I have not corrected for the heliocentric redshift in these data.

**************************************************
Perr must stand for photon noise error.
I assume no reddening correction either

NGC 628 = M74
heliocentric velocity
from lines in sn spectra  +631 km/s  iauc 7822 S. Smartt & P. Meikle
from Leda  in radio       +656 km/s
from Leda  in optical     +639 km/s
from Leda  mean           +656 km/s

Foreground extinction in
B from Leda/Schlegel   0.30
E(B-V)=.30/4           0.075
E(B-V)=.30/4.1         0.073  See Cardelli p. 249
Paolo E(B-V)           0.08


**********************************************

Polarization  2002 mar 07

lambda(A), q(%), u(%), P(%), theta(deg), Perr.

END:
  5081.23193  0.453999996
  5341.64111  0.579900026
  5485.604  0.628600001
  5611.15479  0.767099977
  5750.38184  0.467500001
  5863.66309  0.577099979
  5950.28418  0.676699996
  6030.15576  0.817499995
  6105.80078  0.75940001
  6173.87305  0.586399972
  6233.27979  0.693499982
  6287.16797  0.543600023
  6341.07617  0.503899992
  6395.52881  0.491299987
  6449.15283  0.612800002
  6503.29297  0.592499971
  6557.06689  0.49059999
  6610.95703  0.476999998
  6664.96582  0.507399976
  6718.9751  0.693099976
  6772.99805  0.811399996
  6826.98486  0.900600016
  6889.04004  0.852599978
  6949.07617  0.891200006
  7002.80518  0.879499972
  7050.04492  0.792999983
  7090.521  0.708899975
  7130.99512  0.629899979
  7170.97803  0.842100024
  7212.52979  0.832599998
  7252.65283  0.768000007
  7292.88818  0.672500014
  7333.35107  0.907199979
  7373.66992  0.826099992
  7413.93896  0.681299984
  7460.79199  0.880500019
  7521.021  1.09259999
  7597.1792  0.555499971
  7680.14404  0.649399996
  7724.82617  0.544799984
  7765.38623  0.523299992
  7806.13379  0.417400002
  7846.18408  0.726100028
  7893.25098  0.857800007
  7947.13721  0.983399987
  8001.00879  1.21959996
  8060.82617  1.6164
  8140.93799  2.15809989
  8246.49023  1.08720005
  8335.27441  0.497799993
  8387.28125  0.532599986
  8427.69727  0.349999994
  8460.85254  0.50940001
  8487.84961  0.475899994
  8514.91895  0.399399996
  8541.84277  0.50819999
  8568.77441  0.467799991
  8595.63867  0.417800009
  8622.59863  0.524200022
  8649.56836  0.694999993
  8676.56543  0.576699972
  8703.5459  0.563300014
  8730.45508  0.454100013
  8757.4209  0.502799988
  8784.40723  0.521799982
  8811.4541  0.369100004
  8845.21973  0.547900021
  8885.64258  0.416500002
  8925.96387  0.512099981
  8966.30469  0.593299985
  9014.45215  0.616999984