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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. GRB 200219C: Fermi GBM detection
  2. LIGO/Virgo S200213t: AT2020clw/ZTF20aanaoyz, AT2020crd/ZTF20aanakge and AT2020cly/ZTF20aanakes 10.4m GTC spectroscopy
  3. LIGO/Virgo S200213t: Swift UVOT and XRT observations of ZTF20aamvmzj (AT2020cja)
  4. GRB 200219C: Tiled Swift observations
  5. GRB 200219C: Fermi-LAT detection
  6. GRB 200215A: LCO Optical Upper Limits
  7. LIGO/Virgo S200219ac: No transient candidates in CALET observations
  8. GRB 200219A, Swift-BAT refined analysis
  9. LIGO/Virgo S200219ac: no counterpart candidates in the Swift/BAT observations
  10. Fermi trigger No 603849435: Global MASTER-Net observations report
  11. GRB 200219C: Fermi GBM Final Real-time Localization
  12. LIGO/Virgo S200219ac: Fermi GBM transient event not confidently associated with GW signal
  13. LIGO/Virgo S200219ac: No counterpart candidates in Fermi-LAT observations
  14. GRB 200219A: Swift-XRT refined Analysis correction
  15. LIGO/Virgo S200219ac: upper limits from AGILE/GRID observations
  16. LIGO/Virgo S200213t: Keck/LRIS spectroscopy of counterpart candidates from the Zwicky Transient Facility
  17. GRB 200219A: Swift-XRT refined Analysis
  18. GRB 200219A: Enhanced Swift-XRT position
  19. GRB 200219A: Fermi GBM observation
  20. LIGO/Virgo S200219ac: upper limits from AGILE/MCAL observations
  21. LIGO/Virgo S200219ac : no neutrino counterpart candidate in ANTARES search
  22. LIGO/Virgo S200219ac: Upper limits from IceCube neutrino searches
  23. LIGO/Virgo S200219ac: No counterpart candidates in HAWC observations
  24. LIGO/Virgo S200219ac: Coverage and upper limits from MAXI/GSC observations
  25. LIGO/Virgo S200219ac: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  26. LIGO/Virgo S200219ac: Identification of a GW compact binary merger candidate
  27. LIGO/Virgo S200219ac: Global MASTER-Net observations report
  28. GRB 200216B: second epoch optical upper limit at Mondy observatory
  29. GRB 200219B: Fermi GBM Final Real-time Localization
  30. GRB 200219A: MASTER catalog automatic possible Host Galaxy candidate
  31. GRB 200219A: Swift detection of a short burst
  32. Swift GRB200219.32: Global MASTER-Net observations report
  33. GRB 200219A: Fermi GBM Final Real-time Localization
  34. GRB 200216B: Mondy and AbAO optical upper limits
  35. LIGO/Virgo (S200213t/IceCube neutrino candidate: No counterpart candidates in the Swift-XRT Observations
  36. GRB 200216B: Swift-XRT refined Analysis
  37. LIGO/Virgo S200213t: No EM counterparts found from continued GECKO observation of host galaxy candidates
  38. LIGO/Virgo S200213t: APO Upper Limits for ZTF20aanakes/AT2020cly
  39. GRB 200216B: Swift-BAT refined analysis
  40. LIGO/Virgo S200213t : No significant candidates in FRAM - OAJ - TAROT - GRANDMA observations
  41. Further Swift-XRT observations of Swift J0840.7-3516
  42. GRB 200216B - possible IR counterpart from VLT
  43. GRB 200215A: CALET Gamma-Ray Burst Monitor detection
  44. GRB 200216A: Fermi GBM detection
  45. LIGO/Virgo S200213t: AstroSat CZTI upper limits
  46. GRB 200216B: z-band limit from NOT
  47. GRB 200216B: Fermi GBM observation
  48. GRB 200216B: Swift/UVOT Upper Limits
  49. GRB 200216A: Swift/BAT detection and arcminute localization from GUANO
  50. GRB 200216B: Enhanced Swift-XRT position
  51. GRB 200215A: RATIR Optical Observations
  52. GRB 200216B: Nanshan/NEXT early optical upper limit and possible host galaxy
  53. GRB 200216B: GMG upper limit
  54. GRB 200216B: Swift detection of a burst
  55. GRB 200216B: Fermi GBM Final Real-time Localization
  56. Swift GRB200216.56: Global MASTER-Net observations report
  57. GRB 200215A: UKIRT H-band observations
  58. GRB 200215A: Swift-BAT refined analysis
  59. GRB 200216A: Fermi GBM Final Real-time Localization
  60. LIGO/Virgo S200213t: Updated Sky Localization
  61. LIGO/Virgo S200213t: Updated coverage and candidate list for the Zwicky Transient Facility
  62. LIGO/Virgo S200213t: CLU/NED Galaxies in the 4-Update Localization Volume
  63. LIGO/Virgo S200213t: Possible host galaxies in the bilby skymap
  64. LIGO/Virgo S200213t: Updated Sky Localization
  65. GRB 200215A: Swift-XRT refined Analysis
  66. GRB 200215A: Swift/UVOT Upper Limits
  67. GRB 200215A: Enhanced Swift-XRT position
  68. GRB 200215A: Optical observations form Calar Alto 2.2m
  69. GRB 200215A: Fermi GBM detection
  70. GRB 200215A: Liverpool Telescope upper limits
  71. LIGO/Virgo S200213t: Pre-discovery detections of MASTER OT J044008.76-651302.3
  72. LIGO/Virgo S200213t: No transient candidates in CALET observations
  73. GRB 200215A Possible host galaxy in PanSTARRS
  74. LIGO/Virgo S200213t: Lulin Follow-Up Observations
  75. GRB 200215A: Nanshan/NEXT optical upper limit
  76. Swift GRB200215.61: Global MASTER-Net observations report
  77. GRB 200215A: Swift detection of a burst
  78. GRB 200215A: Fermi GBM Final Real-time Localization
  79. LIGO/Virgo S200213t: MASTER possible Kilonova candidate in PGC315337
  80. LIGO/Virgo S200213t: No neutrino candidates at Pierre Auger Observatory
  81. LIGO/Virgo S200213t: P200 Spectroscopy of ZTF20aanakcd/AT2020cmr
  82. LIGO/Virgo S200213t: DBSP spectroscopy of AT2020cjb/ZTF20aamvnth, AT2020cja/ZTF20aamvmzj, AT2020cjc/ZTF20aamvoeh
  83. LIGO/Virgo S200114f: Gemini Spectra of AT 2020vu, AT 2020vw, AT 2020vy, and AT 2020vz
  84. LIGO/Virgo S200213t: MASTER OT detection in PGC673735
  85. LIGO/Virgo S200213t: Upper limits from Insight-HXMT/HE observations
  86. LIGO/Virgo S200213t: No counterpart candidates from Nanshan-0.6m observations
  87. LIGO/Virgo S200213t: No notable candidates in GOTO imaging
  88. LIGO/Virgo S200213t: One additional candidate from the Zwicky Transient Facility
  89. LIGO/Virgo S200213t: No Counterparts from GECKO observation of host galaxy candidates in GW-neutrino detection overlap area
  90. LIGO/Virgo S200213t: No candidates found in J-GEM follow-up observations
  91. LIGO/Virgo S200213t: More Candidates from the Zwicky Transient Facility
  92. LIGO/Virgo S200213t: No counterpart candidates in KAIT observations
  93. LIGO/Virgo S200213t: AT2020ciz/ZTF20aamvnat, AT2020cjb/ZTF20aamvnth and 2020cjf/ZTF20aamvodd 10.4m GTC spectroscopy
  94. LIGO/Virgo S200213t: No counterpart candidates in Fermi-LAT observations
  95. LIGO/Virgo S200213t: No Counterparts in DDOTI/OAN Optical Observations
  96. LIGO/Virgo S200213t: AT2020ciy/ZTF20aamvqxl, AT2020cjg/ZTF20aamvoxx and AT2020cje/ZTF20aamvtip 10.4m GTC spectroscopy
  97. LIGO/Virgo S200213t: MANGROVE catalog galaxy ranking
  98. LIGO/Virgo S200213t: Swift/BAT in the South Atlantic Anomaly
  99. LIGO/Virgo S191213g: AT2019wxt Wendelstein optical observations
  100. LIGO/Virgo S200213t: not observable by Fermi-GBM

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