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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"

2803 results found.

  1. GRB 201029A: Swift-XRT refined Analysis
  2. IceCube-201021A: Optical counterpart of WISEA J172314.13+142101.5
  3. Fermi-LAT Gamma-ray Observations of IceCube-201021A and detection of a new gamma-ray source, Fermi J1725.5+1312
  4. IceCube-201021A: IceCube observation of a high-energy neutrino candidate event
  5. GRB 201017A: SAO RAS optical observations
  6. GRB 201017A: Assy and Mondy optical observations, possible afterglow detection
  7. GRB 201015A: Redshift from GTC/OSIRIS
  8. GRB 201013A: TSHAO and AbAO optical observations, afterglow confirmation
  9. IceCube-201014A - IceCube observation of a high-energy neutrino candidate track-like event
  10. GRB 201013A: FRAM-ORM possible afterglow candidate
  11. GRB 201008A: Swift/BAT-GUANO detection and possible arcminute localization
  12. IceCube-201007A - IceCube observation of a high-energy neutrino candidate track-like event
  13. IceCube-200929A: IceCube observation of a high-energy neutrino candidate event
  14. IceCube-200926B: IceCube observation of a high-energy neutrino candidate event
  15. IceCube-200926A: IceCube observation of a high-energy neutrino candidate event
  16. GRB 200922A: Swift detection of a burst with possible optical counterpart
  17. IceCube-200921A: IceCube observation of a high-energy neutrino candidate event
  18. IceCube-200916A - ZTF20acaapwk/SN2020tno classified as SN Ia
  19. IceCube-200916A - IceCube observation of a high-energy neutrino candidate track-like event
  20. IceCube-200911A: IceCube observation of a high-energy neutrino candidate event
  21. GRB 200826A: uGMRT radio upper limit at 1.25 GHz
  22. GRB 200901A: Swift/UVOT Detection
  23. GRB 200826A
  24. GRB 200826A: Lowell Discovery Telescope observations of ZTF20abwysqy
  25. Zwicky Transient Facility discovery of ZTF20abtxwfx/AT2020sev, a fast optical transient and candidate afterglow
  26. GRB 200826A: further analysis of the Konus-Wind data and classification
  27. GRB200826A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 620108997)
  28. Swift Trigger 992444: a possible GRB 200821A
  29. GRB 200806A: Swift/UVOT Possible Detection
  30. IceCube-200806A: IceCube observation of a high-energy neutrino candidate event
  31. GRB 200723A: ATLAS observations of GOTO candidate AT2020qer
  32. GRB 200716C: Kitab optical observations
  33. GRB 200716C: CrAO, Terskol, Assy-Turgen optical observations
  34. Konus-Wind observation of GRB 200716C: correction to GCN 28147
  35. Konus-Wind observation of GRB 200716C
  36. GRB 200716C: possible host galaxy from the SDSS
  37. GRB 200716C: Swift-XRT refined analysis correction
  38. GRB 200623A: Further MMTCam Observations of XRT Source #3
  39. GRB 200623A: LBT optical observations
  40. IceCube-200620A - IceCube observation of a high-energy neutrino candidate track-like event
  41. IceCube-200530A - SN2020lls likely unrelated
  42. Fermi-LAT Gamma-ray Observations of IceCube-200614A and detection of a new gamma-ray source, Fermi J0202.8+3132
  43. IceCube-200615A: IceCube observation of a high-energy neutrino candidate event
  44. IceCube-200614A - IceCube observation of a high-energy neutrino candidate track-like event
  45. GRB 200612A: Swift detection of a burst
  46. IceCube-200530A - SN2020lam classified as SN II without evidence of CSM interaction
  47. IceCube-200530A - IceCube observation of a high-energy neutrino candidate event
  48. Fermi-LAT Gamma-ray Observations of IceCube-190523A
  49. GRB 200522A: Correction to GCN 27792
  50. IceCube-200523A - IceCube observation of a high-energy neutrino candidate event
  51. GRB 200522A: Coincident catalogued galaxy at z~0.4
  52. IceCube-200512A: IceCube observation of a high-energy neutrino candidate event
  53. GRB 200509A: Swift detection of a burst with a possible optical counterpart
  54. SGR 1935+2154: MASTER optical observations
  55. Gagarin-day GRB 200412B: observations with the 3.6m Devasthal Optical Telescope
  56. IceCube-200425A - IceCube observation of a high-energy neutrino candidate event
  57. GRB 200415A correction to GCN 27627 (possible magnetar Giant Flare in Sculptor Galaxy): INTEGRAL observations
  58. GRB 200415A (possible magnetar Giant Flare in Sculptor Galaxy): INTEGRAL observations
  59. IceCube-200421A - IceCube observation of a high-energy neutrino candidate event
  60. GRB 200415A: MASTER imspection and possible localisation
  61. GRB 200415A: Fermi GBM observation
  62. IPN triangulation of GRB 200415A (possible Magnetar Giant Flare in Sculptor Galaxy?)
  63. GRB 200405B: Further Swift-XRT observations
  64. IceCube-200410A: Possible associated excess in INTEGRAL SPI-ACS prompt observation
  65. IceCube-200410A - IceCube observation of a high-energy neutrino candidate event
  66. GRB 200410A: Swift detection of a burst with a possible optical counterpart
  67. GRB 200405B: Swift-XRT observations
  68. GRB 200405B: Swift/BAT-GUANO detection and *possible* arcminute localization of a short GRB
  69. Chandra observations of GW170817 at 2.5 years since merger (All epochs 4 of 4)
  70. LIGO/Virgo S200316bj: No counterpart candidates in Fermi-LAT observations
  71. LIGO/Virgo S200311bg: No significant counterpart candidates in Fermi-LAT observations
  72. Chandra observations of GW170817 ~ 2.5 years since merger (epoch 1 of 4)
  73. LIGO/Virgo S200302c: No significant counterpart candidates in Fermi-LAT observations
  74. GRB 200228B: Mondy, TSHAO, AbAO and CrAO optical observations, afterglow candidate
  75. GRB 200228B: Liverpool Telescope imaging
  76. IceCube-200227A: IceCube observation of a high-energy neutrino candidate event
  77. LIGO/Virgo S200225q: No counterpart candidates in Fermi-LAT observations
  78. LIGO/Virgo S200224ca: No counterpart candidates in Fermi-LAT observations
  79. GRB 200219C: Mondy and TSHAO optical observations
  80. GRB 200219C: Nanshan/NEXT optical upper limit and possible host galaxy from PanSTARRS
  81. LIGO/Virgo S200219ac: No counterpart candidates in Fermi-LAT observations
  82. GRB 200216B: second epoch optical upper limit at Mondy observatory
  83. GRB 200219A: MASTER catalog automatic possible Host Galaxy candidate
  84. GRB 200216B: Mondy and AbAO optical upper limits
  85. GRB 200216B - possible IR counterpart from VLT
  86. GRB 200216B: Nanshan/NEXT early optical upper limit and possible host galaxy
  87. GRB 200216B: Swift detection of a burst
  88. LIGO/Virgo S200213t: Possible host galaxies in the bilby skymap
  89. GRB 200215A Possible host galaxy in PanSTARRS
  90. LIGO/Virgo S200213t: MASTER possible Kilonova candidate in PGC315337
  91. LIGO/Virgo S200114f: Gemini Spectra of AT 2020vu, AT 2020vw, AT 2020vy, and AT 2020vz
  92. LIGO/Virgo S200213t: More Candidates from the Zwicky Transient Facility
  93. LIGO/Virgo S200213t: No counterpart candidates in Fermi-LAT observations
  94. LIGO/Virgo S200213t: Neutrino and galaxies cross-match
  95. LIGO/Virgo trigger S200213t: Possible host galaxies
  96. LIGO/Virgo S200208q: No counterpart candidates in Fermi-LAT observations
  97. GRB 200205A = Swift J0840.7-3516, A newly discovered transient X-ray Pulsar
  98. GRB 200205A: Swift detection of a burst with a possible UV counterpart
  99. AMON IceCube-HAWC_200202A: MASTER optical inspect
  100. LIGO/Virgo S200129m: No counterpart candidates in Fermi-LAT observations

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