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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"

99 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. Fermi trigger No 737247400: Global MASTER-Net observations report
  27. IceCube-220624A: One Candidate Counterpart from Swift/XRT follow up observations
  28. Fermi-LAT Gamma-ray Observations of IceCube-220509A
  29. Fermi-LAT Gamma-ray Observations of IceCube-211125A
  30. MeerLICHT follow-up of GRB 211106A
  31. IceCube 135113_19489408.amon: Swift-XRT observations
  32. GRB 210222B: Swift detection of a burst with an optical counterpart
  33. Swift-XRT observations of IceCube-210210A
  34. Fermi-LAT Gamma-ray Observations of IceCube-201021A and detection of a new gamma-ray source, Fermi J1725.5+1312
  35. Swift-XRT observations of IceCube 201021A
  36. Swift-XRT observations of IceCube 200929A
  37. Swift-XRT observations of IceCube 200615A
  38. Correction to the GCN 27886: Previous bursts of 1RXS J1708-4009 (Swift trigger 975998)
  39. 1RXS J1708−4009: Swift-BAT refined analysis
  40. Swift detection of an SGR-like burst from 1RXS J1708−4009
  41. IceCube-200109A: Swift-XRT and UVoT Follow-up Observations
  42. Swift follow-up observations of IceCube-200107A: Identification of X-ray high state for 4FGL J0955.1+3551
  43. Fermi-LAT Gamma-ray Observations of IceCube-200107A
  44. Fermi-LAT Gamma-ray Observations of IceCube-190819A
  45. LIGO/Virgo S190728q/IceCube neutrino candidate: No counterpart candidates in the Swift-XRT Observations
  46. IceCube-190504A: Swift-XRT Follow-up Observations
  47. LIGO/Virgo S190426c: Swift-XRT sources
  48. IceCube-190331A - IceCube observation of a high-energy neutrino candidate event
  49. Swift trigger 831888: misidentification of 4U 1416-62
  50. Swift detection of MAXI J1820+070
  51. IceCube-171106A: Swift Observations
  52. IceCube-170922A: Swift-XRT observations
  53. LIGO/Virgo G299232: Swift-XRT sources
  54. GRB 170830A: iTelescope optical observations
  55. LIGO/Virgo G297595: Swift-XRT sources
  56. LIGO/Virgo G288732: Swift-XRT follow up of the putative LAT counterpart
  57. Fermi-LAT Gamma-ray Observations of IceCube-170321
  58. IceCube-170312A: Swift-XRT observations
  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 G275697: Further Swift-XRT sources
  63. LIGO/Virgo G268556: Swift-XRT detection of ATLAS17aeu
  64. LIGO/Virgo G268556: Swift-XRT sources
  65. Fermi/LAT search for counterpart to the IceCube event 67093193 (run 127853)
  66. LIGO/Virgo G211117: Swift-XRT sources
  67. LIGO/Virgo G184098: Swift follow-up observations
  68. Swift-XRT observations of GRB 150710A
  69. Swift trigger 648437: A GRB or a burst from 1RXS J125754.7+141850
  70. GRB 150305A: Swift XRT confirms weak INTEGRAL event as a new GRB
  71. Trigger 630047: Swift detection of 1RXS J180408.9-342058
  72. Swift Trigger 629206 is likely 1RXS J180408.9-342058
  73. GRB141208.63: MASTER OT Detection During the Fermi Error Box inspection
  74. MAXI GRB 141029A is likely an X-ray flare from 1RXS J043657.1-161258
  75. GRB 140110A: Swift XRT observations
  76. Swift Trigger 575905/possible GRB 131026A: Swift-XRT observations
  77. GRB 120819A: Swift/UVOT Upper Limits
  78. GRB 120510A: Swift XRT and UVOT observations
  79. GRB 111204A: Swift/UVOT Upper Limits
  80. GRB 110428A : Swift-XRT observations
  81. GRB 110420B: Swift-XRT afterglow candidate retraction
  82. GRB 110213B: Swift XRT observation
  83. Swift-BAT trigger 431582 likely is IGR J17464-2811
  84. GRB 100216A: Swift/UVOT Observations
  85. GRB 100216A: XRT Refined Analysis
  86. Swift Trigger 381434 is not a GRB
  87. GRB 090305: Swift detection of a short burst
  88. GRB 080822 (SGR 0501+4516): archival optical observations
  89. Trigger 317393: Swift detection of a possible GRB
  90. GRB 060930: A long X-ray rich GRB detected by INTEGRAL
  91. GRB 060425: IPN localization and KW spectrum of a short, hard burst
  92. H4043, an unusual high-energy transient observed by HETE
  93. GRB 060204A: Swift XRT upper limit
  94. Possible GRB 040903 - further analysis
  95. GRB020819(=H2275): A Long Burst Localized by the HETE WXM and SXC
  96. BeppoSAX ALERT: Possible X-ray rich GRB011030
  97. GRB010214: BeppoSAX/NFI Observations
  98. GRB990806 BeppoSAX follow up
  99. BeppoSAX NFI observations of GRB 980703

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