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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 200216B: Swift detection of a burst
  2. GRB 200216B: Fermi GBM Final Real-time Localization
  3. Swift GRB200216.56: Global MASTER-Net observations report
  4. GRB 200215A: UKIRT H-band observations
  5. GRB 200215A: Swift-BAT refined analysis
  6. GRB 200216A: Fermi GBM Final Real-time Localization
  7. LIGO/Virgo S200213t: Updated Sky Localization
  8. LIGO/Virgo S200213t: Updated coverage and candidate list for the Zwicky Transient Facility
  9. LIGO/Virgo S200213t: CLU/NED Galaxies in the 4-Update Localization Volume
  10. LIGO/Virgo S200213t: Possible host galaxies in the bilby skymap
  11. LIGO/Virgo S200213t: Updated Sky Localization
  12. GRB 200215A: Swift-XRT refined Analysis
  13. GRB 200215A: Swift/UVOT Upper Limits
  14. GRB 200215A: Enhanced Swift-XRT position
  15. GRB 200215A: Optical observations form Calar Alto 2.2m
  16. GRB 200215A: Fermi GBM detection
  17. GRB 200215A: Liverpool Telescope upper limits
  18. LIGO/Virgo S200213t: Pre-discovery detections of MASTER OT J044008.76-651302.3
  19. LIGO/Virgo S200213t: No transient candidates in CALET observations
  20. GRB 200215A Possible host galaxy in PanSTARRS
  21. LIGO/Virgo S200213t: Lulin Follow-Up Observations
  22. GRB 200215A: Nanshan/NEXT optical upper limit
  23. Swift GRB200215.61: Global MASTER-Net observations report
  24. GRB 200215A: Swift detection of a burst
  25. GRB 200215A: Fermi GBM Final Real-time Localization
  26. LIGO/Virgo S200213t: MASTER possible Kilonova candidate in PGC315337
  27. LIGO/Virgo S200213t: No neutrino candidates at Pierre Auger Observatory
  28. LIGO/Virgo S200213t: P200 Spectroscopy of ZTF20aanakcd/AT2020cmr
  29. LIGO/Virgo S200213t: DBSP spectroscopy of AT2020cjb/ZTF20aamvnth, AT2020cja/ZTF20aamvmzj, AT2020cjc/ZTF20aamvoeh
  30. LIGO/Virgo S200114f: Gemini Spectra of AT 2020vu, AT 2020vw, AT 2020vy, and AT 2020vz
  31. LIGO/Virgo S200213t: MASTER OT detection in PGC673735
  32. LIGO/Virgo S200213t: Upper limits from Insight-HXMT/HE observations
  33. LIGO/Virgo S200213t: No counterpart candidates from Nanshan-0.6m observations
  34. LIGO/Virgo S200213t: No notable candidates in GOTO imaging
  35. LIGO/Virgo S200213t: One additional candidate from the Zwicky Transient Facility
  36. LIGO/Virgo S200213t: No Counterparts from GECKO observation of host galaxy candidates in GW-neutrino detection overlap area
  37. LIGO/Virgo S200213t: No candidates found in J-GEM follow-up observations
  38. LIGO/Virgo S200213t: More Candidates from the Zwicky Transient Facility
  39. LIGO/Virgo S200213t: No counterpart candidates in KAIT observations
  40. LIGO/Virgo S200213t: AT2020ciz/ZTF20aamvnat, AT2020cjb/ZTF20aamvnth and 2020cjf/ZTF20aamvodd 10.4m GTC spectroscopy
  41. LIGO/Virgo S200213t: No counterpart candidates in Fermi-LAT observations
  42. LIGO/Virgo S200213t: No Counterparts in DDOTI/OAN Optical Observations
  43. LIGO/Virgo S200213t: AT2020ciy/ZTF20aamvqxl, AT2020cjg/ZTF20aamvoxx and AT2020cje/ZTF20aamvtip 10.4m GTC spectroscopy
  44. LIGO/Virgo S200213t: MANGROVE catalog galaxy ranking
  45. LIGO/Virgo S200213t: Swift/BAT in the South Atlantic Anomaly
  46. LIGO/Virgo S191213g: AT2019wxt Wendelstein optical observations
  47. LIGO/Virgo S200213t: not observable by Fermi-GBM
  48. LIGO/Virgo S200213t: upper limits from AGILE/GRID observations
  49. LIGO/Virgo S200208q : No significant candidates in TAROT - FRAM - GRANDMA observations
  50. LIGO/Virgo S200208q: no counterpart candidate in SVOM/C-GFT observations
  51. LIGO/VIRGO S200213t: upper limits from AGILE/MCAL observations
  52. LIGO/Virgo S200213t: Candidates from the Zwicky Transient Facility
  53. LIGO/Virgo S200213t: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  54. LIGO/Virgo S200213t : no neutrino counterpart candidate in ANTARES search
  55. LIGO/Virgo S200213t: Coverage and upper limits from MAXI/GSC observations
  56. LIGO/Virgo S200213t: Neutrino and galaxies cross-match
  57. GRB 2002011A: AstroSat CZTI detection
  58. LIGO/Virgo trigger S200213t: Possible host galaxies
  59. LIGO/Virgo S200213t: NED Galaxies in the 90% Localization Volume
  60. LIGO/Virgo S200213t: 1 counterpart neutrino candidate from IceCube neutrino searches
  61. LIGO/Virgo S200213t: Identification of a GW compact binary merger candidate
  62. LIGO/Virgo S200213t: Global MASTER-Net observations report
  63. GRB 200212A: Fermi GBM Final Localization Correction
  64. ZTF20aajnksq: Upper limits from Konus-Wind observations
  65. Fermi trigger No 603197394: Global MASTER-Net observations report
  66. GRB 200212A: Fermi GBM Final Real-time Localization
  67. LIGO/Virgo S200208q: Updated Sky Localization
  68. GRB 200131A: Tautenburg observations
  69. Konus-Wind observation of GRB 200205B
  70. LIGO/Virgo S200208q: No counterpart candidates in KAIT observations
  71. GRB 200211A: BALROG localization (Fermi Trigger 603098793 / GRB 200211310)
  72. GRB 200211A: Fermi GBM Final Real-time Localization
  73. LIGO/Virgo S200208q: Not observable by CALET
  74. GRB 200207A: AstroSat CZTI detection
  75. LIGO/Virgo S200208q: No counterpart candidates in Fermi-LAT observations
  76. GRB 200205B: Chilescope optical observations
  77. LIGO/Virgo S200129m: Upper limits from Insight-HXMT/HE observations
  78. GRB 200120A: Fermi GBM observation
  79. LIGO/Virgo S200208q: Coverage and upper limits from MAXI/GSC observations
  80. LIGO/Virgo S200208q: no counterpart candidates in the Swift/BAT observations
  81. LIGO/Virgo S200208q: Upper limits from Fermi-GBM Observations
  82. LIGO/Virgo S200208q : upper limits from AGILE/GRID observations
  83. LIGO/Virgo S200208q: upper limits from AGILE/MCAL observations
  84. LIGO/Virgo S200208q: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  85. LIGO/Virgo S200208q: Global MASTER-Net observations report
  86. LIGO/Virgo S200208q: No counterpart candidates in HAWC observations
  87. LIGO/Virgo S200208q : no neutrino counterpart candidate in ANTARES search
  88. LIGO/Virgo S200208q: Upper limits from IceCube neutrino searches
  89. LIGO/Virgo S200208q: Identification of a GW compact binary merger candidate
  90. Fermi trigger No 602817262: Global MASTER-Net observations report
  91. GRB 200205B: Swift-BAT refined analysis
  92. GRB 200208A: Fermi GBM Final Real-time Localization
  93. Swift J0840.7-3516 (AKA GRB 200205A): Swift-BAT refined analysis
  94. Fermi trigger No 602731380: Global MASTER-Net observations report
  95. Swift Trigger 954840 is not a GRB
  96. Swift GRB200207.13: Global MASTER-Net observations report
  97. GRB 200205B: Swift/UVOT Detection
  98. GRB 200207A: Fermi GBM Final Real-time Localization
  99. GRB 200205B: ESO/NTT near-infrared imaging
  100. GRB 200205A = Swift J0840.7-3516: optical photometry in Chilescope observatory

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