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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"

96 results found.

  1. The EP-WXT trigger 01709259773 is likely a flaring star
  2. EP-WXT trigger 01709258989: KAIT confirmation of a stellar flare
  3. EP-WXT trigger 01709258989: confirmation of a stellar flare by BOOTES-7
  4. The EP-WXT trigger 01709258989 is likely a flaring star
  5. SVOM/sb25091517: Confirmation of a stellar flare by SVOM/VT
  6. SVOM/sb25091517: FRAM-ORM stellar flare - transient observation
  7. SVOM/sb25091517: SVOM detection of an X-ray transient
  8. EP#01709201209: Swift-XRT observations
  9. The EP-WXT trigger 01709201209 is likely a flaring star
  10. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  11. EP250901a: Swift-XRT observations
  12. EP250901a: Einstein Probe detection of an X-ray transient
  13. IceCube-250406A: Swift-XRT observations
  14. SVOM/sb25022102: SVOM detection of an X-ray transient
  15. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  16. EPWXT01709129925: Xinglong optical observations
  17. The EP-WXT trigger 01709129925 is likely a flaring star
  18. Swift-XRT observations of IceCube -241127A
  19. EP trigger ID 01709065118: Keck/LRIS spectroscopic observations
  20. EP trigger ID 01709065118: KAIT confirmation of the stellar flare
  21. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  22. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  23. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  24. GRB 240905E: Swift detection of a burst
  25. GRB 240514E: A possible candidate BD-21 1074
  26. IceCube-220624A: One Candidate Counterpart from Swift/XRT follow up observations
  27. Fermi-LAT Gamma-ray Observations of IceCube-220509A
  28. Fermi-LAT Gamma-ray Observations of IceCube-211125A
  29. MeerLICHT follow-up of GRB 211106A
  30. IceCube 135113_19489408.amon: Swift-XRT observations
  31. GRB 210222B: Swift detection of a burst with an optical counterpart
  32. Swift-XRT observations of IceCube-210210A
  33. Fermi-LAT Gamma-ray Observations of IceCube-201021A and detection of a new gamma-ray source, Fermi J1725.5+1312
  34. Swift-XRT observations of IceCube 201021A
  35. Swift-XRT observations of IceCube 200929A
  36. Swift-XRT observations of IceCube 200615A
  37. Correction to the GCN 27886: Previous bursts of 1RXS J1708-4009 (Swift trigger 975998)
  38. 1RXS J1708−4009: Swift-BAT refined analysis
  39. Swift detection of an SGR-like burst from 1RXS J1708−4009
  40. IceCube-200109A: Swift-XRT and UVoT Follow-up Observations
  41. Swift follow-up observations of IceCube-200107A: Identification of X-ray high state for 4FGL J0955.1+3551
  42. Fermi-LAT Gamma-ray Observations of IceCube-200107A
  43. Fermi-LAT Gamma-ray Observations of IceCube-190819A
  44. LIGO/Virgo S190728q/IceCube neutrino candidate: No counterpart candidates in the Swift-XRT Observations
  45. IceCube-190504A: Swift-XRT Follow-up Observations
  46. LIGO/Virgo S190426c: Swift-XRT sources
  47. IceCube-190331A - IceCube observation of a high-energy neutrino candidate event
  48. Swift trigger 831888: misidentification of 4U 1416-62
  49. Swift detection of MAXI J1820+070
  50. IceCube-171106A: Swift Observations
  51. IceCube-170922A: Swift-XRT observations
  52. LIGO/Virgo G299232: Swift-XRT sources
  53. GRB 170830A: iTelescope optical observations
  54. LIGO/Virgo G297595: Swift-XRT sources
  55. LIGO/Virgo G288732: Swift-XRT follow up of the putative LAT counterpart
  56. Fermi-LAT Gamma-ray Observations of IceCube-170321
  57. IceCube-170312A: Swift-XRT observations
  58. LIGO/Virgo G275697: Further Swift-XRT sources
  59. LIGO/Virgo G275697: Further Swift-XRT sources
  60. LIGO/Virgo G275697: Further Swift-XRT sources
  61. LIGO/Virgo G275697: Further Swift-XRT sources
  62. LIGO/Virgo G268556: Swift-XRT detection of ATLAS17aeu
  63. LIGO/Virgo G268556: Swift-XRT sources
  64. Fermi/LAT search for counterpart to the IceCube event 67093193 (run 127853)
  65. LIGO/Virgo G211117: Swift-XRT sources
  66. LIGO/Virgo G184098: Swift follow-up observations
  67. Swift-XRT observations of GRB 150710A
  68. Swift trigger 648437: A GRB or a burst from 1RXS J125754.7+141850
  69. GRB 150305A: Swift XRT confirms weak INTEGRAL event as a new GRB
  70. Trigger 630047: Swift detection of 1RXS J180408.9-342058
  71. Swift Trigger 629206 is likely 1RXS J180408.9-342058
  72. GRB141208.63: MASTER OT Detection During the Fermi Error Box inspection
  73. MAXI GRB 141029A is likely an X-ray flare from 1RXS J043657.1-161258
  74. GRB 140110A: Swift XRT observations
  75. Swift Trigger 575905/possible GRB 131026A: Swift-XRT observations
  76. GRB 120510A: Swift XRT and UVOT observations
  77. GRB 110428A : Swift-XRT observations
  78. GRB 110420B: Swift-XRT afterglow candidate retraction
  79. GRB 110213B: Swift XRT observation
  80. Swift-BAT trigger 431582 likely is IGR J17464-2811
  81. GRB 100216A: Swift/UVOT Observations
  82. GRB 100216A: XRT Refined Analysis
  83. Swift Trigger 381434 is not a GRB
  84. GRB 090305: Swift detection of a short burst
  85. GRB 080822 (SGR 0501+4516): archival optical observations
  86. Trigger 317393: Swift detection of a possible GRB
  87. GRB 060930: A long X-ray rich GRB detected by INTEGRAL
  88. GRB 060425: IPN localization and KW spectrum of a short, hard burst
  89. H4043, an unusual high-energy transient observed by HETE
  90. GRB 060204A: Swift XRT upper limit
  91. Possible GRB 040903 - further analysis
  92. GRB020819(=H2275): A Long Burst Localized by the HETE WXM and SXC
  93. BeppoSAX ALERT: Possible X-ray rich GRB011030
  94. GRB010214: BeppoSAX/NFI Observations
  95. GRB990806 BeppoSAX follow up
  96. BeppoSAX NFI observations of GRB 980703

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