF21aayokph (AT2021lfa): Nanshan/NEXT optical upper limit
  70. GRB 210506A: Swift/BAT-GUANO detection and possible arcminute localization of a short hard burst
  71. GRB 210504A: Lowell Discovery Telescope optical observations
  72. ZTF21aayokph (AT2021lfa): Redshift from Gemini South
  73. GRB 210504A: Swift-XRT refined Analysis
  74. DDOTI Observations of ZTF21aayokph (AT2021lfa)
  75. GRB 210504A: Swift-BAT refined analysis
  76. GRB 210504A: MITSuME Akeno optical upper limits
  77. Fermi GRB 210503A: DDOTI Upper Limits on the Afterglow
  78. GRB 210504A: Swift/UVOT Detection
  79. GRB 210504A: Swift detection of a burst
  80. Swift GRB210502.74: Global MASTER-Net observations report
  81. Swift Detection of MAXI J1803-298 including an optical counterpart
  82. MAXI GRB210501.83: Global MASTER-Net observations report
  83. GRB 210430A: BOOTES-1 optical limit
  84. GRB 210424B: MITSuME Akeno optical upper limits
  85. GRB 210501A: Fermi GBM Final Real-time Localization
  86. GRB 210430A: Swift-BAT refined analysis
  87. GRB 210323B: Swift-XRT observations
  88. GRB 210427A: GECAM detection
  89. GRB 210427A: BALROG localization (Fermi Trigger / GRB 210427206)
  90. GRB 210420B: Assy optical observations
  91. Fermi trigger No 640975205: Global MASTER-Net observations report
  92. GRB 210425A: GECAM detection
  93. GRB 210424.694: DDOTI Upper Limits on the Afterglow
  94. GRB 210422A: Swift-BAT refined analysis
  95. GRB 210420B: follow-up photometry of optical afterglow at INASAN/Simeiz
  96. GRB 210420B: Zeiss-1000 of Koshka optical observations
  97. GRB 210421A: Swift-BAT refined analysis
  98. GRB 210421B: Swift-XRT observations
  99. GRB 210420B: continued Tautenburg observations
  100. GRB 210421A: GECAM detection

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