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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"

26340 results found.

  1. GRB 210518.889: DDOTI Upper Limits on the Afterglow
  2. Fermi-LAT Gamma-ray Observations of IceCube-210516A
  3. IceCube Alert 210515.01: Global MASTER-Net observations report
  4. GRB 210517A: Swift-BAT refined analysis
  5. GRB 210517A: Swift-XRT refined Analysis
  6. IceCube-210516A: No significant detection in HAWC
  7. GRB 210517A: Swift/UVOT Upper Limits
  8. GRB 210515C: Swift/UVOT Upper Limits
  9. IceCube-210516A: Upper limits from a search for additional neutrino events in IceCube
  10. GRB 210517A: VLT/X-shooter optical afterglow and redshift
  11. GRB 210517A: Enhanced Swift-XRT position
  12. GRB 210517A: Swift detection of a burst
  13. GRB 210515C: LCO Optical Upper Limit
  14. GRB 210504A: LCO Optical Afterglow Detection
  15. GRB 210514A: Swift/UVOT Upper Limits
  16. AMON IC_HAWC NuEm-210515A / NuEm-210515B : No neutrino counterpart detected with ANTARES
  17. GRB 210515C: Swift-XRT refined Analysis
  18. GRB 210515C: Swift-BAT refined analysis
  19. GRB 210514A: Swift-BAT refined analysis
  20. Fermi GRB 210515A: Global MASTER-Net observations report
  21. GRB 210514A: Swift-XRT refined Analysis
  22. GRB 210514A: Enhanced Swift-XRT position
  23. GRB 210512.786: DDOTI Upper Limits on the Afterglow
  24. IceCube-210510A: Upper limits from a search for additional neutrino events in IceCube
  25. Short GRB 210323A: likely host galaxy detection
  26. GRB 210511B: DDOTI Upper Limits on the Afterglow
  27. IPN triangulation of GRB 210427A
  28. GRB 210511B: Fermi GBM observation
  29. Fermi-LAT Gamma-ray Observations of IceCube-210510A
  30. Fermi GRB 210510A: DDOTI Upper Limits on the Afterglow
  31. GRB 210511B: GECAM detection
  32. GRB 210511B: BALROG localization (Fermi Trigger 642425204 / GRB 210511477)
  33. GRB 201228B: Swift/BAT-GUANO archival detection and arcminute localization
  34. GRB 200716A: Swift/BAT-GUANO archival detection and arcminute localization
  35. IceCube-210510A: DDOTI Upper Limits
  36. GRB 210509A: RATIR Optical and NIR Upper Limits
  37. GRB 210509A: Swift/UVOT Upper Limits
  38. GRB 210509A: Swift-XRT refined Analysis
  39. GRB 210509A: Swift-BAT refined analysis
  40. GRB 210509A: Enhanced Swift-XRT position
  41. GRB 210509A: Swift-XRT observations
  42. GRB 210506A: Swift/BAT-GUANO position retraction
  43. HAWC-210507A: No neutrino counterpart candidates in ANTARES search
  44. Fermi-LAT Gamma-ray Observations of IceCube-210503A and detection of a new gamma-ray source, Fermi J0931.9+3633
  45. GRB 210506A: Swift-XRT observations
  46. ZTF21aayokph (AT2021lfa): MASTER OT detection 3h befor ZTF
  47. Alert from the HAWC Burst Monitor HAWC-210507A
  48. HAWC GRB 210507.443: DDOTI Upper Limit
  49. GRB 210506A: Nanshan/NEXT optical upper limit
  50. GRB 210506A: TNG NIR upper limits
  51. ZTF21aayokph (AT2021lfa): Mondy and Koshka observatory optical observations
  52. ZTF21aayokph (AT2021lfa): X-ray Detection with Swift/XRT
  53. Lowell Discovery Telescope Observations of ZTF21aayokph (AT2021lfa)
  54. ZTF21aayokph (AT2021lfa): Assy optical observations
  55. ZTF21aayokph (AT2021lfa): Nanshan/NEXT optical upper limit
  56. GRB 210506A: Swift/BAT-GUANO detection and possible arcminute localization of a short hard burst
  57. GRB 210504A: Lowell Discovery Telescope optical observations
  58. ZTF21aayokph (AT2021lfa): Redshift from Gemini South
  59. GRB 210504A: Swift-XRT refined Analysis
  60. DDOTI Observations of ZTF21aayokph (AT2021lfa)
  61. GRB 210504A: Swift-BAT refined analysis
  62. GRB 210504A: MITSuME Akeno optical upper limits
  63. Fermi GRB 210503A: DDOTI Upper Limits on the Afterglow
  64. GRB 210504A: Swift/UVOT Detection
  65. GRB 210504A: Swift detection of a burst
  66. Swift GRB210502.74: Global MASTER-Net observations report
  67. Swift Detection of MAXI J1803-298 including an optical counterpart
  68. MAXI GRB210501.83: Global MASTER-Net observations report
  69. GRB 210430A: BOOTES-1 optical limit
  70. GRB 210424B: MITSuME Akeno optical upper limits
  71. GRB 210501A: Fermi GBM Final Real-time Localization
  72. GRB 210430A: Swift-BAT refined analysis
  73. GRB 210323B: Swift-XRT observations
  74. GRB 210427A: GECAM detection
  75. GRB 210427A: BALROG localization (Fermi Trigger / GRB 210427206)
  76. GRB 210420B: Assy optical observations
  77. Fermi trigger No 640975205: Global MASTER-Net observations report
  78. GRB 210425A: GECAM detection
  79. GRB 210424.694: DDOTI Upper Limits on the Afterglow
  80. GRB 210422A: Swift-BAT refined analysis
  81. GRB 210420B: follow-up photometry of optical afterglow at INASAN/Simeiz
  82. GRB 210420B: Zeiss-1000 of Koshka optical observations
  83. GRB 210421A: Swift-BAT refined analysis
  84. GRB 210421B: Swift-XRT observations
  85. GRB 210420B: continued Tautenburg observations
  86. GRB 210421A: GECAM detection
  87. GRB 210421A: Swift/UVOT Upper Limits
  88. GRB 210420B: follow-up photometry of the optical afterglow at Konkoly
  89. GRB 210421A: MITSuME Akeno optical upper limits
  90. GRB 210420B: Swift-BAT refined analysis
  91. GRB 210421B: Swift/BAT-GUANO detection and arcminute localization
  92. GRB 210420B: Swift-XRT refined Analysis
  93. GRB 210421A: Swift-XRT refined Analysis
  94. Fermi GRB 210421C: Global MASTER-Net observations report
  95. GRB 210419C: Swift/UVOT Upper Limits
  96. GRB 210421A: Enhanced Swift-XRT position
  97. GRB 210420B: RATIR Optical and NIR Observations
  98. GRB 210420B: Tautenburg observations
  99. GRB 210420B: Swift/UVOT Detection
  100. GRB 210413B: MITSuME Okayama optical upper limits

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