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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').
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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"

28039 results found.

  1. GRB 230628E: Swift-XRT refined Analysis
  2. GRB 230628E: Enhanced Swift-XRT position (Correction to name in GCN 34115)
  3. GRB 230628A: Enhanced Swift-XRT position
  4. LIGO/Virgo/KAGRA S230628ax: Identification of a GW compact binary merger candidate
  5. GRB 230628E: LCOGT Optical Upper Limit
  6. GRB 230628E: Swift detection of a burst
  7. GRB 230628D: BALROG localization (Fermi Trigger 709676556 / GRB 230628849)
  8. LIGO/Virgo/KAGRA low-significance gravitational wave candidate S230628aj: one counterpart neutrino candidate from IceCube neutrino searches
  9. GRB 230628B: Swift/BAT-GUANO detection of a burst outside the coded FOV
  10. ZTF23aaoohpy /AT2023lcr: TNG NIR detection
  11. LIGO/Virgo/KAGRA S230527c: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  12. LIGO/Virgo/KAGRA S230627c: ATLAS information on the ZTF candidates
  13. LIGO/Virgo/KAGRA S230627c: Upper limits from Fermi-GBM Observations
  14. GRB230626A: Fermi GBM Detection
  15. LIGO/Virgo/KAGRA S230627c: Coverage and upper limits from MAXI/GSC observations
  16. LIGO/Virgo/KAGRA S230627c: Updated Sky localization and EM Bright Classification
  17. LIGO/Virgo/KAGRA S230627c: Identification of a GW compact binary merger candidate
  18. GRB 230618A: Swift-BAT refined analysis
  19. GRB 230625B: Swift/BAT-GUANO detection of a long burst
  20. LIGO/Virgo/KAGRA S230624av: Updated Sky localization
  21. GRB 230622A: Swift-BAT refined analysis
  22. GRB 230623A: Swift-XRT observations
  23. INTEGRAL upper limit on any GRB associated with ZTF23aaoohpy/AT2023lcr
  24. ZTF23aaoohpy/AT2023lcr: further SAO RAS observations
  25. ATLAS23msn/ZTF23aaoohpy/AT2023lcr: Zeiss-1000 of Koshka observatory optical observations
  26. GRB 230623B: Swift/BAT-GUANO detection of a long burst outside the coded FOV 
  27. LIGO/Virgo/KAGRA S230624av: Identification of a GW compact binary merger candidate
  28. IceCube-Cascade 230622A: Upper limits from a search for additional neutrino events in IceCube
  29. GRB 230622A: Swift-XRT refined Analysis
  30. GRB 230623A: MAXI/GSC detection
  31. ZTF23aaoohpy/AT2023lcr: SAO RAS observations
  32. Fermi GBM-230619: AstroSat CZTI non-detection and upper limits for the sub-threshold candidate
  33. GRB 230622A: Swift detection of a burst
  34. IceCube-Cascade 230621A: Upper limits from a search for additional neutrino events in IceCube
  35. Fermi GBM-230619: A soft subthreshold candidate potentially associated with a subthreshold LIGO/Virgo compact binary merger candidate
  36. ZTF23aaoohpy/AT2023lcr: Montarrenti Observatory optical observations
  37. ZTF23aaoohpy (AT2023lcr/ATLAS23msn): Upper limits from Konus-Wind observations
  38. ZTF23aaoohpy/AT2023lc: Mondy optical observations
  39. IPN triangulation of GRB 230616A (short)
  40. LIGO/Virgo/KAGRA S230619bg: one counterpart neutrino candidate from IceCube neutrino searches
  41. AT2023lcr: Neil Gehrels Swift Observatory X-ray detection
  42. AT2023lcr (ATLAS23msn/ZTF23aaoohpy): Kinder observations with Lulin observatory and a probable plateau in the g-band light curve
  43. AT2023lcr: Pan-STARRS & ATLAS Observations
  44. ZTF23aaoohpy/AT2023lcr: Keck/LRIS spectroscopy and redshift
  45. ZTF23aaoohpy/AT2023lcr: Xinglong-2.16m optical observations
  46. LIGO/Virgo/KAGRA S230615az: Wendelstein observations of DESI galaxies and GIT candidates
  47. ZTF23aaoohpy/AT2023lcr: OHP/T193 and OHP/T120 optical follow-up observations
  48. ZTF23aaoohpy/AT2023lcr: GROWTH-India Telescope follow-up observations
  49. GRB 230618A: Osservatorio Astronomico Nastro verde upper limit
  50. ZTF23aaoohpy/AT2023lcr: GOTO early optical observations and constraint
  51. ZTF23aaoohpy/AT2023lcr: Zwicky Transient Facility discovery of a fast fading red transient
  52. GRB 230618A: Enhanced Swift-XRT position
  53. GRB 230618A: Swift/UVOT Upper Limits
  54. GRB 230618A: Swift-XRT refined Analysis
  55. GRB 230616A: Swift-XRT observations
  56. LIGO/Virgo S230616aa: Global MASTER-Net observations report
  57. LIGO/Virgo S230615an: Global MASTER-Net observations report
  58. GRB230618A: LCOGT Optical Observations
  59. GRB 230618A: Swift detection of a burst
  60. LIGO/Virgo/KAGRA S230615az: T80S Search and Candidate Counterpart Identification
  61. GRB 230616A: Swift/BAT-GUANO detection of a short burst outside the coded FOV
  62. LIGO/Virgo/KAGRA S230615az: Xinglong-2.16m photometric observations of GIT candidates
  63. LIGO/Virgo/KAGRA S230529ay: Upper limits from a two-week IceCube neutrino search
  64. LIGO/Virgo/KAGRA S230615az: GROWTH-India candidates
  65. GRB 230614B: Fermi GBM Observation
  66. GRB 230614C: Fermi GBM Detection
  67. LIGO/Virgo S230613at: Global MASTER-Net observations report
  68. LIGO/Virgo S230614t: Global MASTER-Net observations report
  69. GRB 230614B: Swift/BAT-GUANO detection outside the coded FOV
  70. Fermi trigger No 708426906: Global MASTER-Net observations report
  71. GRB 230606A: LCOGT Optical Observations
  72. IceCube-Cascade 230610A: Upper limits from a search for additional neutrino events in IceCube
  73. LIGO/Virgo/KAGRA S230608as: Updated Sky localization
  74. LIGO/Virgo/KAGRA S230606d: Updated Sky localization
  75. LIGO/Virgo/KAGRA S230609u: Updated Sky localization
  76. LIGO/Virgo/KAGRA S230609u: Identification of a GW compact binary merger candidate
  77. LIGO/Virgo S230608as: Global MASTER-Net observations report
  78. ZTF23aamxeqf/AT2023jxk: 1.3m DFOT Optical upper limit
  79. LIGO/Virgo/KAGRA S230608as: Identification of a GW compact binary merger candidate
  80. Fermi GRB 230603A: Global MASTER-Net observations report
  81. Fermi trigger No 707039690: Global MASTER-Net observations report
  82. ZTF and GIT Observations of the Candidate Optical Afterglow AT2023jxk
  83. GRB 230606A: Swift-BAT refined analysis
  84. GRB 230606A: Gaoyazi/GOT optical upper limit
  85. GRB 230606A: Fermi GBM Observation
  86. GRB 230606A: Swift-XRT refined Analysis
  87. GRB 230604A: GRBAlpha detection
  88. GRB 230606A: Swift/UVOT Upper Limits
  89. GRB 230606A: Enhanced Swift-XRT position
  90. LIGO/Virgo/KAGRA S230606d: Identification of a GW compact binary merger candidate
  91. Fermi-LAT gamma-ray observations of IceCube-230603A
  92. LIGO/Virgo/KAGRA S230605o: Updated Sky localization
  93. IceCube-230603A: Upper limits from a search for additional neutrino events in IceCube
  94. LIGO/Virgo/KAGRA S230601bf: Updated Sky localization
  95. LIGO/Virgo/KAGRA S230605o: Identification of a GW compact binary merger candidate
  96. LIGO/Virgo S230602ap: Global MASTER-Net observations report
  97. LIGO/Virgo/KAGRA S230518h: Upper limits from a two-week IceCube neutrino search
  98. GRB 230521A: VZLUSAT-2 detection
  99. GRB 230522A: GRBAlpha and VZLUSAT-2 joint detection
  100. LIGO/Virgo/KAGRA S230601bf: Identification of a GW compact binary merger candidate

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