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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"

2623 results found.

  1. Swift Trigger 1014012 (possible GRB 201221C) is likely not an astrophysical event
  2. GRB 201221D: Archival PS1 Imaging of the Putative Host Galaxy
  3. IceCube-201222A: IceCube observation of a high-energy neutrino candidate event
  4. Swift Trigger 1014012: possible GRB 201221C
  5. IceCube-201221A: IceCube observation of a high-energy neutrino candidate event
  6. GRB 201214B: Swift BAT location of short burst
  7. GRB 201015A: optical observations and supernova identification
  8. GRB 200826A: GMOS-N detected source magnitude (Correction)
  9. GRB 201015A: 5-GHz radio afterglow detection with the EVN
  10. IceCube-201209A: IceCube observation of a high-energy neutrino candidate event
  11. IceCube-201130A: IceCube observation of a high-energy neutrino candidate event
  12. IceCube-201120A: IceCube observation of a high-energy neutrino candidate event
  13. ZTF20acozryr/AT2020yxz (GRB 201103B): correction to the GCN #28883 CrAO/ZTSh optical observations
  14. IceCube 201114A: Swift followup of Fermi J0703.5+0505
  15. Swift XRT observations of the Fermi-LAT source 4FGL J0658.6+0636, positionally consistent with the IceCube high-energy neutrino alert
  16. VLASS identifies possible radio counterparts to IceCube-201115A, including a bright BL Lac candidate
  17. IceCube-201115A: IceCube observation of a high-energy neutrino candidate event
  18. IceCube-201114A - IceCube observation of a high-energy neutrino candidate event
  19. ZTF20acozryr/AT2020yxz (GRB 201103B): Flattening of the optical light curve
  20. GRB 201103B: GMG observation (2nd epoch)
  21. GRB 201029A: Swift-XRT refined Analysis
  22. IceCube-201021A: Optical counterpart of WISEA J172314.13+142101.5
  23. Fermi-LAT Gamma-ray Observations of IceCube-201021A and detection of a new gamma-ray source, Fermi J1725.5+1312
  24. IceCube-201021A: IceCube observation of a high-energy neutrino candidate event
  25. GRB 201017A: SAO RAS optical observations
  26. GRB 201017A: Assy and Mondy optical observations, possible afterglow detection
  27. GRB 201015A: Redshift from GTC/OSIRIS
  28. GRB 201013A: TSHAO and AbAO optical observations, afterglow confirmation
  29. IceCube-201014A - IceCube observation of a high-energy neutrino candidate track-like event
  30. GRB 201013A: FRAM-ORM possible afterglow candidate
  31. GRB 201008A: Swift/BAT-GUANO detection and possible arcminute localization
  32. IceCube-201007A - IceCube observation of a high-energy neutrino candidate track-like event
  33. IceCube-200929A: IceCube observation of a high-energy neutrino candidate event
  34. IceCube-200926B: IceCube observation of a high-energy neutrino candidate event
  35. IceCube-200926A: IceCube observation of a high-energy neutrino candidate event
  36. GRB 200922A: Swift detection of a burst with possible optical counterpart
  37. IceCube-200921A: IceCube observation of a high-energy neutrino candidate event
  38. IceCube-200916A - ZTF20acaapwk/SN2020tno classified as SN Ia
  39. IceCube-200916A - IceCube observation of a high-energy neutrino candidate track-like event
  40. IceCube-200911A: IceCube observation of a high-energy neutrino candidate event
  41. GRB 200826A: uGMRT radio upper limit at 1.25 GHz
  42. GRB 200901A: Swift/UVOT Detection
  43. GRB 200826A
  44. GRB 200826A: Lowell Discovery Telescope observations of ZTF20abwysqy
  45. Zwicky Transient Facility discovery of ZTF20abtxwfx/AT2020sev, a fast optical transient and candidate afterglow
  46. GRB 200826A: further analysis of the Konus-Wind data and classification
  47. GRB200826A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 620108997)
  48. Swift Trigger 992444: a possible GRB 200821A
  49. GRB 200806A: Swift/UVOT Possible Detection
  50. IceCube-200806A: IceCube observation of a high-energy neutrino candidate event
  51. GRB 200723A: ATLAS observations of GOTO candidate AT2020qer
  52. GRB 200716C: Kitab optical observations
  53. GRB 200716C: CrAO, Terskol, Assy-Turgen optical observations
  54. Konus-Wind observation of GRB 200716C: correction to GCN 28147
  55. Konus-Wind observation of GRB 200716C
  56. GRB 200716C: possible host galaxy from the SDSS
  57. GRB 200716C: Swift-XRT refined analysis correction
  58. GRB 200623A: Further MMTCam Observations of XRT Source #3
  59. GRB 200623A: LBT optical observations
  60. IceCube-200620A - IceCube observation of a high-energy neutrino candidate track-like event
  61. IceCube-200530A - SN2020lls likely unrelated
  62. Fermi-LAT Gamma-ray Observations of IceCube-200614A and detection of a new gamma-ray source, Fermi J0202.8+3132
  63. IceCube-200615A: IceCube observation of a high-energy neutrino candidate event
  64. IceCube-200614A - IceCube observation of a high-energy neutrino candidate track-like event
  65. GRB 200612A: Swift detection of a burst
  66. IceCube-200530A - SN2020lam classified as SN II without evidence of CSM interaction
  67. IceCube-200530A - IceCube observation of a high-energy neutrino candidate event
  68. Fermi-LAT Gamma-ray Observations of IceCube-190523A
  69. GRB 200522A: Correction to GCN 27792
  70. IceCube-200523A - IceCube observation of a high-energy neutrino candidate event
  71. GRB 200522A: Coincident catalogued galaxy at z~0.4
  72. IceCube-200512A: IceCube observation of a high-energy neutrino candidate event
  73. GRB 200509A: Swift detection of a burst with a possible optical counterpart
  74. SGR 1935+2154: MASTER optical observations
  75. Gagarin-day GRB 200412B: observations with the 3.6m Devasthal Optical Telescope
  76. IceCube-200425A - IceCube observation of a high-energy neutrino candidate event
  77. GRB 200415A correction to GCN 27627 (possible magnetar Giant Flare in Sculptor Galaxy): INTEGRAL observations
  78. GRB 200415A (possible magnetar Giant Flare in Sculptor Galaxy): INTEGRAL observations
  79. IceCube-200421A - IceCube observation of a high-energy neutrino candidate event
  80. GRB 200415A: MASTER imspection and possible localisation
  81. GRB 200415A: Fermi GBM observation
  82. IPN triangulation of GRB 200415A (possible Magnetar Giant Flare in Sculptor Galaxy?)
  83. GRB 200405B: Further Swift-XRT observations
  84. IceCube-200410A: Possible associated excess in INTEGRAL SPI-ACS prompt observation
  85. IceCube-200410A - IceCube observation of a high-energy neutrino candidate event
  86. GRB 200410A: Swift detection of a burst with a possible optical counterpart
  87. GRB 200405B: Swift-XRT observations
  88. GRB 200405B: Swift/BAT-GUANO detection and *possible* arcminute localization of a short GRB
  89. Chandra observations of GW170817 at 2.5 years since merger (All epochs 4 of 4)
  90. LIGO/Virgo S200316bj: No counterpart candidates in Fermi-LAT observations
  91. LIGO/Virgo S200311bg: No significant counterpart candidates in Fermi-LAT observations
  92. Chandra observations of GW170817 ~ 2.5 years since merger (epoch 1 of 4)
  93. LIGO/Virgo S200302c: No significant counterpart candidates in Fermi-LAT observations
  94. GRB 200228B: Mondy, TSHAO, AbAO and CrAO optical observations, afterglow candidate
  95. GRB 200228B: Liverpool Telescope imaging
  96. IceCube-200227A: IceCube observation of a high-energy neutrino candidate event
  97. LIGO/Virgo S200225q: No counterpart candidates in Fermi-LAT observations
  98. LIGO/Virgo S200224ca: No counterpart candidates in Fermi-LAT observations
  99. GRB 200219С: Mondy and TSHAO optical observations
  100. GRB 200219C: Nanshan/NEXT optical upper limit and possible host galaxy from PanSTARRS

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