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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"

143 results found.

  1. SVOM GRB 260515A: Global MASTER-Net observations report
  2. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  3. GRB 260206A: Swift-XRT observations
  4. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  5. GRB 260120B: Swift detection of a burst
  6. GRB 251203A: SVOM/GRM observation
  7. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  8. GRB 250828B: Swift detection of a burst
  9. LIGO/Virgo/KAGRA S250818t: Identification of a GW compact binary merger candidate
  10. sb25081602: Swift-XRT observations
  11. SVOM/sb25081602: detection of a likely X-ray transient
  12. GRB 250806A: SVOM/VT refined analysis
  13. GRB 250806A: SVOM/VT optical upper limit
  14. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  15. GRB 250507A: SVOM detection of a long burst
  16. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  17. LIGO/Virgo/KAGRA S250206dm: SAGUARO Detection of Two Potential Optical Counterparts
  18. GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
  19. Fermi GRB 241209E: Global MASTER-Net observations report
  20. GRB 240727A: Swift-XRT refined Analysis
  21. GRB 240513A: Fermi GBM observation
  22. Swift Trigger 1220736: detection of 4U 1543-62.
  23. Fermi GRB 240112D: Global MASTER-Net observations report
  24. LIGO/Virgo/KAGRA S231118an: Identification of a GW compact binary merger candidate
  25. Swift Triggers 1192234, 1192235 and 1192236 are not astrophysical events
  26. LIGO/Virgo/KAGRA S230704f: Updated Sky localization
  27. LIGO/Virgo S230615i: Global MASTER-Net observations report
  28. GRB 230307A: further analysis of the Konus-Wind detection and rest-frame energetics
  29. GRB 230321B: AstroSat CZTI detection
  30. GRB 230320B: AstroSat CZTI detection
  31. Trigger 1160641: Swift detection of 4U 1630-472 (a.k.a. SWIFT J1633.8-4724A)
  32. GRB 220806A: Swift detection of a burst
  33. Konus-Wind detection of GRB 220203A
  34. GRB 211227A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  35. GRB 211221A: Swift detection of a burst
  36. Fermi GRB 211211B: Global MASTER-Net observations report
  37. IceCube Alert 211125.27: Global MASTER-Net observations report
  38. Trigger 1062273: Swift detection of 4U 1700-377
  39. GRB 210708A: Swift/UVOT Upper Limits
  40. GRB 210610B: Swift/UVOT Detection
  41. Swift-BAT Trigger 1055000/GRB210612.54: MASTER optical source observation
  42. Swift-BAT Trigger 1055000: Swift detection of an outburst from 4U 1543-47
  43. Swift trigger 1047857 is 4U 1700-377
  44. GRB 210424B: AstroSat CZTI detection
  45. GECAM detection of a burst possibly from the X-ray burster 4U 0614+09 or GRB 210124A
  46. GRB 200529A: Swift detection of a burst
  47. GRB 200514B: Fermi GBM observation
  48. Fermi trigger No 611434353: Global MASTER-Net observations report
  49. GRB 200107B: Swift detection of a burst
  50. Konus-Wind observation of GRB 191221B
  51. Swift GRB 191221B: Global MASTER-Net observations report
  52. Fermi trigger No 596690552: Global MASTER-Net observations report
  53. Fermi trigger No 596387570: Global MASTER-Net observations report
  54. LIGO/Virgo S190901ap: Second Epoch Hobby-Eberly Telescope observations of ZTF19abvionh
  55. LIGO/Virgo S190814bv: No radio counterpart detected in ASKAP observations
  56. Fermi trigger No 587775150 Global MASTER-Net observations report
  57. GRB 190718A: Swift detection of a burst
  58. LIGO/Virgo S190426c: Updated localization from LIGO and Virgo data
  59. Problem with GCN Circular and status of the fix
  60. GRB 190311A: Swift detection of a burst with optical counterpart
  61. GRB 190220A: Swift detection of a burst with an optical counterpart
  62. Trigger 888312: Swift detection of 4U 1901+03
  63. GRB 190109B: Swift detection of a burst
  64. Swift trigger 831888: misidentification of 4U 1416-62
  65. LIGO/Virgo G297595: NIR Observations following GW170814
  66. LIGO/VIRGO G298048: AAT/AAO spectroscopic observations of the GW counterpart candidate SSS17a/DLT17ck
  67. LIGO/Virgo G296853: Fermi-LAT search for high-energy gamma-ray counterpart
  68. Fermi GBM Detection of possible burst from AXP 4U 0142+61
  69. GRB 170604A: Swift/UVOT Observations
  70. GRB 170419A: Swift detection of a burst
  71. LIGO/Virgo G277583: Asiago spectroscopic classification of ATLAS17byo and ATLAS17cgg
  72. LIGO/Virgo G275697: optical spectroscopy of Swift/XRT source 1
  73. GRB 170208B: Swift/UVOT Upper Limits
  74. GRB 170101B: Astrosat CZTI detection
  75. Swift Trigger 718766 is not an astrophysical event.
  76. Swift Trigger 707545 is likely 4U 1850-03/GS1843-02
  77. LIGO/Virgo G197392 / LVT151012: Identification of a GW CBC Candidate
  78. GRB 160409A found in Swift BAT ground analysis
  79. GRB 160412A: Swift-XRT refined Analysis
  80. GRB 160314A: Swift detection of a burst
  81. GRB 160121A: Swift detection of a burst
  82. Swift detection of 4U 1850-03
  83. GRB 150428A: Swift detection of a burst
  84. GRB 150317A: Swift detection of a burst
  85. GRB 150301A: Fermi GBM observation
  86. Swift-BAT refined analysis of magnetar 4U 0142+61 (Trigger 632888)
  87. Fermi GBM Observations of Magnetar 4U 0142+61
  88. Trigger 632888: Swift detection of the magnetar 4U 0142+61
  89. Trigger 631747: Swift detection of 4U 0614+09
  90. Swift detection of 4U 1700+24 (= V* V934 Her)
  91. Swift detection of 4U 1700+24 (= V934 Her)
  92. GRB 141020A: Swift detection of a burst with an optical counterpart
  93. Swift detection of outburst from 4U 1700+24
  94. Swift trigger 609139 is probably 4U 1850-03
  95. GRB 140706A: Swift detection of a burst with an optical counterpart
  96. GRB 140305A: Swift detection of a burst
  97. Observation of possible GRB/TDE 130925A by INTEGRAL/SPI-ACS: three activity episodes
  98. Swift Trigger 558828 is not an interesting event
  99. Swift Trigger 557674 was due to an onboard position error
  100. GRB130427A: Swift/UVOT followup observations of an Optical Afterglow

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