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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"

19595 results found.

  1. GRB 251013C: Swift/UVOT Detection
  2. Konus-Wind detection of GRB 251007A
  3. GRB 251013D: Swift-XRT observations
  4. Swift Trigger 1404295: possible GRB 251015A
  5. GRB 251014B: Swift-XRT observations
  6. GRB 251014B: Swift/UVOT Upper Limits
  7. GRB 251014B: VLT/FORS2 Optical Observation
  8. GRB 251014D: Swift/UVOT Upper Limits
  9. GRB 251014D: BOOTES-6/DPRT optical upper limit
  10. GRB 251014D: Swift-XRT afterglow detection
  11. GRB 251011B: SVOM/VT optical upper limit
  12. GRB 251013C: Swift ToO observations
  13. GRB 251013D: Fermi GBM Observation
  14. GRB 251014A: Swift-BAT refined analysis
  15. GRB 251014D: Swift detection of a burst
  16. GRB 251014A: PRIME near-infrared upper limits
  17. GRB 251014A: Glowbug gamma-ray detection of a likely short burst
  18. GRB 251014A: VLT/FORS2 Optical Observation
  19. GRB 251014B: Swift ToO observations
  20. GRB 251013D: LAST optical upper limit on Swift/BAT-GUANO localization
  21. GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst
  22. GRB 251013C: Fermi GBM Observation
  23. GRB 251013D: Swift ToO observations
  24. GRB 251014A: DDOTI Upper Limit
  25. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  26. GRB 251014A: SAO RAS optical upper limit
  27. GRB 251014A: Fermi GBM Observation
  28. GRB 251011A: Swift/BAT-GUANO arcminute localization of a burst
  29. GRB 251013D: Swift/BAT-GUANO arcminute localization of a burst
  30. Swift GRB 251014A: Global MASTER-Net observations report
  31. GRB 251014A: Swift detection of a possibly-short burst
  32. GRB 251013C: Swift-XRT counterpart detection
  33. GRB 251003A: Mondy optical upper limit
  34. GRB 251011B inspection: MASTER orphan GRB detection
  35. GRB 251011B: Swift/UVOT Upper Limits
  36. GRB 251011B: SVOM/GRM observation
  37. GRB 251011B: Swift-XRT refined Analysis
  38. GRB 251011B: Fermi GBM Observation
  39. GRB 251011B : MASTER optical observations
  40. GRB 251011B: Enhanced Swift-XRT position
  41. GRB 251011B: Swift detection of a burst
  42. GRB 251007B: Swift/UVOT Upper Limits
  43. GRB251007A: Swift/UVOT Detection
  44. GRB 251007A: Swift-BAT refined analysis
  45. GRB 251007A: SVOM/GRM observation
  46. GRB 251007A: Insight-HXMT detection
  47. GRB 251006A: CALET Gamma-Ray Burst Monitor detection
  48. GRB 251006A: Fermi GBM Observation
  49. GRB 251007A: 1.5m OSN and 2.2m CAHA optical follow-up
  50. GRB 251003A: Fermi GBM Observation
  51. GRB 251007B: COLIBRÍ optical upper limit
  52. GRB 251007A: AstroSat CZTI detection
  53. GRB 250917B: iTelescope T-26 upper limit
  54. GRB 251007A: Swift-XRT refined Analysis
  55. GRB 251007A: Enhanced Swift-XRT position
  56. GRB 251007B: Swift-XRT refined Analysis
  57. GRB 251007B: Enhanced Swift-XRT position
  58. GRB 251007A: AKO Optical Upper Limit
  59. GRB 251007A: CALET Gamma-Ray Burst Monitor detection
  60. GRB 251007A: SVOM/C-GFT optical observations
  61. GRB 251005C: PRIME J-band upper limit
  62. Swift GRB 251007B: Global MASTER-Net observations report
  63. GRB 251007A: Glowbug gamma-ray detection
  64. Swift GRB 251007A: Global MASTER-Net observations report
  65. GRB 251007B: SVOM detection of a faint burst
  66. GRB 251007B: Swift detection of a burst
  67. GRB 251007A: Swift detection of a burst with an optical counterpart
  68. GRB 251006A: Swift/BAT-GUANO subthreshold detection of a short burst
  69. GRB 251005C: SVOM/GRM observation of a likely short GRB
  70. GRB 251005C: COLIBRÍ optical observations
  71. GRB 251003A: LAST optical observations
  72. GRB 251005C: SVOM/VT optical candidate
  73. GRB 251005C: AstroSat CZTI detection
  74. GRB 251005C: Swift/UVOT Upper Limits
  75. GRB 251005C: Swift-XRT refined Analysis
  76. GRB 251005C: Fermi GBM Observation
  77. Swift GRB 251005A: Global MASTER-Net observations report
  78. GRB 251005C: Enhanced Swift-XRT position
  79. GRB 251005C: GOTO optical upper limits
  80. GRB 251005C: Swift detection of a burst
  81. GRB 251003A: Swift-BAT refined analysis
  82. GRB 251003A: Swift/UVOT Upper Limits
  83. GRB 251002A: Swift/UVOT detection
  84. GRB 251003A: Swift-XRT refined Analysis
  85. GRB 251003A: COLIBRÍ photometric redshift
  86. GRB 251003A: Enhanced Swift-XRT position
  87. GRB 251003A: GTC/OSIRIS+ spectroscopic redshift z = 4.412
  88. GRB 251003A: Kilonova-Catcher optical afterglow detection
  89. GRB 251002A: Swift-XRT afterglow detection
  90. GRB 251001B: AbAO optical upper limit
  91. GRB 251003A: LCOGT Optical Detection
  92. GRB 251003A: COLIBRÍ optical detection of the fading afterglow
  93. GRB 251003A: 1.5m OSN afterglow candidate
  94. GRB 251003A: Prompt enhanced Swift-XRT position
  95. GRB 251003A: Swift detection of a burst
  96. Swift GRB251003A: Global MASTER-Net observations report
  97. GRB 251001B: Swift-BAT refined analysis
  98. GRB 251001B: Swift/UVOT Detection
  99. GRB 251001B: GTC/OSIRIS+ spectroscopic redshift z = 2.162
  100. GRB 251001B: Swift-XRT refined Analysis

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