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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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 S230516az: GOTO candidate counterpart GOTO23hu ruled out by Zwicky Transient Facility observations
  2. ZTF23aaoohpy /AT2023lcr: TNG NIR detection
  3. GRB 230628A: Fermi GBM Final Localization
  4. LIGO/Virgo/KAGRA S230627c: Additional observations from the Zwicky Transient Facility
  5. GRB 230626A: GRBAlpha detection
  6. AT2023lcr: JCMT SCUBA-2 sub-mm observations
  7. LIGO/Virgo/KAGRA S230527c: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  8. LIGO/Virgo/KAGRA S230627c: ATLAS information on the ZTF candidates
  9. LIGO/Virgo/KAGRA S230627c: Upper limits from Fermi-GBM Observations
  10. GRB230626A: Fermi GBM Detection
  11. LIGO/Virgo/KAGRA S230627c: Global MASTER-Net observations report
  12. LIGO/Virgo/Kagra S230627c: NED Galaxies in the Localization Volume
  13. Konus-Wind detection of GRB 230616A
  14. LIGO/Virgo/KAGRA S230627c: Correction to HasMassGap probability
  15. LIGO/Virgo/KAGRA S230627c: Zwicky Transient Facility observations and candidates
  16. LIGO/Virgo/KAGRA S230627c: Coverage and upper limits from MAXI/GSC observations
  17. LIGO/Virgo/KAGRA S230627c: Updated Sky localization and EM Bright Classification
  18. LIGO/Virgo/KAGRA S230627c: Identification of a GW compact binary merger candidate
  19. GRB 230618A: Swift-BAT refined analysis
  20. GRB 230625B: Swift/BAT-GUANO detection of a long burst
  21. LIGO/Virgo/KAGRA S230624av: Updated Sky localization
  22. GRB 230622A: Swift-BAT refined analysis
  23. GRB 230623A: Swift-XRT observations
  24. GRB 230625A: Fermi GBM Final Real-time Localization
  25. INTEGRAL upper limit on any GRB associated with ZTF23aaoohpy/AT2023lcr
  26. ZTF23aaoohpy/AT2023lcr: further SAO RAS observations
  27. ATLAS23msn/ZTF23aaoohpy/AT2023lcr: Zeiss-1000 of Koshka observatory optical observations
  28. GRB 230623B: Swift/BAT-GUANO detection of a long burst outside the coded FOV 
  29. LIGO/Virgo/KAGRA S230624av: Identification of a GW compact binary merger candidate
  30. IceCube-Cascade 230622A: Upper limits from a search for additional neutrino events in IceCube
  31. GRB 230623A: Tiled Swift observations
  32. MAXI GRB 230623A: MASTER optical observations
  33. GRB 230623A: Tiled Swift observations
  34. GRB 230622A: ATCA rapid radio follow-up
  35. GRB 230622A: Swift-XRT refined Analysis
  36. GRB 230623A: MAXI/GSC detection
  37. Swift GRB 230622A: Global MASTER-Net observations report
  38. LIGO/Virgo/KAGRA S230615az: LBT spectroscopic classification of GOTO23hn
  39. LIGO/Virgo/KAGRA S230622ba: Retraction of GW compact binary merger candidate
  40. LIGO/Virgo S230622e: Global MASTER-Net observations report
  41. LIGO/Virgo S230621bq: Global MASTER-Net observations report
  42. LIGO/Virgo S230621ad: Global MASTER-Net observations report
  43. LIGO/Virgo/KAGRA S230615az: LBT spectroscopic redshift of the host galaxy of GOTO23hn
  44. ZTF23aaoohpy/AT2023lcr: SAO RAS observations
  45. Fermi GBM-230619: AstroSat CZTI non-detection and upper limits for the sub-threshold candidate
  46. GRB 230622A: Swift detection of a burst
  47. IceCube-Cascade 230621A: Upper limits from a search for additional neutrino events in IceCube
  48. GRB 230621A: Fermi GBM Final Localization Correction
  49. Fermi trigger No 709083929: Global MASTER-Net observations report
  50. Fermi GBM-230619: A soft subthreshold candidate potentially associated with a subthreshold LIGO/Virgo compact binary merger candidate
  51. AT2023lcr: VLA radio detection
  52. ZTF23aaoohpy/AT2023lcr: Montarrenti Observatory optical observations
  53. ZTF23aaoohpy (AT2023lcr/ATLAS23msn): Upper limits from Konus-Wind observations
  54. LIGO/Virgo S230620ad: Global MASTER-Net observations report
  55. ZTF23aaoohpy (AT2023lcr/ATLAS23msn): Swift/UVOT detection
  56. LIGO/Virgo S230620au: Global MASTER-Net observations report
  57. ZTF23aaoohpy/AT2023lc: Mondy optical observations
  58. IPN triangulation of GRB 230616A (short)
  59. LIGO/Virgo/KAGRA S230619bg: one counterpart neutrino candidate from IceCube neutrino searches
  60. AT2023lcr: Neil Gehrels Swift Observatory X-ray detection
  61. AT2023lcr (ATLAS23msn/ZTF23aaoohpy): Kinder observations with Lulin observatory and a probable plateau in the g-band light curve
  62. AT2023lcr: Pan-STARRS & ATLAS Observations
  63. ZTF23aaoohpy/AT2023lcr: Keck/LRIS spectroscopy and redshift
  64. ZTF23aaoohpy/AT2023lcr: Xinglong-2.16m optical observations
  65. LIGO/Virgo/KAGRA S230615az: Wendelstein observations of DESI galaxies and GIT candidates
  66. LIGO/Virgo S230620al: Global MASTER-Net observations report
  67. LIGO/Virgo S230620af: Global MASTER-Net observations report
  68. LIGO/Virgo S230620z: Global MASTER-Net observations report
  69. LIGO/Virgo S230620w: Global MASTER-Net observations report
  70. LIGO/Virgo S230619bg: Global MASTER-Net observations report
  71. LIGO/Virgo S230620g: Global MASTER-Net observations report
  72. LIGO/Virgo S230619ay: Global MASTER-Net observations report
  73. ZTF23aaoohpy/AT2023lcr: Liverpool Telescope detection
  74. ZTF23aaoohpy/AT2023lcr: OHP/T193 and OHP/T120 optical follow-up observations
  75. LIGO/Virgo S230619bd: Global MASTER-Net observations report
  76. LIGO/Virgo S230619bb: Global MASTER-Net observations report
  77. LIGO/Virgo S230619as: Global MASTER-Net observations report
  78. LIGO/Virgo S230619ap: Global MASTER-Net observations report
  79. ZTF23aaoohpy/AT2023lcr: GROWTH-India Telescope follow-up observations
  80. GRB 230618A: Osservatorio Astronomico Nastro verde upper limit
  81. ZTF23aaoohpy/AT2023lcr: GOTO early optical observations and constraint
  82. ZTF23aaoohpy/AT2023lcr: Zwicky Transient Facility discovery of a fast fading red transient
  83. LIGO/Virgo S230619i: Global MASTER-Net observations report
  84. LIGO/Virgo/KAGRA S230615az: GRANDMA observations of GOTO and GIT candidates
  85. LIGO/Virgo S230619aa: Global MASTER-Net observations report
  86. LIGO/Virgo S230619x: Global MASTER-Net observations report
  87. LIGO/Virgo S230619e: Global MASTER-Net observations report
  88. LIGO/Virgo S230618at: Global MASTER-Net observations report
  89. LIGO/Virgo S230618ba: Global MASTER-Net observations report
  90. LIGO/Virgo S230618az: Global MASTER-Net observations report
  91. LIGO/Virgo S230618ae: Global MASTER-Net observations report
  92. LIGO/Virgo S230618aq: Global MASTER-Net observations report
  93. LIGO/Virgo S230618y: Global MASTER-Net observations report
  94. LIGO/Virgo S230618s: Global MASTER-Net observations report
  95. GRB 230618A: Enhanced Swift-XRT position
  96. GRB 230618A: Swift/UVOT Upper Limits
  97. GRB 230618A: Swift-XRT refined Analysis
  98. GRB 230616A: Swift-XRT observations
  99. LIGO/Virgo S230618r: Global MASTER-Net observations report
  100. LIGO/Virgo S230616aa: Global MASTER-Net observations report

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