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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 230709B: BALROG localization (Fermi Trigger 710614579 / GRB 230709706)
  2. IceCube-230708A: Upper limits from a search for additional neutrino events in IceCube
  3. IceCube-230707B: Upper limits from a search for additional neutrino events in IceCube
  4. IceCube-230707A: Upper limits from a search for additional neutrino events in IceCube
  5. LIGO/Virgo/KAGRA S230709bi: Identification of a GW compact binary merger candidate
  6. Swift Trigger 1178410: possible GRB 230709A
  7. LIGO/Virgo/KAGRA S230708cf: Identification of a GW compact binary merger candidate
  8. LIGO/Virgo/KAGRA S230708bi: Retraction of GW compact binary merger candidate
  9. GRB 230628C: GRID Detection
  10. IceCube-230708A - IceCube observation of a high-energy neutrino candidate track-like event
  11. GRB 230707B: Swift/BAT-GUANO detection of a burst outside the coded FOV
  12. GRB 230707A: Swift-XRT observations
  13. IceCube Alert 230708.35: Global MASTER-Net observations report
  14. IceCube-230707B - IceCube observation of a high-energy neutrino candidate track-like event
  15. GRB 230707B: Fermi GBM Final Real-time Localization
  16. IceCube Alert 230707.71: Global MASTER-Net observations report
  17. IceCube-230707A - IceCube observation of a high-energy neutrino candidate track-like event
  18. GRB 230707A: Fermi GBM Detection
  19. LIGO/Virgo/KAGRA S230707ai: Identification of a GW compact binary merger candidate
  20. GRB 230707A: Swift ToO observations
  21. GRB 230707A: Swift/BAT-GUANO arcminute localization of a burst
  22. ZTF23aaoohpy/AT2023lcr : HCT follow-up observations
  23. Fermi GRB 230707A: Global MASTER-Net observations report
  24. GRB 230707A: Fermi GBM Final Real-time Localization
  25. LIGO/Virgo/KAGRA S230706ah: Updated Sky localization
  26. Integral GRB230706.70: Global MASTER-Net observations report
  27. LIGO/Virgo/KAGRA S230704f: Updated Sky localization
  28. LIGO/Virgo/KAGRA S230630bq: Updated Sky localization
  29. IBAS trigger number 10311: not a real GRB
  30. LIGO/Virgo/KAGRA S230702an: Updated Sky localization
  31. GRB 230625A: Detection by GRID
  32. LIGO/Virgo/KAGRA S230529ay: Updated Sky localization and EM Bright Classification
  33. LIGO/Virgo/KAGRA S230706ah: Identification of a GW compact binary merger candidate
  34. LIGO/Virgo/KAGRA S230627c: GECKO optical follow-up observations of host galaxy candidates and ZTF23aaptsuy/AT2023lxu
  35. ZTF23aaoohpy/AT2023lcr: AMI-LA radio detection
  36. Fermi trigger No 710117592: Global MASTER-Net observations report
  37. GRB 230626A: VZLUSAT-2 detection
  38. LVK S230619bd/GBM-230619: Upper limits from a two-week IceCube neutrino search
  39. GRB 230328B: LBT detection of the likely host galaxy
  40. LIGO/Virgo/KAGRA S230704f: Identification of a GW compact binary merger candidate
  41. Konus-Wind detection of GRB 220623A
  42. GRB 230701B: AstroSat CZTI detection
  43. LIGO/Virgo/KAGRA S230627c: observations of ZTF23aaptsuy/AT2023lx in AbAO observatory
  44. LIGO/Virgo/KAGRA S230702an: Identification of a GW compact binary merger candidate
  45. GRB 230628E: Swift/UVOT Detection
  46. GRB 230628E: Swift-BAT refined analysis
  47. GRB 230702A: Fermi GBM Final Real-time Localization
  48. GRB 230628E: ATCA rapid radio follow-up
  49. GRB 230701A: Fermi GBM Final Real-time Localization
  50. LIGO/Virgo/KAGRA S230627c: GRANDMA observations of galaxies and ZTF counterpart candidates
  51. LIGO/Virgo/KAGRA low-significance gravitational wave candidate S230701z: one counterpart neutrino candidate from IceCube neutrino searches
  52. LIGO/Virgo/KAGRA S230627c: Upper limits from Swift/BAT-GUANO
  53. LIGO/Virgo/KAGRA S230630bq: Identification of a GW compact binary merger candidate
  54. IPN triangulation of GRB 230625B (ultra-long)
  55. AT2023lcr (ATLAS23msn/ZTF23aaoohpy): ALMA 100 GHz Detection
  56. LIGO/Virgo/KAGRA S230630am: Identification of a GW compact binary merger candidate
  57. GRB 230625B: CALET Gamma-Ray Burst Monitor detection
  58. GRB 230628E - VLT spectroscopic observations
  59. ZTF23aaoohpy/AT2023lcr: LBT observations
  60. Fermi GRB 230628C: Global MASTER-Net observations report
  61. GRB 230625B: AstroSat CZTI detection
  62. GRB230628E: VLT optical identification of afterglow candidate
  63. GRB 230628E: Swift-XRT refined Analysis
  64. GRB 230628E: Enhanced Swift-XRT position (Correction to name in GCN 34115)
  65. GRB 230628A: Enhanced Swift-XRT position
  66. Fermi GRB 230628D: Global MASTER-Net observations report
  67. LIGO/Virgo/KAGRA S230628ax: Identification of a GW compact binary merger candidate
  68. GRB 230628E: LCOGT Optical Upper Limit
  69. Swift GRB230628.93: Global MASTER-Net observations report
  70. GRB 230628E: Swift detection of a burst
  71. GRB 230628D: BALROG localization (Fermi Trigger 709676556 / GRB 230628849)
  72. GRB 230628D: Fermi GBM Final Real-time Localization
  73. LIGO/Virgo/KAGRA low-significance gravitational wave candidate S230628aj: one counterpart neutrino candidate from IceCube neutrino searches
  74. GRB 230628C: Fermi GBM Final Real-time Localization
  75. GRB 230628B: Swift/BAT-GUANO detection of a burst outside the coded FOV
  76. GRB 230623B: CALET Gamma-Ray Burst Monitor detection
  77. LIGO/Virgo/KAGRA S230516az: GOTO candidate counterpart GOTO23hu ruled out by Zwicky Transient Facility observations
  78. ZTF23aaoohpy /AT2023lcr: TNG NIR detection
  79. GRB 230628A: Fermi GBM Final Localization
  80. LIGO/Virgo/KAGRA S230627c: Additional observations from the Zwicky Transient Facility
  81. GRB 230626A: GRBAlpha detection
  82. AT2023lcr: JCMT SCUBA-2 sub-mm observations
  83. LIGO/Virgo/KAGRA S230527c: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  84. LIGO/Virgo/KAGRA S230627c: ATLAS information on the ZTF candidates
  85. LIGO/Virgo/KAGRA S230627c: Upper limits from Fermi-GBM Observations
  86. GRB230626A: Fermi GBM Detection
  87. LIGO/Virgo/KAGRA S230627c: Global MASTER-Net observations report
  88. LIGO/Virgo/Kagra S230627c: NED Galaxies in the Localization Volume
  89. Konus-Wind detection of GRB 230616A
  90. LIGO/Virgo/KAGRA S230627c: Correction to HasMassGap probability
  91. LIGO/Virgo/KAGRA S230627c: Zwicky Transient Facility observations and candidates
  92. LIGO/Virgo/KAGRA S230627c: Coverage and upper limits from MAXI/GSC observations
  93. LIGO/Virgo/KAGRA S230627c: Updated Sky localization and EM Bright Classification
  94. LIGO/Virgo/KAGRA S230627c: Identification of a GW compact binary merger candidate
  95. GRB 230618A: Swift-BAT refined analysis
  96. GRB 230625B: Swift/BAT-GUANO detection of a long burst
  97. LIGO/Virgo/KAGRA S230624av: Updated Sky localization
  98. GRB 230622A: Swift-BAT refined analysis
  99. GRB 230623A: Swift-XRT observations
  100. GRB 230625A: Fermi GBM Final Real-time Localization

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