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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. GRB 230701B: AstroSat CZTI detection
  2. LIGO/Virgo/KAGRA S230627c: observations of ZTF23aaptsuy/AT2023lx in AbAO observatory
  3. LIGO/Virgo/KAGRA S230702an: Identification of a GW compact binary merger candidate
  4. GRB 230628E: Swift/UVOT Detection
  5. GRB 230628E: Swift-BAT refined analysis
  6. GRB 230702A: Fermi GBM Final Real-time Localization
  7. GRB 230628E: ATCA rapid radio follow-up
  8. GRB 230701A: Fermi GBM Final Real-time Localization
  9. LIGO/Virgo/KAGRA S230627c: GRANDMA observations of galaxies and ZTF counterpart candidates
  10. LIGO/Virgo/KAGRA low-significance gravitational wave candidate S230701z: one counterpart neutrino candidate from IceCube neutrino searches
  11. LIGO/Virgo/KAGRA S230627c: Upper limits from Swift/BAT-GUANO
  12. LIGO/Virgo/KAGRA S230630bq: Identification of a GW compact binary merger candidate
  13. IPN triangulation of GRB 230625B (ultra-long)
  14. AT2023lcr (ATLAS23msn/ZTF23aaoohpy): ALMA 100 GHz Detection
  15. LIGO/Virgo/KAGRA S230630am: Identification of a GW compact binary merger candidate
  16. GRB 230625B: CALET Gamma-Ray Burst Monitor detection
  17. GRB 230628E - VLT spectroscopic observations
  18. ZTF23aaoohpy/AT2023lcr: LBT observations
  19. Fermi GRB 230628C: Global MASTER-Net observations report
  20. GRB 230625B: AstroSat CZTI detection
  21. GRB230628E: VLT optical identification of afterglow candidate
  22. GRB 230628E: Swift-XRT refined Analysis
  23. GRB 230628E: Enhanced Swift-XRT position (Correction to name in GCN 34115)
  24. GRB 230628A: Enhanced Swift-XRT position
  25. Fermi GRB 230628D: Global MASTER-Net observations report
  26. LIGO/Virgo/KAGRA S230628ax: Identification of a GW compact binary merger candidate
  27. GRB 230628E: LCOGT Optical Upper Limit
  28. Swift GRB230628.93: Global MASTER-Net observations report
  29. GRB 230628E: Swift detection of a burst
  30. GRB 230628D: BALROG localization (Fermi Trigger 709676556 / GRB 230628849)
  31. GRB 230628D: Fermi GBM Final Real-time Localization
  32. LIGO/Virgo/KAGRA low-significance gravitational wave candidate S230628aj: one counterpart neutrino candidate from IceCube neutrino searches
  33. GRB 230628C: Fermi GBM Final Real-time Localization
  34. GRB 230628B: Swift/BAT-GUANO detection of a burst outside the coded FOV
  35. GRB 230623B: CALET Gamma-Ray Burst Monitor detection
  36. LIGO/Virgo/KAGRA S230516az: GOTO candidate counterpart GOTO23hu ruled out by Zwicky Transient Facility observations
  37. ZTF23aaoohpy /AT2023lcr: TNG NIR detection
  38. GRB 230628A: Fermi GBM Final Localization
  39. LIGO/Virgo/KAGRA S230627c: Additional observations from the Zwicky Transient Facility
  40. GRB 230626A: GRBAlpha detection
  41. AT2023lcr: JCMT SCUBA-2 sub-mm observations
  42. LIGO/Virgo/KAGRA S230527c: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  43. LIGO/Virgo/KAGRA S230627c: ATLAS information on the ZTF candidates
  44. LIGO/Virgo/KAGRA S230627c: Upper limits from Fermi-GBM Observations
  45. GRB230626A: Fermi GBM Detection
  46. LIGO/Virgo/KAGRA S230627c: Global MASTER-Net observations report
  47. LIGO/Virgo/Kagra S230627c: NED Galaxies in the Localization Volume
  48. Konus-Wind detection of GRB 230616A
  49. LIGO/Virgo/KAGRA S230627c: Correction to HasMassGap probability
  50. LIGO/Virgo/KAGRA S230627c: Zwicky Transient Facility observations and candidates
  51. LIGO/Virgo/KAGRA S230627c: Coverage and upper limits from MAXI/GSC observations
  52. LIGO/Virgo/KAGRA S230627c: Updated Sky localization and EM Bright Classification
  53. LIGO/Virgo/KAGRA S230627c: Identification of a GW compact binary merger candidate
  54. GRB 230618A: Swift-BAT refined analysis
  55. GRB 230625B: Swift/BAT-GUANO detection of a long burst
  56. LIGO/Virgo/KAGRA S230624av: Updated Sky localization
  57. GRB 230622A: Swift-BAT refined analysis
  58. GRB 230623A: Swift-XRT observations
  59. GRB 230625A: Fermi GBM Final Real-time Localization
  60. INTEGRAL upper limit on any GRB associated with ZTF23aaoohpy/AT2023lcr
  61. ZTF23aaoohpy/AT2023lcr: further SAO RAS observations
  62. ATLAS23msn/ZTF23aaoohpy/AT2023lcr: Zeiss-1000 of Koshka observatory optical observations
  63. GRB 230623B: Swift/BAT-GUANO detection of a long burst outside the coded FOV 
  64. LIGO/Virgo/KAGRA S230624av: Identification of a GW compact binary merger candidate
  65. IceCube-Cascade 230622A: Upper limits from a search for additional neutrino events in IceCube
  66. GRB 230623A: Tiled Swift observations
  67. MAXI GRB 230623A: MASTER optical observations
  68. GRB 230623A: Tiled Swift observations
  69. GRB 230622A: ATCA rapid radio follow-up
  70. GRB 230622A: Swift-XRT refined Analysis
  71. GRB 230623A: MAXI/GSC detection
  72. Swift GRB 230622A: Global MASTER-Net observations report
  73. LIGO/Virgo/KAGRA S230615az: LBT spectroscopic classification of GOTO23hn
  74. LIGO/Virgo/KAGRA S230622ba: Retraction of GW compact binary merger candidate
  75. LIGO/Virgo S230622e: Global MASTER-Net observations report
  76. LIGO/Virgo S230621bq: Global MASTER-Net observations report
  77. LIGO/Virgo S230621ad: Global MASTER-Net observations report
  78. LIGO/Virgo/KAGRA S230615az: LBT spectroscopic redshift of the host galaxy of GOTO23hn
  79. ZTF23aaoohpy/AT2023lcr: SAO RAS observations
  80. Fermi GBM-230619: AstroSat CZTI non-detection and upper limits for the sub-threshold candidate
  81. GRB 230622A: Swift detection of a burst
  82. IceCube-Cascade 230621A: Upper limits from a search for additional neutrino events in IceCube
  83. GRB 230621A: Fermi GBM Final Localization Correction
  84. Fermi trigger No 709083929: Global MASTER-Net observations report
  85. Fermi GBM-230619: A soft subthreshold candidate potentially associated with a subthreshold LIGO/Virgo compact binary merger candidate
  86. AT2023lcr: VLA radio detection
  87. ZTF23aaoohpy/AT2023lcr: Montarrenti Observatory optical observations
  88. ZTF23aaoohpy (AT2023lcr/ATLAS23msn): Upper limits from Konus-Wind observations
  89. LIGO/Virgo S230620ad: Global MASTER-Net observations report
  90. ZTF23aaoohpy (AT2023lcr/ATLAS23msn): Swift/UVOT detection
  91. LIGO/Virgo S230620au: Global MASTER-Net observations report
  92. ZTF23aaoohpy/AT2023lc: Mondy optical observations
  93. IPN triangulation of GRB 230616A (short)
  94. LIGO/Virgo/KAGRA S230619bg: one counterpart neutrino candidate from IceCube neutrino searches
  95. AT2023lcr: Neil Gehrels Swift Observatory X-ray detection
  96. AT2023lcr (ATLAS23msn/ZTF23aaoohpy): Kinder observations with Lulin observatory and a probable plateau in the g-band light curve
  97. AT2023lcr: Pan-STARRS & ATLAS Observations
  98. ZTF23aaoohpy/AT2023lcr: Keck/LRIS spectroscopy and redshift
  99. ZTF23aaoohpy/AT2023lcr: Xinglong-2.16m optical observations
  100. LIGO/Virgo/KAGRA S230615az: Wendelstein observations of DESI galaxies and GIT candidates

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