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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"

84 results found.

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

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