[vsnet-survey 74] Nova hunting

["W.Liller" <wliller@compuserve.com>]

Hola Amigos -

First of all, I wish Cristovao the very, very best of luck.  

For the record, he and others might be interested to know that in my
photographic searching, I use Kodak Tech Pan film which has "pixels" with
dimensions of no more than 1 or 2 microns; an 85mm f/1.4 Nikon lens; and a
filter which transmits longward of 6000A.  The Tech Pan film is strongly
sensitive to H-alpha and dies out longward of about 6800A.  Therefore, the
magnitudes that I measure are more or less close to the international R
system. 

Further advantages of using a red system: one is less affected by
moonlight; and frequently, novae are strongly reddened by the interstellar
medium.

When used with 35mm film, the 85mm lens provides a field of 15.3 x 23.5
degrees, and I center my Sagittarius field on Gamma Sgr which sits very
nearly at the "center of mass" of the coordinates of galactic nova. 
Likewise, Lambda Aql is cdentered to get the Scutum Cloud, and 26 Oph to
pick up some of the novae that seem to frequent that part of the Southern
Milky Way.

One other thought: it's quick and relatively easy to take a dozen or so CCD
frames; I do it all the time -- but not for nova searching.  The part that
is time consuming is inspecting the frames.  The process of selecting a
matching archival frame with similar limiting mag, sky brightness, and star
shapes, and then aligning the two frames for blinking or subtraction takes
time.  And finally one has to check out the cosmic ray blemishes,
asteroids, and known variable stars before spreading the word that you've
found a nova suspect.

Now, for those with interests in ornithology, we have no Japanese Blue
Flycatchers around here.  (They must be handsome birds!)  And since we
don't have many flies in this part of Chile, they would not, if imported,
find much to do.

Again, good luck Cristovao.      Bill Liller

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