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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"

144 results found.

  1. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  2. SVOM GRB 260515A: Global MASTER-Net observations report
  3. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  4. GRB 260206A: Swift-XRT observations
  5. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  6. GRB 260120B: Swift detection of a burst
  7. GRB 251203A: SVOM/GRM observation
  8. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  9. GRB 250828B: Swift detection of a burst
  10. LIGO/Virgo/KAGRA S250818t: Identification of a GW compact binary merger candidate
  11. sb25081602: Swift-XRT observations
  12. SVOM/sb25081602: detection of a likely X-ray transient
  13. GRB 250806A: SVOM/VT refined analysis
  14. GRB 250806A: SVOM/VT optical upper limit
  15. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  16. GRB 250507A: SVOM detection of a long burst
  17. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  18. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  19. GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
  20. Fermi GRB 241209E: Global MASTER-Net observations report
  21. GRB 240727A: Swift-XRT refined Analysis
  22. GRB 240513A: Fermi GBM observation
  23. Swift Trigger 1220736: detection of 4U 1543-62.
  24. Fermi GRB 240112D: Global MASTER-Net observations report
  25. LIGO/Virgo/KAGRA S231118an: Identification of a GW compact binary merger candidate
  26. Swift Triggers 1192234, 1192235 and 1192236 are not astrophysical events
  27. LIGO/Virgo/KAGRA S230704f: Updated Sky localization
  28. LIGO/Virgo S230615i: Global MASTER-Net observations report
  29. GRB 230307A: further analysis of the Konus-Wind detection and rest-frame energetics
  30. GRB 230321B: AstroSat CZTI detection
  31. GRB 230320B: AstroSat CZTI detection
  32. Trigger 1160641: Swift detection of 4U 1630-472 (a.k.a. SWIFT J1633.8-4724A)
  33. GRB 220806A: Swift detection of a burst
  34. Konus-Wind detection of GRB 220203A
  35. GRB 211227A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  36. GRB 211221A: Swift detection of a burst
  37. Fermi GRB 211211B: Global MASTER-Net observations report
  38. IceCube Alert 211125.27: Global MASTER-Net observations report
  39. Trigger 1062273: Swift detection of 4U 1700-377
  40. GRB 210708A: Swift/UVOT Upper Limits
  41. GRB 210610B: Swift/UVOT Detection
  42. Swift-BAT Trigger 1055000/GRB210612.54: MASTER optical source observation
  43. Swift-BAT Trigger 1055000: Swift detection of an outburst from 4U 1543-47
  44. Swift trigger 1047857 is 4U 1700-377
  45. GRB 210424B: AstroSat CZTI detection
  46. GECAM detection of a burst possibly from the X-ray burster 4U 0614+09 or GRB 210124A
  47. GRB 200529A: Swift detection of a burst
  48. GRB 200514B: Fermi GBM observation
  49. Fermi trigger No 611434353: Global MASTER-Net observations report
  50. GRB 200107B: Swift detection of a burst
  51. Konus-Wind observation of GRB 191221B
  52. Swift GRB 191221B: Global MASTER-Net observations report
  53. Fermi trigger No 596690552: Global MASTER-Net observations report
  54. Fermi trigger No 596387570: Global MASTER-Net observations report
  55. LIGO/Virgo S190901ap: Second Epoch Hobby-Eberly Telescope observations of ZTF19abvionh
  56. LIGO/Virgo S190814bv: No radio counterpart detected in ASKAP observations
  57. Fermi trigger No 587775150 Global MASTER-Net observations report
  58. GRB 190718A: Swift detection of a burst
  59. LIGO/Virgo S190426c: Updated localization from LIGO and Virgo data
  60. Problem with GCN Circular and status of the fix
  61. GRB 190311A: Swift detection of a burst with optical counterpart
  62. GRB 190220A: Swift detection of a burst with an optical counterpart
  63. Trigger 888312: Swift detection of 4U 1901+03
  64. GRB 190109B: Swift detection of a burst
  65. Swift trigger 831888: misidentification of 4U 1416-62
  66. LIGO/Virgo G297595: NIR Observations following GW170814
  67. LIGO/VIRGO G298048: AAT/AAO spectroscopic observations of the GW counterpart candidate SSS17a/DLT17ck
  68. LIGO/Virgo G296853: Fermi-LAT search for high-energy gamma-ray counterpart
  69. Fermi GBM Detection of possible burst from AXP 4U 0142+61
  70. GRB 170604A: Swift/UVOT Observations
  71. GRB 170419A: Swift detection of a burst
  72. LIGO/Virgo G277583: Asiago spectroscopic classification of ATLAS17byo and ATLAS17cgg
  73. LIGO/Virgo G275697: optical spectroscopy of Swift/XRT source 1
  74. GRB 170208B: Swift/UVOT Upper Limits
  75. GRB 170101B: Astrosat CZTI detection
  76. Swift Trigger 718766 is not an astrophysical event.
  77. Swift Trigger 707545 is likely 4U 1850-03/GS1843-02
  78. LIGO/Virgo G197392 / LVT151012: Identification of a GW CBC Candidate
  79. GRB 160409A found in Swift BAT ground analysis
  80. GRB 160412A: Swift-XRT refined Analysis
  81. GRB 160314A: Swift detection of a burst
  82. GRB 160121A: Swift detection of a burst
  83. Swift detection of 4U 1850-03
  84. GRB 150428A: Swift detection of a burst
  85. GRB 150317A: Swift detection of a burst
  86. GRB 150301A: Fermi GBM observation
  87. Swift-BAT refined analysis of magnetar 4U 0142+61 (Trigger 632888)
  88. Fermi GBM Observations of Magnetar 4U 0142+61
  89. Trigger 632888: Swift detection of the magnetar 4U 0142+61
  90. Trigger 631747: Swift detection of 4U 0614+09
  91. Swift detection of 4U 1700+24 (= V* V934 Her)
  92. Swift detection of 4U 1700+24 (= V934 Her)
  93. GRB 141020A: Swift detection of a burst with an optical counterpart
  94. Swift detection of outburst from 4U 1700+24
  95. Swift trigger 609139 is probably 4U 1850-03
  96. GRB 140706A: Swift detection of a burst with an optical counterpart
  97. GRB 140305A: Swift detection of a burst
  98. Observation of possible GRB/TDE 130925A by INTEGRAL/SPI-ACS: three activity episodes
  99. Swift Trigger 558828 is not an interesting event
  100. Swift Trigger 557674 was due to an onboard position error

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