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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"

28057 results found.

  1. GRB 210527A: Enhanced Swift-XRT position
  2. GRB 210527A: Swift-XRT observations
  3. GRB 210306A: LBT observations of the likely host galaxy
  4. ZTF21aayokph (AT2021lfa): LBT optical observations
  5. Fermi GRB 210524B: DDOTI Upper Limits on the Afterglow
  6. Konus-Wind detection of GRB 210524A
  7. IPN triangulation of GRB 210524A
  8. GRB 210524A: BALROG localization (Fermi Trigger 643525204 / GRB 210524208)
  9. GRB 210522A: GECAM detection
  10. GRB 210520A: Swift-XRT observations
  11. MAXI GRB210521.54: Global MASTER-Net observations report
  12. GRB 210521A: MAXI/GSC detection
  13. GRB210413B: further Swift-XRT observations
  14. GRB 210520A: Fermi GBM detection
  15. ZTF21aayokph (AT2021lfa): continued Assy optical observations
  16. GRB 210520A: GECAM detection
  17. GRB 210517A: KCT optical upper limit
  18. GRB 210518.889: DDOTI Upper Limits on the Afterglow
  19. Fermi-LAT Gamma-ray Observations of IceCube-210516A
  20. IceCube Alert 210515.01: Global MASTER-Net observations report
  21. GRB 210517A: Swift-BAT refined analysis
  22. GRB 210517A: Swift-XRT refined Analysis
  23. IceCube-210516A: No significant detection in HAWC
  24. GRB 210517A: Swift/UVOT Upper Limits
  25. GRB 210515C: Swift/UVOT Upper Limits
  26. IceCube-210516A: Upper limits from a search for additional neutrino events in IceCube
  27. GRB 210517A: VLT/X-shooter optical afterglow and redshift
  28. GRB 210517A: Enhanced Swift-XRT position
  29. GRB 210517A: Swift detection of a burst
  30. GRB 210515C: LCO Optical Upper Limit
  31. GRB 210504A: LCO Optical Afterglow Detection
  32. GRB 210514A: Swift/UVOT Upper Limits
  33. AMON IC_HAWC NuEm-210515A / NuEm-210515B : No neutrino counterpart detected with ANTARES
  34. GRB 210515C: Swift-XRT refined Analysis
  35. GRB 210515C: Swift-BAT refined analysis
  36. GRB 210514A: Swift-BAT refined analysis
  37. Fermi GRB 210515A: Global MASTER-Net observations report
  38. GRB 210514A: Swift-XRT refined Analysis
  39. GRB 210514A: Enhanced Swift-XRT position
  40. GRB 210512.786: DDOTI Upper Limits on the Afterglow
  41. IceCube-210510A: Upper limits from a search for additional neutrino events in IceCube
  42. Short GRB 210323A: likely host galaxy detection
  43. GRB 210511B: DDOTI Upper Limits on the Afterglow
  44. IPN triangulation of GRB 210427A
  45. GRB 210511B: Fermi GBM observation
  46. Fermi-LAT Gamma-ray Observations of IceCube-210510A
  47. Fermi GRB 210510A: DDOTI Upper Limits on the Afterglow
  48. GRB 210511B: GECAM detection
  49. GRB 210511B: BALROG localization (Fermi Trigger 642425204 / GRB 210511477)
  50. GRB 201228B: Swift/BAT-GUANO archival detection and arcminute localization
  51. GRB 200716A: Swift/BAT-GUANO archival detection and arcminute localization
  52. IceCube-210510A: DDOTI Upper Limits
  53. GRB 210509A: RATIR Optical and NIR Upper Limits
  54. GRB 210509A: Swift/UVOT Upper Limits
  55. GRB 210509A: Swift-XRT refined Analysis
  56. GRB 210509A: Swift-BAT refined analysis
  57. GRB 210509A: Enhanced Swift-XRT position
  58. GRB 210509A: Swift-XRT observations
  59. GRB 210506A: Swift/BAT-GUANO position retraction
  60. HAWC-210507A: No neutrino counterpart candidates in ANTARES search
  61. Fermi-LAT Gamma-ray Observations of IceCube-210503A and detection of a new gamma-ray source, Fermi J0931.9+3633
  62. GRB 210506A: Swift-XRT observations
  63. ZTF21aayokph (AT2021lfa): MASTER OT detection 3h befor ZTF
  64. Alert from the HAWC Burst Monitor HAWC-210507A
  65. HAWC GRB 210507.443: DDOTI Upper Limit
  66. GRB 210506A: Nanshan/NEXT optical upper limit
  67. GRB 210506A: TNG NIR upper limits
  68. ZTF21aayokph (AT2021lfa): Mondy and Koshka observatory optical observations
  69. ZTF21aayokph (AT2021lfa): X-ray Detection with Swift/XRT
  70. Lowell Discovery Telescope Observations of ZTF21aayokph (AT2021lfa)
  71. ZTF21aayokph (AT2021lfa): Assy optical observations
  72. ZTF21aayokph (AT2021lfa): Nanshan/NEXT optical upper limit
  73. GRB 210506A: Swift/BAT-GUANO detection and possible arcminute localization of a short hard burst
  74. GRB 210504A: Lowell Discovery Telescope optical observations
  75. ZTF21aayokph (AT2021lfa): Redshift from Gemini South
  76. GRB 210504A: Swift-XRT refined Analysis
  77. DDOTI Observations of ZTF21aayokph (AT2021lfa)
  78. GRB 210504A: Swift-BAT refined analysis
  79. GRB 210504A: MITSuME Akeno optical upper limits
  80. Fermi GRB 210503A: DDOTI Upper Limits on the Afterglow
  81. GRB 210504A: Swift/UVOT Detection
  82. GRB 210504A: Swift detection of a burst
  83. Swift GRB210502.74: Global MASTER-Net observations report
  84. Swift Detection of MAXI J1803-298 including an optical counterpart
  85. MAXI GRB210501.83: Global MASTER-Net observations report
  86. GRB 210430A: BOOTES-1 optical limit
  87. GRB 210424B: MITSuME Akeno optical upper limits
  88. GRB 210501A: Fermi GBM Final Real-time Localization
  89. GRB 210430A: Swift-BAT refined analysis
  90. GRB 210323B: Swift-XRT observations
  91. GRB 210427A: GECAM detection
  92. GRB 210427A: BALROG localization (Fermi Trigger / GRB 210427206)
  93. GRB 210420B: Assy optical observations
  94. Fermi trigger No 640975205: Global MASTER-Net observations report
  95. GRB 210425A: GECAM detection
  96. GRB 210424.694: DDOTI Upper Limits on the Afterglow
  97. GRB 210422A: Swift-BAT refined analysis
  98. GRB 210420B: follow-up photometry of optical afterglow at INASAN/Simeiz
  99. GRB 210420B: Zeiss-1000 of Koshka optical observations
  100. GRB 210421A: Swift-BAT refined analysis

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