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Observation by Kevin Gurney: Flux calibrated spectrum: AG Dra

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Kevin Gurney


Kevin Gurney


2020 May 31 - 23:30


2020 Jun 28 - 11:16

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Field centre

RA: 05h55m
Dec: +07°31'
Position angle: -4°49'

Field size

0°25' × 0°14'

  • Celestron C11, Alpy 600
  • RVO 80mm refractor, Baader V filter
  • Atik 460EX (spectroscopy)
  • ZWO ASI 1600mono (photom)
  • Fornax 102 mount

spectrocopy - 10x300s subs; photometry - 10x10s observations



Target name

AG Dra


Flux calibrated spectrum: AG Dra

About this image

My first attempt at flux calibration of a low res spectrum (following
the method of David Boyd). The V-filter magnitude (9.7) used to do this was
from my own observation.  As a kind of cross check, I convolved the
flux calibrated spectrum with a 'Bessel' type B-filter transfer
function and obtained a B-mag of 11.2. I think this compares reasonably
well with AAVSO data that seem bounded between 10.9 and
11.16 for about the same time period as my observation. I tried to use
a Johnson-V transfer function (Baader, like my V-filter) but
this required signal in the spectrum at blue wavelengths I didn't
reliably have  (It seems to have a wider spread than the Bessel).

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