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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"

102 results found.

  1. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  2. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  3. LIGO/Virgo/KAGRA S230919bj: Identification of a GW compact binary merger candidate
  4. LIGO/Virgo S230622e: Global MASTER-Net observations report
  5. Swift GRB 230414B: Global MASTER-Net observations report
  6. Swift triggered on SAX J1806.5-221
  7. GRB 160409A found in Swift BAT ground analysis
  8. Trigger 659734: Swift detection of SAX J1750.8-2900 or other source near Galactic center
  9. Swift detection of SAX J1808.4-3658
  10. Swift detection of SAX J1712.6-3739
  11. Swift-BAT trigger 536502 is not astrophysical
  12. Swift Trigger 536502 is likely a noise fluctuation in coincidence with SAX J1818.6-1703
  13. Swift-BAT trigger 535733 is not astrophysical
  14. Trigger 535733: Swift possible detection of SAX J1828.5-1037
  15. GRB 081008: Galaxy associated with z=1.967 absorber
  16. SAX J1818.6-1703: Swift detection (trigger 306379)
  17. UVOT observations of SAXJ1810.8-2609
  18. Swift detection of a outburst from SAX J1810.8-2609
  19. H11603: An X-ray flare from V4641 Sgr, or a possible XRF
  20. BeppoSAX GRB : GRB020409
  21. GRB020322: Candidate Optical Afterglow
  22. Bepposax GRB020322 The second springtime BSAX GRB
  23. GRB 011211 Optical Observations: Likely Afterglow
  24. Detection of the X-ray afterglow of GRB011121 by BeppoSAX
  25. GRB011121: BeppoSAX-WFC refined positions
  26. BEPPOSAX GRB011121
  27. The X-ray Flash 011030 ('GRB 011030')
  28. IPN triangulation of GRB010629
  29. Support extension to the BeppoSAX mission
  30. GRB010222: possible optical counterpart
  31. GRB010222
  32. GRB 010214, Optical Observations
  33. GRB000528, Radio Observations
  34. IPN triangulation of GRB000516
  35. BeppoSAX GRB000424
  36. GRB000419 [IPN Position]
  37. 1SAXJ1715.0-7134 refined position
  38. RE: Budget cuts in BeppoSAX operations: impact on GRB observation
  39. X-ray burst or X-ray rich GRB 000416 observed by BeppoSAX
  40. Budget cuts in BeppoSAX operations: impact on GRB observations
  41. GRB000226 [IPN Position]
  42. GRB 000210: BATSE Observations
  43. GRB000210, Radio Observations
  44. SAX_WFC_GRB_NOTICE
  45. SAX_WFC_GRB_NOTICE
  46. GCN resumes full operations
  47. IPN error box for GRB991216
  48. GRB 991217 (SAX J2303.2+0015) Optical observations
  49. GRB991217/SAX J2303.2+0015, optical observations
  50. SAX J2303.2+0015 Optical observations
  51. GRB 991217 (SAX J2303.2+0015) Optical observations
  52. GRB 991217
  53. SAX J2303.2+0015: an x-ray/GRB?
  54. BeppoSAX NFI Observation of GRB991106
  55. GRB 991105: BATSE Observations
  56. BeppoSAX refined position for GRB991106
  57. GRB991105: SAX-GRBM/-WFC detection
  58. BeppoSAX MAIL n. 99/30: GRB991105 refined position (fwd)
  59. GRB ALERT: GRB991105
  60. GRB 991014 - X-ray afterglow identification by BeppoSAX-NFI
  61. GRB990908, another BeppoSAX-GRBM/WFC burst detection
  62. GRB990806 BeppoSAX follow up
  63. GRB 990712
  64. Infrared and Optical Observations of GRB990705
  65. GRB990704: SAX-NFI results summary
  66. GRB 990704 X-ray Observations
  67. GRB990705: Intriguing Positional Coincidences
  68. X-ray/GRB 1SAX J0835.9+5118, TNG V and R observations
  69. optical observation of the X-ray/GRB transient SAX J0835.9+5118
  70. Optical report on X-ray/GRB transient
  71. BeppoSAX: A new fast X-ray transient
  72. GRB990123, Probability of gravitational lensing
  73. GRB990123 IPN annulus
  74. GRB990123, refined SAX-WFC position
  75. GRB 981226 Optical Observations
  76. GRB981226 BeppoSAX follow up
  77. GRB980425: X-ray revised positions
  78. GRB980519, Optical Observations
  79. GRB980703, Host galaxy multicolor photometry
  80. GRB 980703 (NFI observations)
  81. BeppoSAX NFI observations of GRB 980703
  82. GRB980703
  83. GRB980613, optical observations
  84. GRB 980613 Optical Observations
  85. GRB980613 BeppoSAX-NFI follow up
  86. GRB980613, BeppoSAX WFC positions
  87. GRB980519 IPN POSITION
  88. GRB980515: SAX-WFC updated position
  89. BSAX Observations of GRB980425 field
  90. GRB980425 BATSE observations
  91. SAX J0840.7+2248 Optical Observations
  92. report on BSAX observations of GRB980425
  93. GRB980329 IPN annulus
  94. GRB980329 near-IR observations
  95. GRB980329 near-IR observations
  96. GRB980329 near IR observations
  97. GRB980329 optical observations
  98. Optical Observations for GRB 971227
  99. GRB 971227: Optical observations
  100. GRB971214: Optical Observations and Calibrations

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