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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"
  1. LIGO/Virgo/KAGRA S230707ai: Updated Sky localization
  2. IceCube-230707A: No candidates from the Zwicky Transient Facility
  3. Fermi-LAT gamma-ray observations of IceCube-230708A
  4. Fermi-LAT gamma-ray observations of IceCube-230707B
  5. Fermi-LAT gamma-ray observations of IceCube-230707A
  6. LIGO/Virgo/KAGRA S230630am: Updated Sky localization
  7. LIGO/Virgo/KAGRA S230630am: Updated Sky localization
  8. GRB 230709B: BALROG localization (Fermi Trigger 710614579 / GRB 230709706)
  9. IceCube-230708A: Upper limits from a search for additional neutrino events in IceCube
  10. IceCube-230707B: Upper limits from a search for additional neutrino events in IceCube
  11. IceCube-230707A: Upper limits from a search for additional neutrino events in IceCube
  12. LIGO/Virgo/KAGRA S230709bi: Identification of a GW compact binary merger candidate
  13. Swift Trigger 1178410: possible GRB 230709A
  14. LIGO/Virgo/KAGRA S230708cf: Identification of a GW compact binary merger candidate
  15. LIGO/Virgo/KAGRA S230708bi: Retraction of GW compact binary merger candidate
  16. GRB 230628C: GRID Detection
  17. IceCube-230708A - IceCube observation of a high-energy neutrino candidate track-like event
  18. GRB 230707B: Swift/BAT-GUANO detection of a burst outside the coded FOV
  19. GRB 230707A: Swift-XRT observations
  20. IceCube Alert 230708.35: Global MASTER-Net observations report
  21. IceCube-230707B - IceCube observation of a high-energy neutrino candidate track-like event
  22. GRB 230707B: Fermi GBM Final Real-time Localization
  23. IceCube Alert 230707.71: Global MASTER-Net observations report
  24. IceCube-230707A - IceCube observation of a high-energy neutrino candidate track-like event
  25. GRB 230707A: Fermi GBM Detection
  26. LIGO/Virgo/KAGRA S230707ai: Identification of a GW compact binary merger candidate
  27. GRB 230707A: Swift ToO observations
  28. GRB 230707A: Swift/BAT-GUANO arcminute localization of a burst
  29. ZTF23aaoohpy/AT2023lcr : HCT follow-up observations
  30. Fermi GRB 230707A: Global MASTER-Net observations report
  31. GRB 230707A: Fermi GBM Final Real-time Localization
  32. LIGO/Virgo/KAGRA S230706ah: Updated Sky localization
  33. Integral GRB230706.70: Global MASTER-Net observations report
  34. LIGO/Virgo/KAGRA S230704f: Updated Sky localization
  35. LIGO/Virgo/KAGRA S230630bq: Updated Sky localization
  36. IBAS trigger number 10311: not a real GRB
  37. LIGO/Virgo/KAGRA S230702an: Updated Sky localization
  38. GRB 230625A: Detection by GRID
  39. LIGO/Virgo/KAGRA S230529ay: Updated Sky localization and EM Bright Classification
  40. LIGO/Virgo/KAGRA S230706ah: Identification of a GW compact binary merger candidate
  41. LIGO/Virgo/KAGRA S230627c: GECKO optical follow-up observations of host galaxy candidates and ZTF23aaptsuy/AT2023lxu
  42. ZTF23aaoohpy/AT2023lcr: AMI-LA radio detection
  43. Fermi trigger No 710117592: Global MASTER-Net observations report
  44. GRB 230626A: VZLUSAT-2 detection
  45. LVK S230619bd/GBM-230619: Upper limits from a two-week IceCube neutrino search
  46. GRB 230328B: LBT detection of the likely host galaxy
  47. LIGO/Virgo/KAGRA S230704f: Identification of a GW compact binary merger candidate
  48. Konus-Wind detection of GRB 220623A
  49. GRB 230701B: AstroSat CZTI detection
  50. LIGO/Virgo/KAGRA S230627c: observations of ZTF23aaptsuy/AT2023lx in AbAO observatory
  51. LIGO/Virgo/KAGRA S230702an: Identification of a GW compact binary merger candidate
  52. GRB 230628E: Swift/UVOT Detection
  53. GRB 230628E: Swift-BAT refined analysis
  54. GRB 230702A: Fermi GBM Final Real-time Localization
  55. GRB 230628E: ATCA rapid radio follow-up
  56. GRB 230701A: Fermi GBM Final Real-time Localization
  57. LIGO/Virgo/KAGRA S230627c: GRANDMA observations of galaxies and ZTF counterpart candidates
  58. LIGO/Virgo/KAGRA low-significance gravitational wave candidate S230701z: one counterpart neutrino candidate from IceCube neutrino searches
  59. LIGO/Virgo/KAGRA S230627c: Upper limits from Swift/BAT-GUANO
  60. LIGO/Virgo/KAGRA S230630bq: Identification of a GW compact binary merger candidate
  61. IPN triangulation of GRB 230625B (ultra-long)
  62. AT2023lcr (ATLAS23msn/ZTF23aaoohpy): ALMA 100 GHz Detection
  63. LIGO/Virgo/KAGRA S230630am: Identification of a GW compact binary merger candidate
  64. GRB 230625B: CALET Gamma-Ray Burst Monitor detection
  65. GRB 230628E - VLT spectroscopic observations
  66. ZTF23aaoohpy/AT2023lcr: LBT observations
  67. Fermi GRB 230628C: Global MASTER-Net observations report
  68. GRB 230625B: AstroSat CZTI detection
  69. GRB230628E: VLT optical identification of afterglow candidate
  70. GRB 230628E: Swift-XRT refined Analysis
  71. GRB 230628E: Enhanced Swift-XRT position (Correction to name in GCN 34115)
  72. GRB 230628A: Enhanced Swift-XRT position
  73. Fermi GRB 230628D: Global MASTER-Net observations report
  74. LIGO/Virgo/KAGRA S230628ax: Identification of a GW compact binary merger candidate
  75. GRB 230628E: LCOGT Optical Upper Limit
  76. Swift GRB230628.93: Global MASTER-Net observations report
  77. GRB 230628E: Swift detection of a burst
  78. GRB 230628D: BALROG localization (Fermi Trigger 709676556 / GRB 230628849)
  79. GRB 230628D: Fermi GBM Final Real-time Localization
  80. LIGO/Virgo/KAGRA low-significance gravitational wave candidate S230628aj: one counterpart neutrino candidate from IceCube neutrino searches
  81. GRB 230628C: Fermi GBM Final Real-time Localization
  82. GRB 230628B: Swift/BAT-GUANO detection of a burst outside the coded FOV
  83. GRB 230623B: CALET Gamma-Ray Burst Monitor detection
  84. LIGO/Virgo/KAGRA S230516az: GOTO candidate counterpart GOTO23hu ruled out by Zwicky Transient Facility observations
  85. ZTF23aaoohpy /AT2023lcr: TNG NIR detection
  86. GRB 230628A: Fermi GBM Final Localization
  87. LIGO/Virgo/KAGRA S230627c: Additional observations from the Zwicky Transient Facility
  88. GRB 230626A: GRBAlpha detection
  89. AT2023lcr: JCMT SCUBA-2 sub-mm observations
  90. LIGO/Virgo/KAGRA S230527c: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  91. LIGO/Virgo/KAGRA S230627c: ATLAS information on the ZTF candidates
  92. LIGO/Virgo/KAGRA S230627c: Upper limits from Fermi-GBM Observations
  93. GRB230626A: Fermi GBM Detection
  94. LIGO/Virgo/KAGRA S230627c: Global MASTER-Net observations report
  95. LIGO/Virgo/Kagra S230627c: NED Galaxies in the Localization Volume
  96. Konus-Wind detection of GRB 230616A
  97. LIGO/Virgo/KAGRA S230627c: Correction to HasMassGap probability
  98. LIGO/Virgo/KAGRA S230627c: Zwicky Transient Facility observations and candidates
  99. LIGO/Virgo/KAGRA S230627c: Coverage and upper limits from MAXI/GSC observations
  100. LIGO/Virgo/KAGRA S230627c: Updated Sky localization and EM Bright Classification

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