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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"

101 results found.

  1. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  2. LIGO/Virgo/KAGRA S230919bj: Identification of a GW compact binary merger candidate
  3. LIGO/Virgo S230622e: Global MASTER-Net observations report
  4. Swift GRB 230414B: Global MASTER-Net observations report
  5. Swift triggered on SAX J1806.5-221
  6. GRB 160409A found in Swift BAT ground analysis
  7. Trigger 659734: Swift detection of SAX J1750.8-2900 or other source near Galactic center
  8. Swift detection of SAX J1808.4-3658
  9. Swift detection of SAX J1712.6-3739
  10. Swift-BAT trigger 536502 is not astrophysical
  11. Swift Trigger 536502 is likely a noise fluctuation in coincidence with SAX J1818.6-1703
  12. Swift-BAT trigger 535733 is not astrophysical
  13. Trigger 535733: Swift possible detection of SAX J1828.5-1037
  14. GRB 081008: Galaxy associated with z=1.967 absorber
  15. SAX J1818.6-1703: Swift detection (trigger 306379)
  16. UVOT observations of SAXJ1810.8-2609
  17. Swift detection of a outburst from SAX J1810.8-2609
  18. H11603: An X-ray flare from V4641 Sgr, or a possible XRF
  19. BeppoSAX GRB : GRB020409
  20. GRB020322: Candidate Optical Afterglow
  21. Bepposax GRB020322 The second springtime BSAX GRB
  22. GRB 011211 Optical Observations: Likely Afterglow
  23. Detection of the X-ray afterglow of GRB011121 by BeppoSAX
  24. GRB011121: BeppoSAX-WFC refined positions
  25. BEPPOSAX GRB011121
  26. The X-ray Flash 011030 ('GRB 011030')
  27. IPN triangulation of GRB010629
  28. Support extension to the BeppoSAX mission
  29. GRB010222: possible optical counterpart
  30. GRB010222
  31. GRB 010214, Optical Observations
  32. GRB000528, Radio Observations
  33. IPN triangulation of GRB000516
  34. BeppoSAX GRB000424
  35. GRB000419 [IPN Position]
  36. 1SAXJ1715.0-7134 refined position
  37. RE: Budget cuts in BeppoSAX operations: impact on GRB observation
  38. X-ray burst or X-ray rich GRB 000416 observed by BeppoSAX
  39. Budget cuts in BeppoSAX operations: impact on GRB observations
  40. GRB000226 [IPN Position]
  41. GRB 000210: BATSE Observations
  42. GRB000210, Radio Observations
  43. SAX_WFC_GRB_NOTICE
  44. SAX_WFC_GRB_NOTICE
  45. GCN resumes full operations
  46. IPN error box for GRB991216
  47. GRB 991217 (SAX J2303.2+0015) Optical observations
  48. GRB991217/SAX J2303.2+0015, optical observations
  49. SAX J2303.2+0015 Optical observations
  50. GRB 991217 (SAX J2303.2+0015) Optical observations
  51. GRB 991217
  52. SAX J2303.2+0015: an x-ray/GRB?
  53. BeppoSAX NFI Observation of GRB991106
  54. GRB 991105: BATSE Observations
  55. BeppoSAX refined position for GRB991106
  56. GRB991105: SAX-GRBM/-WFC detection
  57. BeppoSAX MAIL n. 99/30: GRB991105 refined position (fwd)
  58. GRB ALERT: GRB991105
  59. GRB 991014 - X-ray afterglow identification by BeppoSAX-NFI
  60. GRB990908, another BeppoSAX-GRBM/WFC burst detection
  61. GRB990806 BeppoSAX follow up
  62. GRB 990712
  63. Infrared and Optical Observations of GRB990705
  64. GRB990704: SAX-NFI results summary
  65. GRB 990704 X-ray Observations
  66. GRB990705: Intriguing Positional Coincidences
  67. X-ray/GRB 1SAX J0835.9+5118, TNG V and R observations
  68. optical observation of the X-ray/GRB transient SAX J0835.9+5118
  69. Optical report on X-ray/GRB transient
  70. BeppoSAX: A new fast X-ray transient
  71. GRB990123, Probability of gravitational lensing
  72. GRB990123 IPN annulus
  73. GRB990123, refined SAX-WFC position
  74. GRB 981226 Optical Observations
  75. GRB981226 BeppoSAX follow up
  76. GRB980425: X-ray revised positions
  77. GRB980519, Optical Observations
  78. GRB980703, Host galaxy multicolor photometry
  79. GRB 980703 (NFI observations)
  80. BeppoSAX NFI observations of GRB 980703
  81. GRB980703
  82. GRB980613, optical observations
  83. GRB 980613 Optical Observations
  84. GRB980613 BeppoSAX-NFI follow up
  85. GRB980613, BeppoSAX WFC positions
  86. GRB980519 IPN POSITION
  87. GRB980515: SAX-WFC updated position
  88. BSAX Observations of GRB980425 field
  89. GRB980425 BATSE observations
  90. SAX J0840.7+2248 Optical Observations
  91. report on BSAX observations of GRB980425
  92. GRB980329 IPN annulus
  93. GRB980329 near-IR observations
  94. GRB980329 near-IR observations
  95. GRB980329 near IR observations
  96. GRB980329 optical observations
  97. Optical Observations for GRB 971227
  98. GRB 971227: Optical observations
  99. GRB971214: Optical Observations and Calibrations
  100. Optical Observations of GRB 971214 at Keck

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